Intracrine Testosterone Activation in Human Pancreatic Beta Cells Stimulates Insulin Secretion

The study from 2020 demonstrated that testosterone (T) affects β cell function in both men and women. The researchers found that T undergoes intracrine conversion in target tissues to dihydrotestosterone (DHT) via the enzyme 5α-reductase (5α-R), or to the active estrogen 17β-estradiol (E2) via the aromatase enzyme. This process was observed in both male and female human pancreas sections. The study also showed that exposure to 5α-R inhibitors or the aromatase inhibitor inhibited T enhancement of glucose-stimulated insulin secretion (GSIS). The conclusion was that male and female human islets convert T into DHT and E2 via the intracrine activities of SRD5A1 and aromatase, and this process is necessary for T enhancement of GSIS.