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Melatonin Effect on [ 3 H]Glutamate Uptake and Release in the Golden Hamster Retina
Author(s) -
Faillace María P.,
Keller Sarmiento María I.,
Rosenstein Ruth E.
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.67020623.x
Subject(s) - retina , glutamate receptor , hamster , melatonin , golden hamster , chemistry , biology , medicine , endocrinology , biochemistry , neuroscience , receptor
The effect of melatonin on [ 3 H]glutamate uptake and release in the golden hamster retina was studied. In retinas excised in the middle of the dark phase, i.e., at 2400 h, melatonin (0.1 and 10 n M ) significantly increased [ 3 H]glutamate uptake, and this effect persisted in a Ca 2+ ‐free medium. On the other hand, melatonin significantly increased [ 3 H]glutamate release in retinas excised at 2400 h, but this effect was Ca 2+ sensitive. Melatonin significantly increased 45 Ca 2+ uptake by a crude synaptosomal fraction from retinas of hamsters killed at 2400 h. In retinas excised at 1200 h, melatonin had no effect on [ 3 H]glutamate uptake, [ 3 H]glutamate release, or 45 Ca 2+ uptake at any concentration tested. Cyclic GMP analogues, i.e., 8‐bromoguanosine 3′,5′‐cyclic monophosphate and 2′‐ O ‐dibutyrylguanosine 3′,5′‐cyclic monophosphate, significantly increased [ 3 H]glutamate uptake, [ 3 H]glutamate release, and 45 Ca 2+ uptake by tissue removed at 1200 and 2400 h, suggesting that the effects of melatonin could correlate with a previously described effect of melatonin on cyclic GMP levels in the golden hamster retina. Taking into account the key role of glutamate in visual mechanisms, the results suggest the participation of melatonin in retinal physiology.