CONCURRENT ELICITATION OF ELECTROENCEPHALOGRAPHIC DESYNCHRONIZATION AND PENILE ERECTION BY COCAINE IN THE RAT

It is well-known from animal and human studies that, as a central nerv ous stimulant, cocaine induces electroencephalographic (EEG) desynchro nization. Cocaine also purportedly increases sexual behavior as an aph rodisiac. Whether the effects of cocaine on EEG activity and penile er ection are mechanistically linked, however, remains to be fully elucid ated. We evaluated whether this link exists, based on simultaneous rec ording of EEG signals from the somatosensory cortex and intracavernous pressure (ICP, as experimental index for penile erection) in adult, m ale Sprague-Dawley rats. Under intraperitoneal chloral hydrate anesthe sia (400 mg/kg, i.p.), both intravenous (i.v.) and intracavernous (i.c .) administration of cocaine (1.5 or 3.0 mg/kg, and 75 or 150 mu g) do se-dependently induced discernible EEG desynchronization, as represent ed by a decrease in root mean square and an increase in mean power fre quency values, and an increase in ICP. However, the same administratio n of cocaine in animals under pentobarbital sodium anesthesia (50 mg/k g, i.p.) failed to significantly affect EEG activity, despite an appre ciable dose-dependent elevation in ICP. On the other hand, intracerebr oventricular administration of cocaine (7.5, 15, or 30 mu g) induced s ignificant EEG activation without affecting ICP. I.c. application of p apaverine (400 mu g) elicited a discernible increase in ICP, but faile d to evoke EEG desynchronization. These results suggest that the concu rrent EEG desynchronization and penile erection elicited by cocaine ma y take place without a mutually causative relationship. (C) 1996 Wiley -Liss, Inc.