GHRP-6 mimics ghrelin-induced stimulation of food intake and suppression of locomotor activity in goldfish

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• 作者：Satowa Yahashi^a ; Ki Sung Kang^b ; Hiroyuki Kaiya^c ; Kouhei Matsuda^a ; ^d ; ^{kmatsuda@sci.u-toyama.ac.jp}
• 关键词：Capsaicin ; Vagal afferent ; Food intake ; Goldfish ; Ghrelin ; GHRP-6 ; GHS ; GHS-R ; GHS-R2a-1 ; Locomotor activity ; n-Octanoyl ghrelin17
• 刊名：Peptides
• 出版年：2012
• 期刊代码：59_01969781
• 类别：neu
• 出版时间：April, 2012
• 卷：34
• 期：2
• 页码：324-328
• 文件大小：349 K

摘要

Ghrelin was first identified and characterized from rat stomach as an endogenous ligand for the growth hormone secretagogue (GHS) receptor (GHS-R). Ghrelin also acts as an orexigenic factor and regulates energy balance in rodents. In goldfish, native ghrelin consists of 11 molecular variants, the major form being a 17-residue peptide with n-octanoic acid modification (n-octanoyl ghrelin17), and intraperitoneal (IP) administration of n-octanoyl ghrelin17 induces central actions such as stimulation of food intake and suppression of locomotor activity through capsaicin-sensitive afferents. Four types of GHS-Rs (1a-1, 1a-2, 2a-1 and 2a-2) have been identified in goldfish, and one GHS, GHRP-6, can activate only GHS-R2a-1 in vitro. However, there is no information about the effect of GHRP-6 on food intake and locomotor activity in goldfish in vivo. Therefore, in the present study, we examined whether IP-administered GHRP-6 would mimic the orexigenic action of n-octanoyl ghrelin17 and its suppression of locomotor activity. IP administration of GHRP-6 at 1 pmol/g body weight (BW) stimulated food intake, and was equipotent to the orexigenic action of n-octanoyl ghrelin17 at 10 pmol/g BW. IP-injected GHRP-6 at 1 pmol/g BW also induced a significant decrease of locomotor activity, as was the case for IP-injected n-octanoyl ghrelin17 at 10 pmol/g BW. The action of GHRP-6 was blocked by IP-preinjected capsaicin at 160 nmol/g BW. These results suggest that the central action of GHRP-6 might be mediated via the GHS-R2a-1-signaling pathway, and subsequently through capsaicin-sensitive afferents in goldfish.