Inhibition of nitric oxide synthase does not block the development of sensitization to the behavioral activating effects of amphetamine

Pretreatment with the nitric oxide (NO) synthase inhibitor, N G-nitro- L-arginine methyl ester ( L-NAME), a competitive blocker of NO production, did not interfere with the development of sensitization to the behavioral activating effects of amphetamine (AMPH). On five pre-exposure sessions, at 3-day intervals, rats were given two i.p. injections, either 50 mg/kg L-NAME 30 min prior to 1.5 mg/kg D-AMPH sulfate, saline and AMPH, L-NAME and saline, or saline only. L-NAME reduced the levels of activity recorded during the pre-exposure session but had no effect on the degree of sensitization shown to a challenge injection of 0.5 mg/kg AMPH given 10 days later. A separate study using in vivo microdialysis showed that pretreatment with L-NAME did not alter AMPH-stimulated dopamine release in nucleus accumbens.