Pivotal role of cAMP‐PKA‐CREB signaling pathway in manganese‐induced neurotoxicity in PC12 cells

Abstract Manganese (Mn) plays a critical role in individual growth and development, yet excessive exposure can result in neurotoxicity, especially cognitive impairment. Neuronal apoptosis is considered as one of the mechanisms of Mn‐induced neurotoxicity. Recent evidence suggests that cAMP‐PKA‐CREB signaling regulates apoptosis and is associated with cognitive function. However, whether this pathway participates in Mn‐induced neurotoxicity is not completely understood. To fill this gap, in vitro cultures of PC12 cells were exposed to 0, 400, 500, and 600 μmol/L Mn for 24 hours, respectively. Another group of cells were pretreated with 10.0 μmol/L rolipram (a phosphodiesterase‐4 [PDE4] inhibitor) for 1 hour followed by 500 μmol/L Mn exposure for 24 hours. Flow cytometry, immunofluorescence staining, enzyme‐linked immunosorbent assay, and Western blot analysis were used to detect the apoptosis rate, protein levels of PDE4, cAMP signaling, and apoptosis‐associated proteins, respectively. We found that Mn exposure significantly inhibited cAMP signaling and protein expression of Bcl‐2, while increasing apoptosis rate, protein levels of PDE4, Bax, activated caspase‐3, and activated caspase‐8 in PC12 cells. Pretreatment of rolipram ameliorated Mn‐induced deficits in cAMP signaling and apoptosis. These findings demonstrate that cAMP‐PKA‐CREB signaling pathway‐induced apoptosis is involved in Mn‐induced neurotoxicity.