Involvement of nitric oxide in cocaine-induced erections and ejaculations after paradoxical sleep deprivation

Objectives: As nitric oxide (NO) is involved in penile erectile (PE) function and also influences the sleep-wake cycle, we speculated that NO could play a role in PE and ejaculation of paradonical sleep deprivation (PSD) rats. Methods: Animals were pretreated with N-G-nitro-L-arginine methyl ester (L-NAME, ip) and L-arginine (ip, and icv) prior to saline or cocaine injection. Results: Cocaine-induced PE in 90% of PS-D rats, 60% of which ejaculated. L-NAME reduced the frequency of erection, but had no effect in the proportion of PSD-cocaine-injected rats displaying this response. L-NAME had no effect in saline groups. L-Arginine in PSD-saline rats reduced the proportion of animals displaying PE at the highest dose and reduced the frequency of PE at all doses in both saline and cocaine groups. The icv administration of L-arginine reduced PE only in PSD-cocaine rats. Results indicate that common to both drugs, whether it was NO synthase (NOS) inhibitor or NO precursor, was their capacity to strongly reduce PE frequency in cocaine-treated rats. Moreover, L-arginine (ip) played a relevant inhibitory role in the erection displayed by PSD rats. Conclusions: Our findings suggest that the stimulating effects of PSD associated or not with cocaine on erection can be modified by alterations in the NO system. (c) 2006 Elsevier Inc. All rights reserved.