Effects of propofol anesthesia on hippocampal PKA-CREB signaling pathway in neonatal rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of propofol anesthesia on hippocampal protein kinase A (PKA)-cAMP response element binding protein (CREB) signaling pathway in neonatal rats.Methods One hundred and seventy-five male Sprague-Dawley rats,aged 7 days,weighing 8-15 g,were randomly divided into 5 groups (n =35 each) using a random number tablecontrol group (C group) and propofol 25,50,100 and 200 mg/kg groups (P~ groups).Groups P1 and P2 received intraperitoneal propofol 25 and 50 mg/kg,respectively.Groups P3 and P4 received intraperitoneal propofol 100 and 200 mg/kg,respectively,and after righting reflex completely recovered,an increment of propofol 50 mg/kg was given until the total amount was finished.Five animals in each group were chosen and arterial blood samples were obtained immediately after the animals were fully awake for blood gas analysis.Five animals in each group were chosen at 2 h after fully awake and the age of 9 weeks,the rats were sacrificed and their brains were removed for microscopic examination of the ultrastructure of hippocampal neurons and for determination of PKA mRNA,CREB mRNA,PKA protein and pCREB protein in hippocampus (using RT-PCR and Western blot analysis).Results There was no significant difference in the indexes of blood gas analysis anong the five groups (P ＞ 0.05).Nuclear swelling and fragmentation,chromatin condensation,apoptotic bodies,decreased number of synapses and widened synaptic space were observed in P2,P3 and P4 groups.Compared with group C,the expression of PKA mRNA,CREB mRNA,PKA protein and pCREB protein was significantly down-regulated at 2 h after fully awake and the age of 9 weeks in P1,P2,P3 and P4 groups (P ＜ 0.05).Conclusion The mechanism by which propofol anesthesia induces neurotoxicity in neonatal rats may be related to inhibition of the activity of PKA-CREB signaling pathway.