The weeks shown in color represent the start and end points of chemical exposure for each study.

Study Results Study Details References

Results for Chlorpyrifos

Increased 5HT receptor binding markers in females at post-natal day 15; decreased 5HT receptor binding markers over all brain regions studied at post-natal day 20 in both sexes

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Aldridge JE, Seidler FJ, Meyer A, Thillai I, Slotkin TA. 2003. Serotonergic systems targeted by developmental exposure to chlorpyrifos: Effects during different critical periods. Environ Health Perspect 111(14):1736-1743.
Study Results Study Details References

Results for Chlorpyrifos

Increased 5HT receptor binding markers in females at post-natal day 15; decreased 5HT receptor binding markers over all the brain regions studied at post-natal day 20 in both sexes

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 1.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Aldridge JE, Seidler FJ, Meyer A, Thillai I, Slotkin TA. 2003. Serotonergic systems targeted by developmental exposure to chlorpyrifos: Effects during different critical periods. Environ Health Perspect 111(14):1736-1743.
Study Results Study Details References

Results for Chlorpyrifos

Increased 5HT receptor type 1A binding in the cerebral cortex of males; decreased 5HTT binding in the striatum of females

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 60 days of age

Reference [PubMed Link]
Aldridge JE, Seidler FJ, Slotkin TA. 2004. Developmental exposure to chlorpyrifos elicits sex-selective alterations of serotonergic synaptic function in adulthood: Critical periods and regional selectivity for effects on the serotonin transporter, receptor subtypes, and cell signaling. Environ Health Perspect 112(2):148-155.
Study Results Study Details References

Results for Chlorpyrifos

Decreased weight of brain regions; increased binding characteristics of 5HT1A, 5HT2 and 5HTT in the midbrain of males on post-natal day 45; increased binding characteristics of 5HTT in the midbrain of females on post-natal day 45; altered adenylyl cyclase response to 5HT in the midbrain, striatum and cerebral cortex on post-natal day 45; increased binding characteristics of 5HT1A, 5HT2 and 5HTT and increased adenylyl cyclase activity in the cerebral cortex on post-natal day 60

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 45 and 60

Reference [PubMed Link]
Aldridge JE, Meyer A, Seidler FJ, Slotkin TA. 2005. Developmental exposure to terbutaline and chlorpyrifos: pharmacotherapy of preterm labor and an environmental neurotoxicant converge on serotonergic systems in neonatal rat brain regions. Toxicology & Applied Pharmacology 203(2):132-144.
Study Results Study Details References

Results for Chlorpyrifos

Increased binding characteristics of 5HT1A, 5HT2 and 5HTT with a predominant effect on 5HT1A in the hippocampus of males; increased inhibition of adenylyl cyclase response to 5HT in the hippocampus

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 45

Reference [PubMed Link]
Aldridge JE, Meyer A, Seidler FJ, Slotkin TA. 2005. Developmental exposure to terbutaline and chlorpyrifos: pharmacotherapy of preterm labor and an environmental neurotoxicant converge on serotonergic systems in neonatal rat brain regions. Toxicology & Applied Pharmacology 203(2):132-144.
Study Results Study Details References

Results for Chlorpyrifos

Increased binding characteristics of 5HT1A, 5HT2 and 5HTT and increased inhibition of adenylyl cyclase response to 5HT in the brainstem

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 45

Reference [PubMed Link]
Aldridge JE, Meyer A, Seidler FJ, Slotkin TA. 2005. Developmental exposure to terbutaline and chlorpyrifos: pharmacotherapy of preterm labor and an environmental neurotoxicant converge on serotonergic systems in neonatal rat brain regions. Toxicology & Applied Pharmacology 203(2):132-144.
Study Results Study Details References

Results for Chlorpyrifos

Decreased protein concentration and cell size in the forebrain on post-natal day 15; decreased DNA concentration, DNA content and increased cell size in the forebrain on post-natal day 20

Subjects: Unspecified strain rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Other doses tested: 25 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Campbell CG, Seidler FJ, Slotkin TA. 1997. Chlorpyrifos interferes with cell development in rat brain regions. Brain Res Bull 43(2):179-189.
Study Results Study Details References

Results for Chlorpyrifos

Increased DNA concentration, DNA content and protein concentration and decreased cell size in the cerebellum on post-natal day 15; decreased DNA concentration and increased cell size in the cerebellum on post-natal day 20; increased protein concentration and cell size in the brainstem on post-natal day 20

Subjects: Unspecified strain rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Other doses tested: 25 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Campbell CG, Seidler FJ, Slotkin TA. 1997. Chlorpyrifos interferes with cell development in rat brain regions. Brain Res Bull 43(2):179-189.
Study Results Study Details References

Results for Chlorpyrifos

Decreased hemicholinium-3 binding characteristics in the forebrain with a marked effect on post-natal day 15; increased turnover of norepinephrine in the forebrain on post-natal day 15; increased turnover of dopamine in the forebrain on post-natal day 15

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Dam K, Garcia SJ, Seidler FJ, Slotkin TA. 1999. Neonatal chlorpyrifos exposure alters synaptic development and neuronal activity in cholinergic and catecholaminergic pathways. Developmental Brain Research 116(1):9-20.
Study Results Study Details References

Results for Chlorpyrifos

Increased grooming; increased rearing in males at 30 days of age

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 4 through 30 days of age

Reference [PubMed Link]
Dam K, Seidler FJ, Slotkin TA. 2000. Chlorpyrifos exposure during a critical neonatal period elicits gender-selective deficits in the development of coordination skills and locomotor activity. Developmental Brain Research 121(2):179-187.
Study Results Study Details References

Results for Chlorpyrifos

Decreased choline acetyltransferase and hemicholinium-3 binding characteristics; increased turnover of norepinephrine in the brainstem and cerebellum with a marked effect on post-natal day 15; increased turnover of dopamine in the brainstem with a marked effect on post-natal day 15; increased content and turnover of norepinephrine in the cerebellum on post-natal day 15; decreased turnover of norepinephrine in the cerebellum on post-natal day 20

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Dam K, Garcia SJ, Seidler FJ, Slotkin TA. 1999. Neonatal chlorpyrifos exposure alters synaptic development and neuronal activity in cholinergic and catecholaminergic pathways. Developmental Brain Research 116(1):9-20.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of c-Fos mRNA in the forebrain on post-natal day 15

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Dam K, Seidler FJ, Slotkin TA. 2003. Transcriptional biomarkers distinguish between vulnerable periods for developmental neurotoxicity of chlorpyrifos: Implications for toxicogenomics. Brain Res Bull 59(4):261-265.
Study Results Study Details References

Results for Chlorpyrifos

Increased levels of p53 mRNA in the cerebellum on post-natal day 15

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Dam K, Seidler FJ, Slotkin TA. 2003. Transcriptional biomarkers distinguish between vulnerable periods for developmental neurotoxicity of chlorpyrifos: Implications for toxicogenomics. Brain Res Bull 59(4):261-265.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of glial fibrillary acidic protein (GFAP) across all the regions under study in both sexes at post-natal day 15; increased levels of glial fibrillary acidic protein (GFAP) across all the regions under study in males at post-natal day 30; increased levels of glial fibrillary acidic protein (GFAP) in the striatum of females

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal days 15, 20 and 30

Reference [PubMed Link]
Garcia SJ, Seidler FJ, Qiao D, Slotkin TA. 2002. Chlorpyrifos targets developing glia: effects on glial fibrillary acidic protein. Brain Res Dev Brain Res 133(2):151-161.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of glial fibrillary acidic protein (GFAP) across all the regions under study in both sexes at post-natal day 15; increased levels of glial fibrillary acidic protein (GFAP) across all the regions under study in males at post-natal day 30

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal days 15, 20 and 30

Reference [PubMed Link]
Garcia SJ, Seidler FJ, Qiao D, Slotkin TA. 2002. Chlorpyrifos targets developing glia: effects on glial fibrillary acidic protein. Brain Res Dev Brain Res 133(2):151-161.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of myelin and neuronal markers over all brain regions studied in males at post-natal day 30

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal 15, 20 and 30

Reference [PubMed Link]
Garcia SJ, Seidler FJ, Slotkin TA. 2003. Developmental neurotoxicity elicited by prenatal or postnatal chlorpyrifos exposure: Effects on neurospecific proteins indicate changing vulnerabilities. Environ Health Perspect 111(3):297-304.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of myelin and neuronal markers over all brain regions studied in males at post-natal day 30

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal 15, 20 and 30

Reference [PubMed Link]
Garcia SJ, Seidler FJ, Slotkin TA. 2003. Developmental neurotoxicity elicited by prenatal or postnatal chlorpyrifos exposure: Effects on neurospecific proteins indicate changing vulnerabilities. Environ Health Perspect 111(3):297-304.
Study Results Study Details References

Results for Chlorpyrifos

Decreased concentration and content of RNA in the forebrain on post-natal day 15

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Johnson DE, Seidler FJ, Slotkin TA. 1998. Early biochemical detection of delayed neurotoxicity resulting from developmental exposure to chlorpyrifos. Brain Res Bull 45(2):143-147.
Study Results Study Details References

Results for Chlorpyrifos

Decreased concentration of RNA in the brainstem; decreased content of RNA in the brainstem on post-natal day 15;

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Johnson DE, Seidler FJ, Slotkin TA. 1998. Early biochemical detection of delayed neurotoxicity resulting from developmental exposure to chlorpyrifos. Brain Res Bull 45(2):143-147.
Study Results Study Details References

Results for Chlorpyrifos

Decreased rate of habituation during Figure-8 locomotor activity test; lack of reference memory impairment with scopolamine challenge in females

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 4 through 17 weeks of age

Reference [PubMed Link]
Levin ED, Addy N, Nakajima A, Christopher NC, Seidler FJ, Slotkin TA. 2001. Persistent behavioral consequences of neonatal chlorpyrifos exposure in rats. Developmental Brain Research 130(1):83-89.
Study Results Study Details References

Results for Chlorpyrifos

Increased βadrenergic receptor binding in the hippocampus

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 45

Reference [PubMed Link]
Meyer A, Seidler FJ, Aldridge JE, Slotkin TA. 2005. Developmental exposure to terbutaline alters cell signaling in mature rat brain regions and augments the effects of subsequent neonatal exposure to the organophosphorus insecticide chlorpyrifos. Toxicology & Applied Pharmacology 203(2):154-166.
Study Results Study Details References

Results for Chlorpyrifos

Decreased β adrenergic receptor binding in the brainstem while increased in the cerebellum; decreased adenylyl cyclase activity across all measurements in the brainstem

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 45

Reference [PubMed Link]
Meyer A, Seidler FJ, Aldridge JE, Slotkin TA. 2005. Developmental exposure to terbutaline alters cell signaling in mature rat brain regions and augments the effects of subsequent neonatal exposure to the organophosphorus insecticide chlorpyrifos. Toxicology & Applied Pharmacology 203(2):154-166.
Study Results Study Details References

Results for Chlorpyrifos

Decreased beta-adrenergic receptor binding over all brain regions studied in females; decreased basal and isoproterenol-induced activity of adenylyl cyclase over all brain regions studied in males; decreased basal and forskolin-induced adenylyl cyclase activity over all brain regions studied in females

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 60 days of age

Reference [PubMed Link]
Meyer A, Seidler FJ, Aldridge JE, Tate CA, Cousins MM, Slotkin TA. 2004. Critical periods for chlorpyrifos-induced developmental neurotoxicity: alterations in adenylyl cyclase signaling in adult rat brain regions after gestational or neonatal exposure. Environ Health Perspect 112(3):295-301.
Study Results Study Details References

Results for Chlorpyrifos

Decreased beta-adrenergic receptor binding over all brain regions studied in females; decreased basal and isoproterenol-induced activity of adenylyl cyclase over all brain regions studied in males; decreased basal and forskolin-induced activity of adenylyl cyclase over all brain regions studed in females

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 60 days of age

Reference [PubMed Link]
Meyer A, Seidler FJ, Aldridge JE, Tate CA, Cousins MM, Slotkin TA. 2004. Critical periods for chlorpyrifos-induced developmental neurotoxicity: alterations in adenylyl cyclase signaling in adult rat brain regions after gestational or neonatal exposure. Environ Health Perspect 112(3):295-301.
Study Results Study Details References

Results for Chlorpyrifos

Decreased beta-adrenergic receptor binding in females over all brain regions studied; decreased basal and isoproterenol-induced activity of adenylyl cyclase in males over all brain regions studied; decreased basal and forskolin-induced adenylyl cyclase activity in females over all brain regions studied

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 60 days of age

Reference [PubMed Link]
Meyer A, Seidler FJ, Aldridge JE, Tate CA, Cousins MM, Slotkin TA. 2004. Critical periods for chlorpyrifos-induced developmental neurotoxicity: alterations in adenylyl cyclase signaling in adult rat brain regions after gestational or neonatal exposure. Environ Health Perspect 112(3):295-301.
Study Results Study Details References

Results for Chlorpyrifos

Increased levels of adenylyl cyclase in males after forskolin and Mn2+ stimulation and decreased levels of adenylyl cyclase activity across all the measurements in females in the midbrain on post-natal day 45; decreased levels of adenylyl cyclase in the striatum on post-natal day 45; decreased activity of adenylyl cyclase across all the measurements in the cerebral cortex of females on post-natal day 60

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 45 and 60

Reference [PubMed Link]
Meyer A, Seidler FJ, Aldridge JE, Slotkin TA. 2005. Developmental exposure to terbutaline alters cell signaling in mature rat brain regions and augments the effects of subsequent neonatal exposure to the organophosphorus insecticide chlorpyrifos. Toxicology & Applied Pharmacology 203(2):154-166.
Study Results Study Details References

Results for Chlorpyrifos

Increased cell packing density (as measured by DNA concentration) in the forebrain at post-natal day 15; increased cell packing density and decreased membrane surface area (as measured by the ratio of membrane protein over total protein) in the striatum at post-natal day 60; decreased cell size (as measured by the ration between total protein and DNA) across all the regions studied in males at post-natal day 60; decreased m2AChR binding in the forebrain and midbrain at post-natal day 15; increased m2AChR binding across all regions studied at post-natal day 60

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 60

Reference [PubMed Link]
Rhodes MC, Seidler FJ, Qiao D, Tate CA, Cousins MM, Slotkin TA. 2004. Does pharmacotherapy for preterm labor sensitize the developing brain to environmental neurotoxicants? Cellular and synaptic effects of sequential exposure to terbutaline and chlorpyrifos in neonatal rats. Toxicology & Applied Pharmacology 195(2):203-217.
Study Results Study Details References

Results for Chlorpyrifos

Increased cell packing density in the hippocampus at post-natal day 60; decreased cell size (as measured by the ration between total protein and DNA) across all the regions studied in males at post-natal day 60; increased m2AChR binding across all regions studied at post-natal day 60

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 60

Reference [PubMed Link]
Rhodes MC, Seidler FJ, Qiao D, Tate CA, Cousins MM, Slotkin TA. 2004. Does pharmacotherapy for preterm labor sensitize the developing brain to environmental neurotoxicants? Cellular and synaptic effects of sequential exposure to terbutaline and chlorpyrifos in neonatal rats. Toxicology & Applied Pharmacology 195(2):203-217.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of cholinergic markers in the midbrain of females; decreased levels of cholinergic markers in the striatum at post-natal day 30

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal days 30 and 60

Reference [PubMed Link]
Slotkin TA, Cousins MM, Tate CA, Seidler FJ. 2001. Persistent cholinergic presynaptic deficits after neonatal chlorpyrifos exposure. Brain Res 902(2):229-243.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of cholinergic markers in the hippocampus across post-natal day 30 and 60 and across sexes

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal days 30 and 60

Reference [PubMed Link]
Slotkin TA, Cousins MM, Tate CA, Seidler FJ. 2001. Persistent cholinergic presynaptic deficits after neonatal chlorpyrifos exposure. Brain Res 902(2):229-243.
Study Results Study Details References

Results for Chlorpyrifos

Decreased levels of ChAT in the brainstem of males at post-natal day 30; decreased HC3 binding in the brainstem across post-natal day 30 and 60

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal days 30 and 60

Reference [PubMed Link]
Slotkin TA, Cousins MM, Tate CA, Seidler FJ. 2001. Persistent cholinergic presynaptic deficits after neonatal chlorpyrifos exposure. Brain Res 902(2):229-243.
Study Results Study Details References

Results for Chlorpyrifos

Increased cell packing density in the brainstem at post-natal day 60; decreased cell size (as measured by the ration between total protein and DNA) across all the regions studied in males at post-natal day 60; decreased m2AChR binding in the brainstem at post-natal day 15; increased m2AChR binding across all regions studied at post-natal day 60

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 60

Reference [PubMed Link]
Rhodes MC, Seidler FJ, Qiao D, Tate CA, Cousins MM, Slotkin TA. 2004. Does pharmacotherapy for preterm labor sensitize the developing brain to environmental neurotoxicants? Cellular and synaptic effects of sequential exposure to terbutaline and chlorpyrifos in neonatal rats. Toxicology & Applied Pharmacology 195(2):203-217.
Study Results Study Details References

Results for Chlorpyrifos

Increased number of neurons in the septal nucleus at post-natal day 20; increased neuron diameter in the striatum at post-natal day 15; decreased number of neurons in the striatum, decreased number of glial cells over all brain regions studied and decreased glia/neuron ratio in the septal nucleus at post-natal day 15 and 20; varied changes in the proportion of small non-pyramidal and larger pyramidal cells in the somatosensory cortex at post-natal day 20.

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Roy TS, Seidler FJ, Slotkin TA. 2004. Morphologic effects of subtoxic neonatal chlorpyrifos exposure in developing rat brain: regionally selective alterations in neurons and glia. Brain Res Dev Brain Res 148(2):197-206.
Study Results Study Details References

Results for Chlorpyrifos

Decreased layer thickness of the CA1 and CA3 regions of the hippocampus and increased layer thickness of the dentate gyrus on post-natal day 20; decreased number of glia across the CA1, CA3 and DG (dentate gyrus) in the hippocampus; decreased number of neurons across the CA1, CA3 and DG (dentate gyrus) in the hippocampus on post-natal day 15 and across CA1 and CA3 on post-natal day 20; increased area of perikarya across hippocampal regions and cell types

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Roy TS, Sharma V, Seidler FJ, Slotkin TA. 2005. Quantitative morphological assessment reveals neuronal and glial deficits in hippocampus after a brief subtoxic exposure to chlorpyrifos in neonatal rats. Developmental Brain Research 155(1):71-80.
Study Results Study Details References

Results for Chlorpyrifos

Decreased norepinephrine turn-over; decreased dopamine δ-turn-over in midbrain and striatum on post-natal day 60 after nicotine challenge; increased dopamine δ-turn-over in male cerebral cortex after nicotine challenge; decreased norepinephrine turn-over in the striatum on post-natal day 60 after nicotine challenge

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 30 and 60

Reference [PubMed Link]
Slotkin TA, Tate CA, Cousins MM, Seidler FJ. 2002. Functional alterations in CNS catecholamine systems in adolescence and adulthood after neonatal chlorpyrifos exposure. Developmental Brain Research 133(2):163-173.
Study Results Study Details References

Results for Chlorpyrifos

Increased levels of norepinephrine in the cerebellum of females on post-natal day 60; decreased norepinephrine turn-over in the cerebellum of males;

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 30 and 60

Reference [PubMed Link]
Slotkin TA, Tate CA, Cousins MM, Seidler FJ. 2002. Functional alterations in CNS catecholamine systems in adolescence and adulthood after neonatal chlorpyrifos exposure. Developmental Brain Research 133(2):163-173.
Study Results Study Details References

Results for Chlorpyrifos

Decreased α7nAChR receptor binding in the forebrain across post-natal day 15 and 20; decreased α4β2nAChR receptor binding in the forebrain across post-natal day 15 and 20

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Slotkin TA, Southard MC, Adam SJ, Cousins MM, Seidler FJ. 2004. 7 Nicotinic acetylcholine receptors targeted by cholinergic developmental neurotoxicants: Nicotine and chlorpyrifos. Brain Res Bull 64(3):227-235.
Study Results Study Details References

Results for Chlorpyrifos

Decreased α7nAChR receptor binding in the cerebellum across post-natal day 15 and 20; decreased α4β2nAChR receptor binding in the cerebellum and in the brainstem across post-natal day 15 and 20

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15 and 20

Reference [PubMed Link]
Slotkin TA, Southard MC, Adam SJ, Cousins MM, Seidler FJ. 2004. 7 Nicotinic acetylcholine receptors targeted by cholinergic developmental neurotoxicants: Nicotine and chlorpyrifos. Brain Res Bull 64(3):227-235.
Study Results Study Details References

Results for Chlorpyrifos

Increased levels of thiobarbituric acid-reactive species in the forebrain of males

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15

Reference [PubMed Link]
Slotkin TA, Oliver CA, Seidler FJ. 2005. Critical periods for the role of oxidative stress in the developmental neurotoxicity of chlorpyrifos and terbutaline, alone or in combination. Developmental Brain Research 157(2):172-180.
Study Results Study Details References

Results for Chlorpyrifos

Increased levels of thiobarbituric acid-reactive species in males in the cerebellum

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected subcutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: post-natal day 15

Reference [PubMed Link]
Slotkin TA, Oliver CA, Seidler FJ. 2005. Critical periods for the role of oxidative stress in the developmental neurotoxicity of chlorpyrifos and terbutaline, alone or in combination. Developmental Brain Research 157(2):172-180.
Study Results Study Details References

Results for Chlorpyrifos

Decreased 5HT content and increased 5HT turnover in brainstem at 21 days of age but not at 30 days

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: through adulthood

Reference [PubMed Link]
Slotkin TA, Seidler FJ. 2007. Developmental exposure to terbutaline and chlorpyrifos, separately or sequentially, elicits presynaptic serotonergic hyperactivity in juvenile and adolescent rats. Brain Res Bull 73(4-6):301-309.
Study Results Study Details References

Results for Chlorpyrifos

Decreased forebrain basal adenylyl cyclase activity in the presence of G-proteins at 20 days of age; decreased forskolin -Mn2 adenylyl cyclase activity at 15 days of age; decreased forebrain M1 receptor binding at 15 days of age; decreased forebrain M2 receptor binding at 15 and 20 days of age; increased forebrain isoproterenol-stimulated adenylyl cyclase activity in the presence of carbachol at 15 days of age

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected sub-cutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 15 and 20 days of age

Reference [PubMed Link]
Song X, Seidler FJ, Saleh JL, Zhang J, Padilla S, Slotkin TA. 1997. Cellular mechanisms for developmental toxicity of chlorpyrifos: Targeting the adenylyl cyclase signaling cascade. Toxicology & Applied Pharmacology 145(1):158-174.
Study Results Study Details References

Results for Chlorpyrifos

Decreased brainstem cholinesterase activity; increased cerebellum adenylyl cyclase activity (-GTP) at 15 days of age; decreased cerebellum adenylyl cyclase activity in the presence and absence of G-proteins at 20 days of age; increased forskolin-Mn2+ stimulated activity in the cerebellum at 15 days of age; decreased isoproterenol-stimulated activity at 20 days of age

Subjects: Sprague-Dawley rats

Chemical: Chlorpyrifos

Low doses tested: 5.0 mg/kg bw/d

Route of administration: dissolved in DMSO and injected sub-cutaneously

Exposure duration: post-natal day 11 – post-natal day 14 (comparable to human prenatal development from approximately day 1 of week 31 to day 1 of week 35)

Age of measurement: 15 and 20 days of age

Reference [PubMed Link]
Song X, Seidler FJ, Saleh JL, Zhang J, Padilla S, Slotkin TA. 1997. Cellular mechanisms for developmental toxicity of chlorpyrifos: Targeting the adenylyl cyclase signaling cascade. Toxicology & Applied Pharmacology 145(1):158-174.