Meeting Abstract

87.5  Thursday, Jan. 7  Expression of Insulin and Insulin Receptor mRNAs is Regulated by Growth Hormone and Somatostatin in Rainbow Trout CARUSO, M.A.*; SHERIDAN, M.A.; North Dakota State University Michael.Caruso@ndsu.edu

Insulin (INS) coordinates various aspects of growth, development, and metabolism. In teleost fish, the INS signaling system consists of multiple INSs as well as multiple insulin receptor (IR) subtypes. In this study, we used rainbow trout (Oncorhynchus mykiss) as a model to examine the regulation of the INS signaling system by growth hormone (GH) and somatostatin-14 (SS-14). Juvenile fish were implanted with mini-osmotic pumps containing saline, GH, or SS for 21 days, and the expression of INS- (INS1, INS2) and IR- (IR1, IR2, IR3, and IR4) encoding mRNAs was measured by quantitative real-time PCR. GH regulated the expression of INS and IR in a subtype- and tissue-specific manner. GH- implanted animals displayed reduced INS1 in adipose, increased INS2 in the brain, reduced IR1, IR2, IR3, and IR4 expression in cardiac muscle, reduced IR1 in the gill, increased IR3 in the liver, and increased INS1, INS2, IR2, IR3, and IR4 in the pancreas. SS-14 also regulated INS and IR expression in a subtype- and tissue-specific manner. SS-14-implanted animals displayed increased INS1 and INS2 in adipose, increased INS1 in the brain, reduced expression of IR1, IR2, and IR4 in cardiac muscle, reduced IR2 and IR3 in gill, reduced IR2 and IR4 in the liver, increased INS1 and reduced INS2, IR1, and IR2 in the pancreas. These results demonstrate that GH and SS-14 modulate the expression of INS1, INS2, IR1, IR2, IR3, and IR4, and imply that independent mechanisms may serve to regulate the various hormone isoforms and receptor subtypes in a tissue-specific manner. (Supported by NSF IOS 0920116)