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Title: APPEARANCE OF INSULIN-LIKE GROWTH FACTOR (IGF) MRNA IN THE LIVER AND PYLORIC CAECA OF A TELEOST IN RESPONSE TO EXOGENOUS GROWTH HORMONE

Author
item SHAMBLOTT, M - U. OF MARYLAND, BALTIMORE
item CHENG, C - U. OF MARYLAND, BALTIMORE
item BOLT, D - 1265-10
item CHEN, T - U. OF MARYLAND, BALTIMORE

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: In vertebrates, growth hormone (GH) regulates growth primarily by regulating insulin-like growth factor I (IGF I) and IGF II. The role of GH in regulating growth in fish is largely unknown. This study characterized the effect of GH on IGF I and IGF II mRNA by RNAse protection assays in various tissues over a three day post-injection period in rainbow trout. Growth hormone-dependent IGF mRNA was found primarily in the liver and pyloric caeca. The GH-dependent appearance of IGF II mRNA suggests important roles for this peptide hormone exclusive of IGF I in the trout. These findings are useful to researchers in the general area of GH endocrinology and the specific area of improving the efficiency of producing food by aquaculture.

Technical Abstract: Augmentation of vertebrate growth by growth hormone (GH) is primarily due to its regulation of insulin-like growth factor I (IGF I) and IGF II levels. In order to characterize the effect of GH on the levels of IGF I and IGF II mRNA in a teleost, 10 ug bovine GH (bGH)/g body weight was administered to juvenile rainbow trout (Oncorhynchus mykiss) through intraperitoneal injection. The levels of IGF I and IGF II mRNA were determined simultaneously, by using RNAse protection assays, in the liver, pyloric caeca, kidney, and gill at 0, 1, 3, 6, 12, 24, 48, 72 h post injection. In the liver, IGF I mRNA levels were significantly elevated at 6 and 12 h (approx. 2-3 fold, P