Coolen LM, Amstalden KAZ, Allard J (2005) Involvement of lumbar spinothalamic cells in relay of sensory cues related to vaginocervical stimulation in female rats. Neuroscience 2005 Abstracts 321.13. Society for Neuroscience, Washington, DC.
Summary: The rat lumbar spinal cord contains a population of galanin containing spinothalamic (LSt) cells, which in male rats play a pivotal role in the control of ejaculation. However, the function of LSt cells in female rats is unknown. LSt cells project to the parvocellular subparafascicular thalamic nucleus (SPFp), where Fos is expressed following vaginocervical stimulation (VCS). Hence, we hypothesize that LSt cells are involved in relay of sensory cues related to VCS to the brain. To test this hypothesis, the effects of LSt lesions were investigated on two parameters that are dependent on relay of VCS-related cues: pseudopregancy and Fos expression in the SPFp. Adult female Sprague Dawley rats received infusions of substance P-conjugated (SSP-SAP) or unconjugated saporin (control) in lumbar levels 3-4. Females were investigated for: estrous cyclicity, expression of sexual behavior, and induction of pseudopregnancy by mating with vasectomized male partners including 5, 10, or 15 intromissions. For the final test, females received 10 or 15 intromissions from male partners, were perfused one hour later, and brains and spinal cords were examined for Fos expression and LSt lesions. SSP-SAP treatment resulted in severe reduction of LSt cells, but did not affect cyclicity or expression of sexual behavior, suggesting that LSt cells are not involved in regulation of these functions. In contrast, LSt lesions significantly reduced mating-induced Fos expression in the SPFp, supporting the involvement of LSt cells in relay of VCS-related sensory information to the SPFp. However, LSt lesions did not prevent mating-induced pseudopregancy and only partly blocked mating-induced neural activation in SPFp, indicating the possible involvement of alternate pathways. Alternatively, the few remaining LSt cells in lesioned females are sufficient for induction of Fos in SPFp and pseudopregnancy.
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