Gribkoff V K, Ashe J H
Cell Mol Neurobiol. 1984 Jun;4(2):177-83. doi: 10.1007/BF00711003.
Extracellular recording techniques were used to study the effects of dopamine on postactivation excitability of rat area CA1 hippocampal neurons maintained in vitro. Population spikes were elicited by delivery of conditioning and test stimulus pulses to afferent fibers. The interval between the conditioning and test volley was set to separate delivery of stimuli by 10 to 80 msec. The effect of superfusion or microtopical application of dopamine (DA) on population responses to test stimulus pulses was studied. When paired stimulus volleys, separated by brief intervals (up to 40 msec), were delivered to afferent fibers, paired-pulse suppression (PPS) was indicated by the amplitude of the population spike elicited by the test volley being smaller than that elicited by the conditioning volley. When paired volleys were separated by longer intervals (40 to 80 msec), the response elicited by the test volley was larger in amplitude than that elicited by the conditioning volley, indicating paired-pulse facilitation (PPF). Following exposure to DA, the amplitude of the population response elicited by the conditioning volley was larger than the amplitude before exposure to DA. This effect was long-lasting, enduring for tens of minutes. However, when the amplitude of the conditioning population response was held constant, the PPS was decreased, indicating disinhibition. It is suggested that dopamine produces a long-lasting attenuation of an intervening inhibitory influence onto CA1 pyramidal neurons.
采用细胞外记录技术研究多巴胺对体外培养的大鼠海马CA1区神经元激活后兴奋性的影响。通过向传入纤维施加条件刺激和测试刺激脉冲来诱发群体峰电位。条件刺激和测试刺激群峰之间的间隔设定为10至80毫秒，以分离刺激的传递。研究了多巴胺（DA）的灌注或微量局部应用对群体对测试刺激脉冲反应的影响。当以短间隔（最长40毫秒）向传入纤维施加配对刺激群峰时，测试群峰诱发的群体峰电位幅度小于条件群峰诱发的群体峰电位幅度，表明存在配对脉冲抑制（PPS）。当配对群峰间隔较长（40至80毫秒）时，测试群峰诱发的反应幅度大于条件群峰诱发的反应幅度，表明存在配对脉冲易化（PPF）。暴露于多巴胺后，条件群峰诱发的群体反应幅度大于暴露于多巴胺之前的幅度。这种效应持续时间长，可持续数十分钟。然而，当条件群体反应的幅度保持恒定时，PPS降低，表明去抑制。提示多巴胺对CA1锥体神经元产生一种持久的、对中间抑制性影响的减弱作用。
