Radiation-induced decrease in nitric oxide synthase--containing nerves in the rat penis.
OBJECTIVE
Evaluate effect of prostatic irradiation on erectile function.


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.


CONCLUSIONS
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.
Carrier
S
S
Department of Urology, University of California San Francisco School of Medicine 94143-0628.
Hricak
H
H
Lee
S S
SS
Baba
K
K
Morgan
D M
DM
Nunes
L
L
Ross
G Y
GY
Phillips
T L
TL
Lue
T F
TF
D000594:Amino Acid Oxidoreductases / Q000032:analysis*; D000818:Animals; D018783:Impotence, Vasculogenic / Q000209:etiology*; D008297:Male; D009252:NADPH Dehydrogenase / Q000032:analysis*; D009412:Nerve Fibers / Q000201:enzymology* / Q000528:radiation effects; D019001:Nitric Oxide Synthase; D010410:Penile Erection / Q000528:radiation effects*; D010413:Penis / Q000294:innervation*; D011467:Prostate / Q000528:radiation effects*; D011833:Radiation Injuries, Experimental / Q000150:complications*; D051381:Rats; D017207:Rats, Sprague-Dawley
D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D009252:NADPH Dehydrogenase