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Sci Rep. 2017 Aug 31;7(1):10226. doi: 10.1038/s41598-017-09778-x.

Intracellular Chloride Regulation in AVP+ and VIP+ Neurons of the Suprachiasmatic Nucleus.

Author information

1
Neuroscience Graduate Program, School of Medicine, Oregon Health & Science University, Portland, OR, 97239, USA.
2
Oregon Institute for Occupational Health Sciences, School of Medicine, Oregon Health & Science University, Portland, OR, 97239, USA.
3
Oregon Institute for Occupational Health Sciences, School of Medicine, Oregon Health & Science University, Portland, OR, 97239, USA. allenc@ohsu.edu.
4
Department of Behavioral Neuroscience, School of Medicine, Oregon Health & Science University, Portland, OR, 97239, USA. allenc@ohsu.edu.

Abstract

Several reports have described excitatory GABA transmission in the suprachiasmatic nucleus (SCN), the master pacemaker of circadian physiology. However, there is disagreement regarding the prevalence, timing, and neuronal location of excitatory GABA transmission in the SCN. Whether GABA is inhibitory or excitatory depends, in part, on the intracellular concentration of chloride ([Cl-]i). Here, using ratiometric Cl- imaging, we have investigated intracellular chloride regulation in AVP and VIP-expressing SCN neurons and found evidence suggesting that [Cl-]i is higher during the day than during the night in both AVP+ and VIP+ neurons. We then investigated the contribution of the cation chloride cotransporters to setting [Cl-]i in these SCN neurons and found that the chloride uptake transporter NKCC1 contributes to [Cl-]i regulation in SCN neurons, but that the KCCs are the primary regulators of [Cl-]i in SCN neurons. Interestingly, we observed that [Cl-]i is differentially regulated between AVP+ and VIP+ neurons-a low concentration of the loop diuretic bumetanide had differential effects on AVP+ and VIP+ neurons, while blocking the KCCs with VU0240551 had a larger effect on VIP+ neurons compared to AVP+ neurons.

PMID:
28860458
PMCID:
PMC5579040
DOI:
10.1038/s41598-017-09778-x
[Indexed for MEDLINE]
Free PMC Article

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