Effects of Leonurine on oocyte maturation and parthenogenetic embryo development in sheep.

Leonurine (LEO), an alkaloid isolated from Leonurus spp., has anti-oxidant, anti-inflammatory and anti-apoptotic effects and can prevent damage caused by reactive oxygen species (ROS). These properties suggest that it can improve the maturation rate of oocytes and developmental ability of embryos, which are key parameters in animal breeding. In this study, the effects of LEO on in vitro maturation and early embryonic development in sheep oocytes were evaluated. Among various doses examined (0, 10, 20 and 40 µM), a dose of 20 µM was optimal with respect to the oocyte maturation rate. Compared with estimates in the control group, GSH levels and mitochondrial membrane potential of sheep oocytes treated with 20 µM LEO were significantly higher, and 40 µM LEO would affect oocyte maturation. Additionally, ROS levels were significantly lower, expression levels of the antioxidant genes CAT and SOD1 were significantly higher, and there was no significant difference in GPX3 expression. The Bax/Bcl-2 ratio and Caspase-3 expression were significantly reduced in the 20 µM LEO group. During early embryonic development in vitro, the cleavage rate and blastocyst rate were significantly higher in the 20 µM LEO treatment group compared to other groups. GSH levels and mitochondrial membrane potential were significantly higher, while ROS levels were significantly lower, and expression levels of the antioxidant genes CAT, GPX3 and SOD1 were significantly higher in eight-cell embryos treated with 20 µM LEO than in the control group. The Bax/Bcl-2 ratio and Caspase-3 levels were significantly decreased. In summary, LEO can reduce the effect of oxidative stress, improve the oocyte maturation rate and enhance embryonic development.

Peroxisome Proliferator-Activated Receptor γ Regulates Lipid Metabolism in Sheep Trophoblast Cells through mTOR Pathway-Mediated Autophagy.

Peroxisome proliferator-activated receptor gamma (PPARγ) is a key nuclear receptor transcription factor that is highly expressed in trophoblastic cells during embryonic attachment and is accompanied by rapid cell proliferation and increased lipid accumulation. We previously showed that the autophagy pathway is activated in cells after activation of PPARγ, accompanied by increased lipid accumulation. In this study, we used PPARγ agonist rosiglitazone and inhibitor GW9662, as well as autophagy activator rapamycin and inhibitor 3-methyladenine, to unravel the probable mechanism of PPARγ engaged in lipid metabolism in sheep trophoblast cells (STCs). After 12 h, 24 h, and 48 h of drug treatment, the levels of autophagy-related proteins were detected by Western blot, the triglyceride content and MDA level of cells were detected by colorimetry, and the lipid droplets and lysosomes were localized by immunofluorescence. We found that PPARγ inhibited the activity of mammalian target of rapamycin (mTOR) pathway in STCs for a certain period of time, promoted the increase of autophagy and lysosome formation, and enhanced the accumulation of lipid droplets and triglycerides. Compared with cells whose PPARγ function is activated, blocking autophagy before activating PPARγ will hinder lipid accumulation in STCs. Pretreatment of cells with rapamycin promoted autophagy with results similar to rosiglitazone treatment, while inhibition of autophagy with 3-methyladenine reduced lysosome and lipid accumulation. Based on these observations, we conclude that PPARγ can induce autophagy by blocking the mTOR pathway, thereby promoting the accumulation of lipid droplets and lysosomal degradation, providing an energy basis for the rapid proliferation of trophoblast cells during embryo implantation. In brief, this study partially revealed the molecular regulatory mechanism of PPARγ, mTOR pathway, and autophagy on trophoblast cell lipid metabolism, which provides a theoretical basis for further exploring the functional regulatory network of trophoblast cells during the attachment of sheep embryos.

ArPNO-Catalyzed Acylative Dynamic Kinetic Resolution of 3-Hydroxyphthalides: Access to Enantioenriched Phthalidyl Esters.

A chiral 4-aryl-pyridine-N-oxide nucleophilic organocatalyst was used to synthesize chiral phthalidyl ester prodrugs by the acylative dynamic kinetic resolution process. By using the 3,5-dimethylphenyl-derived ArPNO catalyst, the phthalidyl esters were obtained in up to 97% yield with 97% ee at room temperature. Two phthalidyl esters of prodrugs, talosalate and talmetacin, were generated. By control experiments and density functional theory calculations, an acyl transfer mechanism was proposed.