Changes in islet cell composition during development of diabetes in Macaca nigra

Area of Science:

• Endocrinology
• Cell Biology
• Metabolic Research

Background:

• The islets of Langerhans are crucial endocrine micro-organs within the pancreas.
• These islets contain distinct cell types, including alpha cells (glucagon), beta cells (insulin), and delta cells (somatostatin).
• Understanding the cellular composition changes in islets is vital for comprehending diabetes pathogenesis.

Purpose of the Study:

• To investigate the quantitative changes in pancreatic islet cell populations (insulin, glucagon, somatostatin) during the progression of metabolic deterioration in Macaca nigra.
• To correlate these cellular alterations with the stages of impaired glucose metabolism.

Main Methods:

• Immunohistochemical staining of pancreatic islet sections from Macaca nigra using antisera for insulin, glucagon, and somatostatin.
• Quantitative analysis of the stained cell area relative to the total islet area using computerized photometry.
• Categorization of monkeys into nondiabetic (ND), hormonally impaired (HI), borderline diabetic (BD), and diabetic (D) groups based on metabolic status.

Main Results:

• Insulin-positive beta cell area significantly decreased from 77% in ND monkeys to 39% in BD and <1% in D monkeys.
• Glucagon-positive alpha cell area increased from 7% in ND to 13% in HI monkeys, then decreased to 3% in D monkeys.
• Somatostatin-positive delta cell area showed a slight increase in HI monkeys (7%) before decreasing in BD (3%) and D (2%) monkeys.
• A notable peripheral staining pattern of beta cells was observed in HI monkeys.

Conclusions:

• Progressive diabetes in Macaca nigra is characterized by a substantial reduction in beta cell mass and a dynamic alteration in alpha and delta cell populations.
• These quantitative changes in islet endocrine cells correlate with the observed metabolic and clinical deterioration.
• The findings highlight the cellular basis of diabetes progression in this primate model.