title: Insulin is not a prerequisite for rapid regulation of neuropeptide Y gene transcription in the arcuate nucleus in food-restricted rats.
abstract: Neuropeptide Y (NPY), synthesized in the arcuate nucleus of the hypothalamus, is one of the most potent orexigenic neuropeptides in the brain. The NPY neurons project to other hypothalamic nuclei, such as paraventricular nucleus (PVN), and it is reported that NPY contents in the PVN, but not NPY mRNA levels in the arcuate nucleus, decreased rapidly after food consumption. While many signals reflecting energy balance in the periphery are integrated at the NPY neurons, insulin has been implicated as one of the key regulators for NPY neurons. In the present study, we first examined whether there exist dynamic changes in NPY gene transcription in the arcuate nucleus in association with food intake in rats which had access to food only 4h a day. To detect possible changes in NPY gene transcription, we measured the expression levels of NPY heteronuclear (hn) RNA, a sensitive indicator of gene transcription, with intronic in situ hybridization. Our data showed that NPY hnRNA levels in the arcuate nucleus decreased rapidly after food consumption. We next examined whether postprandial increases in insulin release might contribute to the rapid downregulation of NPY gene transcription. To do so, insulin-deficient rats by streptozotocin injection were subjected to the same paradigm. Our data showed that NPY hnRNA levels also decreased rapidly after food consumption, suggesting that the postprandial increase in insulin release is not a prerequisite for the rapid downregulation of NPY gene transcription in the arcuate nucleus.
authors.affiliation: Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Motomitsu
authors.initials: M
authors.lastname: Goto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Arima
authors.forename: Maiko
authors.initials: M
authors.lastname: Hiroi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimizu
authors.forename: Minemori
authors.initials: M
authors.lastname: Watanabe
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hayashi
authors.forename: Ryouichi
authors.initials: R
authors.lastname: Banno
authors.forename: Ikuko
authors.initials: I
authors.lastname: Sato
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Ozaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagasaki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Oiso
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D003345:Corticosterone / Q000097:blood; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004435:Eating / Q000502:physiology; D005215:Fasting / Q000502:physiology*; D054439:Ghrelin / Q000097:blood; D007328:Insulin / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009478:Neuropeptide Y / Q000096:biosynthesis / Q000235:genetics*; D019518:Postprandial Period / Q000502:physiology; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D001786:Blood Glucose; D054439:Ghrelin; D007328:Insulin; D009478:Neuropeptide Y; D012313:RNA; D003345:Corticosterone