Porcine endometrial heat shock proteins are differentially influenced by pregnancy status, heat stress, and altrenogest supplementation during the peri-implantation period

Heat Stress Impairs Endometrial Function During Implantation by Regulating Autophagy in Hainan Black Goat

Heat stress (HS) is a significant factor that adversely affects the health, welfare, and productivity of domestic animals, particularly impacting embryo implantation rates. However, the effects of HS on endometrial function during the peri-implantation period in Hainan black goats remain unclear. This study explores the influence of HS on the endometrium of these goats. We collected uterine tissue samples from both control and heat-stressed goats and performed in vitro experiments using a 2 × 2 factorial design. This design included two temperature conditions (37 °C as the control and 42 °C to simulate heat stress) and two pharmacological treatments: chloroquine (CQ), an autophagy inhibitor, and rapamycin (RAPA), an autophagy activator. Our results showed that heat stress initially suppresses autophagy activity, which is subsequently enhanced with prolonged exposure. The pharmacologic modulation of autophagy, through activation or inhibition, resulted in corresponding upregulation or downregulation of the endometrial epithelial cells' (EECs) receptivity markers. The overexpression of ATG7 partially reversed the HS-induced downregulation of these markers. Additionally, TJP1, a tight-junction marker, was degraded under the pharmacologic and genetic activation of autophagy in HS conditions but accumulated more in the EECs pre-treated with CQ. These findings suggest that autophagy plays a protective role in maintaining endometrial function under HS conditions in Hainan black goats. This study offers valuable insights into the role of autophagy in endometrial receptivity and proposes a potential strategy to mitigate the adverse effects of HS on goat reproduction.

Development and application of a multi-step porcine in vitro system to evaluate feedstuffs and feed additives for their efficacy in nutrient digestion, digesta characteristics, and intestinal immune responses

In vitro model provides alternatives to the use of live animals in research. In pig nutrition, there has been a tremendous increase in in vivo research over the decades. Proper utilization of in vitro models could provide a screening tool to reduce the needs of in vivo studies, research duration, cost, and the use of animals and feeds. This study aimed to develop a multi-step porcine in vitro system to simulate nutrient digestion and intestinal epithelial immune responses affected by feedstuffs and feed additives. Seven feedstuffs (corn, corn distillers dried grains with solubles [corn DDGS], barley, wheat, soybean meal, soy protein concentrates, and Corynebacterium glutamicum cell mass [CGCM]), feed enzymes (xylanase and phytase), and supplemental amino acids (arginine, methionine, and tryptophan), were used in this in vitro evaluation for their efficacy on digestibility, digesta characteristics, and intestinal health compared with the results from previously published in vivo studies. All in vitro evaluations were triplicated. Data were analyzed using Mixed procedure of SAS9.4. Evaluations included (1) nutrient digestibility of feedstuffs, (2) the effects of feed enzymes, xylanase and phytase, on digestibility of feedstuffs and specific substrates, and (3) the effects of amino acids, arginine, tryptophan, and methionine, on anti-inflammatory, anti-oxidative, and anti-heat stress statuses showing their effects (P < 0.05) on the measured items. Differences in dry matter and crude protein digestibility among the feedstuffs as well as effects of xylanase and phytase were detected (P < 0.05), including xylo-oligosaccharide profiles and phosphorus release from phytate. Supplementation of arginine, tryptophan, and methionine modulated (P < 0.05) cellular inflammatory and oxidative stress responses. The use of this in vitro model allowed the use of 3 experimental replications providing sufficient statistical power at P < 0.05. This indicates in vitro models can have increased precision and consistency compared with in vivo animal studies.

Heat stress alters the ovarian proteome in prepubertal gilts

Heat stress (HS) occurs when exogenous and metabolic heat accumulation exceeds heat dissipation; a thermal imbalance that compromises female reproduction. This study investigated the hypothesis that HS alters the ovarian proteome and negatively impacts proteins engaged with insulin signaling, inflammation, and ovarian function. Prepubertal gilts (n = 19) were assigned to one of three environmental groups: thermal neutral with ad libitum feed intake (TN; n = 6), thermal neutral pair-fed (PF; n = 6), or HS (n = 7). For 7 d, HS gilts were exposed to 12-h cyclic temperatures of 35.0 ± 0.2 °C and 32.2 ± 0.1 °C, while TN and PF gilts were housed at 21.0 ± 0.1 °C. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed on ovarian protein homogenates. Relative to TN gilts, 178 proteins were altered (P ≤ 0.05, log2foldchange ≥ 1) by HS, with 76 increased and 102 decreased. STRING gene ontology classified and identified 45 biological processes including those associated with chaperone protein refolding, cytoplasmic translational initiation, and immune activation; with a protein-protein interaction web network of 158 nodes and 563 edges connected based on protein function (FDR ≤ 0.05). Relative to PF, HS altered 330 proteins (P ≤ 0.05, log2foldchange ≥ 1), with 151 increased and 179 decreased. Fifty-seven biological pathways associated with protein function and assembly, RNA processing, and metabolic processes were identified, with a protein-protein interaction network of 303 nodes and 1,606 edges. Comparing HS with both the TN and PF treatments, 72 ovarian proteins were consistently altered by HS with 68 nodes and 104 edges, with biological pathways associated with translation and gene expression. This indicates that HS alters the ovarian proteome and multiple biological pathways and systems in prepubertal gilts; changes that potentially contribute to female infertility.

Climate change and pregnancy complications: From hormones to the immune response

Pregnant women are highly vulnerable to adverse environments. Accumulating evidence highlights that increasing temperatures associated with the ongoing climate change pose a threat to successful reproduction. Heat stress caused by an increased ambient temperature can result in adverse pregnancy outcomes, e.g., preterm birth, stillbirth and low fetal weight. The pathomechanisms through which heat stress interferes with pregnancy maintenance still remain vague, but emerging evidence underscores that the endocrine system is severely affected. It is well known that the endocrine system pivotally contributes to the physiological progression of pregnancy. We review – sometimes speculate - how heat stress can offset hormonal dysregulations and subsequently derail other systems which interact with hormones, such as the immune response. This may account for the heat-stress related threat to successful pregnancy progression, fetal development and long-term children’s health.

A Synopsis of the NE1727 Multistate Project Collection in the Journal of Animal Science

This article provides a synopsis of the collection of papers provided by participants of the NE1727 Multistate project. Five reviews and thirteen primary research articles are included that provide contributions the group has made to understanding the role of the corpus luteum in reproduction, describing how the ovary influences fertility, delineating mechanisms controlling oocyte quality and early embryo development, and exploring new reproductive management schemes.