Zn2+ differentially modulates glycine receptors versus GABA receptors in isolated carp retinal third-order neurons.
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.
Li
P
P
Shanghai Institute of Physiology, Chinese Academy of Sciences, People's Republic of China.
Yang
X L
XL
D000818:Animals; D002347:Carps; D018757:GABA Modulators / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology*; D018009:Receptors, Glycine / Q000187:drug effects / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000502:physiology*; D015032:Zinc / Q000494:pharmacology / Q000502:physiology*
D018757:GABA Modulators; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; D015032:Zinc