Early-Life Exposure to Testosterone Programs the Hypothalamic Melanocortin System

TAp63 is a transcription factor that has been reported to be important for energy and glucose homeostasis. However, where and how TAp63 functions is unclear. Chow-fed mutant mice with TAp63 deleted from pro-opiomelanocortin (POMC) neurons showed normal body weight and glucose metabolism in both sex. However, HFD fed male and female mice that lack TAp63 from POMC neurons both showed glucose intolerance (GTT) and insulin resistance independent of body weight. Strikingly, deletion of TAp63 in POMC neurons confers “male-like” diet-induced obesity (DIO) to female mice, but does not affect DIO phenotypes in male mice. In contrast, overexpression of TAp63 in POMC neurons partially prevents DIO in male mice but not in female mice. Here we show that POMC neurons in female mice display higher neural activities and express higher POMC mRNAs compared to male counterparts, and both these enhancements in female POMC neurons are correlated to higher expression levels of TAp63. Further, we found that the deletion of TAp63 reduced POMC neuronal activity and diminished the sexual dimorphism of POMC neural activity by decreasing the responsiveness of ERα-positive POMC neurons to the ERα agonist. Finally, we found that TAp63 binds to the promoter of POMC gene and regulate POMC gene expression in POMC neurons. In addition, the expression of energy homeostasis related genes like SRC-1, ERα and TAp63 target genes Sirt1, AMPKα2, LKB1 were also decreased in mice lacking TAp63 in POMC neurons. Collectively, TAp63 in mature POMC neurons regulates glucose homeostasis and TAp63 is one key molecular driver for the sexual dimorphism in energy homeostasis. Disclosure C. Wang: None. Y. He: None. P. Xu: None. Y. Yang: None. Y. Xu: None.

μ-Opioid receptor agonist diminishes POMC gene expression and anorexia by central insulin in neonatal chicks

Sirt6 in pro-opiomelanocortin neurons controls energy metabolism by modulating leptin signaling

Glucagon-like peptide 1 (GLP-1) is a potent inhibitor of food intake. GLP-1 receptor mRNA is densely expressed in hypothalamic arcuate nucleus (ARC) and precisely overlaps the area occupied by proopiomelanocortin (POMC) neurons. Activation of POMC neurons suppresses appetite, and lack of POMC-derived peptides or inhibition of POMC neuronal firing causes obesity. Here, we identify living POMC cells in mouse ARC brain slices by targeted expression of green fluorescent protein. Using whole-cell patch-clamp recordings, we show that GLP-1 increases the spontaneous action-potential firing of POMC neurons. The stimulatory effect of GLP-1 was mimicked by GLP-1 receptor agonist exendin-4 and abolished by the receptor antagonist exendin 9-39. The effect of GLP-1 was unchanged in the presence of the synaptic blockers DAP5 (D(-)-2-amino-5-phosphonopentanoic acid)/CNQX (6-cyano-7-nitroquinoxaline-2,3-dione disodium salt) and picrotoxin. These results suggest that GLP-1 excites POMC neurons postsynaptically, via interaction with GLP-1 receptors on POMC cells. Whole-cell Ca2+ currents increased approximately 70% in the presence of GLP-1, and this effect was abolished by L-type Ca2+ channel antagonist nifedipine. Forskolin (which activates cAMP) mimicked the effects of GLP-1 and the PKA inhibitor Rp-8-Bromo-cAMPS (8-bromoadenosine-3',5'-cyclic monophosphorothioate, Rp-isomer) blocked GLP-1 action. These data indicate that GLP-1 stimulates the electrical activity of hypothalamic POMC neurons by activation of PKA and a subsequent increase in L-type Ca2+ current. This effect may contribute to the anorectic action of GLP-1, because excitation of POMC cells is well established to reduce food intake.

Serotonin 2C Receptor Activates a Distinct Population of Arcuate Pro-opiomelanocortin Neurons via TRPC Channels

Proopiomelanocortin (POMC) neurons contribute to the regulation of many physiological processes; the majority of which have been attributed to the release of peptides produced from the POMC prohormone such as α-MSH, which plays key roles in food intake and metabolism. However, it is now clear that POMC neurons also release amino acid transmitters that likely contribute to the overall function of POMC cells. Recent work indicates that constitutive deletion of these transmitters can affect metabolic phenotypes, but also that the expression of GABAergic or glutamatergic markers changes throughout development. The goal of the present study was to determine whether the release of glutamate or GABA from POMC neurons in the adult mouse contributes notably to energy balance regulation. Disturbed release of glutamate or GABA specifically from POMC neurons in adult mice was achieved using a tamoxifen-inducible Cre construct (Pomc-CreERT2) expressed in mice also carrying floxed versions of Slc17a6 (vGlut2) or Gad1 and Gad2, encoding the vesicular glutamate transporter type 2 and GAD67 and GAD65 proteins, respectively. All mice in the experiments received tamoxifen injections, but control mice lacked the tamoxifen-inducible Cre sequence. Body weight was unchanged in Gad1- and Gad2- or vGlut2-deleted female and male mice. Additionally, no significant differences in glucose tolerance or refeeding after an overnight fast were observed. These data collectively suggest that the release of GABA or glutamate from POMC neurons in adult mice does not significantly contribute to the metabolic parameters tested here. In light of prior work, the data also suggest that amino acid transmitter release from POMC cells may contribute to separate functions in the adult versus the developing mouse.

Tachykinin-induced changes in β-endorphin gene expression in the rat arcuate nucleus

The anatomical locations of proopiomelanocortin (POMC) and luteinizing hormone-releasing hormone (LHRH) neurons were examined in brain tissue from peripubertal female calves and from mature, luteal-phase cows. Biotin-avidin-peroxidase procedures were used for single- and double-labeled immunostaining. LHRH perikarya formed a loosely arranged continuum, extending posteriorly from the diagonal band of Broca, passing through the medial and lateral preoptic areas, and ending within the anterior hypothalamic area. LHRH fibers, apparently directed toward the median eminence, passed (1) posteroventrally in the periventricular area and through the arcuate nucleus, and (2) ventromedially lateral to the arcuate nucleus and medial to the supraoptic nucleus. POMC perikarya were located within and about the arcuate nucleus, some penetrating into the median eminence. Fibers from these POMC perikarya passed ventrally to terminate in the median eminence and to regions ventral to the mammillary nuclei. POMC fibers also projected dorsally and laterally from the arcuate nucleus to other hypothalamic regions as well as anteriorly along the third ventricular wall to the preoptic area, bed nucleus of stria terminalis, and stria terminalis. Less than 6% of the POMC or LHRH processes were in close anatomical apposition to LHRH perikarya and dendrites. Extensive intermingling of LHRH and POMC fibers occurred within zona externa of the median eminence.

Leptin regulates energy balance, in part, by modulating the activity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus. Leptin-deficient (ob/ob) mice differ from wild-type mice in the number of excitatory and inhibitory post-synaptic densities and currents onto NPY and POMC neurons. When leptin was delivered to ob/ob mice, the synaptic density rapidly normalized, an effect detectable within 6 hours, several hours before leptin's effect on food intake. Synaptic currents were also shifted toward wild-type values in leptin-replaced ob/ob mice. These data suggest that leptin-mediated plasticity in the ob/ob hypothalamus may underlie some of the hormone's behavioral effects. In an effort to determine whether the observed synaptic plasticity is leptin specific, we analyzed the effects of an orexigenic hormone, ghrelin, and anorexigenic hormone, estradiol. Ghrelin rearranged synapses in wild type animals to support suppressed POMC tone, whereas the estradiol triggered a robust increase in the number of excitatory, glutamate inputs of POMC neurons. The rearrangement of synapses by estradiol was leptin independent, because it was also evident in leptin- (ob/ob) and leptin receptor-deficient (db/db) mice and was paralleled with decreased food intake and increased energy expenditure in these mutant, obese animals. Such plasticity was also observed in other hypothalamic regions and extrahypothalamic sites. These observations raise the notion that synaptic plasticity is a major way through which peripheral metabolic hormones influence brain functions.

Cannabinoids play a major role in the regulation of homeostasis, mainly those governed by the hypothalamus such as reproduction and stress responses. The present study investigated the effects of cannabinoids...

The brain regulates energy homeostasis by balancing energy intake, expenditure and storage. To accomplish this, it has evolved specialized neurons that receive and integrate afferent neural and metabolic signals conveying information about the energy status of the body. These sensor-integrator-effector neurons are located in brain areas involved in homeostatic functions such as the hypothalamus, locus coeruleus, basal ganglia, limbic system and nucleus tractus solitarius. The ability to sense and regulate glucose metabolism is critical because of glucose's primacy as a metabolic substrate for neural function. Most neurons use glucose as an energy substrate, but glucosensing neurons also use glucose as a signaling molecule to regulate neuronal firing and transmitter release. There are two types of glucosensing neurons that either increase (glucose responsive, GR) or decrease (glucose sensitive, GS) their firing rate as brain glucose levels rise. Little is known about the mechanism by which GS neurons sense glucose. However, GR neurons appear to function much like the pancreatic beta-cell where glycolysis regulates the activity of an ATP-sensitive K(+) (K(ATP)) channel. The K(ATP) channel is composed of four pore-forming units (Kir6.2) and four sulfonylurea binding sites (SUR). Glucokinase (GK) appears to modulate K(ATP) channel activity via its gatekeeper role in the glycolytic production of ATP. Thus, GK may serve as a marker for GR neurons. Neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus are critical components of the energy homeostasis pathways in the brain. Both express Kir6.2 and GK, as well as leptin receptors. They also receive visceral neural and intrinsic neuropeptide and transmitter inputs. Such metabolism-related signals can summate upon K(ATP) channel activity which then alters membrane potential, neuronal firing rate and peptide/transmitter release. The outputs of these neurons are integral components of effector systems which regulate energy homeostasis. Thus, arcuate NPY and POMC neurons are probably prototypes of this important class of sensor-integrator-effector neurons.

Time and metabolic state-dependent effects of GLP-1R agonists on NPY/AgRP and POMC neuronal activity in vivo

Obesity is a global epidemic that reflects a chronic state of energy imbalance. There is critical need to better understand integrative mechanisms of obesity and related cardiovascular complications to develop more targeted therapies with mitigated adverse effects. The control of energy balance involves interactions of circulating hormones with brain regions including the arcuate nucleus of the hypothalamus. Within the arcuate nucleus, activation of proopiomelanocortin (POMC) neurons decreases food intake and increases energy expenditure, whereas stimulation of agouti-related protein neurons has converse effects. Our goal is to identify novel hormonal targets that can engage these neural circuits to restore energy balance in obesity. Angiotensin-(1-7), a cardioprotective renin-angiotensin hormone, induces weight loss in obese mice and may provide this ideal target. Angiotensin-(1-7) binds mas receptors, which based on our preliminary data are highly localized to arcuate POMC neurons. The extent to which angiotensin-(1-7) activates POMC neurons, however, is unknown. Thus, in this study, we tested the hypothesis that systemic angiotensin-(1-7) administration activates arcuate POMC neurons. To test this, male C57BL/6J mice were placed on a control diet or 60% high fat diet for 12 weeks (n=4-6 per group). Mice then received a single subcutaneous injection of either angiotensin-(1-7) [2 mg/kg] or saline, with brains harvested at 60 minutes post-injection. RNAscope in situ hybridization was used to determine the presence of c-fos mRNA, a marker of acute neuronal activity, in POMC neurons within the arcuate nucleus. We found that angiotensin-(1-7) significantly increases c-fos expression in arcuate POMC neurons in control diet mice (percentage c-fos/POMC positive neurons: 53±8 vs. 26±5 saline; p=0.033). This ability of angiotensin-(1-7) to increase c-fos expression, however, was not observed in high fat diet mice (percentage c-fos/POMC positive neurons: 30±13 vs. 25±6 saline; p=0.706). These findings suggest that angiotensin-(1-7) can activate arcuate POMC neurons under normal conditions, with changes to this circuit observed in the context of diet-induced obesity. Additional studies are needed to determine the physiological relevance of these findings, such as whether angiotensin-(1-7) activates these neurons to provide cardiometabolic protection. NIH R01 HL156986, NIH F31 HL170693, Pennsylvania Department of Health Tobacco CURE Funds This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Proopiomelanocortin gene expression is decreased in the infundibular nucleus of postmenopausal women

The sense of smell has potent effects on appetite, but the underlying neural pathways remain undefined. Here we investigated how olfactory signals reach two subsets of appetite-linked neurons in the hypothalamic arcuate nucleus: AgRP (agouti-related peptide) neurons, which stimulate appetite, and POMC (pro-opiomelanocortin) neurons, which suppress it. Using polysynaptic viral tracing, we show that AgRP and POMC neurons receive indirect input from partially overlapping but distinct areas of the olfactory cortex, indicating that they process different sets of olfactory information. We also identify different complements of neurons directly upstream of AgRP and POMC neurons that can relay olfactory cortical signals to the appetite neurons. Single cell transcriptomics shows heterogeneous expression of neuromodulator receptors among AgRP neurons, suggesting variations in the signals they receive. Integrated viral tracing and RNA localization further reveals selected brain areas where upstream neurons express cognate receptor ligands. Together, these findings outline multiple pathways by which distinct olfactory and modulatory signals are differentially routed to neurons that promote versus inhibit appetite.