Metabolic and histological pancreatic changes induced by ovariectomy in the female dog.

The actions of ovariectomy performed 4 months in advance on pancreas cytology and also upon the blood sugar, serum immunoreactive insulin and circulating free fatty acid changes over glucose and insulin tests, were studied in female dogs. We concluded that ovariectomy does not affect blood sugar -basally or during the tests-, glucose space and clearance rate of glucose from circulation. Conversely, the integrated insulinemic response over glucose test was highly risen (956%) by ovariectomy in such animals; the rise occurs despite they show a broadened (59%) insulin space, is slightly mediated by a reduction (132%) in insulin clearance from circulation, and appears to be chiefly mediated by a major enhancement in insulin secretion. The immunocytolocalization of insulin in the pancreatic tissue of ovariectomized female dogs showed hypertrophy of Langerhans islets, beta-degranulation but no vacuolation. However, the piling up of the beta-granules by the vascularly pole of the B-cells as well as the appearance of a pretty number of small islets and microislets widespread over the acini, absent in the pancreatic tissue of the untreated controls in anestrous, indicate for the insulin secretory potency of the pancreas of the ovariectomized female dog to be apparently high. In the female dog, ovariectomy affects serum free fatty acid levels via at least two mechanisms, viz., a) stimulation of lipid storage over the glucose test, and b) reduction in lipomobilization as insulin antagonism predominates.