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Increasing Muscle Mass Improves Cavernosal Function in Obesity
Author(s) -
MicKinac Nathan K.,
Larion Sebastian,
Mintz James D.,
Fulton David J.,
Stepp David W.
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.956.5
Subject(s) - myostatin , endocrinology , medicine , myokine , phenylephrine , lean body mass , muscle hypertrophy , leptin , obesity , vasodilation , chemistry , skeletal muscle , body weight , blood pressure
Obesity is a known risk factor for erectile dysfunction but the causal mechanisms remain poorly understood. Moreover, exercise is known to improve erectile function but the components of exercise (weight loss, aerobic capacity, or muscle mass) that contribute are unclear. The purpose of our study was to investigate whether increased muscle mass in an obese mouse model improves the erectile function of the corpus cavernosum. Lean mice heterozygous for db , the leptin receptor, were bred to mice lacking myostatin, a myokine the limits muscle growth. Four groups were studied. Lean controls, lean myostatin‐null mice, obese control and obese myostatin‐null mice. All mice were phenotyped using metabolic cages and analysis of plasma chemistry. Responses of cavernosal strips were assessed in vitro in response to phenylephrine and acetylcholine. Obese mice compared to lean were characterized by a two‐fold increase in body weight, marked adiposity, low oxygen consumption, muscle atrophy, dyslipidemia and hyperglycemia. Deletion of myostatin in lean mice markedly increased muscle mass (35%, p <0.05) but otherwise produced no phenotypic alterations. Deletion of myostatin increased muscle mass to a similar degree as lean mice and improved glucose control in obese mice with no effect on lipids, body weight or body composition. Despite similar cavernosal mass, obese mice showed increased vasoconstrictor force generation (which would restrain erection) to phenylephrine when compared to the lean controls (102%, p <0.05). Deletion of myostatin had no effect in lean mice but reduced constriction to normal values in obese mice. Vasodilation to acetylcholine tended to be reduced in obese mice but no significant differences emerged among the four groups. Overall, these results support the hypothesis that increased muscle tone can improve erectile function in obese mice. This effect, potentially due to improved glucose tolerance by the larger muscle mass, may explain to some degree how exercise improves erectile function in obesity. Support or Funding Information Work supported by NHLBI 092446 and 124773 and the Dean's Summer Research Program