title: Melatonin modulates intercellular communication among cultured chick astrocytes.
abstract: Melatonin, a pineal neurohormone, mediates circadian and seasonal processes in birds and mammals. Diencephalic astrocytes are sites of action, at least in birds, since they express melatonin receptors and melatonin affects their metabolism. We tested whether astrocytic calcium waves are also modulated by melatonin. Calcium waves, which we found to be regulated in cultured chick glial cells by an IP(3)-dependent mechanism, were potentiated by physiological concentrations of melatonin. Melatonin also increased resting calcium levels and reduced gap junctional coupling among astrocytes, at concentrations that facilitated calcium waves. These modulatory effects were diminished by melatonin receptor blockade and pertussis toxin (PTX). Thus, melatonin induced a functional shift in the mode of intercellular communication, between junctional coupling and calcium waves, among glial cells. We suggest a mechanism where neuroglial physiology, involving GTP-binding protein signaling pathways, links rhythmic circadian outputs to pervasive neurobehavioral states.
authors.affiliation: Department of Biology and Center for Biological Clocks Research, Texas A&M University, Room 231, College Station, TX 77843-3258, USA. jpeters@mail.bio.tamu.edu
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Peters
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Cassone
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Zoran
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D002940:Circadian Rhythm / Q000502:physiology; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism; D008550:Melatonin / Q000378:metabolism* / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D044094:Receptors, Melatonin / Q000037:antagonists & inhibitors
chemical_list: D044094:Receptors, Melatonin; D037342:Pertussis Toxin; D008550:Melatonin