TY - JOUR
T1 - Diurnal rhythm of galanin-like immunoreactivity in the paraventricular and suprachiasmatic nuclei and other hypothalamic areas
AU - Akabayashi, Akira
AU - Zaia, C. T.B.V.
AU - Koenig, James I.
AU - Gabriel, Steven M.
AU - Silva, Ivan
AU - Leibowitz, Sarah F.
N1 - Funding Information:
This research was supported by USPHS Grant MH43422 (S.F.L.), by a fellowship from The Naito Foundation (A.A.), and by a fellowship from Conselho Nacional de Pesquisa (CNPq) and P.I.C.D., Brazil (C.T.B.V.Z.). The authors thank Ms. Yim Dam of the Obesity Core Center at St. Luke's-Roosevelt Hospital for assistance with the insulin and glucose determinations, and Ms. Jesline Alexander and Mr. Hee-Jin Chae of The Rockefeller University for their excellent technical assistance.
PY - 1994
Y1 - 1994
N2 - The peptide galanin (GAL), when injected into the rat hypothalamus, is known to stimulate feeding behavior and affect the secretion of various hormones, including insulin and the adrenal steroid, corticosterone. To determine whether endogenous peptide levels shift in relation to natural rhythms of feeding and circulating hormone levels, rats were sacrificed at different times of the light/dark cycle, and their GAL levels were measured, via radioimmunoassay, in medial hypothalamic dissections and micropunched hypothalamic areas. The results suggest the existence of two distinct diurnal rhythms for hypothalamic GAL. One rhythm, detected exclusively in the area of the SCN, is characterized by bimodal peaks of GAL, threefold higher than basal peptide levels, around the onset of the dark and light periods. The second rhythm shows a single peak of GAL towards the middle of the nocturnal feeding cycle, specifically between the third and sixth hour. This latter rhythm is evident in the dorsal region of the medial hypothalamus, localized specifically to the lateral portion of the PVN. Moreover, it is inversely related to circulating insulin but unrelated to the adrenal steroids, suggesting a possible association between this pancreatic hormone and GAL in the PVN.
AB - The peptide galanin (GAL), when injected into the rat hypothalamus, is known to stimulate feeding behavior and affect the secretion of various hormones, including insulin and the adrenal steroid, corticosterone. To determine whether endogenous peptide levels shift in relation to natural rhythms of feeding and circulating hormone levels, rats were sacrificed at different times of the light/dark cycle, and their GAL levels were measured, via radioimmunoassay, in medial hypothalamic dissections and micropunched hypothalamic areas. The results suggest the existence of two distinct diurnal rhythms for hypothalamic GAL. One rhythm, detected exclusively in the area of the SCN, is characterized by bimodal peaks of GAL, threefold higher than basal peptide levels, around the onset of the dark and light periods. The second rhythm shows a single peak of GAL towards the middle of the nocturnal feeding cycle, specifically between the third and sixth hour. This latter rhythm is evident in the dorsal region of the medial hypothalamus, localized specifically to the lateral portion of the PVN. Moreover, it is inversely related to circulating insulin but unrelated to the adrenal steroids, suggesting a possible association between this pancreatic hormone and GAL in the PVN.
KW - Circadian
KW - Galanin
KW - Hypothalamus
KW - Insulin
UR - https://www.scopus.com/pages/publications/0028173401
U2 - 10.1016/0196-9781(94)90121-X
DO - 10.1016/0196-9781(94)90121-X
M3 - Article
C2 - 7535427
AN - SCOPUS:0028173401
SN - 0196-9781
VL - 15
SP - 1437
EP - 1444
JO - Peptides
JF - Peptides
IS - 8
ER -