Fig. 1.

Nicotine and MAO inhibition effects on FST in adolescent and adult rats. Adult and adolescent rats were tested in the FST 20 h following tranylcypromine (3 mg/kg, i.p.) or saline (1.5 ml/kg, i.p.) pretreatment and 10 min following saline or nicotine (0.05 or 0.2 mg/kg, s.c.) treatment. A synergistic action of tranylcypromine pretreatment and nicotine (0.2 mg/kg) treatment induced an antidepressant-like effect in adolescent. *p < 0.05 versus saline–saline; **p < 0.01 versus saline–nicotine 0.05 mg/kg, and tranylcypromine–nicotine 0.05 mg/kg; ***p < 0.001 versus saline–nicotine 0.2 mg/kg; #p < 0.05 versus saline–nicotine 0.05 mg/kg and tranylcypromine–nicotine 0.05 mg/kg; ##p < 0.01 versus saline–nicotine 0.2 mg/kg. In adults, nicotine 0.2 mg/kg i.p. induces a significant antidepressant-like effect. *p < 0.05; **p < 0.01 versus saline–saline. A significant age difference was obtained. ##p < 0.05 versus corresponding adolescent group. n = 8 per group