title: Circadian modulation of the Cl(-) equilibrium potential in the rat suprachiasmatic nuclei.
abstract: The suprachiasmatic nuclei (SCN) constitute a circadian clock in mammals, where γ-amino-butyric acid (GABA) neurotransmission prevails and participates in different aspects of circadian regulation. Evidence suggests that GABA has an excitatory function in the SCN in addition to its typical inhibitory role. To examine this possibility further, we determined the equilibrium potential of GABAergic postsynaptic currents (E(GABA)) at different times of the day and in different regions of the SCN, using either perforated or whole cell patch clamp. Our results indicate that during the day most neurons in the dorsal SCN have an E(GABA) close to -30 mV while in the ventral SCN they have an E(GABA) close to -60 mV; this difference reverses during the night, in the dorsal SCN neurons have an E(GABA) of -60 mV and in the ventral SCN they have an E(GABA) of -30 mV. The depolarized equilibrium potential can be attributed to the activity of the Na(+)-K(+)-2Cl(-) (NKCC) cotransporter since the equilibrium potential becomes more negative following addition of the NKCC blocker bumetanide. Our results suggest an excitatory role for GABA in the SCN and further indicate both time (day versus night) and regional (dorsal versus ventral) modulation of E(GABA) in the SCN.
authors.affiliation: División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, 04510 México, DF, Mexico ; Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, Canada L8S 4K1.
authors.forename: Javier
authors.identifier: 0000-0002-9666-5490
authors.initials: J
authors.lastname: Alamilla
authors.affiliation: División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, 04510 México, DF, Mexico ; McMaster Brain-Body Institute, St Joseph's Healthcare, Hamilton, ON, Canada L8N 4A6.
authors.forename: Azucena
authors.initials: A
authors.lastname: Perez-Burgos
authors.affiliation: División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, 04510 México, DF, Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Quinto
authors.affiliation: División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, 04510 México, DF, Mexico.
authors.forename: Raúl
authors.initials: R
authors.lastname: Aguilar-Roblero
mesh_terms: D000818:Animals; D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism; D064506:Solute Carrier Family 12, Member 2 / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000378:metabolism; D009435:Synaptic Transmission / Q000235:genetics*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D011963:Receptors, GABA-A; C578879:Slc12a2 protein, rat; D064506:Solute Carrier Family 12, Member 2; D005680:gamma-Aminobutyric Acid