Abstract
Thyroparathyroidectomy (TPTX) caused a significant increase in serum glucose and a corresponding fall in serum calcium in both fed and fasted rats. The increase in serum glucose, induced by TPTX, was markedly potentiated by a single intraperitoneal administration of calcium (2mg/100g BW) which caused a significant elevation of serum calcium in thyroparathyroidectomized rats. Parathyroid hormone (PTH; 20U/100g BW) administered subcutaneously to thyroparathyroidectomized rats, caused a significant decrease in serum glucose, but did not increase serum calcium. A single intraperitoneal administration of glucose (0.1g/100g BW) to sham-operated rats significantly increased both serum glucose and insulin. The rise of serum glucose produced by a glucose load was markedly potentiated by TPTX, but the increase in serum insulin was not promoted significantly. The administration of PTH decreased both serum glucose and insulin levels increased by a glucose load to thyroparathyroidectomized rats, in a dose-dependent manner. The administration of calcitonin (80MRC mU/100g BW) significantly prevented the effect of PTH to decrease serum glucose after a glucose load to thyroparathyroidectomized rats, and calcitonin increased serum insulin. These results suggest that the effect of PTH on serum glucose does not involve insulin secretion.
