The direct effects of saccharin sodium, cyclamate sodium and stevioside on insulin and glucagon secretion were investigated using the isolated perfused rat pancreas. Following preperfusion with 2.8 mM glucose and respective sweeteners (cyclamate sodium: 440 μM, saccharin sodium: 50 μM, stevioside: 15 μM) for 20 min, L-arginine hydrochloride (to give a final concentration of 19.2 mM) was introduced through a side arm for the next 30 min. The addition of arginine to the perfusate of 2.8 mM glucose without any sweeteners caused a biphasic increase in the insulin and glucagon concentrations. The perfusion of 2.8 mM glucose plus cyclamate sodium revealed no significant change in insulin and glucagon secretion as compared to glucose alone. Saccharin sodium and stevioside produced a slight increase in the insulin and a slight decrease in the glucagon secretion induced by arginine, although the changes were not significant, as compared to those with glucose alone. These resultssuggest that cyclamate sodium, saccharin sodium and stevioside have no direct action on pancreatic A and B cells.
Sixty-four newborn Chinese hamsters were divided into three groups. Group A received injection of monosodium glutamate (MSG) at a dose of 4 mg per g of body weight during 3 days after birth, and was fed the standard diet containing 0 1% synthetic trypsin inhibitor, N, N-dimethylcarbamoylmethyl 4-(4-guanidinobenzoyloxy)-phenylacetatej methansulfonate. Group B received 3 days injection of MSG, and was fed the standard diet. Group C received saline injection and was fed the standard diet. The mean plasma glucose level in group B was significantly high compared to that in group C at the 11th week. A slight significant difference was noted between groups A and C. Hyperglycemia of over 160 mg/dl was seen in 5.6% of group A, 44.4% of group B and 0% of group C at the 7th week. At the 11th week, hyperglycemia of over 300 mg/dl was observed in 63.0% of group B, but none was noted in groups A and C. These results suggest that the synthetic trypsin inhibitor may suppress MSG-induced hyperglycemia in newborn Chinese hamsters.