Modulatory Factors of Circadian Phagocytic Activity

Abstract

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.

Time and Dose Dependent Effects of Continuous Consumption of Monosodium Glutamate on Organ Histology (Kidney and Liver), Haematological and Biochemical Profiles of Albino Wistar Rats.

“…Two main types of idiosyncratic drug/ chemical-induced neutropenia are recognized, one type is a dose-related toxicity due to interference of drug/ chemical with protein synthesis which glutamate toxicity might lead to such Ramaiahet al (2007). This work agrees with Hirscu, (2005) where neonatal administration of neurotoxic agent Monosodium glutamate in rats induced massive destruction of arcuate nucleus, and suppresses phagocytic responses of decreased neutrophils. There was significant increase (P<0.05) of lymphocytes in all the test groups (A -E) in weeks 2 -4 which is similar with the work of Oguntayoet al, (2005) in rabbits administered with oral dose of Monosodium glutamate.…”

Cardiomyocyte-specific Bmal1 deletion in mice triggers diastolic dysfunction, extracellular matrix response, and impaired resolution of inflammation

“…As leukocytes are known to display higher phagocytic ability and cytotoxicity during the active phase, the disruption of the circadian clocks leads to acute inflammatory insults (2,18). Moreover, after myocardial injury diurnal rhythm disruptions alter neutrophil and macrophage kinetics and delays the resolving phase (1).…”

From blood to brain: amoeboid microglial cell, a nascent macrophage and its functions in developing brain

“…In addition to its immunomodulatory actions, melatonin has also been reported to be important for phagocytosis under physiological conditions [113] . AMC showed a significant increase in cell numbers and upregulation of CR3, MHC I and MHC II, and CD4 antigens in response to melatonin administration [114] , indicating enhanced endocytic and antigen-presenting capacity.…”