Environmental cues associated with morphine modulate release of glutamate and γ-aminobutyric acid in ventral subiculum

Objective To investigate whether environmental cues associated with different properties of morphine could regulate the extracellular levels of glutamate and y-aminobutyric acid （GABA） in the hippocampal ventral subiculum, which play a critical role in the reinstatement of drug-seeking behavior induced by environmental cues. Methods Conditioning place preference （CPP） and conditioning place aversion （CPA） models were used to establish environment associated with rewarding and aversive properties of morphine respectively. Microdialysis and high performance liquid chromatography were used to measure the extracelluar level of glutamate and GABA in the ventral subiculum under these environmental cues. Results Exposure to the environmental cues associated with rewarding properties of morphine resulted in a decrease （approximately 11%） of extracellular level of GABA in ventral subiculum, and exposure to the environmental cues associated with aversive properties of morphine resulted in an increase （approximately 230%） of extracellular level of glutamate in ventral subiculum. Conclusion Environmental cues associated with different properties of morphine modulate the release of distinct neurotransmitters in the hippocampal ventral subiculum possibly through different neural circuit.

吗啡依赖大鼠伏隔核与海马腹侧下托放电频率的改变

目的:用胞外记录的方法分别观察伏隔核和海马腹侧下托对吗啡的反应性,探讨其在药物心理依赖形成过程中所处的地位。方法:吗啡依赖大鼠及正常大鼠各10只,依照大鼠脑立体定向图谱,将电极下至将要记录核团附近,依次注射吗啡、纳洛酮,观察各核团对药物的反应性。结果:吗啡依赖组大鼠伏隔核放电频率从15Hz±s3Hz变化至<3Hz甚至放电中断,正常组大鼠从6Hz±s2Hz变化至0·5-3Hz;吗啡依赖组大鼠海马腹侧下托放电频率7Hz±s2Hz变化不明显,正常组放电频率6Hz±s2Hz变化不明显。结论:在药物心理依赖形成过程中,伏隔核发生了较明显的变化,而海马腹侧下托变化不明显。