CHANGES IN THE BLOOD GLUCOSE, LIVER GLYCOGEN AND HISTOLOGY FO THE PANCREATIC ISLETS OF URMASTIX HARDWICKII AFTER ADMINISTRATION OF INSULIN, GLUCOSE AND COCL2

Abstract

VARIATIONS in the blood glucose, liver glycogen and histology of the pancreatic Islets were studied after administration of Insulin, glucose and Cobalt Chloride in the lizard Uromastix hardwickii . Doses of Insulin less than 500 lU/Kg have no effect on blood glucose, liver glycogen and histologycr the Pancreatic Islets. Minimum dose that produced a reaction was 500 lU . Insulin ( 500- p-7 00 - 1000 lU/Kg) was administered intraperitoneally and changes were observed after 20, 30 and 60 minutes of injection . Hypoglycemia was observed only during first 20 ~ 30 minutes and after 60 minutes a compensatory hyperglycemia and a decrease in liver glycogen was noted. The magnitude of hyperglycemia caused by insulin was dose dependent. Uromastix hardwickii was found to be more resistant to insulin as compared to other poikilothermic vertebrates and this resistance may be due to pre-ponderance of glucagon secreting alpha cells in this species. Histologically, insulin at higher doses induced degranulation of both the beta and alpha cells. 25% solution of glucose was injected intramuscularly in uromastix in doses of 1-2 g/Kg body weight . Changes in the blood glucose liver glycogen and histology of the pancreatic Islets were observed at 1,6,24,48 hours after the injection of glucose. Hyperglycemia and an increase in glycogen content of the liver was observed. A maximal 3 glycemic response was observed at 1 hour stage and blood sugar returned to normal value after 48 hours of glucose administration . This delay in restoration to norma l l evel is perhaps due to l ower level o f circulating Insulin in Uromastix . The observation that the beta cells are concerned with the production of insulin is reinforced by the degranulation of beta cells after glucose administration . Gluc~e (2g/Kg) was also administered in combination with Insulin (700 lU/Kg) and changes were observed after 1,6,24 hours of injection . It resulted in hyperglycemia, increase in the liver glycogen and degranulation of beta cells. Hyperglycemia induced by combination of glucose and insulin was not 50% of tha t p r oduced by g luc ose a lone . This may be due to low sensitivity of u r omastix to Insulin . 5% sol u t ion o f Cobalt Chl o r ide was injected intramuscularly in Uromastix in doses of 25, 50, 100 mg/Kg body weight . With higher dosages(50 , 100 mg/kg) changes were observed at 1/2, 1,2,3, hours after injection (since the animal could not survive more than 3 hours) . With 25 mg/kg dose changes were observed at 1,3, 6,24 hours . Elevation of blood glucose and a decrease in liver glycogen was observed with all the doses employed . This hyperglycemia was explained by some authors as a result of release of glu cagon . The Islet cell alterations included degranulation of alpha cells, while beta c ells s howed v acuol isation and contr action .