The Beneficial Effect of Fesoterodine, a Competitive Muscarinic Receptor Antagonist on Erectile Dysfunction in Streptozotocin-induced Diabetic Rats

Effect of Extracts of the Aerial Parts and Roots from Four Ferulago Species on Erectile Dysfunction in Rats with Streptozotocin-Induced Diabetes

Objectives

The extracts of Ferulago species are used as aphrodisiacs in Turkey and so we aimed to demonstrate in vivo and in vitro the relaxant effect of four Ferulago species' extracts on the corpus cavernosum (CC).

Materials and Methods

A total of 30 adult male Sprague Dawley rats were divided into control and diabetic groups. Diabetes was induced by a single intraperitoneal injection of 40 mg/kg streptozotocin. In vivo erectile responses were obtained by stimulation of the cavernosal nerves and repeated after intracavernosal injection of extracts in rats, and the data were expressed as intracavernosal pressure (ICP)/mean arterial pressure and total ICP. The relaxant and contractile responses of CC strips were analyzed in the presence or absence of extracts.

Results

The extracts were active in both control and diabetic rats. The extract-induced maximum relaxation responses (especially of methanol extract of the root of Ferulago bracteata) (98.30±2.6%) were decreased after incubation with L-NAME (44.8±1.8). ODQ, a soluble guanylate cyclase inhibitor, inhibited 77% of extract-induced maximum relaxation in the CC from the control rats.

Conclusion

These species can be utilized in erectile dysfunction and may be an herbal alternative to synthetic drugs.

Mirabegron, A Selective β3-Adrenoceptor Agonist Causes an Improvement in Erectile Dysfunction in Diabetic Rats

AIM

To investigate the possible beneficial effect of mirabegron [a selective β₃-adrenoceptor (AR) agonist] treatment on erectile dysfunction (ED) in streptozotocin-induced diabetic rats.

METHODS

Sprague-Dawley rats (n=20) were divided into two groups: control group and streptozotocin-induced diabetic group. In vivo erectile responses were evaluated after intracavernosal injection of mirabegron (0.4 mg/kg) in rats. The relaxation responses to electrical field stimulation (EFS, 10 Hz), sodium nitroprusside (SNP, 10 nM) and sildenafil (1 μM) of corpus cavernosum (CC) strips were examined after the incubation with mirabegron (10 μM). β₃-ARs expression and localization were determined by Western blot and immunohistochemical analyses in CC tissue.

RESULTS

In vivo erectile responses of diabetic rats [intracavernasal pressure (ICP) / mean arterial pressure, 0.17±0.01] were decreased, which were restored after administration of mirabegron (0.75±0.01, P<0.001). The basal ICP (7.1±0.6 mmHg) in diabetic rats was markedly increased after mirabegron (36.1 ±5.4 mmHg, P<0.01). Mirabegron caused markedly relaxation in diabetic rat CC after phenylephrine precontraction. The relaxation responses to EFS and sildenafil were reduced in diabetic CC, which were increased in the presence of mirabegron. Mirabegron enhanced SNP-induced relaxation response in both groups. The expression and immunoreactivity of β₃-ARs localized to CC smooth muscle were observed in control and diabetic rats.

CONCLUSIONS

This is the first study to show that intracavernosal administration of mirabegron improved erectile function and neurogenic relaxation of CC in diabetic rats. These results may be supported by further studies using combinations of mirabegron and phosphodiesterase type 5 (PDE5) inhibitors for the treatment of diabetic ED, especially in patients who do not respond to PDE5 inhibitor therapy.