In rhesus monkeys with hypothalamic lesions that abolish gonadotropic hormone release by the pituitary gland, the constant infusion of exogenous gonadotropin-releasing hormone (GnRH) fails to restore sustained gonadotropin secretion. In marked contrast, intermittent administration of the synthetic decapeptide once per hour, the physiological frequency of gonadotropin release in the monkeys, reestablishes pituitary gonadotropin secretion. This phenomenon is attributable to the pattern of GnRH delivery rather than to the amounts of this hormone to which the cells of the pituitary are exposed. Moreover, the initiation of continuous GnRH administration in animals with lesions and in which gonadotropin secretion is reestablished by intermittent GnRH replacement can result in a "desensitization" or "down regulation" of the processes responsible for gonadotropin release.

Erectile dysfunction (ED) is a common problem in general medical practice affecting especially the elderly and those with cardiovascular disease and diabetes mellitus. A study was undertaken by questionnaire distributed to consecutive adult male attendees at 62 general medical practices. 1240 completed questionnaires were available for analysis. The mean age of participants was 56.4 y (range 18 ± 91 y). 488 men (39.4%) reported ED: 119 (9.6%)`occasionally', 110 (8.9%)`often', and 231 (18.6%)`all the time' (complete ED). Among 707 men aged 40±69 y 240 (33.9%) reported ED and 84 (11.9%) had complete ED. The prevalence of complete ED increased with age, rising from 2.0% in the 40 ± 49 y age group to 44.9% in the 70±79 y age group. Only 11.6% of men with ED had received treatment. Hypertension, ischaemic heart disease, peripheral vascular disease and diabetes mellitus were frequently associated with ED. 40% of diabetic men aged 60 y or older had ED all the time.

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