Relationship between anorexigenic action of pituitary adenylate cyclase-activating polypeptide (PACAP) and that of corticotropin-releasing hormone (CRH) in the goldfish, Carassius auratus.
Our recent research has indicated that intracerebroventricular (ICV) injection of pituitary adenylate cyclase-activating polypeptide (PACAP) suppresses food intake and locomotor activity in the goldfish. However, the anorexigenic mechanism of PACAP has not yet been clarified. The aim of this study was to investigate the relationship between the anorexigenic action of PACAP and that of corticotropin-releasing hormone (CRH), which is implicated in the regulation of energy homeostasis as a powerful anorexigenic peptide in the goldfish brain. We first examined feeding-induced changes in the expression of CRH mRNA, and the effect of ICV administration of PACAP on the expression of CRH mRNA in the goldfish brain. Semiquantitative analysis revealed that the expression of CRH mRNA was significantly increased by excessive feeding for 7 days. ICV administration of PACAP at a dose sufficient to suppress food intake induced a significant increase in the expression of CRH mRNA. We also examined the effect of alpha-helical CRH(9-41), a CRH antagonist, on the anorexigenic action of PACAP in the goldfish. The inhibitory effect of PACAP was completely suppressed by treatment with alpha-helical CRH(9-41). We finally investigated the effect of ICV-administered CRH on locomotor activity in the goldfish. CRH at a dose sufficient to suppress food intake induced a significant increase in locomotor activity, unlike ICV-injected PACAP. These results suggest that, in the goldfish, the anorexigenic action of PACAP is related to the CRH neuronal pathway, but that the modulation of locomotor activity by PACAP is independent of modulation by CRH.
Maruyama
Keisuke
K
Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama, Toyama 930-8555, Japan.
Miura
Tohru
T
Uchiyama
Minoru
M
Shioda
Seiji
S
Matsuda
Kouhei
K
D000818:Animals; D001835:Body Weight; D001921:Brain / Q000378:metabolism; D002552:Cerebral Ventricles / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D004435:Eating; D006054:Goldfish; D009068:Movement; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
D018076:DNA, Complementary; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D003346:Corticotropin-Releasing Hormone