title: Exercise training improves the defective centrally mediated erectile responses in rats with type I diabetes.
abstract: BACKGROUND
  Erectile dysfunction is a serious and common complication of diabetes mellitus. Apart from the peripheral actions, central mechanisms are also responsible for the penile erection.
  
  
  OBJECTIVE
  The goal of the present study was to determine the impact of exercise training (ExT) on the centrally mediated erectile dysfunction in streptozotocin (STZ)-induced type I diabetic (T1D) rats.
  
  
  METHODS
  Male Sprague-Dawley rats were injected with STZ to induce diabetes mellitus. Three weeks after STZ or vehicle injections, rats were assigned to either ExT (treadmill running for 3-4 weeks) or sedentary groups to produce four experimental groups: control + sedentary, T1D + sedentary, control + ExT, and T1D + ExT.
  
  
  METHODS
  After 3-4 weeks ExT, central N-methyl-D-aspartic acid (NMDA) or sodium nitroprusside (SNP)-induced penile erectile responses were measured. Neuronal nitric oxide synthase (nNOS) expression in the paraventricular nucleus (PVN) of the hypothalamus was measured by using histochemistry, real time polymerase chain reaction (PCR) and Western blot approaches.
  
  
  RESULTS
  In rats with T1D, ExT significantly improved the blunted erectile response, and the intracavernous pressure changes to NMDA (50 ng) microinjection within the PVN (T1D + ExT: 3.0 ± 0.6 penile erection/rat; T1D + sedentary: 0.5 ± 0.3 penile erection/rat within 20 minutes, P < 0.05). ExT improved erectile dysfunction induced by central administration of exogenous nitric oxide (NO) donor, SNP in T1D rats. Other behavior responses including yawning and stretching, induced by central NMDA and SNP microinjection were also significantly increased in T1D rats after ExT. Furthermore, we found that ExT restored the nNOS mRNA and protein expression in the PVN in T1D rats.
  
  
  CONCLUSIONS
  These results suggest that ExT may have beneficial effects on the erectile dysfunction in diabetes through improvement of NO bioavailability within the PVN. Thus, ExT may be used as therapeutic modality to up-regulate nNOS within the PVN and improve the central component of the erectile dysfunction in diabetes mellitus.
authors: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA.
authors: Hong
authors: H
authors: Zheng
authors: William G
authors: WG
authors: Mayhan
authors: Kaushik P
authors: KP
authors: Patel
mesh_terms: D000818:Animals; D015153:Blotting, Western; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000503:physiopathology; D007172:Erectile Dysfunction / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D052248:Nitric Oxide Synthase Type I / Q000032:analysis; D009599:Nitroprusside / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000201:enzymology; D010410:Penile Erection / Q000187:drug effects / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D013739:Testosterone / Q000097:blood
chemical_list: D009599:Nitroprusside; D013739:Testosterone; D016202:N-Methylaspartate; D052248:Nitric Oxide Synthase Type I