Effects of growth hormone on the salmon pituitary proteome

Growth hormone 1 (GH1), a pituitary hormone, plays a key role in the regulation of growth. Both excess GH1 treatment and overexpression of a GH1 transgene promote growth of salmon, but these animals exhibit physiological abnormalities in viability, fertility and metabolism, which might be related to pituitary function. However, the molecular dynamics induced in the pituitary by excess GH1 remain unknown. In this study, we performed iTRAQ proteome analysis of the amago salmon pituitary, with and without excess GH1 treatment, and found that the expression levels of proteins related to endocrine systems, metabolism, cell growth and proliferation were altered in the GH1-treated pituitary. Specifically, pituitary hormone prolactin (2.29 fold), and somatolactin α (0.14 fold) changed significantly. This result was confirmed by proteome and transcriptome analyses of pituitary from the GH1-transgenic (GH1-Tg) amago salmon. The dynamics of protein and gene expression in the pituitary of GH1-Tg amago salmon were similar to those of pituitary treated with excess GH1. Our findings suggest that not only excess GH1 hormone, but also the quantitative changes in other pituitary hormones, might be essential for the abnormal growth of amago salmon. These data will be useful in future attempts to increase the productivity of fish farming.