Ikeda H, Hankins M W, Kay C D
Vision Research Unit of Sherrington School, UMDS, Rayne Institute, St. Thomas' Hospital, London, U.K.
Eur J Pharmacol. 1990 Nov 6;190(1-2):1-9. doi: 10.1016/0014-2999(90)94106-8.
The effects of the GABAB (gamma-amino butyric acidB) receptor agonist, baclofen and its antagonist, phaclofen on physiologically identified retinal ganglion cells were studied in the optically intact eye of pentobarbitone-anaesthetized cats. These results were compared with the effects of the GABAA receptor agonist, muscimol and its antagonist, bicuculline. Baclofen inhibited the total visually driven firing of both ON- and OFF-cells more effectively upon OFF- than ON-cells; this action was weaker and slower than that of muscimol. Whilst bicuculline raised the firing level of only ON-cells in the area centralis together with all peripheral cells, phaclofen raised that of all OFF-cells. Paradoxically, in OFF-cells, baclofen enhanced the driven transient component and suppressed the sustained component, whilst phaclofen raised the sustained component. Thus, GABAB receptors activated by tonically released GABA may modulate the sustained and transient excitatory inputs to OFF-cells.
在戊巴比妥麻醉猫的光学完整眼中，研究了γ-氨基丁酸B（GABAB）受体激动剂巴氯芬及其拮抗剂法氯芬对生理特性明确的视网膜神经节细胞的影响。将这些结果与GABAA受体激动剂蝇蕈醇及其拮抗剂荷包牡丹碱的作用进行了比较。巴氯芬对OFF细胞的抑制作用比对ON细胞更有效地抑制了ON细胞和OFF细胞的总视觉驱动放电；这种作用比蝇蕈醇的作用更弱且更慢。虽然荷包牡丹碱仅提高了中央凹区域的ON细胞以及所有周边细胞的放电水平，但法氯芬提高了所有OFF细胞的放电水平。矛盾的是，在OFF细胞中，巴氯芬增强了驱动瞬态成分并抑制了持续成分，而法氯芬提高了持续成分。因此，由持续释放的GABA激活的GABAB受体可能会调节对OFF细胞的持续和瞬态兴奋性输入。
