2020 article
Insulin potentiates the synchronous firing of arcuate nucleus Kiss1 neurons that protects against diet-induced obesity
Qiu, J., Stincic, T. L., Bosch, M. A., Connors, A. M., Petrie, S. K., Rønnekleiv, O. K., & Kelly, M. J. (2020, September 11). [], Vol. 9.
open access via www.jneurosci.org (publisher PDF)
Source: ORCID
Added: May 22, 2024
Abstract Kisspeptin (Kiss1) neurons are essential for reproduction, but their role in the control of energy balance and other homeostatic functions remains unclear. High frequency firing of hypothalamic arcuate Kiss1 (Kiss1 ARH ) neurons releases kisspeptin into the median eminence, and neurokinin B (NKB) and dynorphin onto neighboring Kiss1 ARH neurons to generate a slow excitatory postsynaptic potential (EPSP) mediated by TRPC5 channels that entrains intermittent, synchronous firing of Kiss1 ARH neurons. High frequency optogenetic stimulation of Kiss1 ARH neurons releases glutamate to excite the anorexigenic proopiomelanocortin (POMC) neurons and inhibit the orexigenic neuropeptide Y/agouti-related peptide (AgRP) neurons via metabotropic glutamate receptors. At the molecular level, the endoplasmic reticulum calcium-sensing protein stromal interaction molecule 1 (STIM1) is critically involved in the regulation of neuronal Ca 2+ signaling and neuronal excitability through its interaction with plasma membrane calcium ( e . g ., TRPC) channels. 17β-estradiol (E2) downregulates Stim1 mRNA expression in female arcuate neurons. Therefore, we hypothesized that deletion of Stim1 in Kiss1 ARH neurons would increase neuronal excitability and their synchronous firing, which ultimately would affect energy homeostasis. Using optogenetics in combination with whole-cell recording and GCaMP6 imaging in slices, we discovered that the deletion of Stim1 in Kiss1 neurons significantly increased the amplitude of the slow EPSP and augmented synchronous [Ca 2+ ]i oscillations in Kiss1 ARH neurons. Deletion of Stim1 in Kiss1 ARH neurons amplified the actions of NKB and protected ovariectomized female mice from developing obesity and glucose intolerance with high-fat dieting. Therefore, STIM1 appears to play a critical role in regulating synchronous firing of Kiss1 ARH neurons, which ultimately affects energy homeostasis. Significance Statement Hypothalamic arcuate kisspeptin (Kiss1 ARH ) neurons are essential for stimulating the pulsatile release of gonadotropin releasing hormone (GnRH) and maintaining fertility. However, Kiss1 ARH neurons appear to be a key player in coordinating energy balance with reproduction. The regulation of calcium channels and hence calcium signaling is critically dependent on the endoplasmic reticulum calcium-sensing protein stromal interaction molecule 1 (STIM1), which interacts with the plasma membrane calcium channels. We have conditionally deleted Stim1 in Kiss1 ARH neurons and found that it significantly increased the excitability of Kiss1 ARH neurons and protected ovariectomized female mice from developing obesity and glucose intolerance with high-fat dieting.