Ion Homeostasis in Rhythmogenesis: The Interplay Between Neurons and Astroglia.
Proper function of all excitable cells depends on ion homeostasis. Nowhere is this more critical than in the brain where the extracellular concentration of some ions determines neurons' firing pattern and ability to encode information. Several neuronal functions depend on the ability of neurons to change their firing pattern to a rhythmic bursting pattern, whereas, in some circuits, rhythmic firing is, on the contrary, associated to pathologies like epilepsy or Parkinson's disease. In this review, we focus on the four main ions known to fluctuate during rhythmic firing: calcium, potassium, sodium, and chloride. We discuss the synergistic interactions between these elements to promote an oscillatory activity. We also review evidence supporting an important role for astrocytes in the homeostasis of each of these ions and describe mechanisms by which astrocytes may regulate neuronal firing by altering their extracellular concentrations. A particular emphasis is put on the mechanisms underlying rhythmogenesis in the circuit forming the central pattern generator (CPG) for mastication and other CPG systems. Finally, we discuss how an impairment in the ability of glial cells to maintain such homeostasis may result in pathologies like epilepsy and Parkinson's disease.
Département de Neurosciences and Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada; and.
Aklesso
A
Kadala
Département de Neurosciences and Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada; and.
Dorly
D
Verdier
Département de Neurosciences and Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada; and.
Philippe
P
Morquette
Département de Neurosciences and Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada; and Faculté de Médecine Dentaire and Réseau de Recherche en Santé Bucco-dentaire et Osseuse du Fonds de Recherche Québec-Santé, Université de Montréal, Montréal, Québec, Canada Arlette.kolta@umontreal.ca.
Arlette
A
Kolta
D000200:Action Potentials; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism; D002450:Cell Communication; D063226:Central Pattern Generators / Q000378:metabolism* / Q000503:physiopathology; D002712:Chlorides / Q000378:metabolism; D004827:Epilepsy / Q000378:metabolism / Q000503:physiopathology; D006706:Homeostasis; D006801:Humans; D017136:Ion Transport; D007700:Kinetics; D009069:Movement Disorders / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000378:metabolism*; D010507:Periodicity; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D012964:Sodium; D011188:Potassium; D002118:Calcium