title: Avian biological clock - Immune system relationship.
abstract: Biological rhythms in birds are driven by the master clock, which includes the suprachiasmatic nucleus, the pineal gland and the retina. Light/dark cycles are the cues that synchronize the rhythmic changes in physiological processes, including immunity. This review summarizes our investigations on the bidirectional relationships between the chicken pineal gland and the immune system. We demonstrated that, in the chicken, the main pineal hormone, melatonin, regulates innate immunity, maintains the rhythmicity of immune reactions and is involved in the seasonal changes in immunity. Using thioglycollate-induced peritonitis as a model, we showed that the activated immune system regulates the pineal gland by inhibition of melatonin production at the level of the key enzyme in its biosynthetic pathway, arylalkylamine-N-acetyltransferase (AANAT). Interleukin 6 and interleukin 18 seem to be the immune mediators influencing the pineal gland, directly inhibiting Aanat gene transcription and modulating expression of the clock genes Bmal1 and Per3, which in turn regulate Aanat.
authors.affiliation: University of Warsaw, Faculty of Biology, Institute of Zoology, Department of Animal Physiology, Miecznikowa 1 Str., 02-096, Warsaw, Poland. Electronic address: markosia@biol.uw.edu.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Markowska
authors.affiliation: University of Warsaw, Faculty of Biology, Institute of Zoology, Department of Animal Physiology, Miecznikowa 1 Str., 02-096, Warsaw, Poland.
authors.forename: Paweł M
authors.initials: PM
authors.lastname: Majewski
authors.affiliation: University of Warsaw, Faculty of Biology, Institute of Zoology, Department of Animal Physiology, Miecznikowa 1 Str., 02-096, Warsaw, Poland.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Skwarło-Sońta
mesh_terms: D056930:ARNTL Transcription Factors / Q000378:metabolism; D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism; D001683:Biological Clocks; D002645:Chickens / Q000276:immunology*; D002940:Circadian Rhythm; D006801:Humans; D007107:Immune System; D007249:Inflammation / Q000276:immunology*; D020382:Interleukin-18 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008550:Melatonin / Q000378:metabolism; D015213:Neuroimmunomodulation; D056950:Period Circadian Proteins / Q000378:metabolism
chemical_list: D056930:ARNTL Transcription Factors; D030161:Avian Proteins; D020382:Interleukin-18; D015850:Interleukin-6; D056950:Period Circadian Proteins; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin
keywords: Chicken; Immunity; Peritonitis; Photoperiod; Pineal gland; Seasonality