Maintenance of pancreatic endocrine B cells of neonatal rat: Part-XIV--Effect of maternal hyperglycemia on the secretion of insulin and glucagon.

ABSTRACT

Effects of gestational hyperglycemia on A and B cells were examined in pancreatic monolayer islet cell cultures of neonatal rats from mothers of normoglycemia (C) and made slightly (SH), moderately (MH) and highly hyperglycemic (HH) by streptozotocin injection. Monolayer cultures were maintained for 7 days in the medium with 5.5 mM glucose plus 1 mM 2-deoxyglucose. On day 0, B cells of the SH group were more responsive to glucose and 2-ketoisocaproate than those of other groups. On day 7, the response of B cells in the C and SH groups was remarkably enhanced, thus displaying a dose-dependent increasing pattern of insulin secretion in response to glucose, 2-ketoisocaproate and arginine, and a convex-type secretion to leucine. However, there was no response by B cells in the MH and HH groups. Further, a dose-dependent inhibition of glucagon secretion due to glucose was seen in A cells of the C and SH groups on day 0 and day 7. The responses of these A cells to other nutrients were slightly decreased or were of a low convex-type. In the MH group, however, the glucagon secretion was remarkably enhanced due to leucine and 2-ketoisocaproate on day 0 and day 7, and due to arginine on day 7, although it remained suppressed by glucose. A cells of the HH group were unresponsive through the whole culture period. These results suggest that the development of A- and B-cell responses in vitro of neonates was differently affected by the degree of maternal hyperglycemia.