Transneuronal Tracing of Neural Pathways Involved in the Innervation of the Rat Vagina by Pseudorabies Virus

Choi, Jae Hoon; Cho, Kyeong Jae; Hyun, Jae Seog

Abstract

PURPOSE: Female sexual dysfunction is a new, rapidly expanding area of sexual medicine. However, there is little knowledge of the neuroanatomy and pathophysiology involved in female sexual responses, especially with respect to the vagina. The purpose of this study was to identify the neurons in the spinal cord and brain, which are involved in the innervation of the rat vagina, and regulate vaginal sexual functions. To address this issue, a retrograde transneuronal tracing technique, with a pseudorabies virus, was used.
MATERIALS AND METHODS
Eight Female Sprague-Dawley rats (250-300gm) were anesthetized with a ketamine/xylazine mixture, and the pseudorabies virus injected into the distal, posterior wall of the vaginas. At 3 (n=2), 4 (n=2) and 5 (n=2) days post-inoculation, the whole brain and spinal cord were cut in serial sections (30micrometer), and the virus-labeled neurons identified immunohistochemically.
RESULTS
In the spinal cord, the majority of virus-labeled neurons were seen in L5-S1 segments, most of which were found in the lateral gray matter, the intermediate gray matter, and the dorsal gray commissure. In addition, virus-labeled neurons were seen in the T12-L4 and S2-S4 segments, which were found in the intermediolateral cell column (IML) and the lamina II, III, VII and X. In the brain, virus-labeled neurons were found in the nuclei gigantocellularis, raphe magnus nuclei, A5 noradrenalin cells, periaqueductal gray substance and paraventricular hypothalamic nuclei.
CONCLUSIONS
The present findings provide the first morphological data on the multisynaptic circuit of the central nervous system neurons, involving the vagina, and presumably, the circuit of the vaginal sexual functions.