Peripheral nerves mediating penile erection in the rat

Area of Science:

• Neuroscience
• Urology
• Reproductive Biology

Background:

• Erectile function is a complex process involving both central and peripheral neural pathways.
• The roles of the hypogastric nerve (HgN) and the viscerocutaneous branch of the pelvic nerve (Vc) in mediating erectile responses are not fully elucidated.
• Noncontact erection (NCE) in rats is a model for psychogenic erection in humans, with the HgN previously implicated.

Purpose of the Study:

• To investigate the specific roles of the HgN and Vc in mediating different types of erectile responses in male rats.
• To determine if transection of these nerves affects copulation, reflexive erection, and noncontact erection (NCE).
• To assess the potential for neural plasticity or recovery after nerve transection.

Main Methods:

• Bilateral transection of the HgN and/or Vc in male rats.
• Testing for copulatory behavior, reflexive erections, and NCE (response to remote cues from estrous females).
• Functional assessment of nerve integrity through observation of bladder and seminal plug deposition.

Main Results:

• Transection of the Vc alone caused moderate to severe deficits in erectile function across all tested contexts.
• Transection of the HgN alone had no significant pro- or anti-erectile effect.
• Combined transection of both nerves did not result in a greater impairment than Vc transection alone; erectile deficits appeared transient, with some recovery observed.

Conclusions:

• The HgN may not play a significant pro-erectile role in rats, even in NCE, which is analogous to human psychogenic erection.
• The Vc is the primary nerve mediating pro-erectile function in NCE, reflexive erection, and copulation in rats.
• Erectile function in rats, particularly NCE, may not be entirely dependent on the Vc, suggesting potential redundancy or alternative pathways.