title: [Effects of low-dose chlorpyrifos exposure on dopaminergic neurons in the midbrain substantia nigra and neural behavioral development in neonatal rats].
abstract: OBJECTIVE
  To explore the effects of low-dose chlorpyrifos (CPF) exposure on dopaminergic (DA) neurons in the midbrain substantia nigra and neural behavioral development in neonatal rats.
  
  
  METHODS
  Postnatal 11 day old Sprague-Dawley rats were randomly assigned into CPF, menstruum dimethysulfoxide (DMSO) and normal saline (NS) groups. The rats in the CPF group were injected with low-dose CPF (5 mg/kg?d) on postnatal days 11-14. The two control groups were injected with DMSO or NS respectively. The rats were sacrificed on postnatal days 15, 20, 30, and 60. Body weight gain, outward appearance of brain tissue, the coefficient of brain and the water content of brain tissue were measured. Tyrosine hydroxylase (TH) expression in DA neurons in the midbrain substantial nigra was examined by immunohistochemical straining. Immune electron microscopy was used to examine the subcellular structure of DA neurons. Open field test, grip strength test, slope test and Morris water maze test were used to examine the neurobehavioral changes.
  
  
  RESULTS
  The outward appearance of brain tissue was normal in the three groups. There were no significant differences in the absolute value of body weight gain, the coefficient of brain and the water content of brain tissue among the three groups. CPF exposure decreased the level of TH immunoreactivity (P<0.05) in the substantia nigra of CPF group since postnatal day 30 compared with the DMSO and NS groups. The subcellular structures of some DA neurons in the CPF group were impaired. Decreased motor activity and learning and memory impairments were observed in the CPF group compared with those in the DMSO and NS groups (P<0.05) since postnatal day 30.
  
  
  CONCLUSIONS
  CPF exposure during the neonatal period can cause long-term motor activity and learning and memory impairments in accompany with DA neurons damage in the midbrain substantia nigra.
authors.affiliation: Department of Neurology, Second Xiangya Hospital, Central South University, Changsha 410011, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Zhao
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Hu
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.forename: Li
authors.initials: L
authors.lastname: Deng
authors.forename: Fen
authors.initials: F
authors.lastname: Gu
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Dai
authors.forename: Min
authors.initials: M
authors.lastname: Huang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects*; D004390:Chlorpyrifos / Q000633:toxicity*; D059290:Dopaminergic Neurons / Q000187:drug effects*; D005260:Female; D007306:Insecticides / Q000633:toxicity*; D007858:Learning / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000187:drug effects*
chemical_list: D007306:Insecticides; D004390:Chlorpyrifos