Glucocorticoids increase neuropeptide Y and agouti-related peptide gene expression via adenosine monophosphate-activated protein kinase signaling in the arcuate nucleus of rats.
Recent studies suggest that the AMP-activated protein kinase (AMPK) signaling in the hypothalamus is the master regulator of energy balance. We reported in previous studies that glucocorticoids play a permissive role in the regulation of orexigenic neuropeptide Y (Npy) gene expression in the arcuate nucleus. In this study, we examined whether any cross talk occurs between glucocorticoids and AMPK signaling in the hypothalamus to regulate Npy as well as agouti-related peptide (Agrp) gene expression in the arcuate nucleus. In the hypothalamic organotypic cultures, the addition to the medium of the AMPK activator, 5-aminoimidazole-4-carboxamide-1-b-d-ribofuranoside, increased phosphorylated AMPK (p-AMPK) as well as phosphorylated acetyl-coenzyme A carboxylase (p-ACC) in the explants, accompanied by significant increases in Npy and Agrp gene expression in the arcuate nucleus. The incubation with dexamethasone (DEX) also activated AMPK signaling in the explants, accompanied by significant increases in Npy and Agrp gene expression in the arcuate nucleus. The addition of the AMPK inhibitor compound C to the medium, which blocked increases of p-AMPK and p-ACC by DEX, significantly attenuated Npy and Agrp gene expression stimulated by DEX. Furthermore, p-AMPK and p-ACC levels in the arcuate nucleus were significantly decreased in adrenalectomized rats compared with sham-operated rats, and a replacement of glucocorticoids reversed the AMPK signaling in adrenalectomized rats. Thus, our data demonstrated that glucocorticoids up-regulate the Npy and Agrp gene expression in the arcuate nucleus through AMPK signaling, suggesting that the activation of the hypothalamic APMK signaling by glucocorticoids might be essential to the energy homeostasis.
Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
Hiroshi
H
Shimizu
Hiroshi
H
Arima
Minemori
M
Watanabe
Motomitsu
M
Goto
Ryoichi
R
Banno
Ikuko
I
Sato
Nobuaki
N
Ozaki
Hiroshi
H
Nagasaki
Yutaka
Y
Oiso
D055372:AMP-Activated Protein Kinases; D000315:Adrenalectomy; D054369:Agouti-Related Protein / Q000235:genetics* / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D008297:Male; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000502:physiology*; D009478:Neuropeptide Y / Q000235:genetics* / Q000378:metabolism; D009924:Organ Culture Techniques; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012265:Ribonucleotides / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
C515197:AGRP protein, rat; D054369:Agouti-Related Protein; D005938:Glucocorticoids; D007004:Hypoglycemic Agents; D009097:Multienzyme Complexes; D009478:Neuropeptide Y; D012333:RNA, Messenger; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D003907:Dexamethasone; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide