The Divergent Effects Of Inhaled Anesthetics Sevoflurane On Spinal Nociceptive Transmission

Objective To explore the spinal mechanism of divergent analgesic and hyperalgesic effect of inhaled anesthesics sevoflurane by observing the effect of sevoflurane on the expression ofp-CREB(phosphorylated cAMP response element binding protein) which as spinal nociceptive transmission marker.Methods In this study, adult male SD rats were used as research object, and behavior analysis, immunohistochemistry and Western Blot were used to observe:â‘ the expression change of spinal p-CREB at different time points after injection of formalin, and the effect of sevoflurane on the expression of spinal p-CREB in the inflammatory pain model which was made by intra-plantar subcutaneous injection of formalin;â‘¡the expression change of spinal p-CREB after simple sevoflurane anesthesia directly;â‘¢the effect of sevoflurane withdrawal on ipsilateral PWT at2h and3h after low concentration formalin injection and spinal p-CREB expression at3h after injection in sevoflurane withdrawal model, which was made by injection of0.5%formalin under sevoflurane, and maintaining anesthesia for1h after injection, and then removing the anesthesia.Resultsâ‘ The effect of sevoflurane on expression of spinal p-CREB in inflammatory pain induced by formalin:intra-plantar injection of formalin induced rapid increasing expression of bilateral spinal p-CREB, which was reached to the peak at10min after injection, thereafter the expression of p-CREB was decreased but still higher than the control level at1h after injection; sevoflurane anesthesia could inhibit the expression of spinal p-CREB at1h after injection;â‘¡The expression change of spinal p-CREB after simple sevoflurane anesthesia:simple sevoflurane anesthesia could inducethe expression of spinal p-CREB which was increased along with the time of anesthesia;â‘¢The effect of sevoflurane withdrawal on PWT and the expression of spinal p-CREB after injection of low concentration formalin: sevoflurane withdrawal could induce the decreasing of PWT at2h and3h after injection of low concentration, and activate the expression of p-CREB in ipsilateral dorsal horn of spinal cord at3h after injection.Conclusion Sevoflurane has divergent regulating effect on spinal p-CREB:sevoflurane anesthesia can inhibit the expression of spinal p-CREB in inflammatory pain; but sevoflurane alone and withdrawal of sevoflurane in persistent inflammatory pain can both induce the expression of spinal p-CREB.All these suggest that sevoflurane may have divergent hyperalgesia and analgesia effect mediated by spinal p-CREB.