Impact of Excess Activin A on the Lipids, Metabolites, and Steroids of Adult Mouse Reproductive Organs

Bioactivity of the hormone and growth factor activin A is central to fertility and health. Dysregulated circulating activin levels occur with medication usage and multiple pathological conditions. The inhibin-alpha knockout mouse (InhaKO) models chronic activin elevation and unopposed activin A bioactivity. In InhaKO fetal testes, lipid droplet, steroid profiles, and seminiferous cords are abnormal; adults develop gonadal and adrenal tumors due to chronic activin A excess exposure. Here we address how this exposure affects lipid, metabolite, and steroid composition in whole testes, ovaries, and adrenals of adult InhaKO mice using histological, transcriptomic, and mass spectrometry (MS) methods, including MS imaging (matrix-assisted laser desorption/ionization-MS imaging). Matrix-assisted laser desorption/ionization-MS imaging delineated spatial lipid profiles within interstitial, inner cord, and outer cord regions containing normal spermatogenesis; these differed between wild-type and KO samples. In proximity to tumors, lipids showed distinctive distribution patterns both within and adjacent to the tumor. Significantly altered lipids and metabolic profiles in whole InhaKO testes homogenates were linked to energy-related pathways. In gonads and adrenal glands of both sexes, steroidogenic enzyme transcription, and steroids are different, as expected. Lipid profiles and steroidogenic enzyme proteins, HSD3B1 and CYP11A1, are affected within and near gonadal tumors. This documents organ-specific effects of chronic activin A elevation on lipid composition and cellular metabolism, in both histologically normal and tumor-affected areas. The potential for activin A to influence numerous steroidogenic processes should be considered in context and with spatial precision, particularly in relationship to pathologies.