What is the Origin of Insulin-Like Factor 3?

The term is descriptive, reflecting its structural homology to insulin and its sequential discovery within the insulin-like growth factor family of peptides. Its origin is rooted in reproductive endocrinology research, particularly the study of male fetal development where its essential role in testicular descent was first identified. The number three designates its specific identity among the related peptide hormones.

What is the Mechanism of Insulin-Like Factor 3?

INSL3 exerts its biological effects by binding to and activating its cognate receptor, RXFP2, a G protein-coupled receptor found on target cells. During fetal life, this binding is critical for the anatomical migration of the testes. In adult males, the INSL3/RXFP2 signaling pathway is thought to play a role in maintaining the integrity of the testicular microenvironment and contributing to bone health. The mechanism involves activating specific intracellular signaling cascades that support cell differentiation and survival.

Insulin-Like Factor 3 ∞ Area

Insulin-Like Factor 3

Meaning

Insulin-Like Factor 3 (INSL3) is a two-chain peptide hormone, structurally related to insulin, predominantly secreted by the Leydig cells within the testes of males. This hormone serves as a reliable, direct clinical biomarker for the functional status of the Leydig cells, which are the primary source of androgens. Crucially, adult INSL3 levels remain relatively stable and are largely independent of the hypothalamic-pituitary-gonadal axis feedback loop, making it a unique and valuable indicator of intrinsic gonadal endocrine capacity.