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Abstract #6304 Published in IGR 3-2
Involvement of melatonin MT(3) receptors in the regulation of intraocular pressure in rabbits
Pintor J; Martin L; Pelaez T; Hoyle CH; Peral AEuropean Journal of Pharmacology 2001; 416: 251-254
Melatonin, a neurohormone secreted by the pineal gland, can stimulate three subtypes of receptors, namely: mt(1), MT(2) and MT(3). The authors examined the ability of melatonin and the selective MT(3) receptor agonist, 5-methoxycarbonylamino-N-acetyltryptamine (5-MCA-NAT), to modify intraocular pressure (IOP) in rabbits. Both compounds significantly reduced IOP, maximally by 24% and 43%, respectively, with IC(50) values of 363 ± 23.0 and 423 ± 30.0 ng/10 μl (1.6 ± 0.1 and 1.8 ± 0.1 nmol, respectively). The non-specific melatonin receptor antagonist, luzindole, abolished the depressant effect of both compounds, thus confirming the involvement of melatonin receptors. These results show, for the first time, a functional response that may be regulated by melatonin MT(3) receptors, and provide evidence that supports a role of melatonin in the circadian changes of IOP.
Dr J. Pintor, Departamento de Bioquimica, E.U. Optica, Universidad Complutense de Madrid, c/ Arcos de Jalon s/n, 28037, Madrid, Spain. jpintor@eucmos. sim.ucm.es
Classification:
1.3 Pathogenesis (Part of: 1 General aspects)
5 Experimental glaucoma; animal models
