The administration of exogenous melatonin during the daytime lowers the thermoregulatory setpoint in humans

Aizawa, Seika; Tokura, Hiromi; Morita, Takeshi

doi:10.1016/s0306-4565(01)00024-9

Cited by 11 publications

(5 citation statements)

References 15 publications

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“…In the present study, this downward shift in the cutaneous vasoconstrictor response on the forearm with respect to internal temperature by exogenous melatonin is similar to the day-night changes seen earlier [13]. Several earlier studies reported that the internal temperature threshold for the cutaneous vasodilator response to heat stress is shifted to lower internal temperatures by daytime melatonin administration [5,6] or elevated by bright light exposure, a suppressor of melatonin secretion [43]. These observations suggest the reflex control of cutaneous vasoconstrictor and cutaneous vasodilator responses to thermoregulatory changes have a parallel relationship to the changes in resting internal temperature associated with melatonin levels.…”

Section: Discussionsupporting

confidence: 87%

“…Support for such a role, in part, comes from exogenous melatonin administration. Administered in the daytime, when the endogenous secretion of melatonin is low, exogenous melatonin leads to a fall in internal temperature of 0.15–0.3°C [5–9] and an increase in skin temperatures of the hands and feet [10, 11]. Altogether, these findings are in keeping with a role for melatonin in the nocturnal alterations in the regulation of T int via effects on the reflex control of the cutaneous circulation.…”

Section: Introductionmentioning

confidence: 77%

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Exogenous melatonin administration modifies cutaneous vasoconstrictor response to whole body skin cooling in humans

Aoki

Zhao

Yamazaki

et al. 2007

Journal of Pineal Research

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Humans and other diurnal species experience a fall in internal temperature (T(int)) at night, accompanied by increased melatonin and altered thermoregulatory control of skin blood flow (SkBF). Also, exogenous melatonin induces a fall in T(int), an increase in distal skin temperatures and altered control of the cutaneous active vasodilator system, suggesting an effect of melatonin on the control of SkBF. To test whether exogenous melatonin also affects the more tonically active vasoconstrictor system in glabrous and nonglabrous skin during cooling, healthy males (n = 9) underwent afternoon sessions of whole body skin temperature (T(sk)) cooling (water-perfused suits) after oral melatonin (Mel; 3 mg) or placebo (Cont). Cutaneous vascular conductance (CVC) was calculated from SkBF (laser Doppler flowmetry) and non-invasive blood pressure. Baseline T(int) was lower in Mel than in Cont (P < 0.01). During progressive reduction of T(sk) from 35 degrees C to 32 degrees C, forearm CVC was first significantly reduced at T(sk) of 34.33 +/- 0.01 degrees C (P < 0.05) in Cont. In contrast, CVC in Mel was not significantly reduced until T(sk) reached 33.33 +/- 0.01 degrees C (P < 0.01). The decrease in forearm CVC in Mel was significantly less than in Cont at T(sk) of 32.66 +/- 0.01 degrees C and lower (P < 0.05). In Mel, palmar CVC was significantly higher than in Cont above T(sk) of 33.33 +/- 0.01 degrees C, but not below. Thus exogenous melatonin blunts reflex vasoconstriction in nonglabrous skin and shifts vasoconstrictor system control to lower T(int). It provokes vasodilation in glabrous skin but does not suppress the sensitivity to falling T(sk). These findings suggest that by affecting the vasoconstrictor system, melatonin has a causal role in the nocturnal changes in body temperature and its control.

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Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 77%

Exogenous melatonin administration modifies cutaneous vasoconstrictor response to whole body skin cooling in humans

Aoki

Zhao

Yamazaki

et al. 2007

Journal of Pineal Research

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“…Such a phenomenon might imply a seasonal change in the individual's sensitivity to light, followed by an increase of the melatonin peak level in the autumn in humans. Aizawa et al (2002) reported that melatonin administration reduced human tympanic temperature (T ty ) and it made cutaneous vasodilation and local sweating of the forearm occur at significantly lower T ty during local body warming in a hot water bath. They concluded that melatonin administration lowers the thermoregulatory setpoint.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Variations of Melatonin Secretion in Young Females under Natural and Artificial Light Conditions in Fukuoka, Japan

Ueno-Towatari

Norimatsu

Błażejczyk

et al. 2007

J Physiol Anthropol

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The purpose of this study was to examine the seasonal variations of melatonin secretion of subjects and of their surrounding light conditions. Eight Japanese female students (20.1Ϯ2.6 yrs, MeanϮSD) living in Fukuoka, Japan, participated in the present study. Saliva samples were collected every 3 hours over the course of a day, and the light intensity during daily life was measured every 1 min for 5 days in the four seasons. Almost all subjects had different melatonin secretory profiles in autumn, with only two subjects showing similar rhythms in all four seasons. The peak values of melatonin secretion calculated by a spline interpolation were higher in autumn than those in other seasons (pϽ0.001, Fisher's PLSD) and its peak time in this season was significantly delayed compared with those in spring and summer (pϽ0.05, Fisher's PLSD). The amount of time during daytime exposure to light of Ͼ1,000 lux was at least thirty minutes in all the seasons, and there were no significant differences among them. The relationship between peak level of melatonin secretion and amount of time of daytime light exposure to Ͼ1,000 lux was significant only in the autumn. During this season, there was a significant positive correlation (rϭ0. 83, pϽ0.05, nϭ6), except for two subjects, whose melatonin secretion remained low.

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“…In humans, a transient post-prandial elevation of serum melatonin has been detected and related to the release of melatonin from the GIT. This has been linked to postprandial somnolence [ 85 ] and a decrease in the core body temperature [ 91 , 92 ], although it is not clear whether this slight increase in serum melatonin after a meal is sufficient to cause this effect.…”

Section: Biologymentioning

confidence: 99%

Melatonin and Cancer: A Polyhedral Network Where the Source Matters

Bonmatí-Carrión

Tomás-Loba

2021

Antioxidants

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Melatonin is one of the most phylogenetically conserved signals in biology. Although its original function was probably related to its antioxidant capacity, this indoleamine has been “adopted” by multicellular organisms as the “darkness signal” when secreted in a circadian manner and is acutely suppressed by light at night by the pineal gland. However, melatonin is also produced by other tissues, which constitute its extrapineal sources. Apart from its undisputed chronobiotic function, melatonin exerts antioxidant, immunomodulatory, pro-apoptotic, antiproliferative, and anti-angiogenic effects, with all these properties making it a powerful antitumor agent. Indeed, this activity has been demonstrated to be mediated by interfering with various cancer hallmarks, and different epidemiological studies have also linked light at night (melatonin suppression) with a higher incidence of different types of cancer. In 2007, the World Health Organization classified night shift work as a probable carcinogen due to circadian disruption, where melatonin plays a central role. Our aim is to review, from a global perspective, the role of melatonin both from pineal and extrapineal origin, as well as their possible interplay, as an intrinsic factor in the incidence, development, and progression of cancer. Particular emphasis will be placed not only on those mechanisms related to melatonin’s antioxidant nature but also on the recently described novel roles of melatonin in microbiota and epigenetic regulation.

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The administration of exogenous melatonin during the daytime lowers the thermoregulatory setpoint in humans

Cited by 11 publications

References 15 publications

Exogenous melatonin administration modifies cutaneous vasoconstrictor response to whole body skin cooling in humans

Exogenous melatonin administration modifies cutaneous vasoconstrictor response to whole body skin cooling in humans

Seasonal Variations of Melatonin Secretion in Young Females under Natural and Artificial Light Conditions in Fukuoka, Japan

Melatonin and Cancer: A Polyhedral Network Where the Source Matters

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