Search PubMed⌕ Search

Biomedical subjects

J C Rostain

Publications and source records attributed to J C Rostain.

18 recordsLinked to original sources
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↗
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

Effects of the administration of a-methyl-p-tyrosine on the striatal dopamine increase and the behavioral motor disturbances in rats exposed to high pressure.

When human divers and experimental animals are exposed to increased environmental pressure, they develop the high pressure neurological syndrome (HPNS). Moreover, it has been recently demonstrated that pressure exposure induced an increase in striatal dopamine (DA) release. In this study, the effects of intracerebroventricular administration of a-methyl-p-tyrosine on the pressure-induced striatal DA increase, and the behavioral motor disturbances of HPNS, including hyperlocomotor activity (HLA), tremor, and myoclonia were monitored in free-moving rats. Striatal DA release was monitored by in vivo voltammetry, and behavioral symptoms using piezoelectrical sensors. Results suggested that the pressure-induced striatal DA increase could be the consequence of a release in both newly synthesized and vesicular DA. Elsewhere, data also confirmed that the pressure-induced DA disturbances would be involved in the development of HLA.

Animals↗
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↗
PubMed1991

Sleep organization in man during long stays at 30 and 40 bar in a helium-oxygen mixture.

Sleep organization was studied during 5 dives with long holds (from 6 to 15 days) at 30 and 40 bar in a helium-oxygen mixture. In total, 16 professional divers participated in these saturation dives; 337 nights were analyzed. Sleep was disrupted by compression and the stay at pressure, but the disturbances were greater at 40 bar than at 30 bar. There was an increase of awake periods, stages I and II, a decrease of stages III and IV, and instability of rapid eye movement periods. These changes were more intense at the beginning of the stay; some improvements could be found between Days 4 and 6 of the stay but the return to control values was recorded only during the decompression after 20 bar. The disturbances of sleep seem to be related to compression speed and to the pressure itself and appear as another symptom of the high pressure nervous syndrome.

Body Temperature↗
PubMed1990

Electromyographic study of respiratory muscles during human diving at 46 ATA.

Electromyographic (EMG) recordings of the 6th to 7th intercostal space (thoracic EMG) and abdominal muscles, ventilatory pattern, and the work of breathing were studied in 4 human subjects exposed for 12 days to 46 ATA of helium-oxygen (density = 8.7 g.liter-1) then of nitrogen-helium-oxygen gas mixture (ternary mixture) (density = 11.1 g.liter-1). We found that the respiratory muscle work necessary for eupneic ventilation was multiplied by 4 at 46 ATA. During quiet breathing as well as during forced inspiratory maneuvers, the power spectrum of thoracic EMG shifted to the left in three individuals during the sojourn at maximal pressure, whichever gas mixture was inhaled. This was corroborated by the decreased ratio of EMG power in a high to that in a low band of frequencies. These alterations disappeared at the end of the decompression period, suggesting the existence of inspiratory muscle fatigue at high pressure. Hyperbaric tremor was recorded on the thoracic EMG and was maximal with He-O2 inhalation. It disappeared at the end of the period at 46 ATA (He-N2-O2).

Adult↗
PubMed1989

Effect of helium-oxygen pressure on dopamine detected in vivo in the striatum of hamsters.

Free-moving hamsters chronically implanted in the striatum with carbon multifiber electrodes selective to dopamine were compressed in a helium-oxygen breathing mixture to 81 bars. Under these conditions, there was an increase in the electrochemical responses recorded from the carbon electrode by differential pulse voltammetry, which occurred during the compression and disappeared when the animals returned to the surface. This change was related to an increase in extracellular dopamine levels induced by the increase in pressure of the helium-oxygen mixture.

Animals↗
PubMed1988

Sleep disturbances in man during different compression profiles up to 62 bars in helium-oxygen mixture.

Studies of sleep organization of 8 subjects were performed during 4 dives between 500 and 610 msw (51 and 62 bar) in a helium-oxygen mixture. The results of the 156 sleep records showed that sleep was disrupted from 30 bar: awake periods and stages I and II increased, stages III and IV and REM periods decreased. These disturbances, which were more intense with fast compression and recovered during decompression, can be considered as further symptoms of the high pressure nervous syndrome (HPNS).

Adult↗
PubMed1985

Effects of 2-amino-7-phosphonoheptanoic acid on EEG of rats.

2-APH is an antagonist of excitation due to dicarboxylic amino acids and has a protective effect against several types of experimental seizures. We have studied its effect on EEG of rats. Following either intracerebroventricular or intraperitoneal administration of 2-APH produces slow waves of high voltage in central cortex. The anticonvulsant action of this drug may be related to altered activity in neurones of this area.

2-Amino-5-phosphonovalerate↗
PubMed1978

A study on the Valsalva manoeuvre in young healthy subjects.

The Valsalva manoeuvre was performed by 2 groups of young healthy male subjects: novice divers and professional divers. The electrophysiological features of this manoeuvre are summarized and the results of the test are correlated with subject age, motivation and FEV1/VC coefficient (forced expiratory volume sec/vital capacity). Positive test results (fainting caused by the Valsalva manoeuvre) increased with subject motivation (novice divers), FEV1/VC coefficient and decreasing subject age. The various hypotheses proposed to account for fainting caused by the Valsalva manoeuvre are discussed with respect to these data. The implications of Valsalva positivity in young divers are discussed.

Adult↗
PubMed1976

[Vsiual evoked potentials and excitability cycle during simulated diving at -610 m in oxygen-helium atmosphere (Physalie VI)].

Visual evoked potential (VEPs) and visual excitability cycles (VECs) were studied during compression in an oxygen--helium breathing mixture, up to a pressure of 62 ATA, equivalent to a depth of 610 m in sea water (Physalie VI). Records were taken at atmospheric pressure (control responses in confined helium--oxygen atmosphere) and at different depths during compression and decompression; recording was always performed at the same hours; subjects were lying with closed eyes. Isolated or double flashes were delivered every 1.2 sec, from a stroboscopic lamp located in the tank, at a maximum distance of 20 cm from the eyes. Responses were recorded with hook electrodes left in situ throughout the experiment (mid-vertex occipital derivation). VEP and VEC changes occurred in three stages: (1) Between surface and -435 m, components II-V of the VEP decreased in amplitude, while component VI increased. The after-discharge, and the PEV to the second of a pair of stimuli were facilitated. (2) Below 435 m, latencies and amplitudes of waves II-V increased, while those of wave VI decreased. After-discharge and response to the second stimulus were reduced. (3) During decompression up to -120 m, VEPs and VECs again changed, in a way similar to compression from 0 to -435 m. VEP and VEC changes, which are thus opposite during compression, may depend upon speed of compression, although the latter factor is probably not alone. Other factors, like pressure itself or the nature of the gas mixture may well intervene. It is likely that the observed modifications are the result of various factors interacting at various depths.

Adult↗
PubMed1976

Effects upon the EEG of psychometric performance during deep dives in helium--oxygen atmosphere.

A study of EEG modifications and psychometric performances was performed during two dives in hyperbarbic chambers with a helium--oxygen breathing mixture (pO2 maintained at 0.4 ATA). The depths attained were 500 m for the first experiment (Sagittaire II) and 610 m for the second (Physalie VI). Four subjects were studied. EEG modifications that could be considered as high pressure nervous syndrome began at 300 m. They were characterized by an increase of slow activity (particularly theta), depression of fast activity and transformation of the waking EEG into one resembling that of stage I sleep. The psychometric tests revealed a diminution of sensorimotor performance in all subjects (10--20%). Performance in intellectual tests varied according to subject and experiment, and did not fall more than 15% below normal values.

Alpha Rhythm↗
PubMedDate not supplied

[The Vasalva manoeuvre and the E.E.G. in a study of professional and trainee diverse (author's transl)].

The E.E.G., the oculocardiac reflex (OCR), the Valsalva manoeuvre and respiratory capacity, were studied and compared in 183 professional or trainee divers. There was a positive correlation between an alpha rhythm at or below 9 c/sec and a positive OCR. The Valsalva was more often positive in young subjects and trainee divers than in older subjects and professional divers. Also the Valsalva response was more likely to be positive when the subject's respiratory capacity was greater. These observations are used to make conclusions about the significance of a positive response to the Valsalva manoeuvre and about the value that can be attached to these various tests in subject selection.

Adolescent↗