Estrogen and ghrelin increase number of submucosal urethral and anal canal blood vessels in ovariectomized rats

Objectives. Urinary and fecal control deteriorates after menopause, but it is not clear whether this is age or hormone related. This study investigates whether administration of estrogen and/or the anti-aging growth hormone-releasing peptide, ghrelin, improves the adverse effects of menopause/aging on urethral and anal canal submucosal blood vessel counts in middle-age rats. Methods. Female Wistar rats (13 months old) underwent ovariectomy, followed 1 month later by intraperitoneal once-daily administration of 17-β estradiol (10 μg/kg), ghrelin (2 μg/kg), both hormones, or vehicle (n = 6 in each of four groups) for 42 days. An age-matched sham group (n = 6) received no intervention. Submucosal blood vessels were counted by light microscopy in five randomly selected fields from five nonconsecutive sections (5 μm thick) per rat of formalin-fixed and paraffin-embedded tissue blocks of the urethra and anal canal stained with hematoxylin-eosin. The results are expressed as the mean vessel number per high power field (×400). Results. Ovariectomy significantly reduced submucosal urethral and anal vascular counts below the sham values (7.41 ± 0.98 versus 5.46 ± 0.82, P = 0.003 and 7.16 ± 1.11 versus 4.92 ± 0.65, P = 0.0009, respectively). Estrogen restored the urethral counts (7.76 ± 0.88, P = 0.5) and ghrelin or combined estrogen and ghrelin administration significantly increased the counts to greater than the sham counts (8.68 ± 0.99, P = 0.04 and 9.72 ± 1.21, P = 0.004, respectively). Estrogen, ghrelin, and combined estrogen and ghrelin administration also restored the anal counts to sham levels (7.26 ± 0.97, P = 0.8; 6.56 ± 0.78, P = 0.3; and 7.76 ± 0.88, P = 0.3, respectively). Conclusions. Combined or individual replacement of estrogen and ghrelin produces a beneficial effect by reversing the ovariectomy-induced decrease in urethral and anal canal submucosal vessel numbers in middle-age rats.