Effect of cAMP concentration on apoptosis of sheep granulosa cells in vitro

Cyclic adenosine monophosphate (cAMP), an intracellular messenger, regulates granulosa cell (GC) proliferation, differentiation, and apoptosis via downstream effectors like PKA. Previous studies focused on cAMP promoting GC proliferation and its unidirectional transfer from GC to oocytes through gap junctions to sustain meiotic arrest. This study hypothesized cAMP bidirectionally interacts between GC and oocytes: partially entering oocytes to maintain meiotic arrest, while regulating GC apoptosis in a concentration-dependent manner. Immunofluorescence confirmed intracellular cAMP signaling in GC. Treatment with 0-10 μmol/L cAMP for 48 h revealed dual effects: low concentrations (2-4 μmol/L) significantly suppressed apoptosis and enhanced viability (CCK-8 assay), whereas concentrations > 4 μmol/L increased apoptosis and inhibited proliferation. This study provides new insights into the direct regulatory role of cAMP in sheep GC, emphasizes its dual role in cell survival and apoptosis, and deepens our understanding of the mechanism of follicular development in sheep.