Activation of Anorexigenic POMC Neurons During Refeeding is Independent of Vagal and Brainstem Inputs
Year: 2012
Type: article
Abstract: Following fasting, satiety is observed within two hours after reintroducing food, accompanied by activation of anorexigenic, proopiomelanocortin (POMC)-synthesizing neurons in the arcuate nucleus, indicative of the critical role alpha-MSH has in the regulation of meal size during refeeding. To determine whether refeeding-induced activation of POMC neurons in the arcuate is dependent upon the vagus nerve and/or ascending brainstem pathways, bilateral subdiaphragmaticvagotomy or transection of the afferent brainstem input to one side of the arcuate nucleus was performed. One day after vagotomy or two weeks after brain surgery, animals were fasted and then refed for 2h. Sections containing the arcuate nucleus from vagotomized animals or animals with effective transection were immunostained for c-Fos and POMC to detect refeeding-induced activation of POMC neurons. Quantitative analyses of double-labeled preparations demonstrated that sham operated and vagotomized animals markedly increased the number of c-Fos-IR POMC neurons with refeeding. Furthermore, transection of the ascending brainstem pathway had no effect on diminishing c-Fos-IR in POMC neurons on either side of the arcuate nucleus, but did diminish activation in a separate, subpopulation of neurons in the dmpARC on the transected side. We conclude that inputs mediated via the vagus nerve and/or arising from brainstem do not have a primary role in refeeding-induced activation of POMC neurons in the arcuate nucleus, and propose that these neurons may be activated solely by direct effects of circulating hormones/metabolites during refeeding. Activation the dmpARC by refeeding indicates a previously unrecognized role for these neurons in appetite regulation in the rat.
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2285498167