Peripheral ghrelin interacts with orexin neurons in glucostatic signalling.
Ghrelin interactions with glycemia in appetite control as well as the potential mechanisms involving the orexin and melanin-concentrating hormone (MCH) neurons in the orexigenic ghrelin signals were investigated by using a specific anti-ghrelin antibody (AGA). Our results confirm that peripheral ghrelin is an important signal in meal initiation and appetite. Employing immunohistochemistry techniques, we found that c-fos positive neurons in the lateral hypothalamus (LH) and perifornical area (PFA) increased after insulin or 2-deoxyglucose administration. Moreover, we have also demonstrated that peripheral ghrelin blockade by the AGA, reduces the orexigenic signal induced by insulin and 2-DG administration probably partly producing a decrease of c-fos immunoreactivity in the LH and PFA as well as a lower activation of orexin neurons. In contrast, the c-fos positive MCH neurons were not apparently affected. In summary, our findings suggest that peripheral ghrelin plays an important role in regulatory "glucostatic" feeding mechanisms by means of its role as a "hunger" signal affecting the LH and PFA areas, which may contribute to energy homeostasis through orexin neurons.
Solomon
Andrew
A
Department of Physiology and Nutrition, University of Navarra, 31008, Pamplona, Spain.
De Fanti
Brant A
BA
Martínez
J Alfredo
JA
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001069:Appetite Regulation / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism*; D004435:Eating / Q000502:physiology; D054439:Ghrelin / Q000276:immunology / Q000378:metabolism*; D007026:Hypothalamic Area, Lateral / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000378:metabolism; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008543:Melanins / Q000378:metabolism; D009474:Neurons / Q000276:immunology / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D000068797:Orexins; D010907:Pituitary Hormones / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction
D000906:Antibodies; D001786:Blood Glucose; D054439:Ghrelin; D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; C019463:melanin-concentrating hormone