海马CA1区GABA受体亚型药物干预后对兔P3波的影响

Changes of P3 potentials after intervention to GABAR subtypes in CA1 region in rabbits

目的：探讨海马ＣＡ１区氨基丁酸Ａ受体（ＧＡＢＡＡＲ）、氨基丁酸Ｂ受体（ＧＡＢＡＢＲ）活动对Ｐ３波的影响机制。方法：１０只健康家兔，用听Ｏｂｄｂａｌ方案，被动条件记录Ｐｚ点Ｐ３波。导管埋植术后，采用海马ＣＡ１区微量注入ＧＡＢＡＡＲ选择性拮抗剂Ｂｉｃｕｃｕｌｉｎｅ，ＧＡＢＡＢＲ激动剂Ｂａｃｌｏｆｅｎ，观察干预ＧＡＢＡ受体亚型对兔Ｐ３波的影响。结果：Ｂｉｃｕｃｕｌｉｎｅ（３、６、１２μｍｏｌ／Ｌ）呈一定量效依赖衰减Ｐ３ｂ波电压振幅，Ｂａｃｌｏｆｅｎ（６．２５，１２．５，２５ｍｍｏｌ／Ｌ）呈明显量效依赖延长、阻抑Ｐ３ｂ波。外源性ＧＡＢＡ（１００ｍｍｏｌ／Ｌ）可翻转Ｂｉｃｕｃｕｌｉｎｅ（１２μｍｏｌ／Ｌ）、Ｂａｃｌｏｆｅｎ（２５ｍｍｏｌ／Ｌ）对Ｐ３ｂ波振幅的抑制，但其潜伏期延长。结论：海马ＣＡ１区ＧＡＢＡＡＲＩＰＳＰ（Ｉｎｈｉｂｉｔｏｒｙｐｏｓｔｓｙｎａｐｔｉｃｐｏｔｅｎｔｉａｌ）可能即是Ｐ３ｂ振幅的重要组成。

Objective: To explore the mechanism for the effects of GABAAR and GABABR on P3 potentials in CA1 region. Methods: P3 potentials at Pz site were recorded in 10 healthy rabbits. After the catheter was implanted, either Bicuculline, a selective antagonist to GABAAR, or Baclofen, an agonist to GABABR, was microinfused into the CA1 region to observe the effects of intervention of GABA subtypes on P3 potentials. Results: P3 amplitude was markedly decreased by Bicuculline in a dose dependent manner (3, 6, 12 μmol/L) and P3 latency was increased by Baclofen in the same manner (6.25, 12.5, 25 mmol/L). The blocking effects of Bicuculline (12 μmol/L) or Baclofen (25 mmol/L) on P3 potentials could be reversed by microinfusion of GABA (100 mmol/L), but the latency was prolonged. Conclusion: GABAAR inhibitory postsynaptic potential in the CA1 region might be one important component of P3b amplitude and GABAR action can prolong P3b latency through reducing capacity of neurons to form P3b potential.