Amodiaquine promotes testosterone production and de novo synthesis of cholesterol and triglycerides in Leydig cells

Testosterone is a hormone essential for male reproductive function. It is produced primarily by Leydig cells in the testicle through activation of steroidogenic acute regulatory protein and a series of steroidogenic enzymes, including a cytochrome P450 side-chain cleavage enzyme (cytochome P450 family 11 subfamily A member 1), 17 alpha-hydroxylase (cyto-chrome P450 family 17 subfamily A member 1), and 30-hydroxysteroid dehydrogenase. These steroido-genic enzymes are mainly regulated at the transcrip-tional level, and their expression is increased by the nuclear receptor 4A1. However, the effect on Leydig cell function of a small molecule-activating ligand, amodiaquine (AQ), is unknown. We found that AQ effectively and significantly increased testosterone production in TM3 and primary Leydig cells through enhanced expression of steroidogenic acute regula-tory protein, cytochome P450 family 11 subfamily A member 1, cytochrome P450 family 17 subfamily A member 1, and 30-hydroxysteroid dehydrogenase. Concurrently, AQ dose-dependently increased the expression of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in the cholesterol synthesis pathway, through induction of the transcriptional and DNA-binding activities of nuclear receptor 4A1, contributing to increased cholesterol synthesis in Leydig cells. Furthermore, AQ increased the expres-sion of fatty acid synthase and diacylglycerol acyl-transferase and potentiated de novo synthesis of fatty acids and triglycerides (TGs). Lipidomics profiling further confirmed a significant elevation of intra-cellular lipid and TG levels by AQ in Leydig cells. These results demonstrated that AQ effectively pro-motes testosterone production and de novo synthesis of cholesterol and TG in Leydig cells, indicating that AQ may be beneficial for treating patients with Ley-dig cell dysfunction and subsequent testosterone deficiency.