Alterations in muscle metabolism and growth during nutritional restrictions and refeeding in rainbow trout.

Authors: Overturf, Kenneth - Ken; JOHANSEN, KATHERINE - FORMER USDA ARS EMPLOYEE

Submitted to: Book of Abstracts Aquaculture America
Publication Type: Proceedings
Publication Acceptance Date: 9/15/2005
Publication Date: 2/13/2006
Citation: Overturf, K., and Johansen, K. (2006) Alterations in muscle metabolism and growth during nutritional restrictions and refeeding in rainbow trout. Book of abstracts Aquaculture America, Pg 221

Interpretive Summary: Rainbow trout, as well as many other species of fish, demonstrate the ability to survive starvation for long periods of time. During starvation, growth rate is decreased and muscle exhibits signs of wasting. However, upon resumption of feeding, accelerated growth (also known as compensatory growth) is often observed. Alterations in muscle metabolism occur during feed restriction and refeeding, although the ways in which these alterations affect the molecular pathways that control muscle growth have not been fully determined. To analyze the changes in muscle metabolism and growth during starvation and refeeding, real-time PCR was used to test the expression of six metabolic factors and seven muscle-specific genes in rainbow trout white muscle prior to and after 30 days of starvation, and after four and 14 days of satiate refeeding. The six metabolic factors chosen were indicative of specific metabolic pathways. The seven muscle specific genes showen were key components in muscle growth and structural integrity. Alterations in expression of the tested metabolic factors and muscle-specific genes suggest that during starvation, specific changes in metabolic pathways initiate changes in muscle that result mainly in the reduction of muscle fiber size.

Technical Abstract: Rainbow trout, as well as many other species of fish, demonstrate the ability to survive starvation for long periods of time. During starvation, growth rate is decreased and muscle exhibits signs of wasting. However, upon resumption of feeding, accelerated growth (also known as compensatory growth) is often observed. Alterations in muscle metabolism occur during feed restriction and refeeding, although the ways in which these alterations affect the molecular pathways that control muscle growth have not been fully determined. To analyze the changes in muscle metabolism and growth during starvation and refeeding, real-time PCR was used to test the expression of six metabolic factors and seven muscle-specific genes in rainbow trout white muscle prior to and after 30 days of starvation, and after four and 14 days of satiate refeeding. The six metabolic factors chosen were indicative of specific metabolic pathways: glycolysis, glycogenesis, gluconeogenesis, the pentose phosphate pathway, and fructose metabolism. The seven muscle specific genes showen were key components in muscle growth and structural integrity. Alterations in expression of the tested metabolic factors and muscle-specific genes suggest that during starvation, specific changes in the glycolytic, glycogenic, pentose phosphate and gluconeogenic pathways initiate changes in muscle that result mainly in the reduction of myotube hypertrophy. During the refeeding and compensatory growth period, alterations in gene expression suggest that specific changes in the pentose phosphate, fructose metabolism, and gludoneogenic pathways initiate changes in both myoblast proliferation and myotube hypertrophy. Many of the metabolic changes observed were different that those previously observed during feeding to satiation.