Diabetes, Vol 36, Issue 8 883-891, Copyright © 1987 by American Diabetes Association
Influence of lactation on morphometric and secretory variables in pancreatic beta-cell of mildly diabetic rats
G Marynissen, WJ Malaisse and FA Van Assche
In nondiabetic rats, lactation accelerates the restoration of pancreatic
beta-cell function after the period of increased secretory activity
associated with pregnancy. To investigate whether a comparable situation
prevails in mildly diabetic animals, streptozocin (22.5 mg/kg body wt) was
administered to female rats at the onset of pregnancy. Plasma glucose and
insulin concentrations, content and release of insulin in isolated islets,
total mass and volume density of both the endocrine pancreas and granulated
beta-cells, and ultrastructural prevalence of light and dark secretory
granules were measured on the 20th day of pregnancy and in lactating and
nonlactating animals 20 days after delivery. In the mildly diabetic
animals, the changes in endocrine pancreatic function normally associated
with pregnancy and lactation were greatly attenuated, albeit not completely
eliminated. We propose that the increased biosynthetic and secretory
activity imposed on surviving beta-cells after streptozocin administration
tends to mask the adaptative changes in beta-cell function otherwise seen
during the postpartum and lactation period.