Agressologie: revue internationale de physio-biologie et de pharmacologie appliquées aux effets de l'agression
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Each class (mu, delta kappa and epsilon) of opioid receptors has a characteristic pattern of distribution in the nervous system, which may, however, exhibit species differences. The effects of opioid receptor stimulation depend on the class of receptor involved, the localization of these specific receptors and the animal species under investigation. Endogenous ligands of opioid receptors, which include more than twenty peptides, derive from three precursors:proopiomelanocortin (beta-endorphin), proenkephalin A (enkephalins) and prodynorphin (dynorphins, neo-endorphins). ⋯ At this level, opioids reduce the activity of spinal neurones that convey the nociceptive messages. The classes of opioid receptors (certainly mu [mu 2?] and a, perhaps kappa) involved in this effect, and their pre- or postsynaptic location are not firmly established to date. Further developments on these points can be expected from the use of new ligands which are highly selective of the various classes of opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
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The effects on intracranial pressure (ICP), cerebral perfusion pressure (CPP) and EEG monitored by Cerebral Function Monitor (CFM) were compared after bolus administration of mannitol (n = 55) and thiopentone (n = 67) to control intracranial hypertension in 18 severely head injured patients. Mannitol increased CPP in 89% of occasions and thiopentone in only 54% (p < 0.001). Thiopentone caused a mean increase in CPP +0.6 kPa (+5.0 +/- 1.6 mmHg) when the minimum pre-bolus voltage of CFM was above 4 microV and a fall in CPP -0.5 kPa (-4.1 +/- 1.6 mmHg) when cortical electrical activity was already severely depressed (p < 0.0002). ⋯ This different effect on CPP was due to a significantly greater fall in mean arterial pressure in the thiopentone sub-group -1.6 versus -0.3 kPa (-12.4 +/- 1.5 mmHg, -2.8 +/- 1.2 mmHg; p < 0.001). Severe and unpredictable hypotension occurred, particularly in the thiopentone low CFM sub-group. This symptomatic therapy seems inadequate but a targeted treatment of intracranial hypertension could be possible only with a more sophisticated monitoring, including continuous data on cerebral blood flow and adequacy to metabolic demand.
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The effect of pentobarbital was evaluated in 12 comatose brain injured patients (Glasgow coma scale < 7 at admission). Mean hemispheric cerebral blood flow (CBF) was studied following intravenous administration of 133Xenon. ⋯ The increase in cerebral perfusion pressure (PP) was found only in patients with diffuse brain injury. The results supports the hypothesis that barbiturate therapy is more effective at reducing ICP while preserving CPP when the cause is a diffuse lesion.