Restoring erectile function by antioxidant therapy in diabetic rats.
OBJECTIVE
Diabetes mediates an increase in reactive oxygen species that can lead to impaired endothelial function, decreased smooth muscle in the diabetic corpus cavernosum and increased apoptosis. We hypothesized that antioxidant therapy may restore erectile function by inhibiting apoptosis in diabetic rat crura.


METHODS
A total of 40 male Sprague-Dawley rats were randomized to 5 groups of 8 each, including healthy controls, rats with diabetes, and rats with diabetes with the antioxidant tempol (4-hydroxytetramethyl-piperidine-1-oxyl) (Sigma-Aldrich), with insulin, and with tempol and insulin. Intracavernous pressure was measured for functional analysis. Smooth muscle and collagen fiber levels in the rat penile corpus cavernosum were assessed by hematoxylin and eosin, and Masson's trichrome staining. Endothelial cells were assessed by CD31 staining. Reactive oxygen species related genes were analyzed by cDNA microarray. We confirmed mRNA and protein expression profiles for these genes in diabetic and treated rats using real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry. TUNEL assay was done to analyze apoptosis status.


RESULTS
Intracavernous pressure in diabetic rats was significantly decreased vs controls. After treatment with tempol or insulin alone intracavernous pressure was significantly increased compared to that in untreated diabetic rats. In the diabetic group mean smooth muscle area significantly decreased but was restored after combined tempol and insulin. Endothelial cell area in diabetic rats significantly decreased and was not restored by any treatments. However, apoptosis was restored to normal by combined insulin and tempol. Of 84 reactive oxidative stress and antioxidant genes 32 were identified specific to diabetic rats compared to healthy controls. UCP3 expression was significantly increased in diabetic rats and normal levels were restored by all treatments.


CONCLUSIONS
To our knowledge this is the first report that tempol and insulin can restore erectile function in diabetic rats by inhibiting apoptosis.
Hirata
Hiroshi
H
Department of Urology, San Francisco Veterans Affairs Medical Center and University of California-San Francisco, California 94121, USA.
Kawamoto
Ken
K
Kikuno
Nobuyuki
N
Kawakami
Toshifumi
T
Kawakami
Kazumori
K
Saini
Sharanjot
S
Yamamura
Soichiro
S
Dahiya
Rajvir
R
D000818:Animals; D000975:Antioxidants / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D003497:Cyclic N-Oxides / Q000627:therapeutic use*; D048909:Diabetes Complications / Q000188:drug therapy* / Q000235:genetics; D003921:Diabetes Mellitus, Experimental / Q000150:complications*; D007172:Erectile Dysfunction / Q000188:drug therapy* / Q000235:genetics; D008297:Male; D046228:Microarray Analysis; D010410:Penile Erection / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D013113:Spin Labels
D000975:Antioxidants; D003497:Cyclic N-Oxides; D013113:Spin Labels; C001803:tempol