諸種ビタミン類のラット血糖に及ぼす影響とその作用機序に関する実験的研究

抄録

In this experiment, the author used nine kinds of vitamins and the normal or alloxan diabetic, male or nonpregnant female Wistar strain rats, weighing over 120 g, to find out if there was a hypoglycemic action without any side effect among those drugs.
The blood sugar content was measured by the method of Somogyi-Nelson's blood sugar determination (micro-micro method).
1) Individual doses of 100 mg/kg of thiamine, 50 mg/kg of nicotinamide, 100 mg/kg of pyridoxine, 100 mg/kg of anthranilic acid, 100 mg/kg of folic acid, 400 γ/kg of cyanocobalamin, 400 γ/kg of hydroxobalamin, 5000 mg/kg of ascorbic acid or 50 mg/kg of hesperidin were administered intravenously in normal rats which had not been fed for 18 hours, with the following results :
a) A potent activity of blood sugar lowering effect was observed in the case of folic acid, cyanocobalamin and hydroxocobalamin.
The maximal hypoglycemic reduction ratio of the blood sugar level in folic acid was 45% one hour after the administration, but was of transient duration. In cyanocobalamin, the reduction ratio was 55% one hour after the administration, but the duration was also transient. In hydroxocobalamin, the reduction ratio was 46% 4 hours after the administration, and its action continued over 8 hours.
b) No hypoglycemic effect was observed in thiamine, nicotinamide, pyridoxine, anthranilic acid, ascorbic acid or hesperidin.
2) Individual doses of 400 mg/kg of folic acid, 1500 γ/kg of cyanocobalamin or 1500 γ/kg of hydroxocobalamin were administered orally via stomach tube in normal rats, which had not been fed for 18 hours, and the blood sugar lowering effect was observed in all of them. The maximal hypoglycemic reduction ratio of blood sugar level in folic acid was found to be 41% one hour after the administration, but it was of transient duration. In cyanocobalamin, the reduction ratio was 51% one hour after the administration and its duration was also transient. In hydroxocobalamin, the reduction ratio was 57% 6 hours after the administration and was of long duration.
3) Individual doses of 400 mg/kg of folic acid, 1500 r/kg of cyanocobalamin or 1500 r/kg of hydroxocobalamin were administered orally via stomach tube in alloxan diabetic rats, and a blood sugar lowering effect of much longer duration was observed in all of them.
The maximal hypoglycemic reduction ratio of boold sugar level in the case of folic acid was found to be 69% 5 hours after the administration. and in the case of cyanocobalamin it was 66% 5 hours after the administration. In both of these cases the rats had not been fed for 18 hours. With rats that had been fed normally, the maximal reduction ratio of the blood sugar level was found to be 43% 3 hours after the administration of cyanocobalamin and 54% 6 hours after the administration of hydroxocobalamin.
4) The administration of folic acid via stomach in normal rats, at a dose rate of 400 mg/kg/day or of cyanocobalamin at a dose rate of 1500 γ/kg/day for a month revealed no histological change in the various organs, including Langerhans' islet.
5) In an experiment involving intravenous administration of folic acid at a dose of 100 mg/kg and of cyanocobalamin at a dose of 400 γ/kg in normal rats, the blood sugar levels were measured under the interruption treatment of the blood supply in the pancreas, and the situation of β-granules in Langerhans' islets was observed after the rats had been killed when they had almost reached the maximal hypoglycemic state.
The results obtained were as follows :
a) With or without interruption of the pancreatic blood supply, no change was found in blood sugar levels in the case of folic acid, cyanocobalamin or hydroxocobalamin.
b) There was no histological change in the β-granules of Langerhans' islets of the pancreas in all cases.
These three kinds of vitamins (folic acid, cyanocobalamin and hydroxocobalamin), therefore,