Effects of silodosin, a selective alpha-1A adrenoceptor antagonist, on erectile function in a rat model of partial bladder outlet obstruction

AIM

We investigated the effects of silodosin (selective α_1A -adrenoceptor antagonist) on erectile dysfunction (ED) in a rat model of bladder outlet obstruction.

METHODS

Adult male Sprague-Dawley rats (n = 32) were divided into four groups: (i) sham-operated control; (ii) silodosin-treated (sham) control (0.1 mg/kg/day); (iii) partial bladder outlet obstruction (PBOO); and (iv) silodosin-treated with PBOO. PBOO was induced by ligation of the urethra for 6 weeks. In vivo, erectile responses were monitored by evaluating ratios of intracavernosal pressure (ICP)/mean arterial pressure (MAP). Organ-bath studies were performed on corpus cavernosum (CC) strips. Penises were assessed at baseline for protein expression of neuronal nitric oxide synthase (nNOS) and Rho-associated protein kinase (ROCK2) by Western blot. Immunohistochemistry and Masson trichrome staining were performed for analysis of nNOS protein levels and tissue alterations.

RESULTS

The ratio of ICP/MAP was significantly decreased in obstructed rats (0.26 ± 0.043, P < 0.01) compared to sham-control rats (0.64 ± 0.10), which was restored by the treatment (0.59 ± 0.14, P < 0.01) compared with obstructed rats. Relaxation responses were significantly reduced in strips from the obstructed group. Silodosin restored nitrergic relaxant responses. nNOS expression in the obstructed group decreased, which was improved by treatment. The decreased smooth muscle/collagen ratio in the bladder obstructed group was reversed by the treatment.

CONCLUSIONS

Silodosin improves erectile function in obstructed rats. Further clinical trials are needed to explore fully the potential benefits of silodosin in patients with benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) in association with ED. Neurourol. Urodynam. 36:597-603, 2017. © 2016 Wiley Periodicals, Inc.

Effect of short- and long-term sildenafil treatment on erectile dysfunction in rats with partial bladder outlet obstruction

AIM

Lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) are frequent problems in older men worldwide. We evaluated the effect of short- and long-term sildenafil treatment on erectile function in rats with surgically induced partial bladder outlet obstruction (PBOO).

METHODS

A total of 60 male Sprague-Dawley rats were randomized in five groups: (1) control (sham-operated); (2) PBOO for 3 weeks; (3) PBOO for 6 weeks; (4) sildenafil (1.5 mg/rat/day) treated PBOO for 3 weeks; and (5) sildenafil treated PBOO for 6 weeks. We assessed erectile function by measuring intracavernous pressures (ICP), mean arterial pressure (MAP) and total ICP after cavernous nerve stimulation. Corpus cavernous smooth muscle (CCSM) strips were isolated and evaluated for relaxation responses using organ-bath preparation. Neuronal nitric oxide synthase (nNOS) expression was determined immunohistochemically.

RESULTS

Experimental PBOO at 3 and 6 weeks showed decreased erectile response based on ICP/MAP ratio, total ICP and decreased expression of nNOS, which returned to normal after prolonged daily treatment with sildenafil. CCSM strips from PBOO rats displayed reduced relaxation responses to both electrical field stimulation (EFS) and acetylcholine (ACh) as well as nNOS enzyme intensity when compared to untreated PBOO group, which was reversed by treatment with sildenafil for 6 weeks.

CONCLUSIONS

Daily sildenafil treatment prevents development of ED in PBOO rats in a time dependent manner. Further studies are needed to explore the effectiveness of sildenafil in patients with BPH/LUTS in association with ED.