Suppression of phosphodiesterase IV enzyme by roflumilast ameliorates cognitive dysfunction in aged rats after sevoflurane anaesthesia via PKA‐CREB and MEK/ERK pathways

Postoperative cognitive dysfunction (POCD) is a prevalent disorder after anaesthesia in the elderly patients. Roflumilast (RF), a phosphodiesterase 4 (PDE‐4) inhibitor, could improve cognition with no side effects. Here, we sought to explore the efficacy of RF in the improvement of cognitive dysfunction caused by sevoflurane (Sev). Sprague–Dawley rats were anaesthetized, and the hippocampal neurons were treated with Sev to develop in vivo and in vitro POCD models, followed by RF administration. The mechanism of the PKA‐CREB and MEK/ERK pathways in the pathogenesis of POCD was explored. Sev impaired the cognitive functions of rats, significantly reduced cyclic adenosine monophosphate (cAMP) concentrations and blocked the PKA‐CREB and MEK/ERK pathways. Moreover, the Sev‐treated rats and neurons exhibited enhanced apoptosis and reactive oxygen species (ROS). After treatment with RF, rats had better learning and memory function, and the activity of neurons in hippocampus and cortex was improved. Loss‐of‐function assay indicated that PKA‐CREB and MEK/ERK signalling impairment reduced cAMP levels and promoted apoptosis and ROS in rat hippocampus and neurons. Generally, RF promotes neuronal activity in rats after Sev treatment by maintaining cAMP levels and sustaining the activation of PKA‐CREB and MEK/ERK pathways. This might offer novel sights for POCD therapy. Sev treatment resulted in POCD in rats, as evidenced by learning and memory deficit and increased apoptosis in hippocampal and cortical tissues. RF protected hippocampal and cortical tissues in rat by activating the PKA‐CREB and MEK‐ERK signalling. Generally, our present study identified RF elicits its protective effects in hippocampal neurons against apoptosis and ROS at least partially through the PKA‐CREB and MEK/ERK pathways.