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Ethanol Suppresses Growth Hormone‐Mediated Cellular Responses in Liver Slices
Author(s) -
Xu Xiaowei,
Ingram Rhonda L.,
Sonntag William E.
Publication year - 1995
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1995.tb01607.x
Subject(s) - medicine , endocrinology , hormone , receptor , ethanol , growth factor , hormone receptor , secretion , insulin like growth factor , chemistry , growth hormone receptor , biology , growth hormone , biochemistry , cancer , breast cancer
Previous studies indicate that both acute and chronic ethanol administration inhibit protein synthesis and decrease the secretion of insulin‐like growth factor‐1 (IGF‐1). Although IGF‐1 synthesis and secretion are regulated by growth hormone secretion from the pituitary gland, we assessed whether ethanol inhibits tissue response to growth hormone. Liver slices from male Sprague‐Dawley rats were prepared, placed into F‐12 media, and incubated at 37°C with [ 3 H]leucine, and either 0.25 or 1 nM rat growth hormone and 0, 37 (physiological levels), or 175 mM (toxic levels) ethanol. Tissues were removed at 0,15,30, and 60 min. Protein synthesis increased linearly during this time period, and administration of growth hormone (1 nM) significantly increased protein synthetic rate by 48% ( p < 0.01), whereas addition of 37 or 175 mM ethanol attenuated the effects of growth hormone ( p < 0.01). Analysis of IGF‐1 mRNA indicated a 2‐fold increase in response to growth hormone ( p < 0.01), whereas ethanol administration decreased the growth hormone‐induced rise of IGF‐1 mRNA. Ethanol (175 mM) inhibited the release of IGF‐1 into the media ( p < 0.05). Ethanol did not alter growth hormone receptor binding, and exposure of tissue slices to ethanol did not influence the number of growth hormone receptors or the affinity of growth hormone for its receptor. Our results demonstrate that (1) growth hormone is a potent acute regulator of IGF‐1 mRNA and IGF‐1 peptide release, (2) ethanol inhibits growth hormone‐induced protein synthesis and induction of IGF‐1 gene expression, and (3) the inhibitory effects of ethanol on growth hormone occur without changing growth hormone receptor number or binding characteristics. We conclude that ethanol suppresses growth hormone‐induced signal transduction, resulting in a decrease in IGF‐1 gene expression.