title: Short periods of fasting followed by refeeding change the expression of muscle growth-related genes in juvenile Nile tilapia (Oreochromis niloticus).
abstract: Muscle growth mechanisms are controlled by molecular pathways that can be affected by fasting and refeeding. In this study, we hypothesized that short period of fasting followed by refeeding would change the expression of muscle growth-related genes in juvenile Nile tilapia (Oreochromis niloticus). The aim of this study was to analyze the expression of MyoD, myogenin and myostatin and the muscle growth characteristics in the white muscle of juvenile Nile tilapia during short period of fasting followed by refeeding. Juvenile fish were divided into three groups: (FC) control, feeding continuously for 42 days, (F5) 5 days of fasting and 37 days of refeeding, and (F10) 10 days of fasting and 32 days of refeeding. At days 5 (D5), 10 (D10), 20 (D20) and 42 (D42), fish (n=14 per group) were anesthetized and euthanized for morphological, morphometric and gene expression analyses. During the refeeding, fasted fish gained weight continuously and, at the end of the experiment (D42), F5 showed total compensatory mass gain. After 5 and 10 days of fasting, a significant increase in the muscle fiber frequency (class 20) occurred in F5 and F10 compared to FC that showed a high muscle fiber frequency in class 40. At D42, the muscle fiber frequency in class 20 was higher in F5. After 5 days of fasting, MyoD and myogenin gene expressions were lower and myostatin expression levels were higher in F5 and F10 compared to FC; at D42, MyoD, myogenin and myostatin gene expression was similar among all groups. In conclusion, this study showed that short periods of fasting promoted muscle fiber atrophy in the juvenile Nile tilapia and the refeeding caused compensatory mass gain and changed the expression of muscle growth-related genes that promote muscle growth. These fasting and refeeding protocols have proven useful for understanding the effects of alternative warm fish feeding strategies on muscle growth-related genes.
authors: São Paulo State University, Institute of Biosciences, Department of Morphology, 18618-970, Botucatu, SP, Brazil. Electronic address: carolnebo@hotmail.com.
authors: Caroline
authors: C
authors: Nebo
authors: São Paulo State University, Aquaculture Center (CAUNESP), 14884-900, Jaboticabal, SP, Brazil. Electronic address: portella@caunesp.unesp.br.
authors: Maria Célia
authors: MC
authors: Portella
authors: São Paulo State University, Institute of Biosciences, Department of Morphology, 18618-970, Botucatu, SP, Brazil. Electronic address: fcarani@gmail.com.
authors: Fernanda Regina
authors: FR
authors: Carani
authors: São Paulo State University, Institute of Biosciences, Department of Morphology, 18618-970, Botucatu, SP, Brazil. Electronic address: fernandalosi@gmail.com.
authors: Fernanda Losi Alves
authors: FL
authors: de Almeida
authors: São Paulo State University, Institute of Biosciences, Department of Biostatistics, 18618-970, Botucatu, SP, Brazil. Electronic address: bioestatistica@ibb.unesp.br.
authors: Carlos Roberto
authors: CR
authors: Padovani
authors: São Paulo State University, Institute of Biosciences, Department of Morphology, 18618-970, Botucatu, SP, Brazil. Electronic address: rcarvalho@ibb.unesp.br.
authors: Robson Francisco
authors: RF
authors: Carvalho
authors: São Paulo State University, UNESP, Institute of Biosciences, Department of Morphology and CAUNESP, 18618-970, Botucatu, Sao Paulo, Brazil. Electronic address: maeli@ibb.unesp.br.
authors: Maeli
authors: M
authors: Dal-Pai-Silva
mesh_terms: D000818:Animals; D001835:Body Weight; D023681:Cichlids / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005215:Fasting / Q000378:metabolism; D015870:Gene Expression; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism*; D017570:MyoD Protein / Q000378:metabolism; D018008:Myogenin / Q000378:metabolism; D055435:Myostatin / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D017570:MyoD Protein; D018008:Myogenin; D055435:Myostatin; D012333:RNA, Messenger
keywords: Fasting; Muscle Growth; Myogenic regulatory factors; Myostatin; Refeeding