Restructuring of pancreatic islets and insulin secretion in a postnatal critical window.
Function and structure of adult pancreatic islets are determined by early postnatal development, which in rats corresponds to the first month of life. We analyzed changes in blood glucose and hormones during this stage and their association with morphological and functional changes of alpha and beta cell populations during this period. At day 20 (d20), insulin and glucose plasma levels were two- and six-fold higher, respectively, as compared to d6. Interestingly, this period is characterized by physiological hyperglycemia and hyperinsulinemia, where peripheral insulin resistance and a high plasmatic concentration of glucagon are also observed. These functional changes were paralleled by reorganization of islet structure, cell mass and aggregate size of alpha and beta cells. Cultured beta cells from d20 secreted the same amount of insulin in 15.6 mM than in 5.6 mM glucose (basal conditions), and were characterized by a high basal insulin secretion. However, beta cells from d28 were already glucose sensitive. Understanding and establishing morphophysiological relationships in the developing endocrine pancreas may explain how events in early life are important in determining adult islet physiology and metabolism.
Aguayo-Mazzucato
Cristina
C
Department of Biophysics, Institute of Cellular Physiology, National Autonomous University of México, Mexico City, Mexico.
Sanchez-Soto
Carmen
C
Godinez-Puig
Victoria
V
Gutiérrez-Ospina
Gabriel
G
Hiriart
Marcia
M
D000367:Age Factors; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002449:Cell Aggregation; D002452:Cell Count; D002478:Cells, Cultured; D004032:Diet; D005934:Glucagon / Q000097:blood; D050416:Glucagon-Secreting Cells / Q000378:metabolism / Q000502:physiology; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000502:physiology; D007515:Islets of Langerhans / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014886:Weaning
D001786:Blood Glucose; D007328:Insulin; D005934:Glucagon