ABSTRACT
More than 30 years have elapsed between the isolation of melatonin from bovine pineal glands by Lerner et al. in 1958 and the purification of its receptor from lizard brain by Rivkees and colleagues in 1990. The kinetic parameters of the affinity chromatography-purified melatonin receptor that were isolated from lizard brain were very similar to the described high affinity binding site. It is rather difficult to assign a specific function for melatonin in the Pars Tuberalis. A very recent study demonstrated that the possible paracrine melatonin action can involve very complex mechanisms. The Harderian gland was considered as a possible target for melatonin action, due to the numerous changes in the morphology and biochemistry of the gland, that take place following photoperiodic manipulations. From the results of clinical trials published to date, it seems that the melatonin binding sites distribution is much wider than initially thought.
