Chrononutrition against oxidative stress in aging.

Free radicals and oxidative stress have been recognized as important factors in the biology of aging and in many age-associated degenerative diseases. Antioxidant systems deteriorate during aging. It is, thus, considered that one way to reduce the rate of aging and the risk of chronic disease is to avoid the formation of free radicals and reduce oxidative stress by strengthening antioxidant defences. Phytochemicals present in fruits, vegetables, grains, and other foodstuffs have been linked to reducing the risk of major oxidative stress-induced diseases. Some dietary components of foods possess biological activities which influence circadian rhythms in humans. Chrononutrition studies have shown that not only the content of food, but also the time of ingestion contributes to the natural functioning of the circadian system. Dietary interventions with antioxidant-enriched foods taking into account the principles of chrononutrition are of particular interest for the elderly since they may help amplify the already powerful benefits of phytochemicals as natural instruments with which to prevent or delay the onset of common age-related diseases.

Melatonin reduces body weight gain and increases nocturnal activity in male Wistar rats.

AIM: This study evaluated the effect of the administration of melatonin, the chief secretory product of the pineal gland, on the body weight in male Wistar rats. MAIN METHODS: The animals were housed for 4months in cages equipped to log horizontal activity within a thermostatically-controlled chamber, under a 12h/12h light/dark photoperiod (lights on at 08:00h). After acclimatization, the animals were divided into two groups: (1) control animals, and (2) melatonin-treated animals. Melatonin was administered in tap water (20µg/ml), and fresh drinking fluid was changed twice weekly. Rats were fed a standard diet ad libitum. KEY FINDINGS: Food and water intake, body weight, the amplitude of the activity/rest rhythm (motor activity), and blood melatonin and glucose concentrations were measured. The administration of melatonin did not influence either food or water intake or glucose levels relative to those found in the control animals. However, melatonin administration reduced body weight gain and increased nocturnal locomotor activity. The peak concentration of melatonin was found at night coinciding with the increase in nocturnal activity. SIGNIFICANCE: The results show that exogenous melatonin reduces body weight gain without having marked effects on metabolism. This may be due in part to the increased nocturnal activity shown by the animals treated with the indoleamine.

Diets enriched with a Jerte Valley cherry-based nutraceutical product reinforce nocturnal behaviour in young and old animals of nocturnal (Rattus norvegicus) and diurnal (Streptopelia risoria) chronotypes.

The decline in melatonin secretion with age seems to be one of the major reasons for increased sleep disruption in older animals. Previously, we showed that the administration with melatonin or its precursor, tryptophan, improved activity/rest rhythms in aged individuals. Here, it was evaluated the effect of a 10-day consumption of a Jerte Valley cherry-based nutraceutical product (patent no. ES2342141B1), which contains high levels of tryptophan, serotonin and melatonin, on the activity/rest rhythms of young and old rats (Rattus norvegicus) and ringdoves (Streptopelia risoria) as representatives of animals with nocturnal and diurnal habits, respectively, and its possible relationship with the serum levels of melatonin and glucose. Total diurnal and nocturnal activity pulses were logged at control, during, and up to 3 days after the treatment. Melatonin and glucose were measured with ELISA and testing kits respectively. In both young and old rats, the intake of the cherry nutraceutical decreased diurnal activity, whereas nocturnal activity increased. The opposite effect was observed for ringdoves. The treatment increased the circulating levels of melatonin in both species and restored the amplitude of the activity rhythm in the old animals to that of the non-treated young groups. The consumption of a Jerte Valley cherry-based nutraceutical product may help to counteract the impaired activity/rest rhythm found in aged animals.

Effect of melatonin and tryptophan on humoral immunity in young and old ringdoves (Streptopelia risoria).

Melatonin is involved in the regulation of both cellular and humoral immunity. In the present study we have evaluated the effect of the oral administration of melatonin and its precursor, the amino acid tryptophan, on humoral immune response in ringdoves (Streptopelia risoria) from different age groups. Male and female ringdoves of 4-5years of age (young) and 12-14years of age (old) were used in this study. The animals received a single capsule of 300mg/kg b.w. of tryptophan (old animals) for 3 consecutive days 1h after lights on or a single oral dose (0.25 or 2.5mg/kg body weight/0.1ml per animal/day, young and old animals, respectively) of melatonin, for 3 consecutive days 1h before lights off. Blood samples were taken before beginning the treatment (basal values) and at the end of the treatment. Immunoglobulins, bactericidal and haemolytic activity were measured. Our results show that in old animals the humoral immune response was reduced with respect to the young. Both melatonin and tryptophan treatment increased the immunoglobulin concentration, with the nocturnal values being significantly higher than diurnal values and with a major effect in old animals. The bactericidal activity of the S. risoria serum against Staphylococcus aureus, after the treatment with melatonin or tryptophan, was increased at night with a greater effect in old animals. No significant differences were observed in the haemolytic activity of the serum in young animals, but there was an increase in old animals, with higher values at night after treatment with melatonin. In general, the oral administration of melatonin or tryptophan produced a stimulation of humoral immune response with greater effects in old ringdoves.

The potential of melatonin in reducing morbidity-mortality after craniocerebral trauma.

Craniocerebral trauma (CCT) is the most frequent cause of morbidity-mortality as a result of an accident. The probable origins and etiologies are multifactorial and include free radical formation and oxidative stress, the suppression of nonspecific resistance, lymphocytopenia (disorder in the adhesion and activation of cells), opportunistic infections, regional macro and microcirculatory alterations, disruptive sleep-wake cycles and toxicity caused by therapeutic agents. These pathogenic factors contribute to the unfavorable development of clinical symptoms as the disease progresses. Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine endogenously produced in the pineal gland and in other organs and it is protective agent against damage following CCT. Some of the actions of melatonin that support its pharmacological use after CCT include its role as a scavenger of both oxygen and nitrogen-based reactants, stimulation of the activities of a variety of antioxidative enzymes (e.g. superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase), inhibition of pro-inflammatory cytokines and activation-adhesion molecules which consequently reduces lymphocytopenia and infections by opportunistic organisms. The chronobiotic capacity of melatonin may also reset the natural circadian rhythm of sleep and wakefulness. Melatonin reduces the toxicity of the drugs used in the treatment of CCT and increases their efficacy. Finally, melatonin crosses the blood-brain barrier and reduces contusion volume and stabilizes cellular membranes preventing vasospasm and apoptosis of endothelial cells that occurs as a result of CCT.

Hydrogen peroxide increases the phagocytic function of human neutrophils by calcium mobilisation.

We have studied the effect of exogenous administration of hydrogen peroxide (H(2)O(2)) on phagocytic activity of human neutrophils. The treatment of cells with increasing concentrations of H(2)O(2) evoke a significant elevation of phagocytic function assayed as phagocytic index, percentage and efficiency; and was similar to that induced by the calcium mobilising agonist formyl-methionyl-leucyl-phenylalanine (fMLP). This stimulatory effect was reduced by pre-treatment of neutrophils with catalase and abolished in neutrophils loaded with the intracellular calcium quelator dimethyl BAPTA. In the absence of extracellular calcium, treatment of cells with H(2)O(2) resulted in a increase in [Ca(2+)]( i ), indicating the release of calcium from intracellular stores. H(2)O(2) abolished the typical calcium release stimulated by the physiological agonist fMLP, while depletion of agonist-sensitive calcium pools by fMLP was able to prevent H(2)O(2)-induced calcium release. We conclude that H(2)O(2) induces calcium release from agonist-sensitive stores and consequently increase the phagocytosis process.

Melatonin, lipid peroxidation, and age in heterophils from the ring dove (Streptopelia risoria).

Numerous recent studies have shown the ability of physiological as well as all pharmacological concentrations of melatonin to prevent oxidative stress. We have found that incubating avian heterophils from young birds with a pharmacological concentration of 100 microM (23x10(6) pg/ml) melatonin reduced superoxide anion levels by modulating the activity of superoxide dismutase while also enhancing phagocytosis. There was also a decline in lipid peroxidation levels with both physiological and pharmacological concentrations of this indolamine. In the present work, we evaluated malonaldehyde (MDA) levels as an indicator of lipid peroxidation (both basal and antigen-induced) in young and old animals (ring doves) at different times of day (16:00 and 00:00) and with two incubation times (15 and 60 min). The lipid peroxidation was also measured in heterophils from old animals, incubated with the physiological concentrations of melatonin measured in young animals (50 and 300 pg/ml, diurnal and nocturnal, respectively). The results, expressed as nmol MDA/mg protein, show that MDA levels were higher in heterophils of old animals than in the young birds in all the experimental groups studied at both 16:00 and 00:00 (00:00 is the time at which the lowest peroxidation levels were obtained). Incubation with melatonin was found to reduce MDA levels, with the maximum reduction being after the 60?min incubation time and the nocturnal melatonin concentration. At both concentrations (diurnal and nocturnal), melatonin also counteracted the enhancement of MDA levels caused by latex beads, with the effect being greater at the longer incubation time. In conclusion, the results are further evidence of the antioxidant effect of melatonin even at physiological concentrations, and suggest its utility as a therapeutic agent in some pathological processes associated with age.

Comparative study of the heterophil phagocytic function in young and old ring doves (Streptopelia risoria) and its relationship with melatonin levels.

A functional connection between the pineal gland (via the hormone melatonin) and the immune system has been suggested. In our previous results in the ring dove, we observed diurnal oscillations in the levels of this neurohormone in young animals and a decline in its plasma levels with advancing age (which is accompanied by the absence of diurnal rhythm). We also noted enhanced phagocytic activity of heterophils from old animals after in vitro incubation with both physiological and pharmacological doses of melatonin. Here, we evaluate the functional capacity of ring dove (Streptopelia risoria) heterophils in young (2 years of age) and old (8 years and more) animals at different times of day (0:00, 10:00 and 16:00, the times when the maximum, minimum, and mean values, respectively, of melatonin levels are observed in young animals). The phagocytic capacities for the ingestion of latex beads and Candida albicans were evaluated, as well as the oxidative metabolism which accompanies phagocytosis. At all three times of day studied, the heterophil phagocytic function with both latex and C. albicans was significantly greater in the young than in the old animals, and in the young animal cells it was significantly higher at 0:00. In addition, in the presence of latex beads, there was a significant decline at 10:00 and 0:00 of superoxide anion levels in the young animals relative to the old. In the young animals, there was a decline at 0:00 in comparison with both 10:00 and 16:00, and in the old animals there was a decline at both 0:00 and 16:00 compared with 10:00. These results could be due, at least in part, to the absence of a diurnal rhythm of melatonin in old animals, and to an enhancing effect of that hormone on young animals' heterophil phagocytic function, which would also neutralize the oxidative stress deriving from this immune function.

Phagocytosis of Candida albicans and superoxide anion Levels in ring dove (Streptopelia risoria) heterophils: effect of melatonin.

We observed in previous studies on avian heterophils that incubation with either physiological or pharmacological concentrations of the neurohormone melatonin increased the phagocytosis of inert particles (latex beads), and also provoked a decline in superoxide anion levels of those phagocytes. In the present study, we wanted to corroborate whether melatonin acts on the oxidative metabolism that accompanies the respiratory burst during phagocytosis by inducing a more effective phagocytic activity at the same time as exerting an antioxidant effect to eliminate and/or scavenge the free radicals left over after the destruction of the foreign material. To this end, we evaluated the ingestion and destruction of Candida albicans (live particles) by ring dove (Streptopelia risoria) heterophils after different times of incubation (30 and 60 min) with physiological concentrations of melatonin (50 pg/ml diurnal and 300 pg/ml nocturnal), as well as with a pharmacological concentration 23 x 106 pg/ml (100 micro m) of the hormone. In parallel, using the same times of incubation, we evaluated the oxidative metabolism by determining the superoxide anion levels (O2-.). The results show that melatonin, at all the times and concentrations studied, increases both the phagocytosis index (number of C. albicans phagocytosed by 100 heterophils) and the candidicide power (percentage of C. albicans killed of those ingested by 100 heterophils). The effect was dose-dependent. With respect to the oxidative metabolism accompanying the digestion and destruction, there was a decline in superoxide anion levels after incubation with all of the concentrations of the hormone studied. The effect was dose-dependent and most pronounced at 60 min. These results thus corroborate the proposal that melatonin enhances the phagocytic function at the same time as neutralizing the oxidative stress derived from this immune function.

Melatonin and aging: in vitro effect of young and mature ring dove physiological concentrations of melatonin on the phagocytic function of heterophils from old ring dove.

We have studied the circadian rhythm of melatonin in the ring dove (Streptopelia risoria) for different age groups: young (1-1.5 years), mature (3-4 years) and old animals (>8 years). Melatonin levels were determined by radioimmunoassay. Results showed a significant decline in plasma melatonin levels in old animals when compared with the concentrations observed in the other two age groups, in which maximum (nocturnal) concentrations were 300 pg/ml and minimum (diurnal) concentrations were 50 pg/ml. We analyzed the in vitro effect of the physiological concentrations found in young and mature animals on the heterophils obtained from old animals, evaluating the capacity for ingestion and destruction of Candida albicans, and the oxidative metabolism associate to phagocytosis by determining the superoxide anion levels. Melatonin induced an increase in both the phagocytosis index and the candidicide capacity. This effect was dose-dependent. In relation with the oxidative metabolism, a decline in superoxide anion levels after incubation with both concentrations of the hormone was observed. Thus our results corroborate in this avian species the decline in plasma melatonin levels with advanced age, as well as the enhancing effect of physiological concentrations of melatonin on the phagocytic function.

Physiological concentrations of melatonin and corticosterone affect phagocytosis and oxidative metabolism of ring dove heterophils.

A functional connection between the neuroendocrine and the immune systems has been established. Of particular interest is the finding that hormones such as melatonin and corticosterone are able to exert modulating effects on the immune function. Therefore, after determining the circadian rhythms of melatonin and corticosterone, we evaluated the in vitro effect of physiological concentrations of melatonin and corticosterone, separately and together, on the phagocytic function and superoxide anion levels of heterophils in ring dove (Streptopelia risoria). Trials were performed with concentrations corresponding to the nocturnal and diurnal levels reached by each of the hormones (50:300 pg/mL and 100:10 ng/mL for melatonin and corticosterone, diurnal:nocturnal, respectively). The phagocytes were incubated with the hormones both alone and concurrently. At the highest (nocturnal) concentration, melatonin augmented phagocytic function and at the same time inducing a fall in superoxide anion levels. At the highest (diurnal) concentration, corticosterone also enhanced phagocytic function, but without modifying the phagocyte oxidative metabolism. In the presence of both hormones, however, whether with nocturnal or diurnal concentrations, there was a greater increase in phagocytic function and a decrease in superoxide anion levels than was produced by either of the hormones alone. In conclusion, our findings suggest that melatonin and corticosterone may have an additive effect in the modulation of phagocytic function.