TNF-alpha knockout mice have increased corpora cavernosa relaxation.

Area of Science:

• Urology
• Cardiovascular Research
• Immunology

Background:

• Erectile dysfunction (ED) is an early indicator of vascular disease, linked to endothelial dysfunction and inflammation.
• Tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, impairs endothelial nitric oxide synthase (eNOS) expression, crucial for erectile function.

Purpose of the Study:

• To investigate the hypothesis that blocking TNF-alpha enhances cavernosal smooth muscle relaxation, given the critical role of nitric oxide (NO) in penile erection.
• To evaluate the impact of TNF-alpha deficiency on erectile function and associated molecular mechanisms.

Main Methods:

• Organ bath studies assessed cavernosal reactivity in wild-type and TNF-alpha knockout (TNF-alpha KO) mice.
• Western blot analyzed endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) expression.
• In vivo videomonitoring evaluated spontaneous erections; Masson trichrome and Verhoff-van Gieson staining assessed collagen and elastin.

Main Results:

• TNF-alpha KO mice showed significantly increased NO-dependent and nonadrenergic-noncholinergic relaxation in corpora cavernosa compared to controls.
• This enhanced relaxation correlated with increased eNOS and nNOS protein expression.
• Contractile responses were attenuated in TNF-alpha KO mice, which also exhibited increased collagen and elastin, and a higher number of spontaneous erections.

Conclusions:

• TNF-alpha deficiency leads to favorable alterations in corpora cavernosa, promoting penile tumescence and indicating a detrimental role of TNF-alpha in erectile function.
• The findings highlight TNF-alpha's role in mediating endothelial dysfunction in ED and suggest the potential efficacy of anti-TNF-alpha therapies.