Article

Metabolic and mitogenic effects of IGF-I and insulin on muscle cells of rainbow trout.

Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, E-08028 Barcelona, Spain.
AJP Regulatory Integrative and Comparative Physiology (Impact Factor: 3.53). 06/2004; 286(5):R935-41. DOI: 10.1152/ajpregu.00459.2003
Source: PubMed

ABSTRACT The relative function of IGF-I and insulin on fish muscle metabolism and growth has been investigated by the isolation and culture at different stages (myoblasts at day 1, myocytes at day 4, and myotubes at day 10) of rainbow trout muscle cells. This in vitro model avoids interactions with endogenous peptides, which could interfere with the muscle response. In these cells, the effects of IGF-I and insulin on cell proliferation, 2-deoxyglucose (2-DG), and l-alanine uptake at different development stages, and the use of inhibitors were studied and quantified. Insulin (10-1,000 nM) and IGF-I (10-100 nM) stimulated 2-DG uptake in trout myocytes at day 4 in a similar manner (maximum of 124% for insulin and of 142% for IGF-I), and this stimulation increased when cells differentiated to myotubes (maximum for IGF-I of 193%). When incubating the cells with PD-98059 and especially cytochalasin B, a reduction in 2-DG uptake was observed, suggesting that glucose transport takes place through specific facilitative transporters. IGF-I (1-100 nM) stimulated the l-alanine uptake in myocytes at day 4 (maximum of 239%), reaching higher values of stimulation than insulin (100-1,000 nM) (maximum of 160%). This stimulation decreased when cells developed to myotubes at day 10 (118% for IGF-I and 114% for insulin). IGF-I (0.125-25 nM) had a significant effect on myoblast proliferation, measured by thymidine incorporation (maximum of 170%), and required the presence of 2-5% fetal serum (FBS) to promote thymidine uptake. On the other hand, insulin was totally ineffective in stimulating thymidine uptake. We conclude that IGF-I is more effective than insulin in stimulating glucose and alanine uptake in rainbow trout myosatellite cells and that the degree of stimulation changes when cells differentiate to myotubes. IGF-I stimulates cell proliferation in this model of muscle in vitro and insulin does not. These results indicate the important role of IGF-I on growth and metabolism of fish muscle.

0 Bookmarks
 · 
113 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the present study a commercial probiotic Fishery Prime TM , acting as water soluble probiotic, was administered to Yellow Perch (Perca flavescens) for 6 weeks. The probiotic effect on growth and growth regulated genes were evaluated with respect to fish group fed on commercial feed (control group). Measures of body weight were performed to assess the growth performance. In addition, the expression of two related and highly indicative candidate genes involved in growth (Insulin-Like Growth Factor IGF-I and Growth Hormone GH) were quantified through real-time PCR. Fish received the probiotic exhibited higher growth performance than control group at significance level (p < 0.05).Up regulation of GH and IGF-I transcriptions were observed in fish group received with probiotic which revealed higher levels than the control. The results confirmed the positive correlation between growth performance, GH and IGF-I mRNA gene expression in both probiotic treated and control groups. In conclusion, probiotic during early developmental stages can confer maximum beneficial effects resulting in magnitude increase in survivorship.
    Global Journal of Fisheries and Aquaculture Researches. 11/2014; 1(2):1-15.
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to elucidate the possible roles of insulin-like growth factors I and II (IGF-I and IGF-II) in the embryonic development of Platichthys stellatus, their cDNAs were isolated and their spatial expression pattern in adult organs and temporal expression pattern throughout embryonic development were examined by quantitative real-time PCR assay. The IGF-I cDNA sequence was 1,268 bp in length and contained an open reading frame (ORF) of 558 bp, which encoded 185 amino acid residues. With respect to IGF-II, the full-length cDNA was 899 bp in length and contained a 648-bp ORF, which encoded 215 amino acid residues. The amino acid sequences of IGF-I and IGF-II exhibited high identities with their fish counterparts. The highest IGF-I mRNA level was found in the liver for both sexes, whereas the IGF-II gene was most abundantly expressed in female liver and male liver, gill, and brain. The sex-specific and spatial expression patterns of IGF-I and IGF-II mRNAs are thought to be related to the sexually dimorphic growth and development of starry flounder. Both IGF-I and IGF-II mRNAs were detected in unfertilized eggs, which indicated that IGF-I and IGF-II were parentally transmitted. Nineteen embryonic development stages were tested. IGF-I mRNA level remained high from unfertilized eggs to low blastula followed by a significant decrease at early gastrula and then maintained a lower level. In contrast, IGF-II mRNA level was low from unfertilized eggs to high blastula and peaked at low blastula followed by a gradual decrease. Moreover, higher levels of IGF-I mRNA than that of IGF-II were found from unfertilized eggs to high blastula, vice versa from low blastula to newly hatched larva, and the different expression pattern verified the differential roles of IGF-I and IGF-II in starry flounder embryonic development. These results could help in understanding the endocrine mechanism involved in the early development and growth of starry flounder.
    Fish Physiology and Biochemistry 11/2014; · 1.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: One of the most fundamental biological processes in living organisms that is affected by environmental fluctuations is growth. In fish, skeletal muscle accounts for the largest proportion of body mass, and the growth of this tissue is mainly controlled by the Insulin-like Growth Factor (IGF) system. By using the carp (Cyprinus carpio), a fish that inhabits extreme conditions during winter and summer, we assessed the skeletal muscle plasticity induced by seasonal acclimatization and the relation of IGF signaling with protein synthesis and ribosomal biogenesis. The expression of igf1 in muscle decreased during winter in comparison with summer, whereas the expression for both paralogues of igf2 did not change significantly between seasons. The expression of igf1 receptor a (igf1ra), but not of igf1rb, was down-regulated in muscle during the winter as compared to the summer. A decrease in protein contents and protein phosphorylation for IGF signaling molecules in muscle was observed in winter-acclimatized carp. This was related with a decreased expression in muscle for markers of myogenesis (myoblast determination factor (myod), myogenic factor 5 (myf5), and myogenin (myog)); protein synthesis (myosin heavy chain (mhc) and myosin light chain (mlc3 and mlc1b)); and ribosomal biogenesis (pre-rRNA and ribosomal proteins). IGF signaling, and key markers of ribosomal biogenesis, protein synthesis, and myogenesis were affected by seasonal acclimatization, with differential regulation in gene expression and signaling pathway activation observed in muscle between both seasons. This suggests that these molecules are responsible for the muscle plasticity induced by seasonal acclimatization in carp.
    Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology 10/2014; · 1.90 Impact Factor

Full-text (2 Sources)

Download
4 Downloads
Available from
Dec 23, 2014