Neuronal Colocalization of Androgen Receptor and Mating-Induced Fos: Hormone-sensitive Neurons Link Spinal Cord, Midbrain, and Forebrain Structures Regulating Copulation in Male Rats
Contact Person: David A Edwards (firstname.lastname@example.org)
In the male rat, lesions of the medial preoptic-anterior hypothalamus (MPAH), lateral tegmentum, medial nucleus of the amygdala (MNA), and bed nucleus of the stria terminalis (BNST) decrease sexual performance. Whether these effects reflect a deficit in sexual motivation or impaired copulatory competence unrelated to a change in motivation has not been decided. Each of these brain regions contains androgen receptor-immunoreactive (AR-ir) neurons, some of which express Fos after mating. After mating, Fos is also found in AR-ir neurons within Lamina X of the lumbosacral spinal cord. In our most recent work, we injected the retrograde tracer Fluorogold (FG) into either the MPAH or lateral tegmentum of male rats. Four days later males were killed after mating, and brain and (after lateral tegmental injection) spinal cord were examined for FG transport, Fos-ir, and AR-ir. After FG injection into the MPAH, Fos and AR were found together in some retrogradely labeled cells within the MNA, BNST, and lateral tegmentum. After FG injection into the lateral tegmentum, Fos and AR were found together in some retrogradely labeled cells within Lamina X, the MPAH, and BNST. Thus, spinal cord, midbrain, and forebrain are linked by androgen-sensitive neurons, some of which are activated during mating. From spinal cord to forebrain, information related to mating is apparently passed between regions through a network of AR-containing neurons. Considered together with results from recent studies of brain lesions and sexual behavior, these results suggest ways of imagining how hormone effects on sexual motivation, arousal, and performance are represented in the organization of the brain -- the subject of the essay that follows.
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|Edwards, DA.; (1998). Neuronal Colocalization of Androgen Receptor and Mating-Induced Fos: Hormone-sensitive Neurons Link Spinal Cord, Midbrain, and Forebrain Structures Regulating Copulation in Male Rats. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Invited Symposium. Available at URL http://www.mcmaster.ca/inabis98/baum/edwards0440/index.html|
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