Smoke and ethanolic extract of nicotiana tabacum altered hippocampal histology and behaviour in mice

The effects of tobacco use on human health are well known and are documented in scientific reports. When tobacco is smoked or chewed, nicotine is absorbed by the lungs and oral cavity and quickly moved into the bloodstream where it is distributed rapidly through the circulatory system to reach the brain and peripheral nervous system. Male and female adult mice (N=32) were used for this study. The animals were randomly divided in to four (4) groups, A, B, C and D, of eight (n=8) animals each. Group A animals were treated by oral administration of 10.72 mg of the extract, B 10.72 mg of the tobacco smoke exposure for 3 min (in a controlled air chamber), C were given 0.2 ml of normal saline and D were expose to equal weight (0.02 g) of cotton wool for 3 min, for 21 experimental days. The mice were sacrificed 4 h after the last administration and the brains excised, blotted, weighed and fixed in formol calcium for histological analysis, using Haematoxylin and Eosin. There was a significant decrease in the body weight, brain weight and relative brain weight in the treatment groups. The pyramidal and granular cell layers showed changes in cell count scores; significant at p<0.05 when compared with the control. The results suggested that the consumption of Nicotiana tabacum leaves; either smoking or chewing may lead to alterations in cell count, brain weight and neurobehavioral patterns. Weight loss was also observed in the treatment and was found to be dependent on the route of administration. Key words: Nicotine tobacco, hippocampus, memory, cell death.