Diminished neurogenic-, but not pharmacologic-induced erections in
the 2-3 month experimentally diabetic fischer-344 rat.
Rehman, Jamil, Eric Chenven, Peter Brink, Beth Grine, Benjamin
Walcott, Yan Pin Wen, Arnold Melman, and George Christ.
Department of Urology, Albert Einstein College of Medicine, Bronx,
NY and Departments of Physiology and Biophysics, and Neurobiology and
Behavior, SUNY at Stony Brook, Stony Brook, NY 11797
APStracts 3:0545H, 1996.
The rapid spread of locally restricted neural and hormonal signals
among the vast array of largely inexcitable corporal smooth muscle
cells is an absolute prerequisite to normal erectile function. And
yet the mechanism(s) responsible for this phenomenon is not well
understood. As a first step toward a more integrative understanding
of erectile physiology/dysfunction, an 8-12 week period of
experimental diabetes was induced in 2 month old male Fischer 344
rats by either intraperitoneal streptozotocin (STZ) injection (35
mg/kg; n=22), or by subtotal pancreatectomy (n=11). Fourteen age
-matched control animals received injection of vehicle only, while
nine others served as sham-operated controls. Eight STZ-diabetic
animals received insulin replacement. Erectile function was assessed
by evaluation of penile reflexes and monitoring intracavernous
pressure responses to both electrical stimulation of the cavernous
nerve, and to intracorporal papaverine or nitroglycerine injection.
Intracavernous pressure responses to neurostimulation were
significantly attenuated in both STZ-diabetic and subtotal
pancreatectomy animals when compared to age-matched control animals
(p<0.05). Penile reflexes were also significantly diminished
(p<0.05). Regression analysis revealed that diabetes-related
decreases in neurostimulated intracavernous pressure responses were
strongly correlated with diminished synaptophysin immunoreactivity in
the corpora (p<0.001; r=0.88). However, there were no
detectable diabetes-related differences in pharmacologic erections
induced by intracavernous papaverine or nitroglycerine injection.
Northern analysis revealed a marked diabetes-related increase in the
amount of Cx43 mRNA measured in frozen corporal tissue. Insulin
replacement partially restored (attenuated loss of) synaptophysin
immunoreactivity and maintained neurostimulated intracavernous
pressure responses to control levels, while having no effect on
penile reflexes. These observations may have important implications
to the understanding of erectile physiology as well as the etiology
of diabetes-related erectile dysfunction.
Received 26 June 1996; accepted in final form 4 November 1996.
APS Manuscript Number H569-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996