title: Early decrease in dietary protein:energy ratio by fat addition and ontogenetic changes in muscle growth mechanisms of rainbow trout: short- and long-term effects.
abstract: As the understanding of the nutritional regulation of muscle growth mechanisms in fish is fragmentary, the present study aimed to (1) characterise ontogenetic changes in muscle growth-related genes in parallel to changes in muscle cellularity; (2) determine whether an early decrease in dietary protein:energy ratio by fat addition affects the muscle growth mechanisms of rainbow trout (Oncorhynchus mykiss) alevins; and (3) determine whether this early feeding of a high-fat (HF) diet to alevins had a long-term effect on muscle growth processes in juveniles fed a commercial diet. Developmental regulation of hyperplasia and hypertrophy was evidenced at the molecular (expression of myogenic regulatory factors, proliferating cell nuclear antigen and myosin heavy chains (MHC)) and cellular (number and diameter of white muscle fibres) levels. An early decrease in dietary protein:energy ratio by fat addition stimulated the body growth of alevins but led to a fatty phenotype, with accumulation of lipids in the anterior part, and less caudal muscle when compared at similar body weights, due to a decrease in both the white muscle hyperplasia and maximum hypertrophy of white muscle fibres. These HF diet-induced cellular changes were preceded by a very rapid down-regulation of the expression of fast-MHC. The present study also demonstrated that early dietary composition had a long-term effect on the subsequent muscle growth processes of juveniles fed a commercial diet for 3 months. When compared at similar body weights, initially HF diet-fed juveniles indeed had a lower mean diameter of white muscle fibres, a smaller number of large white muscle fibres, and lower expression levels of MyoD1 and myogenin. These findings demonstrated the strong effect of early feed composition on the muscle growth mechanisms of trout alevins and juveniles.
authors.affiliation: INRA, UR 1067 Nutrition Métabolisme Aquaculture, Aquapôle,F-64310Saint-Pée-sur-Nivelle,France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Alami-Durante
authors.affiliation: INRA, UR 1067 Nutrition Métabolisme Aquaculture, Aquapôle,F-64310Saint-Pée-sur-Nivelle,France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Cluzeaud
authors.affiliation: INRA, UR 1067 Nutrition Métabolisme Aquaculture, Aquapôle,F-64310Saint-Pée-sur-Nivelle,France.
authors.forename: Carine
authors.initials: C
authors.lastname: Duval
authors.affiliation: INRA, UR 1067 Nutrition Métabolisme Aquaculture, Aquapôle,F-64310Saint-Pée-sur-Nivelle,France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Maunas
authors.affiliation: INRA, UR 1067 Nutrition Métabolisme Aquaculture, Aquapôle,F-64310Saint-Pée-sur-Nivelle,France.
authors.forename: Virginia
authors.initials: V
authors.lastname: Girod-David
authors.affiliation: INRA, UR 1067 Nutrition Métabolisme Aquaculture, Aquapôle,F-64310Saint-Pée-sur-Nivelle,France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Médale
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D004041:Dietary Fats / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage*; D002149:Energy Intake; D006965:Hyperplasia; D006984:Hypertrophy; D008055:Lipids / Q000032:analysis; D024510:Muscle Development; D018656:Muscle Fibers, Fast-Twitch / Q000473:pathology; D018482:Muscle, Skeletal / Q000254:growth & development*; D017570:MyoD Protein / Q000235:genetics; D018008:Myogenin / Q000235:genetics; D018995:Myosin Heavy Chains / Q000235:genetics; D017686:Oncorhynchus mykiss / Q000254:growth & development*; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics
chemical_list: D004041:Dietary Fats; D004044:Dietary Proteins; D008055:Lipids; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D018008:Myogenin; D018809:Proliferating Cell Nuclear Antigen; D018995:Myosin Heavy Chains