INFLUENCE OF CLIMATE FACTORS ON THE REPRODUCTIVE NEUROENDOCRINOLOGY OF THE PLAINS VIZCACHA (Lagostomus maximus)

Climate change negatively impacts the physiology and reproduction of wild animals. This study investigated the influence of environmental temperature and humidity on the reproductive neuroendocrine axis of the South American plains vizcacha (Lagostomus maximus), a hystricomorph rodent native to Argentina. A retrospective analysis was conducted using plasma and brain samples collected in March from 2008 to 2025. The Temperature-Humidity Index (THI) was calculated for each year, defining High THI (N=22) and Low THI (N=12) groups. Plasma levels of estradiol, cortisol, and ACTH were measured by ELISA, and hypothalamic expression of gonadotropin-releasing hormone (GnRH), kisspeptin, and glucocorticoid receptor (GR) was assessed by immunohistochemistry. ACTH levels were significantly higher in the High THI group (p<0.005), whereas cortisol levels and hypothalamic GR-positive neuron number did not differ between groups. In contrast, estradiol levels were significantly lower (p<0.001), accompanied by a reduction in GnRH and kisspeptin-positive neurons in the preoptic area of the hypothalamus (p<0.002). These findings identify temperature and humidity as key environmental factors influencing the reproductive axis of the plains vizcacha and suggest that climate-related changes may affect the species long-term population dynamics.