ABSTRACT
Nicotine, the major specific alkaloid in tobacco smoke, exhibits widespread pharmacological effects and may contribute to deterioration in behaviour. The present study thus examined the effects of its chronic administration on some cognitive and mood associated behaviours. Adult rats weighing between 150 and 200g were randomly divided into 4 groups each of 5 females and 5 males. Three groups were administered graded doses of nicotine at 0.25, 2 and 4mg/kg body weight via subcutaneous injections. One group served as control and received normal saline (vehicle for nicotine). Behavioural tests were performed using the Y-maze, elevated-plus maze (EPM) and tail suspension tests (TST) at various time points. Nicotine produced no significant effect in spontaneous alternation on Y-maze, nor on six parameters scored on EPM (open arm entries, time spent in open arms, time per open arm entries, open/closed arm quotient, closed arm entries, and total arm entries), and also no significant effect on immobility time in TST. This lack of effects was observed to be independent of sex and dose administered. The study shows that nicotine does not produce long-term changes in some cognitive and mood associated behaviours, thus suggesting it could be well tolerated even following chronic administration.
ABSTRACT
Nicotine is readily consumed through cigarettes; however it is also easily consumed through the various forms of non-prescription nicotine replacement therapy. It has been shown to possess potential therapeutic value for the management of neurologic and neurodegenerative diseases in the last decade. Hence, this study examined the effects of chronic subcutaneous nicotine administration on food intake and body weight as well as on nitric oxide concentrations and total antioxidant capacity in female and male rats. Nicotine was administered to rats via subcutaneous injections at doses of 0.25, 2 and 4mg/kg body weight for 28 days. Control groups received normal saline; the vehicle for nicotine. Food intake by each group was monitored daily and body weight of the animals was measured twice weekly. At the end of drug administration, blood was obtained from each animal via cardiac puncture for biochemical determination of serum total antioxidant capacity (TAC) and nitric (NO) concentrations using standard assay kits. Results show significant loss (p<0.05) of body weight in all nicotine treated female rats. In contrast, male rats showed weight gain, though this was significantly lower (p<0.001) in nicotine treated groups compared to control. Nicotine significantly reduced (p<0.001) food consumed in both female and male rats; however dose related changes were observed in only male rats. No significant difference was observed in TAC following nicotine treatments for both female and male rats. Furthermore, only males exhibited changes in NO concentrations following nicotine treatment, as it significantly increased (p<0.01) NO concentrations in all male treated groups. In conclusion, this study has shown that modulation of body weight, food consumption and nitric oxide formation by nicotine is sexually dimorphic. Also, the study suggests that nicotine modulation of food intake and body weight and its modulation of NO may be independent of each other.
