Antonio Argiolas — Page 2

PubMed2002

Reduction of drug-induced yawning and penile erection and of noncontact erections in male rats by the activation of GABAA receptors in the paraventricular nucleus: involvement of nitric oxide.

The effect of muscimol, a GABAA receptor agonist, injected into the paraventricular nucleus (PVN) of the hypothalamus on drug-induced (apomorphine, oxytocin and NMDA) yawning and penile erection, and on the increase in the concentration of NO2- and NO3- occurring in the paraventricular dialysate in these experimental conditions, was studied in male rats. Muscimol (50, 100 and 200 ng) reduced, in a dose-dependent manner, penile erection and yawning induced by apomorphine (50 ng), oxytocin (30 ng) and NMDA (50 ng) delivered into the PVN. The reduction of penile erection and yawning was parallel to a reduction of the concomitant NO2- and NO3- increase that occurs in the paraventricular dialysate in this experimental condition. In contrast, baclofen (200 ng), a GABAB receptor agonist, was ineffective. The muscimol effects on drug-induced penile erection, yawning and NO2- increase were prevented by the prior administration of bicuculline (250 ng into the paraventricular nucleus). Muscimol (200 ng) but not baclofen (200 ng), injected into the PVN, reduced both noncontact erections in male rats placed in the presence of an inaccessible receptive female, and also the NO2- increase that occurs in the paraventricular dialysate in this experimental condition. As found with drug-induced penile erection, the muscimol reduction of noncontact erections and of NO2- increase was prevented by bicuculline. The present results show that the activation of GABAA receptors in the PVN reduces yawning and penile erection induced by drugs or physiological stimuli by reducing the increase in NO activity that occurs in this hypothalamic nucleus in these experimental conditions.

Animals↗

PubMedDate not supplied

[Clinical and diagnostic approach to erectile dysfunction].

Erectile dysfunction (ED), defined as the inability to achieve and/or maintain an erection sufficiently long for a satisfactory sexual performance or intercourse, is an important and common medical problem. ED is not a life-threatening disorder, but it influences the daily routine, social interactions, well-being and quality of life of the patient. Recent epidemiological data have shown a high prevalence and incidence of ED. The Massachusetts Male Aging Study found that 52% of men between the ages of 40 and 70 years reported ED with 9.6% having mild, 22.2% moderate and 17.2% complete or severe ED. In a large Italian cross-sectional study the overall prevalence of self-reported ED was 12.8% and the frequency of ED increases with age. ED may signal serious underlying and potentially life-threatening diseases, such as diabetes, hypertension, cardiovascular disease, peripheral vascular disease and other neurological and endocrine disorders. Also well documented is the role of some drug groups, certain types of surgery, injuries and the role of risk factors related to lifestyle such as smoking, alcohol consumption and inappropriate dietary habits accompanied by an abnormal serum level of cholesterol. The current availability of effective and safe oral drugs for ED in conjunction with the tremendous media interest in the condition, have resulted in an increasing number of men seeking help for ED. As a consequence, many physicians without background knowledge and clinical experience in the diagnosis of ED are involved in making decisions concerning the evaluation of such patients. The result of this is that some males with ED may undergo little or no evaluation before treatment is initiated and, in such circumstances, the disease causing the symptom (ED) may remain untreated. Baseline diagnostic evaluation for ED can identify the underlying pathological condition or the risk factors associated with ED in 80% of patients. This article reports a sequential approach for the diagnosis of ED that may diagnose reversible causes of ED and also unmask medical conditions that manifest with ED as the first symptom.

Algorithms↗