The pineal neurohormone melatonin and its physiologic opiatergic immunoregulatory role

Maestroni, Georges J. M.; Conti, Ario; Pierpaoli, Walter

doi:10.1590/s0074-02761987000600012

Cited by 2 publications

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“…This photoperiod function of melatonin is of unquestionable importance in the entire animal kingdom, from single-cell organisms [Poeggeler et al, 1991;Hardeland et al, 19951 to vertebrates [Reiter, 19931. The study of the two-way relationships be-tween the pineal gland, melatonin, and the immune system has risen notably in importance in recent years. Experiments have shown there to be a functional relationship between the pineal gland and the immune system in mammals and birds [Maestroni, 1993;Rodriguez and Lea, 1994a;Skwarlo-Sonta, 1996;Rodriguez et al, 19971. However, the mechanisms by which melatonin influences the immune function are complex, with the participation of such mediators as endogenous opioids, cytokines, and hormones [Skwarlo-Sonta, 19961, and the existence of specific receptor sites in immune cells [Reiter et al, 19961.…”

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confidence: 99%

Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils

Rodríguez¹,

Marchena²,

Nogales³

et al. 1999

Journal of Pineal Research

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A functional role for melatonin is its relationship to circadian timing mechanisms. In addition, there has recently been assumed to be a functional connection between the pineal gland and the immune system in mammals and birds, with some findings showing melatonin to be a free radical scavenger and general antioxidant. The present study investigates the possible relationship between the circadian rhythm of melatonin and the ingestion capacity as well as superoxide anion levels of ring dove (Streptopelia risoria) heterophils. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defence mechanism. All determinations were made during 24 hr periods at 2 hr intervals. Radioimmunoassay showed an increase of melatonin serum levels during the dark period (from 20:00 to 07:00 hr) with a maximum at 04:00 hr, and a significant decline during the hours of light with a minimum at 16:00 hr. Similarly, the phagocytic index was enhanced during the night, with the maximum at approximately 04:00 hr and the minimum at approximately 18:00 hr. The same was the case in relation to phagocytic percentage. However, the superoxide anion levels were lower during darkness (minimum at 04:00 hr) and higher during the light period (maximum at 14:00 hr). In conclusion, our findings show that one pineal-mediated effect on the immune system may be a direct action of melatonin on phagocytosis and the phagocytic biochemical process, and that this neurohormone might act as an antioxidant.

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Section: Introductionmentioning

confidence: 99%

Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils

Rodríguez¹,

Marchena²,

Nogales³

et al. 1999

Journal of Pineal Research

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Modulatory Factors of Circadian Phagocytic Activity

M¹

2005

Annals of the New York Academy of Sciences

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Basal phagocytosis of neutrophils, a crucial component of non-specific immunity, is an eminently circadian parameter. In mice and rats, rates of phagocytosis peak in the second half of the dark span. A lipopolysaccharide-induced phagocytic response challenged in this period appears the most significant in amplitude and duration. Neonatal administration in rats of the neurotoxic agent monosodium glutamate, which induces massive destruction of the arcuate nucleus, suppresses the phagocytic response and moderately inhibits basal phagocytosis. Physiological phagocytosis in vivo appears to depend on the presence of the nocturnal melatonin surge. Functional pinealectomy, achieved in rats by a 2-week exposure to constant light, lowered the average circadian level of phagocytosis, damped the characteristic rhythm of neutrophil adherence, and decreased the neutrophil count and the amplitude of its circadian oscillation. In an in vivo study, adult rats were given alcohol intraperitoneally (0.1 mL ethanol/kg body weight, 1:10 in saline solution), alone or co-administered with melatonin (1 mg/kg body weight), for 16 days, once a day at 20:00 h. Alcohol-treated animals displayed a drastically depressed and flattened phagocytic curve, a marked decline of the adherence ability, and a reduction of the mean circadian neutrophil and lymphocyte count. Addition of melatonin significantly increased circadian values of phagocytosis, restored adherence, and prevented the numeric depletion of lymphocytes induced by alcohol. In correlation with other experimental evidence, our data speak for a physiological role of melatonin in upkeep of neutrophil phagocytosis and hint towards the existence of several pineal-hypothalamic pathways regulating different components of phagocytosis in vivo.

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The pineal neurohormone melatonin and its physiologic opiatergic immunoregulatory role

Cited by 2 publications

References 0 publications

Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils

Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils

Modulatory Factors of Circadian Phagocytic Activity

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