The Influence Of Cigarette Smoke Exposure On Learning And Memory In Rats

To explore the influence of cigarette smoke exposure on learning and memory function of rats and the role of brain-derived neurotrophicfactor (BDNF). Male SD rats were randomly divided into normal control group and cigarette smoke group (CS group).The CS group rats were exposed to cigarette smoke in ventilated smoking chambers and divided into low-dose group,medium-dose group and high-dose group according to exposure time.The learning and memory function of rats was tested by Morris water maze. Outcome measures included:animal weight, peripheral blood cell parameters, the content of the serum homocysteine(Hcy), H-E staining and immunohistochemistry staining to observe the pathological changes of hippocampus and the expression of BDNF.Comparing with NC group’s, The results of rat in cigarette smoke exposure showed:(1) The increase of body weight was inhibited obviously;(2) WBC increased firstly and then decreased, while RBC showed the opposite tendency;(3) After30d-exposure, the escape latency of CS group was significantly decreased was significantly increased comparing to normal control group(P<0.05); After90d-exposure, the escape latency of medium-dose group was shorter than normal control group.(P<0.05);After180d-exposure, the escape latency of CS group was significantly increased comparing to normal control group(P<0.05).(4) H-E staining showed that rat brain hippocampus no significant change after30d,90d,180d cigarette smoke exposure.(5) After30d to90d-exposure,surum Hcy levels increase in low-dose group and decrease in medium-dose and high-dose group; After180d-exposure, surum Hcy levels in exposured was significantly increased comparing to normal control group.(6) After30d-exposure, the expression of BDNF was significantly increased comparing to normal control group(P<0.05); After90d-exposure, the expression of BDNF of CS group was significantly increased.(P<0.05);After180d-exposure, the expression of BDNF was significantly increased comparing to normal control group(P<0.05).The function of learning and memory of rats was increased after short-term cigarettesmoke exposure but decreased gradually with increased exposure time. This effect was closely related to the expression of BDNF in hippocampus.