Shi Z, Cassaglia PA, Pelletier NE, Brooks VL.
PMID: PMID: 30628058 | DOI: DOI:10.1113/JP277517
KEY POINTS: ICV insulin increased SNA and baroreflex control of SNA and HR dramatically more in obese male rats; in obese females, the responses were abolished. In obese males, the enhanced LSNA responses were associated with reduced tonic inhibition of LSNA by NPY in the PVN. Yet, PVN NPY injection decreased LSNA similarly in OP/OR/CON rats. Collectively, these results suggest that NPY inputs were decreased. In obese females, NPY inhibition in the PVN was maintained. Moreover, NPY neurons in the ArcN became resistant to the inhibitory effects of insulin. A HFD did not alter arcuate NPY neuronal InsR expression in males or females. Obesity-induced "selective sensitization" of the brain to the sympathoexcitatory effects of insulin and leptin may contribute to elevated basal SNA, and therefore hypertension development, in males with obesity. These data may explain in part why obesity increases SNA less in women compared to men. ABSTRACT: Obesity increases sympathetic nerve activity (SNA) in men, but not women; however, the mechanisms are unknown. We tested if intracerebroventricular insulin infusion increases SNA more in obese male than female rats and if sex differences are mediated by changes in tonic inhibition of SNA by Neuropeptide Y (NPY) in the paraventricular nucleus (PVN). When consuming a high fat diet, obesity prone (OP) rats accrued excess fat, whereas obesity resistant (OR) rats maintained adiposity as in rats eating a control (CON) diet. Insulin increased lumbar SNA (LSNA) similarly in CON/OR males and females under urethane-anesthesia. The LSNA response was magnified in OP males, but abolished in OP females. In males, blockade of PVN NPY Y1 receptors with BIBO3304 increased LSNA in CON/OR rats, but not OP rats. Yet, PVN nanoinjections of NPY decreased LSNA similarly between groups. Thus, tonic PVN NPY inhibition of LSNA may be lost in obese males, due to a decrease in NPY inputs. In contrast, in females, PVN BIBO3304 increased LSNA similarly in OP, OR and CON rats. After insulin, PVN BIBO3304 failed to increase LSNA in CON/OR females, but increased LSNA in OP females, suggesting that with obesity NPY neurons become resistant to the inhibitory effects of insulin. These sex differences were not associated with changes in arcuate NPY neuronal insulin receptor expression. Collectively, these data reveal a marked sex difference in the impact of obesity on insulin's sympathoexcitatory actions and implicate sexually dimorphic changes in NPY inhibition of SNA in the PVN as one mechanism.
Qi, Y;Lee, NJ;Ip, CK;Enriquez, R;Tasan, R;Zhang, L;Herzog, H;
PMID: 35167990 | DOI: 10.1016/j.molmet.2022.101455
Aguti-related protein (AGRP) neurons in the arcuate nucleus of the hypothalamus (ARC), which co-express neuropeptide Y (NPY), are key regulators of feeding and energy homeostasis. However, the precise role NPY has within these neurons and the specific pathways that it control are still unclear. In this article, we aimed to determine what aspects of feeding behaviour and energy homeostasis are controlled by NPY originating from AGRP neurons and which Y-receptor pathways are utilised to fulfil this function.Novel conditional Agrpcre/+;Npylox/lox knockout mice were generated and comprehensively phenotyped, both under standard chow as well as high-fat-diet conditions. Designer receptor exclusively activated by designer drugs (DREADD) technology was used to assess the altered responses on feeding and energy homeostasis control in the absence of NPY in these neurons. Rescue experiments utilising Npy1r- and Npy2r-selective NPY ligands were performed to assess which component of the energy homeostasis control is dependent by which specific Y-receptor pathway.We show that the specific deletion of Npy only in AGRP neurons leads to a paradoxical mild obese phenotype associated with reduced locomotion and energy expenditure and increased feeding and Respiratory Quotient (RQ) that remain elevated under a positive energy balance. The activation of Npy-deficient AGRP neurons via DREADD's is still able to drive feeding, yet with a delayed onset. Additionally, Clozapine-N-oxide (CNO) treatment reduces locomotion without impacting on energy expenditure. Rescue experiments re-introducing Npy1r- and Npy2r-selective NPY ligands revealed that the increased feeding and RQ are mostly driven by Npy1r, whereas energy expenditure and locomotion are controlled by Npy2r signalling.Together, these results demonstrate that NPY originating from AGRP neurons is not only critical to initiate but also for continuously driving feeding, and we for the first time identify which Y-receptor controls which pathway.
Ip CK, Zhang L, Farzi A, Qi Y, Clarke I, Reed F, Shi YC, Enriquez R, Dayas C, Graham B, Begg D, Brüning JC, Lee NJ, Hernandez-Sanchez D, Gopalasingam G, Koller J, Tasan R, Sperk G, Herzog H.
PMID: 31031093 | DOI: 10.1016/j.cmet.2019.04.001
Neuropeptide Y (NPY) exerts a powerful orexigenic effect in the hypothalamus. However, extra-hypothalamic nuclei also produce NPY, but its influence on energy homeostasis is unclear. Here we uncover a previously unknown feeding stimulatory pathway that is activated under conditions of stress in combination with calorie-dense food; NPY neurons in the central amygdala are responsible for an exacerbated response to a combined stress and high-fat-diet intervention. Central amygdala NPY neuron-specific Npy overexpression mimics the obese phenotype seen in a combined stress and high-fat-diet model, which is prevented by the selective ablation of Npy. Using food intake and energy expenditure as readouts, we demonstrate that selective activation of central amygdala NPY neurons results in increased food intake and decreased energy expenditure. Mechanistically, it is the diminished insulin signaling capacity on central amygdala NPY neurons under combined stress and high-fat-diet conditions that leads to the exaggerated development of obesity.
Qi, Y;Lee, NJ;Ip, CK;Enriquez, R;Tasan, R;Zhang, L;Herzog, H;
PMID: 37201523 | DOI: 10.1016/j.cmet.2023.04.020
Neuropeptide Y (NPY) in the arcuate nucleus (ARC) is known as one of the most critical regulators of feeding. However, how NPY promotes feeding under obese conditions is unclear. Here, we show that positive energy balance, induced by high-fat diet (HFD) or in genetically obese leptin-receptor-deficient mice, leads to elevated Npy2r expression especially on proopiomelanocortin (POMC) neurons, which also alters leptin responsiveness. Circuit mapping identified a subset of ARC agouti-related peptide (Agrp)-negative NPY neurons that control these Npy2r expressing POMC neurons. Chemogenetic activation of this newly discovered circuitry strongly drives feeding, while optogenetic inhibition reduces feeding. Consistent with that, lack of Npy2r on POMC neurons leads to reduced food intake and fat mass. This suggests that under energy surplus conditions, when ARC NPY levels generally drop, high-affinity NPY2R on POMC neurons is still able to drive food intake and enhance obesity development via NPY released predominantly from Agrp-negative NPY neurons.
Wan XQ, Zeng F, Huang XF, Yang HQ, Wang L, Shi YC, Zhang ZH, Lin S
PMID: 31880085 | DOI: 10.1111/cns.13281
AIMS:
Many patients taking risperidone for the treatment of psychiatric disorders experience substantial body weight gain. Researchers have speculated that risperidone induces obesity by modulating central signals; however, the precise central mechanisms involved remain to be fully elucidated.
METHODS:
Twenty-four C57BL/6J mice were divided into four groups: a control group; a risperidone-treated group; a lorcaserin-treated group; and a combined risperidone + lorcaserin-treated group. The mice were received the corresponding treatments for 4 weeks, and their brains were collected for in situ hybridization analysis. A subset of C57BL/6J mice was administrated with risperidone or placebo, and brains were collected 60 minutes post-treatment for determination of c-fos activity. In addition, brains of NPY-GFP mice treated with or without risperidone were collected to perform colocalization of NPY and c-fos, as well as NPY and 5-HT2c receptor using immunohistochemistry.
RESULTS:
There was significantly elevated c-fos expression in the hypothalamic arcuate nucleus (Arc) of risperidone-treated mice. More than 68% c-fos-positive neurons were NPY-expressing neurons. Furthermore, in situ hybridization revealed that Arc NPY mRNA expression was significantly increased in the risperidone-treated group compared with control group. Moreover, we identified that 95% 5-HT2c receptors were colocalized with NPY positive neurons, and increased Arc NPY mRNA expression induced by risperidone was markedly reduced by cotreatment with lorcaserin, a specific 5-HT2c receptor agonist.
CONCLUSION:
Our findings provide critical insight into the mechanisms underlying antipsychotic-induced obesity, which may assist the development of therapeutic strategies to address metabolic side effects of risperidone.
Journal of cellular physiology
Zhang, CL;Lin, YZ;Wu, Q;Yan, C;Wong, MW;Zeng, F;Zhu, P;Bowes, K;Lee, K;Zhang, X;Song, ZY;Lin, S;Shi, YC;
PMID: 35312067 | DOI: 10.1002/jcp.30719
Chronic high salt intake is one of the leading causes of hypertension. Salt activates the release of the key neurotransmitters in the hypothalamus such as vasopressin to increase blood pressure, and neuropepetide Y (NPY) has been implicated in the modulation of vasopressin levels. NPY in the hypothalamic arcuate nucleus (Arc) is best known for its control in appetite and energy homeostasis, but it is unclear whether it is also involved in the development of salt-induced hypertension. Here, we demonstrate that wild-type mice given 2% NaCl salt water for 8 weeks developed hypertension which was associated with marked downregulation of NPY expression in the hypothalamic Arc as demonstrated in NPY-GFP reporter mice as well as by in situ hybridization analysis. Furthermore, salt intake activates neurons in the hypothalamic paraventricular nucleus (PVN) where mRNA expression of brain-derived neurotrophic factor (BDNF) and vasopressin was found to be upregulated, leading to elevated serum vasopressin levels. This finding suggests an inverse correlation between the Arc NPY level and expression of vasopressin and BDNF in the PVN. Specific restoration of NPY by injecting AAV-Cre recombinase into the Arc only of the NPY-targeted mutant mice carrying a loxP-flanked STOP cassette reversed effects of salt intake on vasopressin and BDNF expression, leading to a normalization of salt-dependent blood pressure. In summary, our study uncovers an important Arc NPY-originated neuronal circuitry that could sense and respond to peripheral electrolyte signals and thereby regulate hypertension via vasopressin and BDNF in the PVN.
The Journal of neuroscience : the official journal of the Society for Neuroscience
Bellusci, L;Garcia DuBar, S;Kuah, M;Castellano, D;Muralidaran, V;Jones, E;Rozeboom, A;Gillis, RA;Vicini, S;Sahibzada, N;
PMID: 35610046 | DOI: 10.1523/JNEUROSCI.0419-22.2022
Activity in the dorsal vagal complex (DVC) is essential to gastric motility regulation. We and others have previously shown that this activity is greatly influenced by local GABAergic signaling primarily due to somatostatin-expressing GABAergic neurons (SST). To further understand the network dynamics associated with gastric motility control in the DVC, we focused on another neuron prominently distributed in this complex, neuropeptide-Y (NPY) neurons. However, the effect of these neurons on gastric motility remains unknown. Here we investigate the anatomical and functional characteristics of the NPY neurons in the nucleus tractus solitarius (NTS) and their interactions with SST neurons using transgenic mice of both sexes. We sought to determine if NPY neurons influence the activity of gastric projecting neurons, synaptically interact with SST neurons, and affect end-organ function. Our results using combined neuroanatomy and optogenetic in vitro and in vivo show that NPY neurons: are part of the gastric vagal circuit as they are trans-synaptically labeled by a viral tracer from the gastric antrum; are primarily excitatory as optogenetic activation of these neurons evoke EPSCs in gastric-antrum projecting neurons; are functionally coupled to each other and reciprocally connected to SST neurons, whose stimulation has a potent inhibitory effect on the action potential firing of the NPY neurons; and affect gastric tone and motility as reflected by their robust optogenetic response in vivo. These findings indicate that interacting NPY and SST neurons are integral to the network that controls vagal transmission to the stomach.Significance StatementThe brainstem neurons in the dorsal nuclear complex are essential for regulating vagus nerve activity that affects the stomach via tone and motility. Two distinct non-overlapping populations of predominantly excitatory neuropeptide Y (NPY) neurons and predominantly inhibitory somatostatin (SST) neurons form reciprocal connections with each other in the nucleus of the tractus solitarius (NTS) and with premotor neurons in the dorsal motor nucleus of the vagus to control gastric mechanics. Light activation and inhibition of NTS. NPY neurons increased and decreased gastric motility, respectively, while both activation and inhibition of NTS SST neurons enhanced gastric motility.
Cho, JH;Kim, K;Cho, HC;Lee, J;Kim, EK;
PMID: 36064426 | DOI: 10.1186/s13041-022-00962-3
Fibroblast growth factor 11 (FGF11) is a member of the intracellular fibroblast growth factor family. Here, we report the central role of FGF11 in the regulation of metabolism. Lentiviral injection of Fgf11 shRNA into the arcuate nucleus of the mouse hypothalamus decreased weight gain and fat mass, increased brown adipose tissue thermogenesis, and improved glucose and insulin intolerances under high-fat diet conditions. Fgf11 was expressed in the NPY-expressing neurons, and Fgf11 knockdown considerably decreased Npy expression and projection, leading to increased expression of tyrosine hydroxylase in the paraventricular nucleus. Mechanistically, FGF11 regulated Npy gene expression through the glycogen synthase kinase 3-cAMP response element-binding protein pathway. Our study defines the physiological significance of hypothalamic FGF11 in the regulation of metabolism in response to overnutrition such as high-fat diet.
AgRP signalling negatively regulates bone mass
Journal of neuroendocrinology
Enriquez, RF;Lee, NJ;Herzog, H;
PMID: 33913541 | DOI: 10.1111/jne.12978
The central nervous system is an active and major regulator of bone structure and remodelling. Specifically, signalling within the hypothalamus has been shown to be critical to ensuring that skeletal functions align with whole body metabolic supply and demand. Here, we identify agouti-related peptide (AgRP), an orexigenic peptide exclusively co-expressed with neuropeptide Y (NPY) in the arcuate nucleus (ARC) of the hypothalamus, as another critical player in the central control of bone homeostasis. Using novel mouse models, we show that AgRP deletion leads to an increase in cortical and trabecular bone mass as a result of an increase in bone thickness despite a lean phenotype, particularly in male mice. Interestingly, male AgRP deficient mice display a significant decrease in pro-opiomelanocortin (POMC) expression in the ARC, but no change in NPY or CART expression, suggesting that the increase in bone mass in AgRP-deficient mice is unlikely to be a result of altered NPY signalling. This is consistent with the observation that bone mass is unchanged in response to the specific deletion of NPY from AgRP expressing neurones. By contrast, POMC expression in the ARC is significantly increased in female AgRP deficient mice, although AgRP deletion results in altered respiratory exchange ratio regulation in response to re-feeding after a fast in both sexes. Taken together, the present study identifies AgRP as being directly involved in the regulation of bone mass and highlights the complexity intrinsic to the neuropeptide regulation of the skeleton.
Lee SJ, Sanchez-Watts G, Krieger JP, Pignalosa A, Norell PN, Cortella A, Pettersen KG, Vrdoljak D, Hayes MR, Kanoski S, Langhans W, Watts AG.
PMID: - | DOI: 10.1016/j.molmet.2018.03.008
Abstract
Objective
Glucagon-like peptide-1 (GLP-1) neurons in the hindbrain densely innervate the dorsomedial hypothalamus (DMH), a nucleus strongly implicated in body weight regulation and the sympathetic control of brown adipose tissue (BAT) thermogenesis. Therefore, DMH GLP-1 receptors (GLP-1R) are well placed to regulate energy balance by controlling sympathetic outflow and BAT function.
Methods
We investigate this possibility in adult male rats by using direct administration of GLP-1 (0.5 ug) into the DMH, knocking down DMH GLP-1R mRNA with viral-mediated RNA interference, and by examining the neurochemical phenotype of GLP-1R expressing cells in the DMH using in situ hybridization.
Results
GLP-1 administered into the DMH increased BAT thermogenesis and hepatic triglyceride (TG) mobilization. On the other hand, Glp1r knockdown (KD) in the DMH increased body weight gain and adiposity, with a concomitant reduction in energy expenditure (EE), BAT temperature, and uncoupling protein 1 (UCP1) expression. Moreover, DMH Glp1r KD induced hepatic steatosis, increased plasma TG, and elevated liver specific de-novo lipogenesis, effects that collectively contributed to insulin resistance. Interestingly, DMH Glp1r KD increased neuropeptide Y (NPY) mRNA expression in the DMH. GLP-1R mRNA in the DMH, however, was found in GABAergic not NPY neurons, consistent with a GLP-1R-dependent inhibition of NPY neurons that is mediated by local GABAergic neurons. Finally, DMH Glp1r KD attenuated the anorexigenic effects of the GLP-1R agonist exendin-4, highlighting an important role of DMH GLP-1R signaling in GLP-1-based therapies.
Conclusions
Collectively, our data show that DMH GLP-1R signaling plays a key role for BAT thermogenesis and adiposity.
International journal of molecular sciences
Torz, L;Niss, K;Lundh, S;Rekling, JC;Quintana, CD;Frazier, SED;Mercer, AJ;Cornea, A;Bertelsen, CV;Gerstenberg, MK;Hansen, AMK;Guldbrandt, M;Lykkesfeldt, J;John, LM;Villaescusa, JC;Petersen, N;
PMID: 35328681 | DOI: 10.3390/ijms23063260
Restoring the control of food intake is the key to obesity management and prevention. The arcuate nucleus (ARC) of the hypothalamus is extensively being studied as a potential anti-obesity target. Animal studies showed that neuropeptide FF (NPFF) reduces food intake by its action in neuropeptide Y (NPY) neurons of the hypothalamic ARC, but the detailed mode of action observed in human neurons is missing, due to the lack of a human-neuron-based model for pharmacology testing. Here, we validated and utilized a human-neural-stem-cell-based (hNSC) model of ARC to test the effects of NPFF on cellular pathways and neuronal activity. We found that in the human neurons, decreased cAMP levels by NPFF resulted in a reduced rate of cytoplasmic calcium oscillations, indicating an inhibition of ARC NPY neurons. This suggests the therapeutic potential of NPFFR2 in obesity. In addition, we demonstrate the use of human-stem-cell-derived neurons in pharmacological applications and the potential of this model to address functional aspects of human hypothalamic neurons.
Muñoz-Manchado AB, Bengtsson Gonzales C, Zeisel A, Munguba H, Bekkouche B, Skene NG, Lönnerberg P, Ryge J, Harris KD, Linnarsson S, Hjerling-Leffler J.
PMID: 30134177 | DOI: 10.1016/j.celrep.2018.07.053
Striatal locally projecting neurons, or interneurons, act on nearby circuits and shape functional output to the rest of the basal ganglia. We performed single-cell RNA sequencing of striatal cells enriching for interneurons. We find seven discrete interneuron types, six of which are GABAergic. In addition to providing specific markers for the populations previously described, including those expressing Sst/Npy, Th, Npy without Sst, and Chat, we identify two small populations of cells expressing Cck with or without Vip. Surprisingly, the Pvalb-expressing cells do not constitute a discrete cluster but rather are part of a larger group of cells expressing Pthlh with a spatial gradient of Pvalb expression. Using PatchSeq, we show that Pthlh cells exhibit a continuum of electrophysiological properties correlated with expression of Pvalb. Furthermore, we find significant molecular differences that correlate with differences in electrophysiological properties between Pvalb-expressing cells of the striatum and those of the cortex.
