Pintor J, Martin L, Pelaez T, Hoyle C H, Peral A
Departamento de Bioquímica, E.U. Optica, Universidad Complutense de Madrid, c/ Arcos de Jalón s/n, 28037, Madrid, Spain.
Eur J Pharmacol. 2001 Mar 30;416(3):251-4. doi: 10.1016/s0014-2999(01)00864-0.
Melatonin, a neurohormone secreted by the pineal gland, can stimulate three subtypes of receptors, namely: mt(1), MT(2) and MT(3). We examined the ability of melatonin and the selective MT(3) receptor agonist, 5-methoxycarbonylamino-N-acetyltryptamine (5-MCA-NAT), to modify intraocular pressure in rabbits. Both compounds significantly reduced intraocular pressure, maximally by 24% and 43%, respectively, with IC(50) values of 363+/-23.0 and 423+/-30.0 ng/10 microl (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. Our 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 intraocular pressure.
褪黑素是一种由松果体分泌的神经激素，它能刺激三种受体亚型，即：mt(1)、MT(2)和MT(3)。我们研究了褪黑素以及选择性MT(3)受体激动剂5-甲氧基羰基氨基-N-乙酰色胺（5-MCA-NAT）降低兔眼内压的能力。两种化合物均能显著降低眼内压，最大降幅分别为24%和43%，IC(50)值分别为363±23.0和423±30.0 ng/10微升（分别为1.6±0.1和1.8±0.1纳摩尔）。非特异性褪黑素受体拮抗剂鲁辛朵消除了两种化合物的降压作用，从而证实了褪黑素受体的参与。我们的结果首次表明了一种可能受褪黑素MT(3)受体调节的功能反应，并提供了支持褪黑素在眼内压昼夜变化中起作用的证据。
