Effects of feeding level and sexual maturation on expression of genes regulating growth mechanisms in rainbow trout (Oncorhynchus mykiss)

The energy and nutrient demands of sexual maturation in salmonids requires a shift from somatic growth to gonadal development, although loss skeletal muscle can be avoided with adequate nutrition. How availability or ration affects the endocrine factor systems that integrate partitioning, metabolism, during is poorly understood. Primary objectives current study were determine how affect expression estrogen receptors, components GH/IGF axis TGF? superfamily system, specific regulatory factors development female rainbow trout (Oncorhynchus mykiss). Female diploid approaching ovulation fed for 12 weeks at 0.25% 0.50% tank biomass, apparent satiation. Controls effects included sterile triploid two females failed undergo development. Expression era1 was increased maturing diploids suggesting an increase catabolic 17?-estradiol (E2) on muscle. In liver, era2 maturation, but all receptors higher rations improved E2 sensitivity vitellogenin production. Hepatic ghrs igfs generally reduced reduction systemic promotion. Increased capacity IGF signaling via igf1 igfr1b expression, potentially lessening circulating IGF-I growth. primary carrier IGFs, hepatic igfbp2b1, likely reducing activity, also elevated rations. All other binding proteins, except igfbp1, showed some several ration. igfbp6b1 suggests restricted myogenesis maturation. Reductions including pax7a, myog myf5, support unaffected by addition, mstn2a only myostatin gene affected ration, altered suggest may inhibit signaling. summary, moderate feeding appears counter many changes system associated perhaps altering regulation spare atrophy better prepare fish post-spawning recovery.