Synergistic effect of standardized extract of Asparagus officinalis stem and heat shock on progesterone synthesis with lipid droplets and mitochondrial function in bovine granulosa cells.

Progesterone (P4) is a well-known steroid hormone that plays a key role in oocyte growth and the maintenance of pregnancy in mammals, including cattle. Heat stress (HS) has an adverse effect on P4 synthesis through an imbalance in the cellular redox status. We have recently revealed that a standardized extract of Asparagus officinalis stem (EAS) increases P4 through non-HS induction of heat shock protein 70 (HSP70) and a synergistic increase of HSP70 by enhancing the intracellular redox balance, which was adversely affected by HS in bovine granulosa cells (GCs). Bovine GCs collected from bovine ovarian follicles were cultured at 38.5 °C and 41 °C for 12 h with or without 5 mg/mL EAS. After treatment, cells and culture suppernatant were collected for the analysis. Enzyme-linked immunosorbent assay (ELISA) was performed to detect in P4 levels. Quantitative reverse-transcription polymerase chain reaction (RT-qPCR) was used to detect expression of steroidogenesis related genes. Fluorescence staining was used to detect mitochondrial activity and lipid droplet. P4 level was increased by EAS treatment in association with increase in steroidogenic acute regulatory protein (STAR), 3ß-hydroxysteroid dehydrogenase (3ß-HSD), mitochondrial membrane activity and lipid droplet both under non-HS and HS conditions. Notably, synergistic effect of EAS with HS co-treatment was observed to show a greater increase in P4 synthesis when comparison with EAS treatment under non-HS condition. Furthermore, inhibition of HSP70 significantly reduced EAS-induced P4 synthesis, mitochondrial activity and synthesis of lipid droplets. These results suggest that P4 synthesis by EAS is mediated by the steroidogenesis pathway via HSP70-regulated activation of STAR and 3ß-HSD, together with improved mitochondrial activity and lipid metabolism in bovine GCs. Moreover, effect of EAS has a synergistic effect of with HSP70-regulated steroidogenesis pathway.

A standardized extract of Asparagus officinalis stem improves HSP70-mediated redox balance and cell functions in bovine cumulus-granulosa cells.

Heat shock (HS) protein 70 (HSP70), a well-known HS-induced protein, acts as an intracellular chaperone to protect cells against stress conditions. Although HS induces HSP70 expression to confer stress resistance to cells, HS causes cell toxicity by increasing reactive oxygen species (ROS) levels. Recently, a standardized extract of Asparagus officinalis stem (EAS), produced from the byproduct of asparagus, has been shown to induce HSP70 expression without HS and regulate cellular redox balance in pheochromocytoma cells. However, the effects of EAS on reproductive cell function remain unknown. Here, we investigated the effect of EAS on HSP70 induction and oxidative redox balance in cultured bovine cumulus-granulosa (CG) cells. EAS significantly increased HSP70 expression; however, no effect was observed on HSP27 and HSP90 under non-HS conditions. EAS decreased ROS generation and DNA damage and increased glutathione (GSH) synthesis under both non-HS and HS conditions. Moreover, EAS synergistically increased HSP70 and HSF1 expression and increased progesterone levels in CG cells. Treatment with an HSP70 inhibitor significantly decreased GSH level, increased ROS level, and decreased HSF1, Nrf2, and Keap1 expression in the presence of EAS. Furthermore, EAS significantly increased progesterone synthesis. Thus, EAS improves HSP70-mediated redox balance and cell function in bovine CG cells.