# Effects of Short-Term Treatment of Hanwoo Satellite Cells with Various Concentrations of Cortisol

## TL;DR

This study examines how short-term cortisol exposure affects Hanwoo cattle muscle stem cells, finding minimal negative impact despite increased antioxidant activity.

## Contribution

The study identifies specific gene and antioxidant responses in Hanwoo muscle cells under cortisol stress, offering potential biomarkers for livestock stress assessment.

## Key findings

- Cortisol treatment increased expression of stress-related genes like HSP70 and antioxidant factors without causing cell death.
- Cellular respiration and ATP production increased with prolonged cortisol exposure, suggesting a stress adaptation response.
- Apoptosis markers showed temporary increases but did not lead to significant cell death in muscle stem cells.

## Abstract

Stress in livestock is inevitable and one of the factors that decrease productivity. In this study, the effect of cortisol on Korean native cattle (Hanwoo) muscle stem cells (HWSCs) under short-term stress was evaluated. No negative effects were observed in terms of antioxidant factors, cell death, or cellular respiration. The specific responses observed in livestock muscle cells in this study can be used as biological indicators to indirectly assess the stress experienced by livestock. These findings provide valuable basic data for developing effective methods to manage and control stress in livestock.

Transportation, environmental changes, and overcrowding can induce short-term stress in livestock, leading to physiological imbalances even within a short period. Cortisol is a stress-response hormone and its concentration in the blood can rapidly fluctuate depending on the individual and situation. This study evaluated the short-term effects of cortisol by applying blood cortisol concentrations that mimicked the normal and stress-induced levels observed in Korean native cattle (Hanwoo) to the culture medium of Hanwoo muscle stem cells (HWSC). Treatments were designed with five cortisol concentrations (0, 5, 10, 30, and 70 ng/mL) and four treatment times (0.5, 1, 2, and 3 h), based on the CCK-8 and viable cell count results. The expression levels of cortisol receptor-related genes (NR3C1, HSP70, and HSP90AA1) increased and reached a peak at 30 min post-treatment. After 30 min, the expression of these genes gradually decreased. However, in the case of HSP70, expression tended to increase again after 3 h of treatment. This could be seen as the regulation of cortisol inflow into the HWSC. Upon examining the oxidative effects of cortisol on superoxide dismutase 1 (SOD1), glutathione peroxidase (GPX), catalase (CAT), and oxygen consumption rate (OCR), the expression of antioxidant factors increased and peaked at 30 min of treatment. Following this peak, their levels generally began to decrease. However, in the 70 ng/mL group, the expression of these factors remained at a high level compared to the control group even after 30 min. In addition, the cellular respiration index and ATP production increased as the treatment prolonged, regardless of the concentration, as shown by the OCR analysis. These results can be considered a phenomenon corresponding to the accumulation of oxidative by products, such as Reactive Oxygen Species (ROS), caused by cortisol. The gene expression of apoptosis factors (p53, BAX, Caspase-3) temporarily increased at 30 min but then decreased. Caspase-3 protein activity was elevated at 30 min in the 70 ng/mL group, which later reduced. These results suggested that short-term cortisol administration had no effect on apoptosis in muscle cell culture. Therefore, the study findings elucidating the effects of short-term cortisol treatment on HWSC suggest that short-term stress may not have a significant negative effect on Hanwoo muscle. However, as this study was limited to muscle stem cells derived from Hanwoo, further investigation is required to determine whether the observed responses are consistent across different species and in vivo environments.