|LE Magazine March 2002|
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Homeostatic versus circadian effects of melatonin on core body temperature in humans.
Evidence obtained in animals has suggested a link of the pineal gland and its hormone melatonin with the regulation of core body temperature (CBT). Depending on the species considered, melatonin intervenes in generating seasonal rhythms of daily torpor and hibernation, in heat stress tolerance, and in setting the CBT set point. In humans, the circadian rhythms of melatonin is strictly associated with that of CBT, the nocturnal decline of CBT being inversely related to the rise of melatonin. Whereas there is inconsistent evidence for the suggestion that the decline of CBT may prompt the release of melatonin, conversely, stringent data indicate that melatonin decreases CBT. Administration of melatonin during the day, when it is not normally secreted, decreases CBT by about 0.3 to 0.4 degree C, and suppression of melatonin at night enhances CBT by about the same magnitude. Accordingly, the nocturnal rise of melatonin contributes to the circadian amplitude of CBT. The mechanisms through which melatonin decreases CBT are unclear. It is known that melatonin enhances heat loss, but a reduction of heat production cannot be excluded. Besides actions on peripheral vessels aimed to favor heat loss, it is likely that the effect of melatonin to reduce CBT is exerted mainly in the hypothalamus, where thermoregulatory centers are located. Recent observations have shown that the acute thermoregulatory effects induced by melatonin and bright light are independent of their circadian phase-shifting effects. The effect of melatonin ultimately brings a saving of energy and is reduced in at least two physiological situations: aging and the luteal menstrual phase. In both conditions, melatonin does not exert its CBT-lowering effects. Whereas in older women this effect may represent an age-related alteration, in the luteal phase this modification may represent a mechanism of keeping CBT higher at night to promote a better embryo implantation and survival.
J Biol Rhythms 1997 Dec;12(6):509-17
Melatonin and sleep in humans.
Early studies on the physiological effects of melatonin typically reported hypnotic ‘side-effects’. Later studies, specifically addressing this action, failed to reliably replicate hypnotic effects using standard polysomnography. This difference may be related to differences in the basic physiological action of melatonin compared with more conventional hypnotics. It is suggested that melatonin exerts a hypnotic effect through thermoregulatory mechanisms. By lowering core body temperature, melatonin reduces arousal and increases sleep-propensity. Thus, in humans, one role of melatonin is to transduce the light-dark cycle and define a window-of-opportunity in which sleep-propensity is enhanced. As such, melatonin is likely to be an effective hypnotic agent for sleep disruption associated with elevated temperature due to low circulating melatonin levels. The combined circadian and hypnotic effects of melatonin suggest a synergistic action in the treatment of sleep disorders related to the inappropriate timing of sleep and wakefulness. Adjuvant melatonin may also improve sleep disruption caused by drugs known to alter normal melatonin production (e.g., beta-blockers and benzodiazepines). If melatonin is to be developed as a successful clinical treatment, differences between the pharmacological profile following exogenous administration and the normal endogenous rhythm should be minimized. Continued development as a useful clinical tool requires control of both the amplitude and duration of the exogenous melatonin pulse. There is a need to develop novel drug delivery systems that can reliably produce a square-wave pulse of melatonin at physiological levels for 8 to 10 hr duration.
J Pineal Res 1993 Aug;15(1):1-12
Melatonin therapy of advanced human malignant melanoma.
We undertook a study to investigate the therapeutic potential of orally administered melatonin in patients with advanced melanoma. Forty-two patients received melatonin in doses ranging from 5 mg/m2/day to 700 mg/m2/day in four divided doses. Two were excluded from analysis. After a median follow-up of 5 weeks, six patients had partial responses, six additional patients had stable disease. Sites of response included the central nervous system, subcutaneous tissue and lung. The median response duration was 33 weeks for the partial responders. There was a suggestion of a dose-response relationship. The toxicity encountered was minimal and consisted primarily of fatigue in 17 of 40 patients. Melatonin also appeared to reduce basal levels of follicle-stimulating hormone (FSH). No significant changes were encountered in serum levels of luteinizing hormone (LH) or thyroid stimulating hormone (TSH). We conclude that further study of melatonin as a potentially useful agent in metastatic melanoma is warranted.
Melanoma Res 1991 Nov-Dec;1(4):237-43
Artificial life extension. The epigenetic approach.
An epigenetic approach starts out from the direct (rather than the underlying genetic) causes. An epigenetic approach to aging has little chance of succeeding before a minimum amount of knowledge has been accumulated on the “genetic programming” that is currently believed to underlie aging. Two recent advances, one empirical and one theoretical, jointly brighten the prospect. The empirical one is the discovery that melatonin functions as an aging-controlling hormone in mammals. In 1979, Dilman and co-workers isolated a biologically active pineal extract (epithalamin) in rats which, as they later showed, stimulates melatonin production. Pierpaoli and co-workers in 1987 directly administered melatonin to mice. Both groups observed a surprising 25-percent increase of life span in conjunction with a postponed senescence. A similar effect was also achieved with an engraftment of young pineal tissue into the thymus of old mice by Pierpaoli’s group. Beneficial effects of epithalamin in humans were reported by Dilman’s group. The second advance is a deductive evolution-theoretical approach to aging discovered in 1988. In populations living in a niche with a fixed carrying capacity, any individual is in the long run replaced by a single successor. It follows that, as the expected cumulative number of adult progeny of the same sex approaches unity as a function of life time of the progenitor, the latter’s survivability must approach zero if the sum is to remain unity. A physiological prediction follows: a centralized physicochemical clock “like a sedimentation process” must exist somewhere in the organism controlling a secreted substance that reaches all cells. In this way, the pineal coacervates and the pineal’s hormonal product melatonin were arrived at on an independent route again. While melatonin as a drug has been used on human volunteers for decades, its anti-aging effect has yet to be proved. Detailed hormone profiles in different age groups and under different life styles have to be performed. A modified Hayflick in vitro experiment is also needed to elucidate the mechanism by which melatonin works in cells.
Ann N Y Acad Sci 1994 May 31;719:474-82
Randomized study with the pineal hormone melatonin versus supportive care alone in advanced nonsmall cell lung cancer resistant to a first-line chemotherapy containing cisplatin.
At present, there is no effective medical therapy in metastatic nonsmall cell (NSC) lung cancer patients who progressed under a first-line chemotherapy containing cisplatin. Since recent data have demonstrated the antineoplastic properties and the lack of toxicity of the pineal hormone melatonin (MLT), a randomized study was designed to evaluate the influence of an MLT treatment (10 mg/day orally at 7.00 p.m.) on the survival time at 1 year from the progression under chemotherapy in respect to supportive care alone in a group of metastatic NSC lung cancer patients, who did not respond to a first-line chemotherapy containing cisplatin. The study includes 63 consecutive metastatic NSC lung cancer patients, who were randomized to receive MLT (n = 31) or supportive care alone (n = 32). The percentage of both stabilizations of disease and survival at 1 year was significantly higher in patients treated with MLT than in those treated only with supportive care. No drug-related toxicity was seen in patients treated with MLT, who, on the contrary, showed a significant improvement in performance status. This randomized study shows that the pineal hormone MLT may be successfully administered to prolong the survival time in metastatic NSC lung cancer patients who progressed under a first-line chemotherapy with cisplatin, for whom no other effective therapy is available up to now.
Decreased toxicity and increased efficacy of cancer chemotherapy using the pineal hormone melatonin in metastatic solid tumor patients with poor clinical status.
Melatonin (MLT) has been proven to counteract chemotherapy toxicity, by acting as an anti-oxidant agent, and to promote apoptosis of cancer cells, so enhancing chemotherapy cytotoxicity. The aim of this study was to evaluate the effects of concomitant MLT administration on toxicity and efficacy of several chemotherapeutic combinations in advanced cancer patients with poor clinical status. The study included 250 metastatic solid tumor patients (lung cancer, 104; breast cancer, 77; gastrointestinal tract neoplasms, 42; head and neck cancers, 27), who were randomized to receive MLT (20 mg/day orally every day) plus chemotherapy, or chemotherapy alone. Chemotherapy consisted of cisplatin (CDDP) plus etoposide or gemcitabine alone for lung cancer, doxorubicin alone, mitoxantrone alone or paclitaxel alone for breast cancer, 5-FU plus folinic acid for gastro-intestinal tumors and 5-FU plus CDDP for head and neck cancers. The 1-year survival rate and the objective tumor regression rate were significantly higher in patients concomitantly treated with MLT than in those who received chemotherapy (CT) alone (tumor response rate: 42/124 CT + MLT versus 19/126 CT only, P < 0.001; 1-year survival: 63/124 CT + MLT versus 29/126 CT only, P < 0.001). Moreover, the concomitant administration of MLT significantly reduced the frequency of thrombocytopenia, neurotoxicity, cardiotoxicity, stomatitis and asthenia. This study indicates that the pineal hormone MLT may enhance the efficacy of chemotherapy and reduce its toxicity, at least in advanced cancer patients of poor clinical status.
Eur J Cancer 1999 Nov;35(12):1688-92
A randomized study of chemotherapy with cisplatin plus etoposide versus chemoendocrine therapy with cisplatin, etoposide and the pineal hormone melatonin as a first-line treatment of advanced non-small cell lung cancer patients in a poor clinical state.
Recent studies suggest that the pineal hormone melatonin may reduce chemotherapy-induced immune and bone marrow damage. In addition, melatonin may exert potential oncostatic effects either by stimulating host anticancer immune defenses or by inhibiting tumor growth factor production. On this basis, we have performed a randomized study of chemotherapy alone vs. chemotherapy plus melatonin in advanced non-small cell lung cancer patients (NSCLC) with poor clinical status. The study included 70 consecutive advanced NSCLC patients who were randomized to receive chemotherapy alone with cisplatin (20 mg/m2/day i.v. for 3 days) and etoposide (100 mg/m2/day i.v. for 3 days) or chemotherapy plus melatonin (20 mg/day orally in the evening). Cycles were repeated at 21-day intervals. Clinical response and toxicity were evaluated according to World Health Organization criteria. A complete response (CR) was achieved in 1/34 patients concomitantly treated with melatonin and in none of the patients receiving chemotherapy alone. Partial response (PR) occurred in 10/34 and in 6/36 patients treated with or without melatonin, respectively. Thus, the tumor response rate was higher in patients receiving melatonin (11/34 vs. 6/35), without, however, statistically significant differences. The percent of 1-year survival was significantly higher in patients treated with melatonin plus chemotherapy than in those who received chemotherapy alone (15/34 vs. 7/36, P < 0.05). Finally, chemotherapy was well tolerated in patients receiving melatonin, and in particular the frequency of myelosuppression, neuropathy, and cachexia was significantly lower in the melatonin group. This study shows that the concomitant administration of melatonin may improve the efficacy of chemotherapy, mainly in terms of survival time, and reduce chemotherapeutic toxicity in advanced NSCLC, at least in patients in poor clinical condition.
J Pineal Res 1997 Aug;23(1):15-9
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