Hypothalamic NPY, AGRP, and POMC mRNA responses to  leptin and refeeding in mice

Food deprivation (FD) increases hypothalamic neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNA levels and decreases proopiomelanocortin (POMC) mRNA levels; refeeding restores these levels. We determined the time course of changes in hypothalamic NPY, AGRP, and POMC mRNA levels on refeeding after 24 h FD in C57BL mice by in situ hybridization. After 24 h deprivation, mice were refed with either chow or a palatable mash containing no calories or were injected with murine leptin (100 μg) without food. Mice were perfused 2 or 6 h after treatment. Food deprivation increased hypothalamic NPY mRNA (108 ± 6%) and AGRP mRNA (78 ± 7%) and decreased hypothalamic POMC mRNA (−15 ± 1%). Refeeding for 6 h, but not 2 h, was sufficient to reduce (but not restore) NPY mRNA, did not affect AGRP mRNA, and restored POMC mRNA levels to ad libitum control levels. Intake of the noncaloric mash had no effect on mRNA levels, and leptin administration after deprivation (at a dose sufficient to reduce refeeding in FD mice) was not sufficient to affect mRNA levels. These results suggest that gradual postabsorptive events subsequent to refeeding are required for the restoration of peptide mRNA to baseline levels after food deprivation in mice.

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Altered Expression of Agouti-Related Protein and Its Colocalization with Neuropeptide Y in the Arcuate Nucleus of the Hypothalamus during Lactation*

Endocrinology ◽

10.1210/endo.140.6.6829 ◽

1999 ◽

Vol 140 (6) ◽

pp. 2645-2650 ◽

Cited By ~ 59

Author(s):

Peilin Chen ◽

Chien Li ◽

Carrie Haskell-Luevano ◽

Roger D. Cone ◽

M. Susan Smith

Keyword(s):

In Situ Hybridization ◽

Food Intake ◽

Neuropeptide Y ◽

Arcuate Nucleus ◽

Mrna Levels ◽

Related Protein ◽

Altered Expression ◽

Caudal Portion ◽

Agouti Related Protein

Abstract During lactation, the levels of neuropeptide Y (NPY), which plays an important role in mediating food intake, are significantly elevated in a number of hypothalamic areas, including the arcuate nucleus (ARH). To identify additional hypothalamic systems that might be important in mediating the increase in food intake and alterations in energy homeostasis during lactation, the present studies examined the expression of agouti-related protein (AGRP), a recently described homologue of the skin agouti protein. AGRP is found in the hypothalamus and has been suggested to play an important role in the regulation of food intake. In the first experiment, animals were studied during diestrus of the estrous cycle, a stage of the cycle when estrogen levels are basal and similar to lactation, or during days 12–13 postpartum. Lactating animals had their litters adjusted to eight pups on day 2 postpartum. Brain tissue sections were used to measure AGRP messenger RNA (mRNA) levels by in situ hybridization. AGRP mRNA signal was found mostly in the ventromedial portion of the ARH, which has been shown to contain a high density of NPY neurons. A significant increase in AGRP mRNA content was observed in the mid- to caudal portion of the ARH of lactating animals compared with diestrous females. No difference was found in the rostral portion of the ARH. In the second experiment, double-label in situ hybridization for AGRP and NPY was performed in lactating animals to determine the extent of colocalization of the two peptides in the ARH, using 35S-labeled and digoxigenin-labeled antisense complementary RNA probes. It was found that almost all of the NPY-positive neurons throughout the ARH also expressed AGRP mRNA signal. Furthermore, AGRP expression was confined almost exclusively to NPY-positive neurons. Thus, the present study showed that during lactation, AGRP gene expression was significantly elevated in a subset of the AGRP neurons in the ARH. The high degree of colocalization of AGRP and NPY, coupled with previous reports from our laboratory demonstrating increased NPY expression in the ARH in response to suckling, suggests that AGRP and NPY are coordinately regulated and may be involved in the increase in food intake during lactation.

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Differential regulation of agouti-related protein and neuropeptide Y in hypothalamic neurons following a stressful event

Journal of Molecular Endocrinology ◽

10.1677/jme.1.01819 ◽

2005 ◽

Vol 35 (1) ◽

pp. 159-164 ◽

Cited By ~ 45

Author(s):

Martien J H Kas ◽

Adrie W Bruijnzeel ◽

Jurgen R Haanstra ◽

Victor M Wiegant ◽

Roger A H Adan

Keyword(s):

Neuropeptide Y ◽

Hpa Axis ◽

Arcuate Nucleus ◽

Eating Behaviour ◽

Melanocortin Receptor ◽

Stressful Event ◽

Mrna Levels ◽

Related Protein ◽

Increased Sensitivity ◽

Agouti Related Protein

Stress affects eating behaviour in rodents and humans, suggesting that the regulation of energy balance and the stress response are coupled physiological processes. Neuropeptide Y (NPY) and agouti-related protein (AgRP) are potent food-stimulating neuropeptides that are highly co-localised in arcuate nucleus neurons of the hypothalamus. Recent studies have shown that NPY and AgRP mRNA levels in these neurons respond similarly to fasting and leptin, indicating functional redundancy of the neuropeptide systems in these orexigenic neurons. However, we have found that NPY and AgRP mRNA expression in arcuate nucleus neurons are dissociated immediately following a stressful event. Two hours following a brief session of inescapable foot shocks, AgRP mRNA levels are down-regulated (P < 0.0001). In contrast, NPY mRNA levels are up-regulated (P < 0.0001). To provide physiological relevance for this acute down-regulation of AgRP, an inverse agonist of melanocortin receptors, we have shown that acute intracerebroventricular injection of a melanocortin receptor agonist, α-melanocyte-stimulating hormone (α-MSH), caused a significantly stronger activation of the hypothalamus–pituitary–adrenal-cortical (HPA) axis following a stressful event than in controls. Thus, AgRP and NPY mRNA levels in similar arcuate nucleus neurons are differentially regulated following a stressful event. This may contribute to increased sensitivity for α-MSH to activate the HPA axis following a repeated stressful experience.

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Progestin increases the expression of gonadotropins in pituitaries of male zebrafish

Journal of Endocrinology ◽

10.1530/joe-16-0073 ◽

2016 ◽

Vol 230 (1) ◽

pp. 143-156 ◽

Cited By ~ 12

Author(s):

Cuili Wang ◽

Dongteng Liu ◽

Weiting Chen ◽

Wei Ge ◽

Wanshu Hong ◽

...

Keyword(s):

Time Course ◽

Ex Vivo ◽

Mrna Levels ◽

Adult Zebrafish ◽

Male Adult ◽

Positive Effects ◽

Time Course Experiment ◽

Nuclear Progesterone Receptor

Our previous study showed that the in vivo positive effects of 17α,20β-dihydroxy-4-pregnen-3-one (DHP), the major progestin in zebrafish, on early spermatogenesis was much stronger than the ex vivo ones, which may suggest an effect of DHP on the expression of gonadotropins. In our present study, we first observed that fshb and lhb mRNA levels in the pituitary of male adult zebrafish were greatly inhibited by 3 weeks exposure to 10nM estradiol (E2). However, an additional 24h 100nM DHP exposure not only reversed the E2-induced inhibition, but also significantly increased the expression of fshb and lhb mRNA. These stimulatory effects were also observed in male adult fish without E2 pretreatment, and a time course experiment showed that it took 24h for fshb and 12h for lhb to respond significantly. Because these stimulatory activities were partially antagonized by a nuclear progesterone receptor (Pgr) antagonist mifepristone, we generated a Pgr-knockout (pgr–/–) model using the TALEN technique. With and without DHP in vivo treatment, fshb and lhb mRNA levels of pgr–/– were significantly lower than those of pgr+/+. Furthermore, ex vivo treatment of pituitary fragments of pgr–/– with DHP stimulated lhb, but not fshb mRNA expression. Results from double-colored fluorescent in situ hybridization showed that pgr mRNA was expressed only in fshb-expressing cells. Taken together, our results indicated that DHP participated in the regulation of neuroendocrine control of reproduction in male zebrafish, and exerted a Pgr-mediated direct stimulatory effect on fshb mRNA at pituitary level.

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Paraventricular Nucleus Administration of Calcitonin Gene-Related Peptide Inhibits Food Intake and Stimulates the Hypothalamo-Pituitary-Adrenal Axis

Endocrinology ◽

10.1210/en.2002-220902 ◽

2003 ◽

Vol 144 (4) ◽

pp. 1420-1425 ◽

Cited By ~ 42

Author(s):

Waljit S. Dhillo ◽

Caroline J. Small ◽

Preeti H. Jethwa ◽

Sabina H. Russell ◽

James V. Gardiner ◽

...

Keyword(s):

Food Intake ◽

Hpa Axis ◽

Male Rats ◽

Mrna Levels ◽

Related Protein ◽

Melanocyte Stimulating Hormone ◽

Calcitonin Gene ◽

Agouti Related Protein ◽

Prior Administration

Abstract Calcitonin gene-related protein (CGRP) inhibits food intake and stimulates the hypothalamo-pituitary-adrenal (HPA) axis after intracerebroventricular injection in rats. However, the hypothalamic site and mechanism of action are unknown. We investigated the effects of intraparaventricular nucleus administration (iPVN) of CGRP on food intake and the HPA axis in rats and the effect of CGRP on the release of hypothalamic neuropeptides in vitro. In addition, we investigated the effects of food deprivation on hypothalamic CGRP expression. CGRP dose-dependently reduced food intake in the first hour after iPVN injection in fasted male rats (saline, 5.1 ± 0.8 g; 0.3 nmol CGRP, 1.1 ± 0.5 g; P < 0.001 vs. saline). iPVN injection of CGRP8–37 (a CGRP1 receptor antagonist) alone had no effect on food intake. However, the reduction in food intake by iPVN CGRP was attenuated by prior administration of CGRP8–37 [CGRP8–37 (10 nmol)/CGRP (0.3 nmol), 3.0 ± 0.8 g; P < 0.05 vs. 0.3 nmol CGRP]. CGRP (100 nm) stimulated the release of α-melanocyte stimulating hormone, cocaine- and amphetamine-related transcript, corticotropin-releasing hormone, and arginine vasopressin from hypothalamic explants to 127 ± 19%, 148 ± 10%, 158 ± 17%, and 198 ± 21% of basal levels, respectively (P < 0.05 vs. basal), but did not alter the release of either neuropeptide Y or agouti-related protein. Hypothalamic CGRP mRNA levels in 24-h fasted rats were increased to 130 ± 8% of control levels [CGRP mRNA (arbitrary units), 4.75 ± 0.4; controls, 3.65 ± 0.34; P < 0.05]. Our data suggest that CGRP administered to the PVN inhibits food intake and stimulates the HPA axis.

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The melanocortin circuit in obese and lean strains of chicks

Journal of Endocrinology ◽

10.1677/joe.1.06783 ◽

2006 ◽

Vol 190 (2) ◽

pp. 527-535 ◽

Cited By ~ 27

Author(s):

Gideon Hen ◽

Sara Yosefi ◽

Victoria Simchaev ◽

Dmitry Shinder ◽

Victor J Hruby ◽

...

Keyword(s):

Food Intake ◽

Broiler Chickens ◽

Egg Production ◽

Feed Restriction ◽

Broiler Chicks ◽

Mrna Levels ◽

Gene Encoding ◽

Wing Vein ◽

Pomc Mrna ◽

Ad Libitum

Agonists of membranal melanocortin 3 and 4 receptors (MC3/4Rs) are known to take part in the complex control mechanism of energy balance. In this study, we compared the physiological response to an exogenous MC3/4R agonist and the hypothalamic expression of proopic melanocortin (POMC) gene, encoding few MC3/4R ligands, between broiler and layer chicken strains. These strains, representing the two most prominent commercial strains of chickens grown for meat (broilers) and egg production (layers), differ in their food intake, fat accumulation, and reproductive performance and, therefore, form a good model of obese and lean phenotypes, respectively. A single i.v. injection of the synthetic peptide melanotan-II (MT-II; 1 mg/kg body weight) into the wing vein of feed-restricted birds led to attenuation of food intake upon exposure to feeding ad libitum in both broiler and layer chickens. A study of the POMC mRNA encoding the two prominent natural MC3/4R agonists, α-MSH and ACTH, also revealed a general similarity between the strains. Under feeding conditions ad libitum, POMC mRNA levels were highly similar in chicks of both strains and this level was significantly reduced upon feed restriction. However, POMC mRNA down-regulation upon feed restriction was more pronounced in layers than in broilers. These results suggest: (i) a role for MC3/4R agonists in the control of appetite; (ii) that the physiological differences between broilers and layers are not related to unresponsiveness of broiler chickens to the satiety signal of MC3/4R ligands. Therefore, these findings suggest that artificial activation of this circuit in broiler chicks could help to accommodate with their agricultural shortcomings of overeating, fattening, and impaired reproduction.

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Chronic food restriction and acute food deprivation decrease mRNA levels of opioid peptides in arcuate nucleus

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1996.270.5.r1019 ◽

1996 ◽

Vol 270 (5) ◽

pp. R1019-R1024 ◽

Cited By ~ 5

Author(s):

E. M. Kim ◽

C. C. Welch ◽

M. K. Grace ◽

C. J. Billington ◽

A. S. Levine

Keyword(s):

Body Weight ◽

Food Intake ◽

Food Deprivation ◽

Food Restriction ◽

Arcuate Nucleus ◽

Mrna Levels ◽

Endogenous Opioid ◽

Pomc Mrna ◽

Opioid Administration ◽

Ad Libitum Intake

Although opioid administration induces food intake, the relationship between endogenous opioid synthesis and food consumption is unclear. Two studies examined the effects of food restriction and deprivation on opioid mRNA levels in the arcuate nucleus (ARC) of the rat. Body weight significantly decreased following food restriction and deprivation (P < 0.0001). In experiment 1, food restriction of 10,20,30, and 40% (g) of ad libitum intake for 14 days decreased proDynorphin (proDyn), proEnkephalin (proEnk), and proOpiomelanocortin (POMC) mRNA levels in a linear fashion relative to changes in body weight (r = 0.398, P = 0.0011; r = 0.455, P = 0.0028; r = 0.292, P = 0.0642, respectively). In experiment 2, 48 h deprivation significantly decreased mRNA levels of proDyn and POMC by 23.7% (P < 0.05) and 45.6% (P < 0.01), respectively, whereas 24 h food deprivation decreased POMC mRNA by 43.% (P < 0.01). proEnk mRNA was not affected by 24- or 48-h food deprivation. Restricting food intake suppressed mRNA levels of proDyn, proEnk, and POMC by 29.7, 22.3, and 44.4%, respectively, in 20% restricted rats and by 35.5, 26.8, and 45.6%, respectively, in 40%restricted rats (P < 0.01). It appears that ARC mRNA levels of proDyn, proEnk, and POMC are directly related to the amount of food consumed and/or changes in body weight in food-restricted and food-deprived rats.

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Levels of pro-opiomelanocortin and prolactin mRNA in the fetal sheep pituitary following hypoxaemia and glucocorticoid treatment in late gestation

Journal of Endocrinology ◽

10.1677/joe.0.1470139 ◽

1995 ◽

Vol 147 (1) ◽

pp. 139-146 ◽

Cited By ~ 26

Author(s):

S G Matthews ◽

J R G Challis

Keyword(s):

Late Gestation ◽

Pars Intermedia ◽

Mrna Levels ◽

Glucocorticoid Treatment ◽

Fetal Sheep ◽

Fetal Plasma ◽

Pomc Mrna ◽

Highly Sensitive ◽

Ovine Fetal

Abstract It is well established that corticotrophin-releasing hormone and vasopressin can induce both synthesis and release of ACTH from the ovine pituitary gland, and that glucocorticoids can inhibit these responses. Changes in the abundance, localization and distribution of proopiomelanocortin (POMC) mRNA and prolactin (PRL) mRNA in the ovine fetal pituitary were examined by in situ hybridization following hypoxaemia applied in the presence or absence of concomitant cortisol in late gestation (day 135). Fetuses were distributed amongst four groups; saline-infused/normoxaemic, cortisol-infused/normoxaemic (0·3 mg/h), saline-infused/hypoxaemic and cortisol-infused/hypoxaemic. Hypoxaemia (6 h) was induced by reducing the maternal PaO2, resulting in a 6–8 mmHg decrease in fetal arterial PO2. Fetal infusions were commenced 5 h prior to and maintained throughout the treatment period. Hypoxaemia, which elevated fetal plasma ACTH and cortisol, caused a significant (P<0·05) increase in POMC mRNA in the pars distalis (PD), but was without effect on POMC mRNA in the pars intermedia (PI). Cortisol infusion attenuated the hypoxaemiainduced increase in POMC mRNA in the PD, but was without effect on non-stimulated steady-state POMC mRNA levels in either the PD or PI. PRL mRNA was only present in the PD and significantly (P<0·05) increased after cortisol infusion and hypoxaemia. In conclusion (i) POMC and PRL mRNA in the PD are increased following moderate hypoxaemia, (ii) cortisol attenuates changes in POMC mRNA but not PRL mRNA in the PD following hypoxaemia and (iii) cortisol increases PRL mRNA levels in the PD. Synthesis of POMC and PRL in the fetal PD is highly sensitive to homeostatic perturbations and glucocorticoids in late gestation. Journal of Endocrinology (1995) 147, 139–146

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The Serum- and Glucocorticoid-Induced Kinase Is a Physiological Mediator of Aldosterone Action*

Endocrinology ◽

10.1210/endo.142.4.8095 ◽

2001 ◽

Vol 142 (4) ◽

pp. 1587-1594 ◽

Cited By ~ 77

Author(s):

Aditi Bhargava ◽

Meryl J. Fullerton ◽

Kathy Myles ◽

Timothy M. Purdy ◽

John W. Funder ◽

...

Keyword(s):

In Situ Hybridization ◽

Messenger Rna ◽

Time Course ◽

Rat Kidney ◽

Distal Colon ◽

Mrna Levels ◽

Epithelial Tissues ◽

Sodium And Potassium

Abstract Aldosterone plays a major role in regulating sodium and potassium flux in epithelial tissues such as kidney and colon. Recent evidence suggests that serum- and glucocorticoid-regulated kinase (SGK) is induced by aldosterone and acts as a key mediator of aldosterone action in epithelial tissues. Induction of SGK messenger RNA (mRNA) has previously been shown within 30 min of addition of supraphysiological doses of aldosterone to Xenopus A6 cells and within 4 h in rat kidney in vivo. In this study we determined the time course of SGK induction, at doses of aldosterone in the physiological range, in rat kidney and colon, using Northern and Western blot analyses and in situ hybridization and determined concurrent changes in urinary sodium and potassium excretion by Kagawa bioassay. On Northern blot analysis, SGK mRNA levels were significantly elevated in both kidney and colon 60 min after the injection of aldosterone. SGK protein in late distal colon was significantly elevated 2 and 4 h after aldosterone treatment. In situ hybridization showed SGK mRNA to be induced in renal collecting ducts and distal tubular elements in both cortex and medulla by doses of aldosterone of 0.1 μg/100 g BW or more within 30 min of steroid treatment. Significant changes in urinary composition were similarly seen with an aldosterone dose of 0.1 μg/100 g BW from 90 min after aldosterone injection. The early onset of SGK induction in kidney and colon and the correlation with urinary changes in terms of both time course and dose response suggest that SGK plays an important role in mediating the effects of aldosterone on sodium homeostasis in vivo.

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Endogenous Melanocortin Antagonist in Fish: Structure, Brain Mapping, and Regulation by Fasting of the Goldfish Agouti-Related Protein Gene

Endocrinology ◽

10.1210/en.2003-0453 ◽

2003 ◽

Vol 144 (10) ◽

pp. 4552-4561 ◽

Cited By ~ 94

Author(s):

José Miguel Cerdá-Reverter ◽

Richard Ector Peter

Keyword(s):

Energy Balance ◽

Food Intake ◽

Brain Mapping ◽

Arcuate Nucleus ◽

Mrna Levels ◽

Central Administration ◽

Related Protein ◽

Melanocortin Peptides ◽

Agouti Related Protein ◽

Tuberal Nucleus

Agouti-related protein (AGRP) is a naturally occurring antagonist of melanocortin. In mammals, central AGRP expression is restricted to the arcuate nucleus in which it plays a key role in the control of energy balance by antagonizing melanocortin effects at melanocortin 4 receptors. In goldfish, melanocortin 4 receptor is profusely expressed within the main brain areas for the control of energy balance, and central administration of agonist or antagonist analogs inhibits or stimulates food intake, respectively. Here we demonstrate that the goldfish genome has a homologous gene to mammalian AGRP. Detailed brain mapping by in situ hybridization shows that AGRP is exclusively expressed in the ventrobasal hypothalamic lateral tuberal nucleus, the teleostean homolog of the arcuate nucleus. Fasting up-regulates its mRNA levels in the lateral tuberal nucleus. In the periphery, AGRP is expressed in several tissues including ovary, muscle, and ventral skin, suggesting that AGRP might regulate peripheral actions of melanocortin peptides. The results provide the first evidence for an endogenous melanocortin antagonist in nontetrapod species and suggest that hypothalamic overexpression during fasting might regulate the inhibitory effects of melanocortin peptides on food intake in goldfish.

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Hypothalamic Cocaine- and Amphetamine-Regulated Transcript (CART) and Agouti-Related Protein (AgRP) Neurons Coexpress the NOP1 Receptor and Nociceptin Alters CART and AgRP Release

Endocrinology ◽

10.1210/en.2004-1659 ◽

2005 ◽

Vol 146 (8) ◽

pp. 3526-3534 ◽

Cited By ~ 31

Author(s):

Gavin A. Bewick ◽

Waljit S. Dhillo ◽

Sarah J. Darch ◽

Kevin G. Murphy ◽

James V. Gardiner ◽

...

Keyword(s):

In Situ Hybridization ◽

Food Intake ◽

Energy Homeostasis ◽

Ex Vivo ◽

Zona Incerta ◽

Related Protein ◽

Orphanin Fq ◽

Anatomical Basis ◽

Agouti Related Protein

Abstract Nociceptin or orphanin FQ (N/OFQ) and its receptor NOP1 are expressed in hypothalamic nuclei involved in energy homeostasis. N/OFQ administered by intracerebroventricular or arcuate nucleus (ARC) injection increases food intake in satiated rats. The mechanisms by which N/OFQ increases food intake are unknown. We hypothesized that N/OFQ may regulate hypothalamic neurons containing peptides involved in the control of food intake such as cocaine- and amphetamine-regulated transcript (CART), αMSH, neuropeptide Y (NPY), and agouti-related protein (AgRP). We investigated the ability of N/OFQ to alter the release of CART, αMSH, NPY, and AgRP using ex vivo medial basal hypothalamic explants. Incubation of hypothalamic explants with N/OFQ (1, 10, 100 nm) resulted in significant changes in CART and AgRP release. One hundred nanomoles N/OFQ caused a 33% decrease in release of CART (55–102) immunoreactivity (IR) and increased release of AgRP-IR to 163% but produced no change in either αMSH-IR or NPY-IR. Double immunocytochemistry/in situ hybridization demonstrated that CART-IR and NOP1 mRNA are colocalized throughout the hypothalamus, in particular in the paraventricular nucleus, lateral hypothalamus, zona incerta, and ARC, providing an anatomical basis for N/OFQ action on CART release. Dual in situ hybridization demonstrated that AgRP neurons in the ARC also express the NOP1 receptor. Our data suggest that nociceptin via the NOP1 receptor may increase food intake by decreasing the release of the anorectic peptide CART and increasing the release of the orexigenic peptide AgRP.

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