Radiology, Vol 195, 95-99, Copyright © 1995 by Radiological Society of North America
Radiation-induced decrease in nitric oxide synthase--containing nerves in the rat penis
S Carrier, H Hricak, SS Lee, K Baba, DM Morgan, L Nunes, GY Ross, TL Phillips and TF Lue
Department of Urology, University of California San Francisco School of Medicine 94143-0628.
PURPOSE: Evaluate effect of prostatic irradiation on erectile function.
MATERIALS AND METHODS: Forty-seven male adult rats were divided into three
groups according to a single radiation dose to the prostate: control (no
irradiation) (n = 15), 1,000 cGy (n = 15), and 2,000 cGy (n = 17). Five
months after irradiation, rats underwent evaluation of penile vascularity
and of erectile response to central and peripheral stimulation. After the
study a proximal-shaft penile segment was obtained for staining. RESULTS:
Histologic evaluation demonstrated that, with increasing radiation, the
number of nitric oxide synthase- containing nerve fibers per penile segment
decreased significantly: control, 225.6 +/- 9.7; 1,000 cGy, 156.3 +/- 12.0;
2,000 cGy, 85.8 +/- 10.1 (standard error of the mean). Maximal
intracavernous pressure induced with electrostimulation decreased
significantly with increasing radiation dose. After injection of
papaverine, maximal intracavernous pressure was significantly decreased in
only the 2,000-cGy group. CONCLUSION: A dose of 2,000 cGy over the
prostatic bed induces erectile dysfunction by causing defects in the
vascular supply of the erectile tissue and in the nerves and smooth muscle.
