Agouti-related protein (AgRP) into the hypothalamic paraventricular nucleus (PVH) increases food hoarding, foraging and food intake in Siberian hamsters

Appetite ◽  
2008 ◽  
Vol 51 (2) ◽  
pp. 407
Author(s):  
C.H. Vaughan ◽  
B.J.W. Teubner ◽  
T.J. Bartness
Keyword(s):  
Food Intake ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Related Protein ◽  
Food Hoarding ◽  
Siberian Hamsters ◽  
Agouti Related Protein

Agouti-related protein increases food hoarding more than food intake in Siberian hamsters

2004 ◽  
Vol 286 (1) ◽  
pp. R38-R45 ◽  
Author(s):  
Diane E. Day ◽  
Timothy J. Bartness
Keyword(s):  
Food Intake ◽  
Arcuate Nucleus ◽  
Third Ventricle ◽  
Mass Gain ◽  
Dark Phase ◽  
Related Protein ◽  
Food Hoarding ◽  
Laboratory Rats ◽  
Siberian Hamsters ◽  
Agouti Related Protein

Agouti-related protein (AgRP), an endogenous melanocortin 3/4 receptor antagonist, appears to play an important role in the control of food intake and energy balance because exogenous administration in rats and overexpression in mice result in hyperphagia and body mass gain. Furthermore, arcuate nucleus AgRP mRNA is increased with fasting in laboratory rats and mice and is decreased with refeeding. In Siberian hamsters, fasting also increases arcuate nucleus AgRP mRNA, but these animals increase food hoarding, rather than food intake with refeeding. Therefore, we tested whether exogenous AgRP increased food hoarding in this species. Hamsters were trained in a hoarding/foraging apparatus to run a programmed number of wheel revolutions to earn food pellets. Four doses of AgRP-(83-132) or vehicle were injected into the third ventricle at the beginning of the dark phase, and food hoarding, food intake, and foraging were measured at various time points subsequently. Overall, food hoarding was stimulated as much as 10 times more than food intake, and both responses occurred as early as 1 h after injection. Food hoarding was increased the greatest at the lowest dose (0.1 nmol), whereas food intake was increased the greatest at the second lowest dose (1 nmol). Food intake and especially food hoarding were increased up to seven days after the AgRP injections. Foraging was increased at all AgRP doses except the highest dose (100 nmol). These results suggest that AgRP triggers the search for food in this species, and once they find it, hoarding predominates over eating.

scholarly journals Third ventricular coinjection of subthreshold doses of NPY and AgRP stimulate food hoarding and intake and neural activation

2012 ◽  
Vol 302 (1) ◽  
pp. R37-R48 ◽  
Author(s):  
Brett J. W. Teubner ◽  
Erin Keen-Rhinehart ◽  
Timothy J. Bartness
Keyword(s):  
Food Intake ◽  
Zona Incerta ◽  
Central Nucleus ◽  
Behavioral Experiment ◽  
Neural Activation ◽  
Food Hoarding ◽  
Siberian Hamsters ◽  
Hypothalamic Nuclei ◽  
Ingestive Behaviors ◽  
Agouti Related Protein

We previously demonstrated that 3rd ventricular (3V) neuropeptide Y (NPY) or agouti-related protein (AgRP) injection potently stimulates food foraging/hoarding/intake in Siberian hamsters. Because NPY and AgRP are highly colocalized in arcuate nucleus neurons in this and other species, we tested whether subthreshold doses of NPY and AgRP coinjected into the 3V stimulates food foraging, hoarding, and intake, and/or neural activation [c-Fos immunoreactivity (c-Fos-ir)] in hamsters housed in a foraging/hoarding apparatus. In the behavioral experiment, each hamster received four 3V treatments by using subthreshold doses of NPY and AgRP for all behaviors: 1) NPY, 2) AgRP, 3) NPY+AgRP, and 4) saline with a 7-day washout period between treatments. Food foraging, intake, and hoarding were measured 1, 2, 4, and 24 h and 2 and 3 days postinjection. Only when NPY and AgRP were coinjected was food intake and hoarding increased. After identical treatment in separate animals, c-Fos-ir was assessed at 90 min and 14 h postinjection, times when food intake (0–1 h) and hoarding (4–24 h) were uniquely stimulated. c-Fos-ir was increased in several hypothalamic nuclei previously shown to be involved in ingestive behaviors and the central nucleus of the amygdala (CeA), but only in NPY+AgRP-treated animals (90 min and 14 h: magno- and parvocellular regions of the hypothalamic paraventricular nucleus and perifornical area; 14 h only: CeA and sub-zona incerta). These results suggest that NPY and AgRP interact to stimulate food hoarding and intake at distinct times, perhaps released as a cocktail naturally with food deprivation to stimulate these behaviors.

scholarly journals Contribution of Noradrenergic and Adrenergic Cell Groups of the Brainstem and Agouti-Related Protein-Synthesizing Neurons of the Arcuate Nucleus to Neuropeptide-Y Innervation of Corticotropin-Releasing Hormone Neurons in Hypothalamic Paraventricular Nucleus of the Rat

Endocrinology ◽  
2007 ◽  
Vol 148 (11) ◽  
pp. 5442-5450 ◽  
Author(s):  
Tamás Füzesi ◽  
Gábor Wittmann ◽  
Zsolt Liposits ◽  
Ronald M. Lechan ◽  
Csaba Fekete
Keyword(s):  
Neuropeptide Y ◽  
Paraventricular Nucleus ◽  
Arcuate Nucleus ◽  
Protein A ◽  
Hypothalamic Paraventricular Nucleus ◽  
Related Protein ◽  
Cell Groups ◽  
Hypothalamic Arcuate Nucleus ◽  
Agouti Related Protein ◽  
Pituitary Adrenal Axis

CRH-synthesizing neurons in the hypothalamic paraventricular nucleus (PVN) integrate neuronal and hormonal inputs and serve as a final common pathway to regulate the hypothalamic-pituitary-adrenal axis. One of the neuronal regulators of CRH neurons is neuropeptide Y (NPY) contained in axons that densely innervate CRH neurons. The three main sources of NPY innervation of the PVN are the hypothalamic arcuate nucleus and the noradrenergic and adrenergic neurons of the brainstem. To elucidate the origin of the NPY-immunoreactive (NPY-IR) innervation to hypophysiotropic CRH neurons, quadruple-labeling immunocytochemistry for CRH, NPY, dopamine-β-hydroxylase, and phenylethanolamine-N-methyltransferase was performed. Approximately 63% of NPY-IR varicosities on the surface of CRH neurons were catecholaminergic (22% noradrenergic and 41% adrenergic), and 37% of NPY-IR boutons were noncatecholaminergic. By triple-labeling immunofluorescence detection of NPY, CRH, and agouti-related protein, a marker of NPY axons projecting from the arcuate nucleus, the noncatecholaminergic, NPY-ergic axon population was shown to arise primarily from the arcuate nucleus. When NPY was administered chronically into the cerebral ventricle of fed animals, a dramatic reduction of CRH mRNA was observed in the PVN (NPY vs. control integrated density units, 23.9 ± 2.7 vs. 77.09 ± 15.9). We conclude that approximately two thirds of NPY-IR innervation to hypophysiotropic CRH neurons originates from catecholaminergic neurons of the brainstem, whereas the remaining one third arises from the arcuate nucleus. The catecholaminergic NPY innervation seems to modulate the activation of CRH neurons in association with glucoprivation and infection, whereas the NPY input from the arcuate nucleus may contribute to inhibition of CRH neurons during fasting.

scholarly journals Differential Effects of Refeeding on Melanocortin-Responsive Neurons in the Hypothalamic Paraventricular Nucleus

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4329-4335 ◽  
Author(s):  
Edith Sánchez ◽  
Praful S. Singru ◽  
Runa Acharya ◽  
Monica Bodria ◽  
Csaba Fekete ◽  
...  
Keyword(s):  
Gene Expression ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Early Action ◽  
Sprague Dawley Rats ◽  
Melanocortin Signaling ◽  
Agouti Related Protein ◽  
Serum Tsh

To explore the effect of refeeding on recovery of TRH gene expression in the hypothalamic paraventricular nucleus (PVN) and its correlation with the feeding-related neuropeptides in the arcuate nucleus (ARC), c-fos immunoreactivity (IR) in the PVN and ARC 2 h after refeeding and hypothalamic TRH, neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNA levels 4, 12, and 24 h after refeeding were studied in Sprague-Dawley rats subjected to prolonged fasting. Despite rapid reactivation of proopiomelanocortin neurons by refeeding as demonstrated by c-fos IR in ARC α-MSH-IR neurons and ventral parvocellular subdivision PVN neurons, c-fos IR was present in only 9.7 ± 1.1% hypophysiotropic TRH neurons. Serum TSH levels remained suppressed 4 and 12 h after the start of refeeding, returning to fed levels after 24 h. Fasting reduced TRH mRNA compared with fed animals, and similar to TSH, remained suppressed at 4 and 12 h after refeeding, returning toward normal at 24 h. AGRP and NPY gene expression in the ARC were markedly elevated in fasting rats, AGRP mRNA returning to baseline levels 12 h after refeeding and NPY mRNA remaining persistently elevated even at 24 h. These data raise the possibility that refeeding-induced activation of melanocortin signaling exerts differential actions on its target neurons in the PVN, an early action directed at neurons that may be involved in satiety, and a later action on hypophysiotropic TRH neurons involved in energy expenditure, potentially mediated by sustained elevations in AGRP and NPY. This response may be an important homeostatic mechanism to allow replenishment of depleted energy stores associated with fasting.

Effect of peptide histidine isoleucine on consummatory behavior in rats

2003 ◽  
Vol 284 (6) ◽  
pp. R1445-R1453 ◽  
Author(s):  
Pawel K. Olszewski ◽  
Michelle M. Wirth ◽  
Timothy J. Shaw ◽  
Martha K. Grace ◽  
Allen S. Levine
Keyword(s):  
Food Intake ◽  
Food Consumption ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Central Nucleus ◽  
Consummatory Behavior ◽  
Inhibitory Influence ◽  
Potent Effect ◽  
Double Immunohistochemistry

Peptide histidine isoleucine (PHI) and VIP are derived from the same precursor. While central VIP decreases food intake, potential effects of PHI on feeding have not been studied. In the current study, we found that PHI administered intracerebroventricularly (ICV) or into the hypothalamic paraventricular nucleus (PVN) or central nucleus of the amygdala (CeA) decreased food consumption in overnight-deprived rats. The magnitude of an anorexigenic response to PHI differed depending on the injection route: ICV-infused peptide evoked the most potent effect. We determined that that only PVN- and CeA-injected PHI did not have aversive consequences. In addition, we infused anorexigenic doses of PHI via the same routes and assessed Fos immunoreactivity of PVN oxytocin (OT) and vasopressin (VP) neurons using double immunohistochemistry. OT and VP are thought to promote feeding termination. PHI increased the percentage of Fos-positive OT neurons regardless of the injection route. PVN- and ICV-infused PHI induced activation of VP cells. We conclude that central PHI has an inhibitory influence on food intake in rats. The PVN, with OT and VP neurons, and CeA may be involved in the mediation of anorexigenic effects of PHI.

scholarly journals Functional requirement of AgRP and NPY neurons in ovarian cycle-dependent regulation of food intake

2009 ◽  
Vol 106 (37) ◽  
pp. 15932-15937 ◽  
Author(s):  
Louise E. Olofsson ◽  
Andrew A. Pierce ◽  
Allison W. Xu
Keyword(s):  
Food Intake ◽  
Estrous Cycle ◽  
Estrogen Receptor Alpha ◽  
Ovarian Cycle ◽  
Central Administration ◽  
Related Protein ◽  
17Β Estradiol ◽  
Cycle Dependent ◽  
Cyclic Changes ◽  
Agouti Related Protein

In female mammals including rodents and humans, feeding decreases during the periovulatory period of the ovarian cycle, which coincides with a surge in circulating estrogen levels. Ovariectomy increases food intake, which can be normalized by estrogen treatment at a dose and frequency mimicking those during the estrous cycle. Furthermore, administration of estrogen to rodents potently inhibits food intake. Despite these well-known effects of estrogen, neuronal subtypes that mediate estrogen's anorexigenic effects have not been identified. In this study, we show that changes in hypothalamic expression of agouti-related protein (Agrp) and neuropeptide Y (Npy) coincide with the cyclic changes in feeding across the estrous cycle. These cyclic changes in feeding are abolished in mice with degenerated AgRP neurons even though these mice cycle normally. Central administration of 17β-estradiol (E2) decreases food intake in controls but not in mice lacking the AgRP neurons. Furthermore, E2 treatment suppresses fasting-induced c-Fos activation in AgRP and NPY neurons and blunts the refeeding response. Surprisingly, although estrogen receptor alpha (ERα) is the key mediator of estrogen's anorexigenic effects, we find that expression of ERα is completely excluded from AgRP and NPY neurons in the mouse hypothalamus, suggesting that estrogen may regulate these neurons indirectly via presynaptic neurons that express ERα. This study indicates that neurons coexpressing AgRP and NPY are functionally required for the cyclic changes in feeding across estrous cycle and that AgRP and NPY neurons are essential mediators of estrogen's anorexigenic function.

Role of NPY and its receptor subtypes in foraging, food hoarding, and food intake by Siberian hamsters

2005 ◽  
Vol 289 (1) ◽  
pp. R29-R36 ◽  
Author(s):  
Diane E. Day ◽  
Erin Keen-Rhinehart ◽  
Timothy J. Bartness
Keyword(s):  
Food Intake ◽  
Wheel Running ◽  
Free Food ◽  
Food Delivery ◽  
Ingestive Behavior ◽  
Receptor Subtypes ◽  
Running Wheel ◽  
Food Hoarding ◽  
Siberian Hamsters ◽  
Ingestive Behaviors

Fasting has widespread physiological and behavioral effects such as increases in arcuate nucleus neuropeptide Y (NPY) gene expression in rodents, including Siberian hamsters. Fasting also stimulates foraging and food hoarding (appetitive ingestive behaviors) by Siberian hamsters but does relatively little to change food intake (consummatory ingestive behavior). Therefore, we tested the effects of third ventricular NPY Y1 ([Pro34]NPY) or Y5 ([d-Trp34]NPY) receptor agonists on these ingestive behaviors using a wheel running-based food delivery system coupled with simulated burrow housing. Siberian hamsters had 1) no running wheel access and free food, 2) running wheel access and free food, or 3) foraging requirements (10 or 50 revolutions/pellet). NPY (1.76 nmol) stimulated food intake only during the first 4 h postinjection (∼200–1,000%) and mostly in hamsters with a foraging requirement. The Y1 receptor agonist markedly increased food hoarding (250–1,000%), increased foraging as well as wheel running per se, and had relatively little effect on food intake (<250%). Unlike NPY, the Y5 agonist significantly increased food intake, especially in foraging animals (∼225–800%), marginally increased food hoarding (250–500%), and stimulated foraging and wheel running 4–24 h postinjection, with the distribution of earned pellets favoring eating versus hoarding across time. Across treatments, food hoarding predominated early postinjection, whereas food intake tended to do so later. Collectively, NPY stimulated both appetitive and consummatory ingestive behaviors in Siberian hamsters involving Y1/Y5 receptors, with food hoarding and foraging/wheel running (appetitive) more involved with Y1 receptors and food intake (consummatory) with Y5 receptors.

Sign in / Sign up

Export Citation Format

Share Document