To elucidate the possible role of thyroid hormone in somatomedin-C (SmC)/ insulin-like growth factor I regulation in diabetes mellitus and starvation, plasma SmC, liver SmC, and kidney SmC concentrations were measured in streptozotocin-induced (60 mg/kg) diabetic and starved (for 72 h) rats. Triiodothyronine (T3, 5.0 µg/kg every 24 h) was subcu-taneously injected into diabetic rats for 7 days and into starved rats at 12, 36, and 60 h after starvation. Plasma T3, plasma SmC, liver SmC, and kidney SmC concentrations were significantly decreased in diabetic and starved rats. T3 administration restored plasma T3 levels to the normal value in diabetic and starved rats. Plasma SmC and kidney SmC concentrations were significantly increased in T3-treated starved rats, while they were not increased in T3-treated diabetic rats. These results suggest that thyroid hormone may have some role in SmC regulation during starvation, but may have no role in diabetes mellitus in the rat.
Catecholamine is well known to have an important role to metabolize ketone bodies. P-ractically, hyperketonemia is frequently observed both in hyperthyroidism 1nd starvation of various species l-71. Besides, several investigators have reported 1n increase of catecholamine in serum and ur-ine during starvation of animals 8101. Beylot et al. 51 have reported an implication that catecholamine affects some symptoms. of hyperthyroidism through S-receptors. However, the role of the adrenergic mechanism in hyperketonemia involved in hyperthyroidism and starvation remains to be fully elucidated. In this study, we investigated the possible role of the adrenergic mechanism in experimental hyperketonemia in thyrotoxic or starved rats.
Using the isolated and perfused liver of rats, we investigated the effect of starvation on hepatic glucose output and hepatic insulin extraction. The rats were starved for 72 h. The intestines of fed and starved rats were isolated and perfused, and portal venous effluent (PVE) was collected. The liver of fed and starved rats was perfused with synthetic medium or PVE containing 100 mg/dl glucose and 100 muU/ml insulin. Fractional uptake of insulin and reduction in glucose output by the perfused liver were almost the same in all groups. These results suggest that the removal and action of insulin in the liver were not altered by short-term starvation in rats.
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