(172) Spinal Contusion Injury-Induced Ejaculatory Dysfunction Is Reduced by Intrathecal Infusions of Gastrin Releasing Peptide in Male Rats

Introduction Spinal cord injury (SCI) has devastating effects on urogenital functions, often leading to severe ejaculatory dysfunction. The development of effective treatments for SCI-related sexual dysfunction has been limited by an incomplete understanding of how SCI affects the spinal ejaculation generator (SEG). The SEG is composed of lumbar spinothalamic (LSt) neurons, which play a pivotal role in coordinating ejaculation. These neurons act through the release of neuropeptides, particularly gastrin-releasing peptide (GRP). In intact male rats, intrathecal administration of GRP strongly facilitates ejaculatory reflexes, while GRP antagonists prevent ejaculation induced by dorsal penile nerve (DPN) stimulation. Furthermore, previous studies have shown that ejaculatory dysfunction is associated with reduced GRP mRNA and protein expression in LSt neurons. Objective This study aimed to test the hypothesis that GRP infusion can restore or facilitate ejaculatory reflexes in male rats after spinal cord injury (SCI). Specifically, the authors examined whether intrathecal GRP administration could trigger or enhance ejaculatory reflexes both in sham-operated and SCI animals. Methods In a first study, male Sprague Dawley rats received either controlled spinal contusion at 200 Kdynes (n=8) or sham treatment (n=8). Four weeks later, animals received an acute spinal transection to remove remaining supraspinal influence on the SEG and subsequent intrathecal infusions (10 μl) of saline and GRP 20-29 (0.2 nmol) while parameters of ejaculatory reflexes were recorded. In addition, DPN was stimulated at frequencies that normally trigger ejaculation in control males (30 Hz) or subthreshold (5 Hz) and reflexes were recorded. GRP, but not saline triggered ejaculatory reflexes and facilitated DPN-stimulated reflexes equally in sham and SCI groups. In a second study, the procedures were repeated, but without the acute spinal transection prior to infusions. Again, GRP, but not saline, triggered and facilitated ejaculatory reflexes with no differences between sham and SCI groups. Results These results indicate that a reduction of GRP in LST cells following SCI may contribute to ejaculatory dysfunction. Conclusions GRP may be a target for development of treatment options for sexual dysfunction following SCI. Disclosure No