IMPACT OF REAL-LIFE ENVIRONMENTAL EXPOSURES ON REPRODUCTION: Systemic and ovarian impacts of heat stress in the porcine model.

In brief: This review describes how heat stress causes systemic endocrine and metabolic alterations that contribute to intracellular ovarian perturbations, resulting in female infertility.

Abstract: Heat stress (HS) in mammals results from an imbalance in heat accumulation and dissipation. Fertility impairments consequential to HS have been recognized for decades in production animals, and more recently, observations have been extended to other species, including women. There are several systemic impacts of HS that can independently affect reproduction, including metabolic endotoxemia, reduced plane of nutrition, and endocrine disruption. At the level of the ovary, molecular pathways are altered by HS, such as inflammation, JAK-STAT, PI3K, oxidative stress, cell death, and heat shock response. Taken together, impaired ovarian function contributes to seasonal infertility that results from HS. This review paper describes the physiological and endocrine systemic impacts of HS that may independently and collaboratively impair fertility in the porcine model. The review then details ovarian intracellular events that are altered during HS and finally determines future needs in this area of research.