Melatonin modulates gamma-aminobutyric acid(A) receptor-mediated currents on isolated carp retinal neurons.
Modulation by melatonin of gamma-aminobutyric acid(A) (GABA(A)) receptor-mediated responses was studied in bipolar and amacrine-like cells acutely isolated from carp retina, using the whole-cell patch-clamp technique. Melatonin of 1 mM accelerated desensitization of the GABA(A) receptors at both bipolar and amacrine-like cells. In addition, 1 mM melatonin hardly changed the GABA(A) receptor-mediated response amplitude of bipolar cells, while it increased or decreased that of amacrine-like cells, depending on the concentration of GABA applied. These modulatory effects, which can not be blocked by luzindole, a melatonin receptor antagonist, may be due to the allosteric action caused by melatonin bound to a site of the GABA(A) receptors.
Institute of Neurobiology, Fudan University and Shanghai Institute of Physiology, CAS, Shanghai 200433, People's Republic of China.
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D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006054:Goldfish; D008550:Melatonin / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects* / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000187:drug effects* / Q000494:pharmacology
D000927:Anticonvulsants; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D008550:Melatonin