title: Obstructive sleep apnea is associated with low GABA and high glutamate in the insular cortex.
abstract: The insular cortex is injured in obstructive sleep apnea (OSA) and responds inappropriately to autonomic challenges, suggesting neural reorganization. The objective of this study was to assess whether the neural changes might result from γ-aminobutyric acid (GABA) and glutamate alterations. We studied 14 OSA patients [mean age ± standard deviation (SD): 47.5 ± 10.5 years; nine male; apnea-hypopnea index (AHI): 29.5 ± 15.6 events h(-1) ] and 22 healthy participants (47.5 ± 10.1 years; 11 male), using magnetic resonance spectroscopy to detect GABA and glutamate levels in insular cortices. We localized the cortices with anatomical scans, and measured neurochemical levels from anterior to mid-regions. Left and right anterior insular cortices showed lower GABA and higher glutamate in OSA versus healthy subjects [GABA left: OSA n = 6: 0.36 ± 0.10 (mean ± SD), healthy n = 5: 0.62 ± 0.18; P < 0.05), right: OSA n = 11: 0.27 ± 0.09, healthy n = 14: 0.45 ± 0.16; P < 0.05; glutamate left: OSA n = 6: 1.61 ± 0.32, healthy n = 8: 0.94 ± 0.34; P < 0.05, right: OSA n = 14: 1.26 ± 0.28, healthy n = 19: 1.02 ± 0.28; P < 0.05]. GABA and glutamate levels were correlated only within the healthy group in the left insula (r: -0.9, P < 0.05). The altered anterior insular levels of GABA and glutamate may modify integration and projections to autonomic areas, contributing to the impaired cardiovascular regulation in OSA.
authors: School of Nursing, University of California at Los Angeles, Los Angeles, CA, USA.|Brain Research Institute, University of California at Los Angeles, Los Angeles, CA, USA.
authors: Paul M
authors: PM
authors: Macey
authors: Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, CA, USA.
authors: Manoj K
authors: MK
authors: Sarma
authors: Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, CA, USA.
authors: Rajakumar
authors: R
authors: Nagarajan
authors: Department of Medicine (Division of Pulmonary and Critical Care), University of California at Los Angeles, Los Angeles, CA, USA.
authors: Ravi
authors: R
authors: Aysola
authors: Department of Psychiatry, University of California at Los Angeles, Los Angeles, CA, USA.
authors: Jerome M
authors: JM
authors: Siegel
authors: Brain Research Institute, University of California at Los Angeles, Los Angeles, CA, USA.|Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA, USA.
authors: Ronald M
authors: RM
authors: Harper
authors: Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, CA, USA.
authors: M Albert
authors: MA
authors: Thomas
mesh_terms: D001341:Autonomic Nervous System / Q000378:metabolism; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D020181:Sleep Apnea, Obstructive / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid
keywords: autonomic; intermittent excitoxicity hypoxia; neurotransmitter