Prior to this proposal, we had discovered that HS altered a number of molecular pathways in the ovary, and these alterations could all adversely impact ovarian function as well as pregnancy maintenance. We published these data in the journal Biology of Reproduction, a premiere journal in reproductive biology. However, we did not know the causative agents. Through the current work, we have discovered the following: 1) HS in the presence of an insulin bolus 15 prior to tissue collection resulted in altered levels of genes and proteins in the pathway through which ovarian hormones are generated, thus, we have additional evidence that HS alters ovarian hormones which could be responsible for lengthened WEI in swine during summer months. 2) Both HS and LPS increased a pathway that is involved in regulating both the health of the ovulated oocyte as well as ovarian hormone production. 3) Acute LPS induced a response in the ovary a mere 8 h after the exposure. 4) LPS altered the machinery responsible for generation of ovarian hormones in a manner that had similarities as well as differences with HS alone. Because we had technical difficulties in counting follicles within the ovary, we extended the study to examine if there could be additional “turnover” of the chief ovarian hormone, 17β-estradiol, within the ovary during HS. We discovered this to be true, the machinery responsible for degrading 17β-estradiol in a cyclical fashion is altered by HS, indicating that this could also play a role in seasonal infertility in swine. Identification of these HS- as well as LPS-induced ovarian changes have set the stage to continue our investigations to lead to mitigation interventions to minimize seasonal infertility in swine.
• HS and LPS alter a pathway in the ovary that regulates when oocyte (egg)-containing follicles are activated to grow and ovulate.
• HS and LPS affect the mechanisms by which the ovary produces key female hormones required for ovulation and maintenance of pregnancy.
• The ovarian transporter protein responsible for degrading 17β-estradiol (estrogen) in a cyclical pattern during the estrous cycle is altered by HS.