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

CONCLUSIONS

There is still a long way until we fully understand the relevance
of melatonin in all the ocular structures. We hope that with our
modest contribution along the recent years, we may established the
foundations for the development of new pharmacological treatments
for the ocular hypertension associated to glaucoma. A good review
on melatonin in the eye, including our findings on IOP, has been
recently published (14). The introduction of new compounds for the
treatment of glaucoma is especially relevant if we take into account
the various side effects that happen with some of the commercially
available compounds. Additionally we wish to get deeper into the
molecular mechanism underlying all these physiological effects,
including the cloning of the MT3 receptor.

ADDENDUM

Melatonin receptors overview

The actions of melatonin in tissues are carried out by several
receptors. The melatonin receptors are referred to by the letters MT.
«MT» represents melatonin receptors with a well defined functional
pharmacology in a native tissue, as well as known molecular
structure, followed by a number subscript (15).

Three mammalian melatonin receptors have been cloned so far:
MT1 (16, 17), MT2 (17), and MT3 (18). Two first are classified as uni-
que subtypes based on their molecular structure and chromosomal
localization, and the third have been affinity-purified from Syrian
hamster kidney (18).

It is particularly interesting to note that non-mammalian
melatonin receptors have been deeply investigated. We are aware
that mammalian melatonin receptors are indeed the ones reported
and classified by the IUPHAR, nonetheless many works originally
were developed in non-mammalian species providing clues for the
search of the corresponding orthologues in mammalian tissues.

Non-mammalian melatonin receptors are classified depending on
their pharmacology and kinetics. Therefore, the ML1 melatonin

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