Morphine injected into the paraventricular nucleus of the hypothalamus prevents noncontact penile erections and impairs copulation: involvement of nitric oxide.

摘要: Male rats show four to six penile erection episodes when put in the presence of an inaccessible receptive female for 80 min. These noncontact erections occur concomitantly with increase nitric oxide production paraventricular nucleus hypothalamus. This is shown by increases NO2- and NO3- concentrations dialysate obtained from these males vivo microdialysis. The concentration increased 0.75 +/- 0. 10 microm 2.89 0.39 that 4.13 58 9.5 1.2 microm. Morphine (0.5, 1 5 microg), given unilaterally into 15 min before introduction female, prevented increases, erections, dose-dependently. In contrast, kappa opioid receptor agonist U-69 593 (5 microg) was ineffective. effects morphine on NO3-, were opiate antagonist naloxone (10 injected morphine. also male during copulation, i.e. copula occurred. As found morphine, but not 593, impaired copulatory behaviour, responses Although some diffusion surrounding brain areas cannot be completely ruled out, present results suggest acts through mu receptors impair copulation. are apparently mediated a prevention occurs hypothalamus sexual activity.