THE PHOTOPERIOD TRANSDUCER MELATONIN AND THE IMMUNE-HEMATOPOIETIC SYSTEM Georges JM Maestroni Center for Experimental Pathology Istituto Cantonale di patologia 6601 Locarno 1, Switzerland. Running Head : Melatonin as immunoregulatory agent Key Words: melatonin, melatonin receptors, T-helper, immunopharmacology, viral diseases, secondary immunodeficiency Correspondence : Dr. Georges JM Maestroni Center for Experimental Pathology Istituto Cantonale di Patologia 6601 Locarno 1, Switzerland Tel +41 91 756 26 71 Fax +41 91 756 26 90 email: icpcps@guest.cscs.ch Aknowledgements The work performed in Locarno has been supported by Swiss Nationalfonds grants no. 3.267.0.85; 31.25350.88; 31.36128.92, 31.45532.95 and by the Helmut Horten Foundation. Abstract The pineal neurohormone melatonin synchronizes functionally the organism with the photoperiod. It is now well recognized that melatonin also plays an important immunoregulatory role. T-helper cells bear G-protein coupled melatonin cell membrane receptors and, perhaps, melatonin nuclear receptors. Activation of melatonin receptors enhances the release of T-helper cell type 1 (Th1) cytokines, such as g-interferon and interleukin-2, as well as of novel opioid cytokines which crossreact immunologically with both interleukin-4 and dynorphin B. Melatonin has been reported also to enhance the production of interleukin-6 from human monocytes. These mediators may counteract secondary immunodeficiences, protect mice against lethal viral and bacterial diseases, synergize with interleukin-2 in cancer patients and influence hematopoiesis. Hematopoiesis is apparently influenced by the action of the melatonin-induced-opioids on kappa-opioid receptors present on stromal bone marrow cells. Most interestingly, g-interferon and colony stimulating factors may modulate the production of melatonin in the pineal gland. A hypothetical pineal-immune-hematopoietic network is, therefore, taking shape. From the immunopharmacological point of view, a call is made for clinical studies on the effect of melatonin in viral disease including human immunodeficiency virus-infected patients and cancer patients. In conclusion, melatonin seems to be an important immunomodulatory hormone which deserves to be further studied to identify its relevance in immune-based diseases, its therapeutic indications and its adverse effects.

| Search for your next job in chemistry here:
©1997-2001 Emedia Science Ltd Virtual Conferences, Internet Science Publishing