Prolonged exposure to hypobaric hypoxia transiently reduces GABAA receptor number in mice cerebral cortex

Viapiano, Mariano S.; Novara, Alba Marta Mitridate de; Plazas, Sara Fiszer de; Bozzini, Carlos E.

doi:10.1016/s0006-8993(00)03194-2

Cited by 19 publications

(11 citation statements)

References 34 publications

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“…Prigatano et al (1983) and Bedard et al (1991) maintain that the frontal lobe is also affected in subjects who suffer from hypoxia continuously. In support of this hypothesis, Viapiano et al (2001), exposed a group of 21 monkeys to hypoxia, found a 30% decrease in maximal binding capacity in γ -amynobutiric acid (GABA) to GABA A receptor sites. The change was reversible after returning to normoxia.…”

Section: Structures Sensitive To Hypoxiamentioning

confidence: 92%

Neuropsychological Functioning Associated with High-Altitude Exposure

et al. 2004

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This article focuses on neuropsychological functioning at moderate, high, and extreme altitude. This article summarizes the available literature on respiratory, circulatory, and brain determinants on adaptation to hypoxia that are hypothesized to be responsible for neuropsychological impairment due to altitude. Effects on sleep are also described. At central level, periventricular focal damages (leuko-araiosis) and cortical atrophy have been observed. Frontal lobe and middle temporal lobe alterations are also presumed. A review is provided regarding the effects on psychomotor performance, perception, learning, memory, language, cognitive flexibility, and metamemory. Increase of reaction time and latency of P300 are observed. Reduced thresholds of tact, smell, pain, and taste, together with somesthetic illusions and visual hallucinations have been reported. Impairment in codification and short-term memory are especially noticeable above 6,000 m. Alterations in accuracy and motor speed are identified at lower altitudes. Deficits in verbal fluency, language production, cognitive fluency, and metamemory are also detected. The moderating effects of personality variables over the above-mentioned processes are discussed. Finally, methodological flaws found in the literature are detailed and some applied proposals are suggested.

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Section: Structures Sensitive To Hypoxiamentioning

confidence: 92%

Neuropsychological Functioning Associated with High-Altitude Exposure

et al. 2004

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“…At the molecular level, impairment due to hypoxia at birth includes the transient reduction in the number of GABA receptors and the reduced expression of glutamate transporters (Viapiano et al 2001). To counteract such harmful effects on heart functions, cardioprotective agents have been developed both for newborn and adult animals.…”

Section: Introductionmentioning

confidence: 99%

Effects of hypoxia on stress proteins in the piglet heart at birth

Louapre

Grongnet²,

Tanguay

et al. 2005

Cell Stress Chaper

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Hypoxia at birth represents a very stressful event that can result in severe lifelong consequences in different tissues, including those of the heart. Heat shock and other associated stress proteins are involved in cellular protection, but their roles are not clearly defined at the time of birth. Newborn piglets were subjected to 5% oxygen and 95% nitrogen for either 1 or 4 hours. They were allowed to recover over periods of 1 to 68 hours. The relative levels of ␣B-crystallin, HspB8, Hsp20, Hsp27, Hsp60, and Hsp70 as well as nitric oxide synthases (NOS) (endothelial NOS, inducible NOS, neuronal NOS) were examined by Western blot analysis. Surprisingly, ␣B-crystallin expression was drastically increased in animals submitted to hypoxia. The hypoxia-associated factor HIFI␣ was also strongly and rapidly overexpressed. Heme oxygenase 1 was also increased. To a lesser extent, neuronal NOS was also increased in the left ventricle of animals submitted to hypoxia. This work clearly shows that the Hsp chaperone ␣B-crystallin is strongly overexpressed in the left ventricle of animals submitted to hypoxia. This observation dissociates the response to low oxygenation of ␣B-crystallin and other stress-associated proteins including Hsp27, and it indicates that heme oxygenase is not alone among HSPs in its oxygen-related gene expression.

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“…It has been suggested that the duration of the CSP depends on the function of inhibitory GABAergic synapses (27,45,48). HX in mammalian cortical neurons led to decreased presynaptic GABA release (39,44) or reduced postsynaptic GABAergic mechanisms (36), both of which reduce the synaptic efficacy of inhibitory transmission. The shortened CSP in our HX condition, therefore, also indicates a deterioration of GABAergic intracortical inhibition in vivo.…”

mentioning

confidence: 99%

The effects of short-term hypoxia on motor cortex excitability and neuromuscular activation

Szubski¹,

Burtscher²,

Löscher³

2006

Journal of Applied Physiology

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Szubski, Christoph, Martin Burtscher, and Wolfgang N. Lö scher. The effects of short-term hypoxia on motor cortex excitability and neuromuscular activation. J Appl Physiol 101: 1673-1677, 2006. First published August 17, 2006 doi:10.1152/japplphysiol.00617.2006.-The effects of acute hypoxia on motor cortex excitability, force production, and voluntary activation were studied using single-and double-pulse transcranial magnetic stimulation techniques in 14 healthy male subjects. Electrical supramaximal stimulations of the right ulnar nerve were performed, and transcranial magnetic stimulations were delivered to the first dorsal interosseus motor cortex area during short-term hypoxic (HX) and normoxic (NX) condition. M waves, voluntary activation, F waves, resting motor threshold (rMT), recruitment curves (100 -140% of rMT), and short-interval intracortical inhibition and intracortical facilitation were measured. Moreover, motor-evoked potentials (MEPs) and cortical silent periods were determined during brief isometric maximum right index finger abductions. Hypoxia was induced by breathing a fraction of inspired oxygen of 12% via a face mask. M waves, voluntary activation, and F waves did not differ between NX and HX. The rMT was significantly lower in HX (55.79 Ϯ 9.40%) than in NX (57.50 Ϯ 10.48%) (P Ͻ 0.01), whereas MEP recruitment curve, short-interval intracortical inhibition, intracortical facilitation, maximum right index finger abduction, and MEPs were unaffected by HX. In contrast, the cortical silent periods in HX (158.21 Ϯ 33.96 ms) was significantly shortened compared with NX (169.42 Ϯ 39.69 ms) (P Ͻ 0.05). These data demonstrate that acute hypoxia results in increased cortical excitability and suggest that acute hypoxia alters motor cortical ion-channel function and GABAergic transmission. transcranial magnetic stimulation; voluntary activation; cortical silent period STUDIES OF HYPOXIA-INDUCED CHANGES in central nervous system function have primarily focused on behavioral parameters and revealed impairments in psychomotor skills (25, 43) and cognitive performances (24,29,32). In addition to these deteriorations in performance, evidence of slowed visual and auditory reaction time has been demonstrated in experimental conditions corresponding to an altitude of ϳ6,100 m (15, 16).Numerous in vitro studies on central neurons strongly suggested that reduced arterial oxygen saturation impairs central nervous system function (34). In particular, the cerebral neuron excitability critically depends on sufficient O 2 supply, but hypoxia may not only compromise ion channels but also signaling pathways and neurotransmitter function (22,35). So far, most of our knowledge about the processes underlying hypoxia-induced alterations of neuronal excitability and synaptic neurotransmission has been gained from in vitro patchclamped studies.As yet, in vivo studies addressing the functional consequences of reduced O 2 supply to the neuromuscular system have primarily focused on effects on muscle force generation (13), endu...

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Prolonged exposure to hypobaric hypoxia transiently reduces GABAA receptor number in mice cerebral cortex

Cited by 19 publications

References 34 publications

Neuropsychological Functioning Associated with High-Altitude Exposure

Neuropsychological Functioning Associated with High-Altitude Exposure

Effects of hypoxia on stress proteins in the piglet heart at birth

The effects of short-term hypoxia on motor cortex excitability and neuromuscular activation

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