title: Recovery of erectile function in aging hypertensive and normotensive rats using exercise and caloric restriction.
abstract: BACKGROUND
  Using aging spontaneously hypertensive rats (SHR), we established that antihypertensive drugs can improve erections and penile vascular structure, and lower arterial pressure. Using kidney cross-transplantations, our findings revealed that the benefit of this treatment resulted from drug-induced changes specific to the penile circulation, and not to the kidney-mediated lowering of pressure.
  
  
  OBJECTIVE
  The objective of the present study was to determine whether increased exercise and/or caloric restriction (CR) can reverse the decline in sexual responses in aging hypertensive and normotensive rats.
  
  
  METHODS
  From 30 to 40 weeks, food intake was restricted (10-40%), and SHR, Wistar, and Sprague-Dawley rats ran on treadmills (30 minutes/day, 5 days/week). Exercise was withdrawn at 40 weeks, and CR was stopped at 50 weeks. Using a separate group of older Wistars (56 weeks) and Sprague-Dawley rats (67 weeks), the effects of 10% CR or exercise plus 10-40% CR on erectile function were determined.
  
  
  METHODS
  Apomorphine-induced erectile responses and body weight were monitored weekly.
  
  
  RESULTS
  An age-related decline in erections was seen from 15 to 29 weeks of age in all strains. This decline paralleled increases in body weight, particularly in the normotensive strains. Exercise and CR induced a 10% weight loss in normotensive rats and improved erections in all animals. In SHR, increased erections occurred without decreasing body weight. Body weight and erectile responses were maintained by CR alone after exercise was withdrawn, but erectile function rapidly declined soon after CR was stopped and paralleled increases in body weight. In aged Wistar and Sprague-Dawley rats treated with exercise and CR, erectile function was also significantly improved.
  
  
  CONCLUSIONS
  Similar to previous studies, erectile function progressively decreased with age in both hypertensive and normotensive rats. Erectile responses were found to be substantially improved by an intervention involving exercise and CR, but not necessarily involving weight loss.
authors.affiliation: Department of Pharmacology & Toxicology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Johanna L
authors.initials: JL
authors.lastname: Hannan
authors.forename: Jeremy P W
authors.initials: JP
authors.lastname: Heaton
authors.forename: Michael A
authors.initials: MA
authors.lastname: Adams
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D031204:Caloric Restriction; D004195:Disease Models, Animal; D008297:Male; D010410:Penile Erection; D010805:Physical Conditioning, Animal; D051381:Rats; D011918:Rats, Inbred SHR / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar