Abstract
Growth hormone (GH) release, hepatic GH and insulin receptors have been studied in the genetically obese male Zucker (fa/fa) rat. In chronically cannulated 14 week-old rats, the pulsatile GH secretion is suppressed in obese rats and the GH pituitary content is 2 times lower in fa/fa than in lean animals. At 2, 3 and 5 weeks of age, no difference in the pituitary GH content is found in the two groups. At 23 days of age, fa/fa rats have a two-fold increase in their plasma insulin level ; the specific binding of 125I-hGH to liver membranes of obese male rats as compared to lean littermates is increased, 2.8 times in plasma membranes, 1.4 times in Golgi fractions. At 5, 11 and 14 weeks of age, plasma insulin is markedly elevated in obese rats and the level of GH receptors is higher in all liver subfractions of obese rats as compared to lean rats. After the 11th week, hyperinsulinemia is associated with a decrease binding of insulin to plasma membranes and to microsomal fractions of obese rats. Before the increase in plasma insulin appears, at 16 days of age, no difference in the level of GH receptors exists in plasma membranes and Golgi fractions of fa/fa rats and of their lean littermates. The increase in GH binding observed in obese male rats is simultaneous with the onset of hyperinsulinemia.
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Postel-Vinay, MC., Durand, P., Lopez, S. et al. 145 GROWTH HORMONE RECEPTORS AND THE ONSET OF HYPERINSULINEMIA IN THE OBESE ZUCKER RAT. Pediatr Res 19, 627 (1985). https://doi.org/10.1203/00006450-198506000-00165
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DOI: https://doi.org/10.1203/00006450-198506000-00165