title: Stimulatory effect of n-octanoylated ghrelin on locomotor activity in the goldfish, Carassius auratus.
abstract: Ghrelin is implicated in growth and feeding regulation in fish. The influence of ghrelin on behavior has not been well studied and the physiological role of des-fatty acid modification of this peptide is unclear. Therefore, the effects of intracerebroventricular (ICV) and intraperitoneal (IP) administration of synthetic n-octanoylated (acyl) goldfish ghrelin and des-n-octanoylated (des-acyl) ghrelin on locomotor and orexigenic activity in the goldfish were examined. ICV administration of acyl ghrelin at doses of 1 and 2 pmol/g body weight (BW) and IP administration at 16 pmol/g BW both induced significant increases in locomotor activity during for 45-60 min after treatment. Cumulative food intake was significantly increased by ICV injection of acyl ghrelin at doses of 1 and 2 pmol/g BW and IP injection at 8 and 16 pmol/g BW during the 60-min post-treatment observation period. In contrast, ICV and IP administration of des-acyl ghrelin produced no changes in locomotor and orexigenic activity. We also analyzed fasting-induced changes in the expression of ghrelin mRNA in the brain and intestine using a real-time PCR method. The level of ghrelin mRNA in the intestine, but not in the brain, obtained from fish fasted for 7 days was significantly higher than that in fish that had been fed normally. These results suggest that, in the goldfish, acyl ghrelin, but not des-acyl ghrelin, stimulates locomotor activity and enhances food intake via central and peripheral pathways.
authors.affiliation: Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan. kmatsuda@sci.toyama-u.ac.jp
authors.forename: Kouhei
authors.initials: K
authors.lastname: Matsuda
authors.forename: Tohru
authors.initials: T
authors.lastname: Miura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kaiya
authors.forename: Keisuke
authors.initials: K
authors.lastname: Maruyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Kenji
authors.initials: K
authors.lastname: Kangawa
authors.forename: Seiji
authors.initials: S
authors.lastname: Shioda
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D004435:Eating; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D054439:Ghrelin; D006054:Goldfish; D007413:Intestinal Mucosa / Q000378:metabolism; D008124:Locomotion / Q000187:drug effects*; D008297:Male; D036361:Peptide Hormones / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones; D010455:Peptides; D012333:RNA, Messenger; C422650:ghrelin, des-n-octanoyl