Importance of Islet Intracrinology for Glucose-Stimulated Insulin Secretion in Males

The study demonstrated that testosterone (T) enhances glucose-stimulated insulin secretion (GSIS) in male pancreatic islet β cells through its local conversion to dihydrotestosterone (DHT) and estradiol (E2) by 5α-reductase (5α-R) and aromatase (Ar), respectively. Using qPCR and immunohistochemistry, the researchers confirmed the expression of 5α-R and Ar in male islets and β cells. The insulinotropic effect of T was partially blocked by 5α-R inhibitors (finasteride and dutasteride) and completely blocked by co-treatment with these inhibitors and the Ar inhibitor anastrozole. This study identified a novel paradigm of islet intracrinology, highlighting the importance of local androgen and estrogen conversion in enhancing GSIS.