Mild nutrient deprivation may potentiate granulosa cell functionality via activation of autophagic processes

This study investigated the effects of short-term serum starvation on autophagy, functional protein expression, and cellular metabolism in porcine granulosa cells (GCs). Fluorescence microscopy revealed that 7.5% and 2.5% serum concentrations significantly increased autophagosome formation compared to the 10% serum group ( P  < 0.01), which was suppressed by the autophagy inhibitor 3-MA ( P  < 0.01). Western blot analysis demonstrated elevated LC3B and reduced p62 protein levels under serum starvation, indicating autophagy activation, while p-mTOR/mTOR decreased and p-AMPK/AMPK increased ( P  < 0.05 or P  < 0.01), suggesting AMPK/mTOR pathway involvement. Additionally, serum starvation enhanced the expression of functional proteins (FSHR, HIF-1α, 3β-HSD) and steroidogenesis (E2, P4), which were attenuated by 3-MA ( P  < 0.05). Reactive oxygen species (ROS) and apoptosis increased significantly under severe starvation (2.5% serum, P  < 0.01), while mild starvation (7.5% serum) elevated ATP levels ( P  < 0.01). Mitochondrial membrane potential declined in the 2.5% serum group ( P  < 0.01), with autophagy inhibition further reducing it. These findings indicate that short-term serum starvation induces protective autophagy via AMPK/mTOR signaling, enhancing GCs' functional protein expression and steroidogenesis, whereas severe starvation promotes oxidative stress and apoptosis.