Injection of alpha-MSH, but not beta-endorphin, into the PVN decreases POMC gene expression in the ARC.
beta-Endorphin (beta-END) and alpha-melanocyte stimulating hormone (alpha-MSH), neuropeptides derived from proopiomelanocortin (POMC), have opposite effects on eating behavior. We injected rats with alpha-MSH (0.6 nmol) or beta-END (1 nmol) into the PVN (three times in a 26 h period). These doses of alpha-MSH and beta-END decreased and increased feeding respectively. Following alpha-MSH administration into the PVN, mRNA levels of POMC decreased by 17%, whereas there was no significant change in gene expression of either proDynorphin or proEnkephalin. PVN injection of beta-END failed to alter gene expression of POMC, proDynorphin or proEnkephalin. These data suggest that a feedback pathway exists between the PVN and ARC for alpha-MSH and POMC, but not for beta-END and POMC.
Kim
Eun-Mee
EM
School of Psychology, University of Ulster, Jordanstown, UK.
Grace
Martha K
MK
O'Hare
Eugene
E
Billington
Charles J
CJ
Levine
Allen S
AS
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D004435:Eating / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects* / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000096:biosynthesis* / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D000521:alpha-MSH / Q000008:administration & dosage* / Q000502:physiology; D001615:beta-Endorphin / Q000008:administration & dosage* / Q000502:physiology
D012333:RNA, Messenger; D000521:alpha-MSH; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin