Nicotine

Effect of nicotine on brain GABA levels in depressed rats. The present study was planned: to study effect of nicotine on brain GABA levels in depressed rats. to compare the effect of nicotine and imipramine on brain GABA levels. Isolation induced hyperactivity model was used to induce depression in rats. Five groups of 10 rats each were taken. Vehicle (D/W) treated rats before and after isolation were considered as baseline reading. Compared results of depression induced animal with results of animal without depression. Following drug treatments were administered: Rats from natural habitat was considered as before isolation. This group was used for normal GABA levels in rat brain. Vehicle (D/W) (1ml/kg) and imipramine (10mg/kg) were administered intraperitoneally. Nicotine was administered in a dose of 0.4mg/kg and 0.2mg kg by subcutaneous or inhalational route respectively. Brain GABA levels were estimated by fluorimetric method. In this model of depression, vehicle treated rats after isolation significantly reduced brain GABA levels as compared to vehicle before isolation.  Results of imipramine treated rats after isolation showing significantly increased in brain GABA levels as compared to vehicle treated rats after isolation. Nicotine administered by inhalational route showed increase in brain GABA levels as compared to vehicle treated rats after isolation. Nicotine administered subcutaneously increased brain GABA levels as compared to vehicle treated rats after isolation. Imipramine and nicotine (inhalation) showed comparable results with  normal GABA level i.e. before isolation rats. GABA level reduced in depressed rats. Imipramine, nicotine(inhalation) and nicotine(sc) increased  brain GABA level in depressed rats.

  To study antidepressant action of nicotine in animal model of depression. The animal model for depression, used was ‘Isolation induced hyperactivity in rats’. Doses given were vehicle 1ml/kg (intra-peritoneal), imipramine10mg/kg (intra-peritoneal), nicotine0.4mg/kg (subcutaneous), nicotine 0.2mg/kg (inhalational) Nicotine administered by subcutaneous route showed significant reduction in hyperactivity at 10 and 20 minutes when compared with that of vehicle (control) group. When it was compared with imipramine, it showed significant reduction in hyperactivity at 10 minutes. Nicotine administered by inhalation route showed significant reduction in hyperactivity at 10 min and at 30, 40 50 minutes when compared with that of control group. When compared with imipramine, it showed significant reduction in hyperactivity at 10 minutes and it showed comparable effect with that of imipramine at 30, 40, and 50 minutes. Nicotine administered by inhalation route produced significant reduction in hyperactivity at 10, 20, 30, 40,50minutes, when compared with that of nicotine administered by subcutaneous route. Combination with imipramine acute or chronic administration of nicotine by inhalational route showed significant reduction in hyperactivity, when compared with imipramine treated rats. Imipramine treated rats showed significant changes in behavior with persistent sniffing, intense biting and paw licking when it compared with vehicle treated rats. Behavioral changes in nicotine treated rats showed     significant change sat persistent sniffing, intense biting, and paw licking. Effects of nicotine with imipramine were studied on all the above parameters. Nicotine administered by subcutaneous and inhalation route showed significant antidepressantactivity. Key words: Behavioral Changes, Depression, Isolation-Induced Hyperactivity, Nicotine