Cell Metabolism
Volume 19, Issue 4, 1 April 2014, Pages 682-693
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Article
Insulin Excites Anorexigenic Proopiomelanocortin Neurons via Activation of Canonical Transient Receptor Potential Channels

https://doi.org/10.1016/j.cmet.2014.03.004Get rights and content
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Highlights

  • Purified insulin excites POMC and kisspeptin neurons but inhibits NPY/AgRP neurons

  • Insulin excitation is through activation of PI3K and TRPC5 channels

  • Zn2+ in insulin formulations inhibits POMC neurons via activation of KATP channels

  • Insulin inhibits food intake and activates c-fos expression in arcuate POMC neurons

Summary

Proopiomelanocortin (POMC) neurons within the hypothalamic arcuate nucleus are vital anorexigenic neurons. Although both the leptin and insulin receptors are coupled to the activation of phosphatidylinositide 3 kinase (PI3K) in POMC neurons, they are thought to have disparate actions on POMC excitability. Using whole-cell recording and selective pharmacological tools, we have found that, similar to leptin, purified insulin depolarized POMC and adjacent kisspeptin neurons via activation of TRPC5 channels, which are highly expressed in these neurons. In contrast, insulin hyperpolarized and inhibited NPY/AgRP neurons via activation of KATP channels. Moreover, Zn2+, which is found in insulin formulations at nanomolar concentrations, inhibited POMC neurons via activation of KATP channels. Finally, as predicted, insulin given intracerebroventrically robustly inhibited food intake and activated c-fos expression in arcuate POMC neurons. Our results show that purified insulin excites POMC neurons in the arcuate nucleus, which we propose is a major mechanism by which insulin regulates energy homeostasis.

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