Kim Jin-Hyoung, Chatchaiphan Satid, Crown Michelle T, White Samantha L, Devlin Robert H
Fisheries and Oceans Canada, Centre for Aquaculture and Environmental Research, 4160 Marine Drive, West Vancouver, BC, Canada.
Unit of Polar Genomics, Korea Polar Research Institute, 26, Songdomirae-ro, Yeonsu-gu, Incheon, Republic of Korea.
Fish Physiol Biochem. 2018 Feb;44(1):119-135. doi: 10.1007/s10695-017-0418-4. Epub 2017 Sep 11.
Growth hormone (GH) transgenic (T) coho salmon consistently show remarkably enhanced growth associated with increased appetite and food consumption compared to non-transgenic wild-type (NT) coho salmon. To improve understanding of the mechanism by which GH overexpression mediates food intake and digestion in T fish, feed intake and gastric evacuation rate (over 7 days) were measured in size-matched T and NT coho salmon. T fish displayed greatly enhanced feed intake levels (~ 2.5-fold), and more than 3-fold increase in gastric evacuation rates relative to NT coho salmon. Despite the differences in feed intake, no differences were noted in the time taken from first ingestion of food to stomach evacuation between genotypes. These results indicate that enhanced feed intake is coupled with an overall increased processing rate to enhance energy intake by T fish. To further investigate the molecular basis of these responses, we examined the messenger RNA (mRNA) levels of several genes in appetite- and gastric-regulation pathways (Agrp1, Bbs, Cart, Cck, Glp, Ghrelin, Grp, Leptin, Mc4r, Npy, and Pomc) by qPCR analyses in the brain (hypothalamus, preoptic area) and pituitary, and in peripheral tissues associated with digestion (liver, stomach, intestine, and adipose tissue). Significant increases in mRNA levels were found for Agrp1 in the preoptic area (POA) of the brain, and Grp and Pomc in pituitary for T coho salmon relative to NT. Mch and Npy showed significantly lower mRNA levels than NT fish in all brain tissues examined across all time-points after feeding. Mc4r and Cart for T showed significantly lower mRNA levels than NT in the POA and hypothalamus, respectively. In the case of peripheral tissues, T fish had lower mRNA levels of Glp and Leptin than NT fish in the intestine and adipose tissue, respectively. Grp, Cck, Bbs, Glp, and Leptin in stomach, adipose tissue, and/or intestine showed significant differences across the time-points after feeding, but Ghrelin showed no significant difference between T and NT fish in all tested tissues.
与非转基因野生型（NT）银大麻哈鱼相比，生长激素（GH）转基因（T）银大麻哈鱼始终表现出显著增强的生长，这与食欲增加和食物消耗增多有关。为了更好地理解GH过表达介导T鱼摄食和消化的机制，对大小匹配的T和NT银大麻哈鱼的采食量和胃排空率（7天内）进行了测量。相对于NT银大麻哈鱼，T鱼的采食量显著提高（约2.5倍），胃排空率增加了3倍多。尽管采食量存在差异，但不同基因型从首次摄食到胃排空的时间没有差异。这些结果表明，采食量的增加与整体加工速率的提高相关联，从而增强了T鱼的能量摄入。为了进一步研究这些反应的分子基础，我们通过qPCR分析检测了大脑（下丘脑、视前区）和垂体以及与消化相关的外周组织（肝脏、胃、肠道和脂肪组织）中几个食欲和胃调节途径相关基因（Agrp1、Bbs、Cart、Cck、Glp、Ghrelin、Grp、Leptin、Mc4r、Npy和Pomc）的信使核糖核酸（mRNA）水平。相对于NT，T银大麻哈鱼大脑视前区（POA）的Agrp1以及垂体中的Grp和Pomc的mRNA水平显著增加。在喂食后的所有时间点，所有检测的脑组织中，Mch和Npy的mRNA水平均显著低于NT鱼。T鱼的Mc4r和Cart在POA和下丘脑的mRNA水平分别显著低于NT鱼。在外周组织中，T鱼在肠道和脂肪组织中的Glp和Leptin的mRNA水平分别低于NT鱼。胃、脂肪组织和/或肠道中的Grp、Cck、Bbs、Glp和Leptin在喂食后的时间点上存在显著差异，但在所有测试组织中，Ghrelin在T和NT鱼之间没有显著差异。
