Fraley GS (2005) Immunolesions of glucoresponsive projections to the arcuate nucleus alter glucoprivic feeding and luteinizing hormone secretion but not sex behavior in adult male rats. Neuroscience 2005 Abstracts 758.7. Society for Neuroscience, Washington, DC.
Summary: Metabolic signals such as insulin, leptin and glucose are known to alter hypothalamic function. Although insulin and leptin are known to directly alter hypothalamic areas that regulate reproduction, the mechanisms by which glucose alters reproductive function are not as clear. Catecholaminergic neurons in the A1/C1 region of the hindbrain are glucose-responsive and project to the arcuate nucleus. To determine if this pathway is involved in the regulation of sex behavior and luteinizing hormone (LH) secretion, this catecholamingergic pathway was lesioned by injecting saporin conjugated to anti-dopamine-β-hydroxalase (DSAP) or unconjugated saporin (SAP) into the arcuate nucleus of adult male rats. Rats were given glucoprivic challenges then feeding and sex behaviors were observed. As was expected, the DSAP treated rats showed a significant decreased in feeding during glucoprivation (250 mg/kg 2-deoxy-D-glucose, 2DG) compared to SAP controls (p < 0.05). Glucoprivation caused a significant reduction in sex behavior (p < 0.05) in both SAP and DSAP animals equally, compared to saline treatments in either treatment group. At the end of the experiment, animals were given a final challenge with 2DG or saline, killed by decapitation and trunk blood was assayed for plasma LH levels. In SAP animals, 2DG elicited a significant decrease in plasma LH levels (p < 0.05). However, in DSAP animals there was a significant increase (p < 0.05) in plasma LH levels compared to saline-treated rats. These data indicate that the A1/C1 efferents to the ventromedial hypothalamus are involved in the glucostatic regulation of feeding behavior and LH secretion, but not sex behavior in the adult male rat.
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