Diabetic rats are unresponsive to the penile erection-inducing effect of intracerebroventriculary injected adrenocorticotropin.

The penile erection-inducing effect of intracerebroventricularly (i.c.v.) injected adrenocorticotropin-(1-24) [ACTH-(1-24)] (4 or 10 microg/animal) was almost completely absent in diabetic rats, either 8 days or 2 months after streptozotocin administration. The other behavioral symptoms (stretching, yawning, excessive grooming) were unevenly affected: stretching was significantly reduced either in early or in long-standing diabetes; yawning was practically absent in early diabetes and significantly reduced at the highest dose of ACTH-(1-24) in long-standing diabetes; grooming was reduced only at the highest dose of ACTH-(1-24), both in early and in long-standing diabetes. The fact that ACTH-induced penile erections (a centrally mediated effect) are practically absent even a few days after streptozotocin injection suggests that diabetes mellitus-induced penile dysfunction occurs, at least in part, through central mechanisms, and is not solely the consequence of peripheral nerve and vascular lesions.