Li P, Yang X L
Shanghai Institute of Physiology, Chinese Academy of Sciences, People's Republic of China.
Neurosci Lett. 1999 Jul 9;269(2):75-8. doi: 10.1016/s0304-3940(99)00416-4.
It was previously reported that strychnine-sensitive glycine receptors and GABAA receptors co-existed on carp retinal third-order neurons (amacrine/ganglion cells) (Li, P. and Yang, X.-L., Strong synergism between GABAA and glycine receptors on isolated carp third-order neurons. NeuroReport, 9 (1998) 2785-2789.). In this study, the effects of the divalent cation Zn2+ on these two receptors were studied in amacrine/ganglion cells acutely isolated from carp, with the use of the whole-cell patch clamp recording technique. The glycine-induced currents were steadily potentiated by Zn2+ of lower concentrations (0.1-10 microM), while being dose-dependently inhibited by Zn2+ of higher concentrations ( > 100 microM). Both the effects involved changes in apparent glycine affinity of the glycine receptor. In contrast, Zn2+ consistently suppressed the GABA(A) mediated currents of these cells, and did not show similar dual effect. The differential modulation by Zn2+ of glycine receptors versus GABA(A) receptors provides a versatility for regulating inhibitory glycinergic and GABAergic inputs converging on most amacrine/ganglion cells.
先前有报道称，士的宁敏感型甘氨酸受体和GABAA受体共存于鲤鱼视网膜的三级神经元（无长突细胞/神经节细胞）上（Li, P. 和Yang, X.-L.，《分离的鲤鱼三级神经元上GABAA和甘氨酸受体之间的强协同作用》。《神经报告》，9 (1998) 2785 - 2789）。在本研究中，利用全细胞膜片钳记录技术，研究了二价阳离子Zn2+对从鲤鱼急性分离出的无长突细胞/神经节细胞中这两种受体的影响。较低浓度（0.1 - 10 microM）的Zn2+能稳定增强甘氨酸诱导的电流，而较高浓度（> 100 microM）的Zn2+则对其有剂量依赖性抑制作用。这两种效应均涉及甘氨酸受体表观甘氨酸亲和力的变化。相比之下，Zn2+持续抑制这些细胞的GABA(A)介导电流，且未表现出类似的双重效应。Zn2+对甘氨酸受体和GABA(A)受体的不同调节作用为调控汇聚于大多数无长突细胞/神经节细胞的抑制性甘氨酸能和GABA能输入提供了多样性。
