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TERESA PELÁEZ Y COLS. ANAL. REAL ACAD. NAC. FARM.

original sobre la melatonina modulando la presión intraocular ha sido mejorada
gracias al empleo de nuevos compuestos selectivos para el receptor MT2
y especialmente para el MT3. El compuesto selectivo 5-metoxiamino N-acetil-
triptamina (5-MCA-NAT) se ha convertido en un compuesto muy atractivo debido
a su capacidad de reducir la PIO hasta un 50%, convirtiéndose en un compuesto
muy interesante para el tratamiento de la hipertensión ocular asociada al glaucoma.
Se han desarrollado y ensayado más compuestos que nos han permitido tener un
panorama más preciso acerca de como estos receptores controlan el proceso
fisiológico de la presión intraocular.

Palabras clave: Melatonina, presión intraocular, receptores de melatonina,
receptor MT3.

MY HISTORICAL PERSPECTIVE

In May 1999, when I was flying back to Spain from an
Ophthalmology meeting in Florida (USA) I started to talk with a
colleague about those persons who take melatonin to avoid jet-lag in
long distance trips. Some people comment that this neurohormone
helps to recover the light/night cycles faster than when you allow
your body to do it without any help.

When I was back in the lab, I had a look to melatonin in the
internet looking for some references regarding jet-lag, and I was
surprised when I saw a graph in which the concentrations of
melatonin along 24 hours was presented. That plot showed that this
indole presented higher concentrations in the night and lower during
the day. There was something funny about this plot: it was just
opposite to one I saw in one of the most popular Ocular Physiology
books (Adler’s Physiology of the Eye) in which intraocular pressure
(IOP) was analysed along 24 hours. If you overlap both graphs you
may see that when melatonin was higher IOP was lower and vice
versa (Figure 1). Did that mean that melatonin levels modify IOP?

At that moment we were working on the effect of nucleotides on
IOP in New Zealand rabbits (1), so it would not be difficult to check
whether or not melatonin was able to change IOP. We performed
that single experiment and indeed melatonin significantly reduced
IOP, but its effect was transitory lasting no more than one hour.
This result was interesting and in some way indebted me to carry on
working on this topic, but not immediately since I was involved in

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