title: A novel galanin receptor 1a gene in zebrafish: tissue distribution, developmental expression roles in nutrition regulation.
abstract: Galanin (Gal), a 29 (30 in human) amino acid neuropeptide, exerts its biological activities through three different G protein-coupled receptors, namely GalR1, GalR2 and GalR3. However, we previously found that only GalR1 and GalR2 exist in fish, and fish GalR1 has two genes (GalR1a and GalR1b), with GalR1a possibly representing the primitive gene form during fish evolution. To uncover the functions of GalR1a in fish, here the tissue distribution, developmental expression and the role in nutrition regulation of GalR1a were investigated in zebrafish (Danio rerio). Interestingly, the expression of GalR1a mRNA was restricted to the intestine and brain in adult zebrafish, while GalR1b mRNA was present in all tissues tested. During embryogenesis, GalR1a mRNA was abundant at 1hpf (hour past fertilization) and decreased gradually in abundance from 3 hpf to 10 hpf; then a significant increase in the amount of GalR1a transcripts was observed at 35 hpf, and this high level was maintained until 5 dpf (day past fertilization). In situ hybridization of embryos and larvae, expression pattern of GalR1a was mainly restricted to the intestine, pectoral fin, branchial arches and head, indicating a role of GalR1a during zebrafish embryogenesis. Quantitative real-time PCR assay suggested that fasting, high fat feeding or linoleic acid (LA) all could significantly induce up-regulation of GalR1a both in vitro and in vivo, suggesting roles of GalR1a in control of nutrition intake, especially to fat. In addition, a potential role of zebrafish GalR1a in accumulation of lipid droplets in cells was also demonstrated. Our study lays a foundation for further investigation of GalR1a function and evolution in fish.
authors.affiliation: College of Marine Life Science, Ocean University of China, Qingdao 266003, China.
authors.forename: Linfang
authors.initials: L
authors.lastname: Li
authors.forename: Shulei
authors.initials: S
authors.lastname: Wei
authors.forename: Qiaoyan
authors.initials: Q
authors.lastname: Huang
authors.forename: Dong
authors.initials: D
authors.lastname: Feng
authors.forename: Shicui
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhenhui
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D002460:Cell Line; D059305:Diet, High-Fat; D047108:Embryonic Development / Q000187:drug effects / Q000235:genetics; D005215:Fasting; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D006801:Humans; D017403:In Situ Hybridization; D019787:Linoleic Acid / Q000494:pharmacology; D008297:Male; D009747:Nutritional Physiological Phenomena / Q000187:drug effects / Q000235:genetics*; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044091:Receptor, Galanin, Type 1 / Q000235:genetics* / Q000378:metabolism; D014018:Tissue Distribution / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D044091:Receptor, Galanin, Type 1; D019787:Linoleic Acid