| Popis: |
During the last decade, attention has centered on melatonin (MT), one of the hormones of the diffuse neuroendocrine system (DNES) which for many years was considered only as a hormone of the pineal gland. Currently, MT has been identified not only in the pineal gland but also in extrapineal tissues such as the retina, harderian gland, gut mucosa, cerebellum, airway epithelium, liver, kidney, adrenals, thymus, thyroid, pancreas, ovary, testis, carotid body, placenta, and endometrium as well as in nonendocrine cells like mast cells, natural killer cells, eosinophilic leukocytes, platelets, and endothelial cells. The above list of the cells storing MT indicates that MT has a unique position among the hormones of the DNES, being found in practically all organ systems. Functionally, MT-producing cells are certain to be part and parcel of the DNES as a universal system of response and control of protection to the organism. Taking into account the large number of MT-producing cells in many organs, the wide spectrum of its biological activities and, especially, its main property as a universal regulator of biological rhythms, it should be possible to consider extrapineal MT as a key paracrine signal molecule for the local coordination of intercellular relationships. Analysis of the experimental results described here shows the direct participation and active role of extrapineal MT and related APUD hormones in both the pathogenesis of tumor growth and the modification of antitumor therapy. |
