Effect of sidestream cigarette smoking on memory of male Long-Evans rats

Abstract

Background: Memory impairment is an important presentation of many diseases. Sidestream cigarette smoke (SCS), a form of passive smoke, causes neural complications such as impaired memory. The aim of this study was to assess the effect of sidestream cigarette smoke on memory of male Long-Evans rats.

Methods: This experimental study was conducted in the Physiology Department of Bangabandhu Sheikh Mujib Medical University. Twelve male Long-Evans rats, having 150 to 200 grams body weight were collected from central animal house of this University. Rats were divided into fresh air group (control) and experimental group (exposer to SCS for 30 minutes twice daily) for 30 consecutive days. For memory evaluation, Morris water maze (MWM) test was performed. Working memory was measured as escape latency in training and four trial phases. Reference memory (escape latency in acquisition phase and target crossings in probe trial. For estimation of hippocampal antioxidant enzymes, catalase and glutathione peroxidase levels were measured by ELISA. Data were expressed as mean (standard error of mean) and t test was done to compare the two groups. P <0.05 was considered as statistically significant.

Results: Two to five times higher escape latency (working memory) was observed in experimental rats compared to those of control rats (P<0.001). Moreover, significantly lower (3.8 versus 7.8) target crossings (P<0.001) were found in experimental rats compared to the control rats. In addition, hippocampal catalase (6.2 versus 17.6 U/mg protein) and glutathione peroxidase (1.9 versus 5.6 U/mg protein) levels were found significantly lower (P<0.001) in experimental rats when compared to control rats.

Conclusion: The sidestream cigarette smoke caused memory impairment and decrement of hippocampal antioxidant enzymes level in male Long-Evans rats.