HCG (Human Chorionic Gonadotropin) is a peptide hormone that mimics the action of luteinizing hormone (LH) in the body. It is primarily studied for its role in supporting endogenous testosterone production and maintaining reproductive function, particularly in models involving exogenous hormone exposure. It has also been examined for its effects on fertility signaling, testicular function, and libido related pathways. For laboratory research only — not for human use.