title: [Effects of subchronic benzo[a]pyrene exposure on hippocampal cholinergic system in rats].
abstract: OBJECTIVE
  To observe the effects of subchronic benzo[a]pyrene (B[a]P) exposure on the neurobehavior and hippocampal acetylcholine (Ach) level, acetylcholinesterase (AChE) activity, and mRNA and protein expression of nicotinic acetylcholine receptor α7 subtype (nAChR α7) in rats, and to investigate the neurotoxic mechanism of B[a]P.
  
  
  METHODS
  Sixty healthy male SD rats were randomly divided into blank control group, solvent control group, and B [a]P exposure groups. Each rat in the exposure groups was intraperitoneally injected with B[a]P at 1.0, 2.5, or 6.25 mg/kg once every other day for 90 days. The learning and memory ability of the rats was examined by Morris water maze test and step-down test; the hippocampal Ach level was measured by alkaline hydroxylamine method; the AChE activity was measured by DNTB method; the mRNA and protein expression levels of hippocampal nAChR α7 were measured by quantitative PCR and Western blot.
  
  
  RESULTS
  The 2.5 and 6.25 mg/kg B[a]P exposure groups showed significantly lower learning and memory abilities than the blank control group and solvent control group (P < 0.05); also, the two groups had significantly lower hippocampal Ach levels than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The 6.25 mg/kg B[a]P exposure group showed significantly lower hippocampal AChE activity than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). There were no significant differences in the mRNA and protein expression levels of nAChR α7 among all groups (P > 0.05). The hippocampal Ach level was negatively correlated with the mean escape latency period and total distance travelled (r = -0.567, P < 0.01; r = -0.503, P < 0.01) but positively correlated with the time in platform quadrant (r = 0.800, P < 0.01).
  
  
  CONCLUSIONS
  Subchronic B[a]P exposure may impair the learning and memory ability in rats, which is related to the downregulation of hippocampal Ach level.
authors: Department of Toxicology, School Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors: Liang
authors: L
authors: Guo
authors: Xin
authors: X
authors: Wang
authors: Jin-yan
authors: JY
authors: Li
authors: Hua-shan
authors: HS
authors: Liang
authors: Yong
authors: Y
authors: Jiang
authors: Shan-shan
authors: SS
authors: Chang
authors: Yu-jing
authors: YJ
authors: Song
authors: Li
authors: L
authors: Cheng
authors: Jin-ping
authors: JP
authors: Zheng
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008568:Memory / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011950:Receptors, Cholinergic / Q000378:metabolism; D059550:Toxicity Tests, Subchronic; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000378:metabolism
chemical_list: D011950:Receptors, Cholinergic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D001564:Benzo(a)pyrene; D000110:Acetylcholinesterase; D000109:Acetylcholine