The Journals of Gerontology Series A: Biological Sciences and Medical Sciences Advance Access originally published online on February 10, 2009
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 2009 64A(3):340-350; doi:10.1093/gerona/gln054
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Melatonin and Tryptophan Affect the Activity–Rest Rhythm, Core and Peripheral Temperatures, and Interleukin Levels in the Ringdove: Changes With Age
1 Department of Physiology (Neuroimmunophysiology Research Group), University of Extremadura, Badajoz, Spain
2 Laboratory of Physiology, Department of Fundamental Biology and Health Sciences, University of the Balearic Islands, Palma de Mallorca, Spain
3 Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio
Address correspondence to Sergio Damián Paredes Royano, PhD, Department of Physiology, Faculty of Science, University of Extremadura, Avda. de Elvas, s/n, 06071, Badajoz, Spain. Email: sparedes{at}unex.es
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Aging is known to alter the circadian rhythms of melatonin, serotonin, thermoregulatory responses, cytokine production, and sleep/wakefulness which affect sleep quality. We tested the possible palliative effects of a 3-day administration of melatonin (0.25 or 2.5 mg/kg of body weight [b.w.] to young and old ringdoves, respectively) or tryptophan (300 mg/kg of b.w. to old ringdoves) on these rhythms. Doves are a monophasic, diurnal species; these characteristics are similar in humans. Old animals presented lower melatonin and serotonin levels; higher interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha values; and reductions in the Midline-Estimating Statistic of Rhythm and amplitude of activity–rest rhythm and in the amplitude of the core temperature rhythm. Melatonin raised serum melatonin levels; tryptophan increased both melatonin and serotonin levels. Melatonin and tryptophan lowered nocturnal activity, core temperature, and cytokine levels and increased peripheral temperature in both groups. Melatonin or tryptophan may limit or reverse some of the changes that occur in sleep–wake rhythms and temperature due to age.
Keywords Melatonin; Tryptophan; Temperature; Interleukins; Aging
Received: April 10, 2008; Accepted: September 24, 2008