In the overweight or obese female, reproductive complications include poor oocyte quality, decreased fecundity, gestational diabetes, and higher risk of reproductive cancers. Using lean and hyperphagia-induced obese female mice aged 10 weeks, we determined that the ovary from obese female mice had elevated (P < 0.10) levels of ataxia telangiectasia mutated (ATM) protein in oocytes of both small and large follicles. Phosphorylated ATM at serine 1981 was greater (P < 0.05) in large relative to small follicles with no additional impact of obesity. Obesity increased (P < 0.05) H2AX in small follicles in obese relative to lean ovaries, while large follicles of both lean and obese mice had detectable levels of H2AX. Cleaved caspase 3 was reduced (P < 0.05) in the small follicles of obese relative to lean ovaries. In large follicles of lean mice, cleaved caspase 3 was increased in large compared to small follicles (P < 0.05) but this was pattern was absent in obese mice. Breast cancer type 1 susceptibility protein (BRCA1) or the phosphorylated BRCA1 proteins were observably altered by obesity. These data demonstrate that markers of DNA damage and repair have a follicle-dependent stage location and that obesity alters ATM and cleaved caspase 3 in a follicular stage-dependent manner.

Heat stress (HS) and Zearalenone (ZEN) exposure affect growth, production efficiency, and animal welfare; and, under extreme situations, both can be lethal. Given that both HS and ZEN independently cause oxidative stress, we hypothesized that simultaneous exposure to HS and ZEN would cause greater oxidative stress in porcine skeletal muscle than either condition, alone. To address this hypothesis, crossbred, prepubertal gilts were treated with either vehicle control (cookie dough) or ZEN (40 μg/kg) and exposed to either thermoneutral (TN; 21.0 °C) or 12-h diurnal HS conditions (night: 32.2 °C; day: 35.0 °C) for 7 d. Pigs were euthanized immediately following the environmental challenge and the glycolytic (STW) and oxidative (STR) portions of the semitendinosus muscle were collected for analysis. In STR, malondialdehyde (MDA) concentration, a marker of oxidative stress, tended to increase following ZEN exposure (P = 0.08). HS increased CAT (P = 0.019) and SOD1 (P = 0.049) protein abundance, while ZEN decreased GPX1 protein abundance (P = 0.064) and activity (P = 0.036). In STR, HS did not alter protein expression of HSP27, HSP70, or HSP90. Conversely, in STW, MDA-modified proteins remained similar between all groups. Consistent with STR, ZEN decreased GPX1 (P = 0.046) protein abundance in STW. In STW, ZEN decreased protein abundance of HSP27 (P = 0.032) and pHSP27 (P = 0.0068), while HS increased protein expression of HSP70 (P = 0.04) and HSP90 (P = 0.041). These data suggest a muscle fiber type-specific response to HS or ZEN exposure, potentially rendering STR more susceptible to HS- and/or ZEN-induced oxidative stress, however, the combination of HS and ZEN did not augment oxidative stress.

Heat stress (HS) compromises almost every aspect of animal agriculture including reproduction. In pigs, this infecundity is referred to as seasonal infertility (SI), a phenotype including ovarian dysfunction. In multiple species, HS-induced hyperprolactinemia has been described; hence, our study objectives were to characterize and compare HS effects on circulating prolactin (PRL) and ovarian Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling during the follicular (FOL) or luteal (LUT) phases of the estrous cycle in postpubertal gilts. Gilts were estrus synchronized using altrenogest and environmental treatments began immediately after altrenogest withdrawal. For the FOL study: postpubertal gilts were allocated to constant thermoneutral (TN; n = 6; 20 ± 1.2 °C) or cyclical HS (n = 6; 25 to 32 ± 1.2 °C) conditions for 5 d. In the LUT study: postpubertal gilts were assigned to either TN (n = 7; 20 ± 2.6 °C) or cyclical HS (n = 7; 32 to 35 ± 2.6 °C) conditions from 2 to 12 days postestrus (dpe). Blood was collected by jugular venipuncture for PRL quantification on day 5 in the FOL and on day 0 and day 12 in the LUT gilts. Ovaries and corpora lutea (CL) were obtained from euthanized FOL and LUT gilts on day 5 and day 12, respectively. Western blotting was performed to quantify prolactin receptor (PRLR) and JAK/STAT pathway protein abundance. In the FOL phase, no difference (P = 0.20) in circulating PRL between thermal groups was observed. There was no effect (P ≥ 0.34) of HS on PRLR, signal transducer and activator of transcription 3 (STAT3), signal transducer and activator of transcription 5α (STAT5α), and phosphorylated signal transducer and activator of transcription α/β tyrosine 694/699 (pSTAT5α/βTyr694/699) abundance and Janus kinase 2 (JAK2), phosphorylated janus kinase 2 tyrosine 1007/1008 (pJAK2Tyr1007/1008), STAT1, phosphorylated signal transducer and activator of transcription 1 tyrosine 701 (pSTAT1Tyr701), phosphorylated signal transducer and activator of transcription 1 serine 727 (pSTAT1Ser727), and phosphorylated signal transducer and activator of transcription 3 tyrosine 705 (pSTAT3Tyr705) were undetectable in FOL gilt ovaries. Ovarian pSTAT5α/βTyr694/699 abundance tended to moderately increase (4%; P = 0.07) in FOL gilts by HS. In the LUT phase, circulating PRL increased progressively from 2 to 12 dpe, but no thermal treatment-induced difference (P = 0.37) was noted. There was no effect (P ≥ 0.16) of HS on CL abundance of PRLR, pJAK2Tyr1007/1008, JAK2, STAT1, pSTAT1Tyr701, pSTAT1Ser727, pSTAT3Tyr705, STAT5α, or pSTAT5α/βTyr694/699. In LUT phase, CL STAT3 abundance was increased (11%; P &lt; 0.03) by HS. There was no impact of HS (P ≥ 0.76) on levels of pJAK2Tyr1007/1008 and pSTAT5α/βTyr694/699 in LUT gilts; however, the CL pSTAT3Tyr705:STAT3 ratio tended to be decreased (P = 0.10) due to HS. These results indicate an HS-induced estrous cycle-stage-dependent effect on the ovarian JAK/STAT pathway, establishing a potential role for this signaling pathway as a potential contributor to SI.

Exposure to environmental toxicants and hyperthermia can hamper reproduction in female mammals including swine. Phenotypic manifestations include poor quality oocytes, endocrine disruption, infertility, lengthened time to conceive, pregnancy loss, and embryonic defects. The ovary has the capacity for toxicant biotransformation, regulated in part by the phosphatidylinositol‐3 kinase signaling pathway. The impacts of exposure to mycotoxins and pesticides on swine reproduction and the potential for an emerging chemical class of concern, the per‐ and polyfluoroalkylated substances, to hamper porcine reproduction are reviewed. The negative impairments of heat stress (HS) on swine reproductive outcomes are also described and the cumulative effect of environmental exposures, such as HS, when present in conjunction with a toxicant is considered.

Zearalenone (ZEA) is an estrogenic mycotoxin produced by strains of Fusarium and is often inadvertently consumed via feed contamination. Heat stress (HS) occurs when heat accumulation exceeds heat dissipation resulting in increased body temperature. Independently, HS and ZEA cause swine reproductive dysfunction such as delayed puberty onset, altered circulating steroid hormones and irregular estrous cycles. During HS, gilts become hyperinsulinemic and insulin regulates hepatic and ovarian chemical metabolism. We hypothesized that during HS, ZEA-induced alterations to reproductive parameters are heightened such that HS is additive to ZEA-induced reproductive toxicity. Prepubertal crossbred gilts (n = 38) were randomly assigned to six treatment groups: thermal neutral (TN) ad libitum fed controls (TNCT; n = 6); TN + ZEA (2 ppm; TNZ; n = 6); pair-fed (PF) control (PFCT; n = 6); PF + ZEA (2 ppm; PFZ; n = 6); cyclical HS control (HSCT; n = 7); and HS + ZEA (2 ppm; HSZ; n = 7) for 7 d. Ovarian and uterine weights (g) were measured, and nipple and vulva diameters (l × w; mm2) were assessed by digital calipers. Ovarian weight was decreased (P = 0.04) in the PFZ relative to PFCT, but ZEA did not affect ovarian weight in the other groups (P &gt; 0.73). There was no impact of ZEA exposure on uterine weight (P &gt; 0.22) or nipple diameter (P &gt; 0.51) in any treatment groups, respectively. There was no effect of ZEA on vulva size in either of the TN groups; however, vulva diameter increased (P = 0.04) in the HSZ relative to HSCT. These data suggest that HS exaggerates some ZEA-induced phenotypic effects in prepubertal gilts. This project was supported by the Iowa Pork Producers Association.