title: Acute physiological stress down-regulates mRNA expressions of growth-related genes in coho salmon.
abstract: Growth and development in fish are regulated to a major extent by growth-related factors, such as liver-derived insulin-like growth factor (IGF) -1 in response to pituitary-secreted growth hormone (GH) binding to the GH receptor (GHR). Here, we report on the changes in the expressions of gh, ghr, and igf1 genes and the circulating levels of GH and IGF-1 proteins in juvenile coho salmon (Oncorhynchus kisutch) in response to handling as an acute physiological stressor. Plasma GH levels were not significantly different between stressed fish and prestressed control. Plasma IGF-1 concentrations in stressed fish 1.5 h post-stress were the same as in control fish, but levels in stressed fish decreased significantly 16 h post-stress. Real-time quantitative PCR (qPCR) analysis showed that ghr mRNA levels in pituitary, liver, and muscle decreased gradually in response to the stressor. After exposure to stress, hepatic igf1 expression transiently increased, whereas levels decreased 16 h post-stress. On the other hand, the pituitary gh mRNA level did not change in response to the stressor. These observations indicate that expression of gh, ghr, and igf1 responded differently to stress. Our results show that acute physiological stress can mainly down-regulate the expressions of growth-related genes in coho salmon in vivo. This study also suggests that a relationship between the neuroendocrine stress response and growth-related factors exists in fish.
authors.affiliation: Marine Biochemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Nakano
authors.forename: Luis O B
authors.initials: LO
authors.lastname: Afonso
authors.forename: Brian R
authors.initials: BR
authors.lastname: Beckman
authors.forename: George K
authors.initials: GK
authors.lastname: Iwama
authors.forename: Robert H
authors.initials: RH
authors.lastname: Devlin
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D029941:Fish Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000378:metabolism; D006854:Hydrocortisone / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D017684:Oncorhynchus kisutch / Q000235:genetics*; D010902:Pituitary Gland / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D060888:Real-Time Polymerase Chain Reaction; D011986:Receptors, Somatotropin / Q000235:genetics; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D017931:DNA Primers; D018076:DNA, Complementary; D029941:Fish Proteins; D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D006854:Hydrocortisone