Growth hormone/STAT5 signaling in proopiomelanocortin neurons regulates glucoprivic hyperphagia

https://doi.org/10.1016/j.mce.2019.110574Get rights and content

Highlights

  • Approximately 60% of POMC neurons of the arcuate nucleus are directly responsive to GH.

  • Ablation of GHR or STAT5 in POMC cells does not affect energy and glucose homeostasis.

  • Glucoprivic hyperphagia is attenuated in POMC-specific GHR knockout mice.

  • Absence of STAT5 in POMC cells prevents glucoprivic hyperphagia only in male mice.

Abstract

Several hypothalamic neuronal populations are directly responsive to growth hormone (GH) and central GH action regulates glucose and energy homeostasis. However, the potential role of GH signaling in proopiomelanocortin (POMC) neurons has not been studied yet. Thus, we investigated whether POMC neurons are responsive to GH and if ablation of GH receptor (GHR) or STAT5 in POMC cells leads to metabolic imbalances. Approximately 60% of POMC neurons of the arcuate nucleus exhibited STAT5 phosphorylation after intracerebroventricular GH injection. Ablation of GHR or STAT5 in POMC cells did not affect energy or glucose homeostasis. However, glucoprivic hyperphagia was blunted in male and female GHR knockout mice, and in male POMC-specific STAT5 knockout mice. Additionally, the absence of GHR in POMC neurons decreased glycemia during prolonged food restriction in male mice. Thus, GH action in POMC neurons regulates glucoprivic hyperphagia as well as blood glucose levels during prolonged food restriction.

Introduction

The arcuate nucleus of the hypothalamus (ARH) contains well-known neuronal populations that regulate energy and glucose homeostasis, including orexigenic neurons that co-express the agouti-related protein (AgRP) and the neuropeptide Y (NPY), as well as anorexigenic neurons that express the proopiomelanocortin (POMC) prohormone (Andermann and Lowell, 2017; Ramos-Lobo and Donato, 2017). POMC is cleaved in bioactive peptides, including α-melanocyte-stimulating hormone (α-MSH), which activates melanocortin receptors 3 and 4 to induce satiety (Coll and Loraine Tung, 2009; Rossi et al., 1998). A key feature of ARH neurons is the capacity to detect different signals that regulate their activity and neuropeptide expression. In this sense, hormones that decrease food intake, such as leptin, insulin or cholecystokinin activate POMC neurons and inhibit AgRP/NPY neurons. On the other hand, humoral factors that induce food intake, i.e. ghrelin, increase the activity of AgRP/NPY neurons (Andermann and Lowell, 2017; Ramos-Lobo and Donato, 2017; Williams et al., 2010). Therefore, POMC and AgRP/NPY ARH neurons regulate food intake and other metabolic aspects through inputs generated by multiple hormonal receptors expressed by these cells.

Growth hormone (GH) is produced by somatotrophs of the pituitary gland. Its classical functions are related to cell proliferation, metabolism, and tissue and somatic growth (Dehkhoda et al., 2018). Interestingly, several pieces of evidence indicate that GH can affect neural circuits that regulate energy metabolism (Kim et al., 2015). For example, GH overexpression in the central nervous system causes hyperphagia and obesity in mice (Bohlooly et al., 2005). Additionally, GH receptor (GHR) deficient mice exhibit blunted feeding response to ghrelin (Egecioglu et al., 2006). Transgenic carp overexpressing GH presents increased food intake associated with higher Agrp hypothalamic expression (Zhong et al., 2013). A recent study also showed that intracerebroventricular (icv) injection of GH increases feeding in mice, inducing upregulation of Agrp and Npy expression in the hypothalamus (Furigo et al., 2019b). Furthermore, GH induces depolarization in a subset of ARH AgRP neurons (Furigo et al., 2019b). Therefore, GH has central orexigenic effects via activation of AgRP/NPY neurons. Accordingly, 95% of ARH AgRP/NPY neurons express the Ghr mRNA (Kamegai et al., 1996) or exhibit phosphorylation of the signal transducer and activator of transcription 5 (pSTAT5) after an acute GH injection (Furigo et al., 2019b).

Despite the evidence that GH acts directly in AgRP/NPY neurons to regulate food intake and energy expenditure, no information exists about the potential role of GH signaling in POMC neurons. Of note, POMC and AgRP/NPY neurons express many hormone receptors concomitantly (Andermann and Lowell, 2017; Ramos-Lobo and Donato, 2017), which makes it plausible to hypothesize that GH may also modulate the metabolism via ARH POMC neurons. Therefore, the objectives of the present study were to determine 1) whether POMC neurons are directly responsive to GH, 2) if ablation of GHR specifically in POMC cells leads to changes in energy and glucose homeostasis, and 3) the consequences of Stat5a/b ablation in POMC neurons since the JAK2/STAT5 pathway is considered the major intracellular signaling pathway induced by the GH/GHR interaction (Dehkhoda et al., 2018; Furigo et al., 2016; Teglund et al., 1998).

Section snippets

Mice

Genetic deletions of Ghr or Stat5a/b genes in POMC cells were obtained through the breeding of POMC-Cre mouse (Stock No: 005965; The Jackson Laboratory) with animals carrying loxP-flanked Ghr (Furigo et al., 2019b; List et al., 2013) or Stat5a/b alleles (Buonfiglio et al., 2015; Furigo et al., 2018). The Cre expression pattern during development in the POMC-Cre mice has been characterized in previous studies (Padilla et al., 2010, 2012). All POMC GHR KO and POMC STAT5 KO mice carried the

POMC neurons are responsive to GH

To determine whether POMC neurons express functional GHR and therefore can exhibit pSTAT5 after an acute GH injection (Furigo et al., 2017), double-labeled pSTAT5/α-MSH immunofluorescent reactions were performed in mice receiving an icv GH injection. GH injection increased pSTAT5 in both POMC and non-POMC cells in the ARH of control mice (Fig. 1A–C). Of note, 64% of ARH POMC neurons were responsive to GH (Fig. 1A–C). As expected, an acute GH injection also induced pSTAT5 in the ARH of POMC GHR

Discussion

POMC and AgRP/NPY neurons are known to regulate energy balance and glucose homeostasis through the input of various hormones (Andermann and Lowell, 2017; Ramos-Lobo and Donato, 2017). Recently, GH has been shown to be capable of modulating the activity of AgRP/NPY neurons in order to promote neuroendocrine responses to weight loss (Furigo et al., 2019b). However, GH responsive cells in the ARH are not restricted to AgRP/NPY neurons (Furigo et al., 2019b). In the present study, we showed that

Conclusions

Our findings indicate that GH is a hormone that acts on POMC neurons to regulate metabolism, in particular the glucoprivic hyperphagia and blood glucose levels during prolonged food restriction. In addition, STAT5 appears to be a downstream signaling pathway recruited by GH to control 2DG-induced food intake in male mice. Thus, our findings help to explain the mechanisms behind some of the metabolic effects induced by GH. Moreover, we provide additional evidence that the brain should be

Conflicts of interest

The authors declare no conflicts of interest.

Acknowledgements

We thank Ana M.P. Campos for the technical assistance. This work was supported by the São Paulo Research Foundation (FAPESP-Brazil) as grants (17/02983-2 to J.D. and 17/21840-8 to R.F.) and scholarships (16/09679-4 to I.F.; 16/20897-3 to F.W.; 17/25281-3 to P.Q. and 17/04006-4 to G.C.), by Pfizer (2017 Global ASPIRE Young Investigator Research Awards to J.D.) and by NIH (NIA): R01AG059779 to J.J.K. and E.O.L.

References (50)

  • J.J. Kopchick et al.

    Evaluation of growth hormone (GH) action in mice: discovery of GH receptor antagonists and clinical indications

    Mol. Cell. Endocrinol.

    (2014)
  • R.L. Li et al.

    Profound hypoglycemia in starved, ghrelin-deficient mice is caused by decreased gluconeogenesis and reversed by lactate or fatty acids

    J. Biol. Chem.

    (2012)
  • L.B. Lima et al.

    Leptin receptor-positive and leptin receptor-negative proopiomelanocortin neurons innervate an identical set of brain structures

    Brain Res.

    (2016)
  • S. Luquet et al.

    NPY/AgRP neurons are not essential for feeding responses to glucoprivation

    Peptides

    (2007)
  • Y. Ozawa et al.

    Repeated glucoprivation delayed hyperphagic responses while activating neuropeptide Y neurons in rats

    Peptides

    (2011)
  • C.M. Patterson et al.

    Leptin action via LepR-b Tyr1077 contributes to the control of energy balance and female reproduction

    Mol Metab

    (2012)
  • J. Rossi et al.

    Melanocortin-4 receptors expressed by cholinergic neurons regulate energy balance and glucose homeostasis

    Cell Metabol.

    (2011)
  • M.A. Silveira et al.

    STAT5 signaling in kisspeptin cells regulates the timing of puberty

    Mol. Cell. Endocrinol.

    (2017)
  • S. Teglund et al.

    Stat5a and Stat5b proteins have essential and nonessential, or redundant, roles in cytokine responses

    Cell

    (1998)
  • C.I. Thompson et al.

    Hypophagia follows the initial hyperphagia produced by 2-deoxy-D-glucose in rats

    Physiol. Behav.

    (1979)
  • C. Zhong et al.

    Increased food intake in growth hormone-transgenic common carp (Cyprinus carpio L.) may be mediated by upregulating Agouti-related protein (AgRP)

    Gen. Comp. Endocrinol.

    (2013)
  • E.D. Berglund et al.

    Direct leptin action on POMC neurons regulates glucose homeostasis and hepatic insulin sensitivity in mice

    J. Clin. Investig.

    (2012)
  • Y.M. Bohlooly et al.

    Growth hormone overexpression in the central nervous system results in hyperphagia-induced obesity associated with insulin resistance and dyslipidemia

    Diabetes

    (2005)
  • S.G. Bouret et al.

    Formation of projection pathways from the arcuate nucleus of the hypothalamus to hypothalamic regions implicated in the neural control of feeding behavior in mice

    J. Neurosci.

    (2004)
  • F. Dehkhoda et al.

    The growth hormone receptor: mechanism of receptor activation, cell signaling, and physiological aspects

    Front. Endocrinol.

    (2018)
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