PHARMACOLOGICAL CONSEQUENCES OF NICOTINERGIC PLUS SEROTONERGIC MANIPULATIONS

The present study investigates the effects of concurrent manipulations of nicotinic cholinergic receptors (nicotinic cholinergic agonist: ni cotine 0.03, 0.1, 0.3 mg/kg, nicotinic cholinergic antagonist: mecamyl amine 7.5 mg/kg) and serotonin neurons (p-chlorophenylalanine (PCPA), 400/kg mg on each of 3 days) on spatial navigation (water maze, WM) an d passive avoidance (PA) performance. Nicotine did not affect PA perfo rmance but at the highest dose slightly impaired WM performance. PCPA did not affect WM navigation or PA performance in saline or nicotine-t reated rats. Nicotine restored WM and PA performance defect in mecamyl amine pretreated rats. PCPA aggravated the WM defect and decreased the WM performance-improving effect of nicotine in mecamylamine pretreate d rats. PCPA did not aggravate the PA performance defect of mecamylami ne but completely blocked the PA performance-improving effect of nicot ine in mecamylamine pretreated rats. These results suggest that seroto nergic and nicotinergic cholinergic systems jointly modulate performan ce in WM and PA tests.