This study investigated the effects of corresponding 11.7 mg/kg body weight and 5.8 mg/kg body weight/day of the tobacco leaves aqueous extract for a period of 20 days on the functions of rats’ brain after extract administration. Nicotiana tabacumis the scientific name of the tobacco plant grown in several countries of the world. It has been used in variables ways such as smoking, snuffing, even chewing, etc. 24 young rats of both sexes were used. They were divided into 3 groups, A, B, C of 8 rats each (Female (n = 4) and male (n = 4)). Group A were given 11.7 mg of the extract per kg body weight, group B 5.8 mg of the extract per kg body weight in 0.5 ml of distilled water per day throughout the 20 experimental days while group C were given equal volume (0.5 ml) of distilled water as well. The rats were sacrificed at day 21 by cervical dislocation and the brains were excised and fixed in formol calcium for 4 days and processed using Haematoxylin and Eosin staining method and Cresyl Fast Violet (CFV) staining technique. There was a statistical significant decrease in the body weight, brain weight and relative brain weight between groups A and B compared to the control group (p < 0.05). There was enlargement of the somata in the group A administered with 11.7 mg/kg B.Wt per day of the extract while those in group B appeared more spindle compared to those cells in group C. Also, the non – homogenous appearance of myelinated neocortex of the neuropil appear clearly in the treated groups compared to control (Figure 3). Therefore, the results suggested that the consumption of the aqueous extract of N. tabacumleaves may alter the normal functions of the brain which may lead to brain dysfunction, despite its “pleasant” effects and also help in reduction in weight gain.

Key words: Nicotiana tabacum, cerebrum, frontal lobe, cytoarchitecture, neocortex.