Biomedical subjects

J H Abraini

Publications and source records attributed to J H Abraini.

9 recordsLinked to original sources

PubMed1992

Psycho-sensorimotor performance in divers exposed to six and seven atmospheres absolute of compressed air.

In the present study, we investigated the psycho-sensorimotor abilities of divers exposed to 6 ATA (50 m of sea water; corresponding to legal limit for occupational diving in North America, United Kingdom, and Northern Europe), or 7 ATA (60 m; the legal limit in France and Southern Europe) of compressed air (1 ATA = 100,000 Pa), using psychometric tests of manual dexterity, visual choice reaction time, and number ordination. The results of the present study showed that abilities in these tests were not significantly altered by pressure exposure to 6 ATA of compressed air. However, data obtained at 7 ATA showed slight but significant decreases in performance. Nevertheless, a few subjects presented large decreases in performance ranging from -20% to -25% of control. Finally, our results supported the ergonomic point of view that the laws limiting occupational diving to 6 ATA (50 m) are better adapted to reality and the requirements of underwater activity.

Adult↗

PubMed1992

Pressure reversed extracellular striatal dopamine decrease produced by D1 receptor agonist SKF 38393, and D2 receptor agonist LY 171555, but failed to change the effect of the activation of both D1 and D2 receptors.

When human divers or experimental animals are exposed to high pressure, they develop the high-pressure neurological syndrome which is characterized by electroencephalographic changes, and behavioral disturbances. Recently, neurochemical disorders such as a pressure-induced increase in dopamine release have been demonstrated. In the present study, pharmacological experiments, using dopamine receptor agonists such as D1 receptor agonist SKF 38393, D2 receptor agonist LY 171555, and D1/D2 receptor agonist apomorphine, were performed to investigate dopamine receptor function at the neurochemical level. Only apomorphine and mixed SKF 38393 + LY 171555 prevented the pressure-induced increase in dopamine release while SKF 38393 or LY 171555 administered alone failed to do so. The results suggest that the D1-D2 link would be reduced under high pressure because of an abnormal function of D1 receptors which would allow high-affinity D2 states for dopamine. If so, such a preponderance of high-affinity states in D2 postsynaptic receptors could be associated with hyperbaric hyperlocomotor activity. Elsewhere, results also suggested that the pressure-induced disorders in dopamine receptor function could be involved in the pressure-induced elevation in dopamine release.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1992

A hypothesis regarding possible interactions between the pressure-induced disorders in dopaminergic and amino-acidergic transmission.

When human divers or experimental animals are exposed to high pressure they develop the high pressure neurological syndrome (HPNS). The main symptoms include electroencephalographic changes and behavioral disturbances such as tremor, myoclonia, and hyperlocomotor activity. Recently, pressure-induced disorders in dopaminergic and amino-acidergic neurotransmission have been reported. In the present theoretical study, we review in vitro and in vivo neurochemical, electrophysiological, and pharmacobehavioral evidence concerning alterations in dopaminergic, glutamatergic, and GABAergic transmission occurring at high pressure, and their possible relationship to the symptoms of HPNS. Moreover, we also examine data concerning interactions, at normal pressure, between dopaminergic, glutamatergic, and GABAergic transmission that we suggest they could apply equally under high pressure between the pressure-induced disorders in dopaminergic and amino-acidergic transmission.

Amino Acids↗

PubMed1991

Long-term depression in striatal dopamine release monitored by in vivo voltammetry in free moving rats.

It was proposed to monitor in free moving rats, by in vivo voltammetry, the effects of intracerebroventricular (i.c.v.) administration of drugs known to act on the synthesis of dopamine (DA), using an original multifiber carbon electrode which enables without-discontinuity long-term recordings in extracellular DA release. Results show that i.c.v. administration of alpha-methyl-p-tyrosine, gamma-butyrolactone, and apomorphine induced long-term depression in striatal DA release, over periods of time of more than 24 h. These results are in agreement with the dopaminergic hypothesis; and we conclude that i.c.v. administration of drugs and the use of the multifiber carbon electrode constitutes a valuable tool to monitor DA metabolism in chronically implanted animals.

4-Butyrolactone↗

PubMed1991

A new device for behavioral analysis on rats exposed to high pressure.

The high pressure nervous syndrome (HPNS) is the term applied to the disturbances which appear when humans or animals are exposed to high pressure. The principal behavioral symptoms include locomotor activity, tremor and myoclonia. These symptoms have often been visually estimated previously, on free-moving animals, only by their onset pressure. In the present study, we report on the use of a new computerized device which enables a quantitative analysis of the behavioral symptoms of HPNS. These disturbances could be essentially dependent on the variations of pressure. This new device could also be profitably employed for other behavioral studies.

Animals↗

PubMed1991

Role of dopamine receptors in the occurrence of the behavioral motor disturbances in rats exposed to high pressure.

When human divers and experimental animals are exposed to an increasing environmental pressure, they develop the high pressure neurological syndrome (HPNS) characterized by electroencephalographic changes and sleep and behavioral disturbances. In rats, behavioral disturbances essentially include hyperlocomotor activity (HLA), tremor and myoclonia. Moreover, HLA has recently been demonstrated to be linked to a pressure-induced striatal increase of dopamine (DA). In these experiments, it was proposed to investigate in rats, at the behavioral level, the role of DA receptors in the occurrence of the pressure-induced DA disturbances. DA receptor agonists were found to induce no significant changes in the development of HLA, tremor, and myoclonia. Alternatively, HLA was found to be dramatically antagonized by the use of DA receptor antagonists (SCH 23390, sulpiride, and haloperidol), while tremor and myoclonia only decreased in SCH 23390 experiments.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1991

Dopamine increase in the nucleus accumbens of rats exposed to high pressure.

When human divers and experimental animals are exposed to high pressure, they develop the high pressure neurological syndrome (HPNS) characterized by electroencephalographic changes, sleep and behavioral disturbances. Free-moving rats chronically implanted in the nucleus accumbens with carbon electrodes essentially selective to dopamine (DA) were compressed to 80 bar. Compression was found to lead to a sustained increase in extracellular DA level (+88%), then during the stay and decompression phases, values progressively decreased. These results are discussed in the field of the involvement of the DA meso-limbic pathways in the occurrence of some of the behavioral disturbances of HPNS in rats including hyperlocomotor activity and hoarding behavior.

Animals↗

PubMed1991

Pressure-induced striatal dopamine release correlates hyperlocomotor activity in rats exposed to high pressure.

Free-moving rats chronically implanted in the striatum with multifiber carbon electrodes selective to dopamine were compressed in a helium-oxygen mixture to 80 bars. Extracellular dopamine level and behavioral symptoms of high-pressure neurological syndrome were simultaneously recorded. Under these conditions, the extracellular level of dopamine monitored by differential pulse voltammetry was found to be pressure dependent, and hyperlocomotor activity, a behavioral symptom of high-pressure neurological syndrome, was found to be linked to these pressure-induced changes in dopamine release.

Animals↗

PubMed1991

Quantitative study of behavioral disturbances in rats exposed to high pressure.

When human divers or experimental animals are exposed to high pressure, they develop the High Pressure Neurological Syndrome (HPNS). Male Sprague-Dawley rats were exposed to high pressure in a conventional helium-oxygen breathing mixture to 80 bars. Pressure-induced behavioral motor disturbances including hyperlocomotor activity (HLA), tremor and myoclonia were monitored with a noninvasive piezoelectrical sensor device enabling a without discontinuity long-term analysis. New data were obtained on the development of the HPNS behavioral motor disturbances. Indeed, the present results suggest myoclonia would be more sensitive to constant high pressure exposure, while HLA and tremor would be more sensitive to increasing pressure. Moreover, myoclonia were found to occur significantly later in rats which developed epileptic seizures than in other. The present results constitute the quantitative basis of HPNS motor disturbances for future pharmacological pressure experiments.

Animals↗