Mori-Okamoto J, Tatsuno J
Department of Physiology, National Defense Medical College, Saitama, Japan.
Brain Res. 1988 May 17;448(2):259-71. doi: 10.1016/0006-8993(88)91263-2.
The effects of noradrenaline (NA) on the responsiveness of cultured cerebellar neurons to excitatory amino acids were intracellularly investigated. NA applied to external medium to a final concentration of 10 microM or lower slightly decreased the firing frequency of spontaneous spikes, induced a small hyperpolarization or slightly increased the input resistance of Purkinje cells. In addition, bath-applied NA was found to enhance the depolarizations induced by iontophoretically applied glutamate and aspartate but to a smaller extent for the latter. These direct and modulating effects of NA were also observed when NA was applied by iontophoresis. The sites sensitive to iontophoresed NA were found to be not uniformly distributed but localized in restricted regions on individual Purkinje cells. The enhancement by NA of the glutamate or aspartate response was blocked by beta-adrenergic antagonists, propranolol or pindolol, and extracellularly applied cAMP mimicked the NA action. These results suggest the possibility that NA physiologically modulates excitatory amino acid-mediating synaptic transmission in the cerebellum probably by acting on beta-rather than alpha-adrenergic receptors.
采用细胞内记录法研究了去甲肾上腺素（NA）对培养的小脑神经元对兴奋性氨基酸反应性的影响。将NA加入到细胞外液中，使其终浓度达到10微摩尔/升或更低，可轻微降低自发放电的频率，引起轻微的超极化或使浦肯野细胞的输入电阻略有增加。此外，还发现通过浴槽给药的NA可增强由离子电泳施加的谷氨酸和天冬氨酸所诱发的去极化，但对后者的增强作用较小。当通过离子电泳施加NA时，也可观察到NA的这些直接作用和调制作用。发现对离子电泳施加的NA敏感的部位并非均匀分布，而是局限于单个浦肯野细胞的特定区域。NA对谷氨酸或天冬氨酸反应的增强作用可被β-肾上腺素能拮抗剂普萘洛尔或吲哚洛尔阻断，而细胞外施加的环磷酸腺苷（cAMP）可模拟NA的作用。这些结果提示，NA可能通过作用于β-而非α-肾上腺素能受体，在生理条件下对小脑内兴奋性氨基酸介导的突触传递起调制作用。
