Effect of hypophysectomy on the chemical composition and intermediary metabolism of the Japanese eel, Anguilla japonica

Abstract

Based on the electrolyte and nitrogen balance of the animal, the chemical composition of the parietal white muscle, the rate of loss in body weight, and the oxygen consumption and carbon dioxide production rates, a metabolic balance sheet has been drawn up for the intact unfed eel kept in fresh water. Catabolism of muscle reserves constitutes the major source of energy supply to the animal. Most of the decline in electrolyte and metabolite concentrations in blood, muscle, and liver following hypophysectomy can be attributed to the gain in water content. However, there was a real decline in the level of glucose, total lipid, and free fatty acids in the blood and a reduction in total liver protein, liver and muscle glycogen, liver transaminases (GOT and GPT), and gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-diphosphatase). The overall effect was a reduction in gluconeogenesis and a shift from utilizing principally fat and protein to the utilization of carbohydrate. The metabolic rate registered declines of 33.6 and 37.9% compared with intact and sham-operated eels, respectively. A metabolic balance sheet was also obtained for the hypophysectomized eel 2 weeks after the operation.