Ikeda H, Robbins J
Brain Res. 1985 Nov;355(1):1-17. doi: 10.1016/0165-3806(85)90002-1.
Intraretinal iontophoresis in the optically intact eye of adult cats (18-22 weeks of age) and kittens (7-9 weeks of age) under pentobarbitone anaesthesia was performed. Studies were concentrated on retinal ganglion cells of the sustained (X) type in the area centralis under photopic conditions. In both the adult and kitten, gamma-aminobutyric acid (GABA) and muscimol inhibited the visually induced excitation, and bicuculline blocked the visually induced inhibition of on-cells. On the other hand, glycine inhibited the excitation and strychnine blocked the inhibition of off-cells. However, a greater current of GABA (muscimol) and glycine was required to produce total inhibition in kitten's on- and off-cells respectively when compared with the adult's. Furthermore, a smaller current of bicuculline and strychnine was needed to abolish the visually induced inhibition of kitten on- and off-cells respectively when compared with the adult's. In the adult, GABA and glycine did not affect the responses of off- and on-cells respectively, but in the kitten GABA inhibited off-cells and glycine inhibited on-cells to some extent. In neither the adult nor the kitten did bicuculline have any effect upon off-cells or strychnine any effect upon on-cells. Thus, the sustained on- and off-cells in the kitten area centralis exhibit: a reduced selectivity to inhibitory transmitters; a reduced sensitivity to exogenously applied inhibitory transmitter agonists; but a greater sensitivity to inhibitory transmitter antagonists, in comparison with the sustained on- and off-cells in the adult area centralis. The observed differences between the kitten and adult cat in transmitter actions on retinal ganglion cells appear to be analogous to those found in the postnatal development of functional synapses at the neuromuscular junction and sympathetic ganglia.
在戊巴比妥麻醉下，对成年猫（18 - 22周龄）和小猫（7 - 9周龄）的视觉完好眼睛进行视网膜内离子电渗疗法。研究集中在明视条件下中央凹区域的持续（X）型视网膜神经节细胞。在成年猫和小猫中，γ-氨基丁酸（GABA）和蝇蕈醇抑制视觉诱发的兴奋，荷包牡丹碱阻断视觉诱发的on细胞抑制。另一方面，甘氨酸抑制兴奋，士的宁阻断off细胞的抑制。然而，与成年猫相比，分别需要更大电流的GABA（蝇蕈醇）和甘氨酸才能在小猫的on细胞和off细胞中产生完全抑制。此外，与成年猫相比，分别需要更小电流的荷包牡丹碱和士的宁来消除视觉诱发的小猫on细胞和off细胞的抑制。在成年猫中，GABA和甘氨酸分别不影响off细胞和on细胞的反应，但在小猫中，GABA在一定程度上抑制off细胞，甘氨酸抑制on细胞。在成年猫和小猫中，荷包牡丹碱对off细胞均无任何影响，士的宁对on细胞也无任何影响。因此，与成年猫中央凹区域的持续on细胞和off细胞相比，小猫中央凹区域的持续on细胞和off细胞表现出：对抑制性递质的选择性降低；对外源性应用的抑制性递质激动剂的敏感性降低；但对抑制性递质拮抗剂的敏感性更高。在小猫和成年猫中观察到的递质对视网膜神经节细胞作用的差异，似乎类似于在神经肌肉接头和交感神经节功能性突触的出生后发育中发现的差异。
