侧脑室注射苯并(a)芘对大鼠学习记忆功能和单胺类神经递质的影响

Effects of benro(a)pyrene on learning and memory and the content of monoamine neurotransmitters in rats

目的探讨苯并(a)芘对大鼠学习记忆功能和单胺类神经递质的影响。方法健康雄性SD大鼠40只,经麻醉后于立体定向仪上固定鼠头,于前卤十字缝交点后1.3～1.5mm、左或右1.5mm处定位插管,一周后称重,按体重将动物随机分为4组:橄榄油组(溶剂对照组)、B(a)P2.5mmol/L组、B(a)P5mmol/L组、B(a)P10mmol/L组。每组8只,麻醉后定位,应用微量注射器通过插管分别向高、中、低浓度组缓慢注入B(a)P溶液10μl,溶剂对照组橄榄油10μl,缝皮。每周给药一次,连续给药3周。跳台试验和水迷宫实验评价染毒大鼠学习记忆功能;高效液相色谱法分别测定海马中5-羟色胺(5-HT)、多巴胺(DA)、5-羟吲哚乙酸(5-HIAA)含量。结果跳台试验结果显示,随染毒剂量的增加,大鼠步下平台的潜伏期缩短,中、高剂量组次数增多,有明显的剂量-反应关系。Morris水迷宫试验结果显示,随染毒剂量的增加,各组大鼠平均潜伏期延长,中、高剂量组在原平台停留时间缩短,与对照组比较差异有显著性(P<0.05,P<0.01),各剂量组间平均潜伏期比较差异无显著性,而在原平台象限停留时间高剂量组与低剂量组间有差异(P<0.05)。大鼠海马5-HT含量明显增高,各剂量组与对照组比较,P<0.01,呈剂量-反应关系,而DA、5-HIAA含量各组未见明显变化。结论苯并(a)芘降低大鼠学习记忆功能可能与海马5-HT含量升高有关。

Objective To investigate the effects of benzo（a）pyrene on learning and memory of rats and the content of monoamine neurotransmitters of rat hippocampus.Methods Forty male adult SD rats were intubated for one week,and all intubated rats were randomly divided into 4 groups：olive oil control,B（a）P 2.5,5 and 10mmol/L.All groups were administered by intracerebroventricular injection once of week for 3 weeks,and the volumes of injection were 10μl.Step-down and Morris water maze tests were applied to assess the capacity of learning and memory in rats.Neuromonoamine transmitters were determined by high performance liquid chromatography（HPLC）.Results Increasing with the dose of B（a）P,the step-down latency was shortern,and times of stepping down increased,there were significant differences in three B（a）P-treated groups in comparison with control.The results indicated that B（a）P could induce impairment of passive avoidance learning and short-term memory.In Morris water maze tests,the mean escape latencies were prolonged and the lengthes of staying in the original quadrant were shorterned in treated groups increasing with dose B（a）P,which suggested that B（a）P would affect the spatial learning and memory functions.In comparition with control,there was an increase trend of 5-HT in treated groups.However,no differences of DA and 5-HIAA content were found between treated groups and control group.Conclusion The functions of learning and memory impaired by B（a）P in rats,associated with the increase of 5-HT content of hippocampus.