In vivo evaluation of serotonergic agents and alpha-adrenergic blockers on premature ejaculation by inhibiting the seminal vesicle pressure response to electrical nerve stimulation.

OBJECTIVE

To evaluate the effect of drugs on premature ejaculation using a rat animal model in which the seminal vesicle was electrically stimulated via its lesser splanchnic nerve and changes in the pressure response monitored.

MATERIALS AND METHODS

Male Wistar rats (aged 12-14 weeks) were injected intravenously with prazosin and serotonergic agents (serotonin, clomipramine, fluoxetine, imipramine and indatraline) at various concentrations 10 min before electrical nerve stimulation (ENS) of the lesser splanchnic nerve; the initial increase in seminal vesicle pressure in response to ENS was then compared.

RESULTS

The pressure response to ENS was reduced in the presence of prazosin or serotonergic agents. The mean (SEM) maximum inhibition values were 84.1 (8.9%) by fluoxetine at 0.1 mg/kg, 67.9 (8.7)% by prazosin at 0.1 mg/kg, 60.9 (11.0)% by serotonin at 3 mg/kg, 54.9 (4.6)% by clomipramine at 3 mg/kg, 30.0 (11.0)% by imipramine at 0.1 mg/kg, and 20.9 (4.3)% by indatraline at 0.1 mg/kg. From the concentration-response curve, the potency of prazosin was lower than that of fluoxetine, but was higher than that of serotonin or clomipramine.

CONCLUSIONS

Like serotonin, fluoxetine and clomipramine can reduce the pressure response of the seminal vesicle to ENS. Among these inhibitory agents, including prazosin, fluoxetine was the most effective and may be valuable for the clinical treatment of ejaculatory dysfunction in man.