Role of alpha4 beta2 neuronal nicotinic acetyicholine receptor in inhibition of synapttc long-term potentiation by isoflurane in rat hippncampal slices / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of alpha4 beta2 neuronal nicotinic acetylcholine receptor in the inhibition of synaptic long-term potentiation (LTP) by isoflurane in the CA1 area of rat hippocampal slices.Methods Hippocampal slices (400 μm thick) were prepared from the brains of adult male SD rats, 2 months old, weighing 200-250 g, anesthetized with ether and decapitated. The slices were incubated in artificial cerebrospinal fluid (aCSF) at room temperature for at least 2 h before use. Seventy slices were randomly divided into 10 groups ( n = 7 each) Ⅰ LTP group in which the slices were perfused with aCSF; Ⅱ , Ⅲ and Ⅳ group in which the slices were perfused with aCSF containing isoflurane 0.125, 0.25 and 0.5 mmol/L respectively (group Ⅰ1-3 );Ⅴ and Ⅵ group in which the slices were perfused with aCSF containing epibatidine 0.1 and 1.0 μmol/L respectively (group E1.2 ); Ⅶ group epibatidine 0.1 μmol/L + isoflurane 0.25 mmol/L (group E1 + I2 ); Ⅷgroup epibatidine 1.0 μmol/L + isoflurane 0.25 mmol/L (group E2 + I2); Ⅸ group DHβE 0.1 μmol/L (group D); Ⅹ group DHβE 0.1 μmol/L + isoflurane 0.125 mmol/L (group D + I1 ). Population spikes (PS) were recorded for at least 30 min before LTP in each group. For LTP induction, high-frequency stimulation (HFS) was applied to the Schaffer collateral-commissural pathway of hippocampus and maintained for 15 min using a stimulating electrode.The changes in PS amplitude were analyzed at 5, 10, 15, 20, 25, 30, 40, 50 and 60 min after HFS in each group. Results Compared with group LTP, the PS amplitude was significantly decreased after HFS in group I1 ,I2, I3 , D, D + I1 and E1 + I2 ( P ＜ 0.05), while increased after HFS in group E1 .2 ( P ＜ 0.05 ), but no significant change was found after HFS in group E2 + I2 ( P ＞ 0.05). The PS amplitude was significantly decreased after HFS in group D + I1 compared with group I1 (P ＜ 0.05). The PS amplitude was significantly increased after HFS in group E1 + I2 and F2 + I2 compared with group I2 ( P ＜ 0.01 ). Conclusion Isoflurane inhibits LTP induction via inhibiting the activation of alpha4 beta2 nicotinic acetylcholine receptor in rat hippocampus.