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Biomedical subjects

D Albe-Fessard

Publications and source records attributed to D Albe-Fessard.

At least 55 records · Page 3Linked to original sources
PubMed1980

Electrophysiological evidence for a release of endogenous opiates in stress-induced'analgesia' in man.

The effects of a repetitive stress induced by anticipation of pain were studied on the following somato-vegetative parameters: monosynaptic reflex (H reflex), nociceptive flexion reflex (RIII reflex), heart rate and respiratory frequency, in normal trained volunteers. A progressive increase in heart rate and in respiratory frequency, as well as a facilitation in H reflex parallel to an inhibition of RIII reflex (threshold increased) were observed in all subjects as a function of repetition of stress during 45 min. At this moment, a double-blind injection of a strong dose of naloxone (4 mg) resulted in a rapid exacerbation in vegetative responses (tachycardia, polypnea) as well as in an increase in the facilitation of the H reflex, whereas the RIII reflex was dramatically facilitated (threshold decreased). In contrast, no significant change in these parameters was observed during placebo (saline) injection compared to a control situation (no injection). These data strongly suggest that endogenous opioids are involved in the phenomenon of stress-induced analgesia in man. Moreover, they show that the release of opiates in these conditions possibly modulates non-specific structures which are known to be activated during stress or emotion.

Adult↗
PubMed1979

Supraspinal influences on nociceptive flexion reflex and pain sensation in man.

The sensation of pain and the nociceptive flexion reflex of the biceps femoris muscle (RIII, Bi) elicited by electrical stimulation of the ipsilateral sural nerve were studied in human during 4 conditions: (1) a mental task; (2) a stress; (3) during noxious stimulation of the contralateral ulnar nerve; (4) after an intense noxious stimulation of the sural nerve itself. An inhibition of both pain sensation and RIII, Bi was observed in (1), while a facilitation of these parameters was noted in (2). In contrast, no change in RIII, Bi occurred in (3) while the pain sensation was inhibited. In (4), just after the noxious stimulation, there was a marked facilitation of RIII, Bi associated with increased pain sensation. However, 10--12 sec later, the pain sensation returned to its control values, while the RIII, Bi reflex was still facilitated. The latter recovered to its control values 28--30 sec later. These results show the possibility of a dissociation between afferent ascending nociceptive messages and nociceptive motor activity (in 3 and 4). They suggest that supraspinal descending influences can act differently on spinal dorsal horn neurons in the case of pain ascending volleys, and in the case of spinal nociceptive motor activity.

Adult↗
PubMed1979

Organization of somatic thalamus in monkeys with and without section of dorsal spinal tracts.

In an attempt to understand the modifications which appears at the thalamic level when dorsal cord sections are performed, peripheral fields of thalamic units were studied in normal and dorsal-cord sectional monkeys, totally awake and implanted with glass micropipettes. Six normal Macaca cynomolgus and 7 having received spinal sections, were studied. Ventricular radiography was performed and all the coordinates were related to new stereotaxic coordinates using the posterior commissure as the origin. Cell-bodies and axon units were recognized on the basis of the shape of the spikes. In normal animals, 972 units were studied; 307 were thalamic units with peripheral fields and 177 were derived from cell bodies. Localization of these cells was studied as a function of their peripheral field and response characteristics. The majority of ventralis posterior (VP) cell bodies were only activated by contralateral stimulation, their peripheral field being frequently found on the extremities. Somatotopic organization consisted of concentric layers rather than zones in apposition. Dorsoventral segregation of afferent modality sensitivity (movement, pressure, light touch) was observed. Somatosensory convergence was found in VP inferior (VPi) as well as convergence of different types of afferents on a few VP cells. Units responding to bilateral or ipsilateral stimulations were found only in posterior VP and in surrounding nuclei. A particular somatotopy was shown to exist in n. reticularis. A total of 838 units were studied in animals having had dorsal columns and Morin's bundle served. Only a few cells (13) responded in VPl to contralateral hindlimb stimulation. Their characteristics recall those noted in layer V spinal cord cells. The other cells (55) still driven by a hindlimb were dispersed in the nuclei just adjacent to VPl. The majority of cells found in the VPl were activated from the forelimb. They were observed in their normal VPl localization as well as in areas where hindlimb representation was found in normal animals. This change of afferent input is attributed to a reinnervation of hindlimb cells (probably at the gracilis level) by sprouting from forelimb afferent.

Animals↗
PubMed1979

Double labelling of blanched neurons in the central nervous system of the rat by retrograde axonal transport of horseradish peroxidase and iron dextran complex.

The retrograde axonal transport of an iron-dextran complex leads to a labelling of neural cell bodies in the central nervous system (CNS) of the rat. This tracer and horseradish peroxidase (HRP) can both be demonstrated histochemically in same cell bodies of intralaminar thalamic neurons in the central lateral nucleus, after injection of iron-dextran in the striatum and injection of HRP in the motor cortex. This is made possible by processing the sections first for HRP and then for ferric ions by Perl's reaction. This method allows an accurate demonstration of divergent axonal projections and is compatible with cytoarchitectonic studies on the same sections.

Animals↗
PubMed1978

[Role played in man by myelinated fibers of different diameters for the evocation of a nociceptive flex reflex and the accompanying pain sensation].

Using simultaneous recordings we have made in Man a comparative study of: the sural nerve afferent volley, the nociceptive flexor reflex of a muscle of the lower limb and the associated painful sensation. Two types of stimulations were used, a single short duration electric stimulus, and a train of electric shocks (100/sec). With a single stimulus, the nociceptive flexor reflex and the painful sensation develop only when A delta fibers are recruited. On the other hand, when the stimulations are given by trains the nociceptive flexor reflex and the painful sensation can develop with a stimulus sub-liminar to the threshold of A delta fibers, when A alpha fibers are recruited. When the stimulus activate both A alpha and A delta fibers, the flexion reflex and the pain disappear when a selective blockade of the A delta group is exerted by means of Lidocain.

Adult↗
PubMed1978

[Current data on pain pathways].

1--The classical notion attributing the conduction of painful messages to only the A delta and C fibres will be discussed. 2--Spinal cord cells of layers I, V and VIII received painful messages and their physiological properties will be compared. 3--The origin within the cell layers of the spinal cord of the various ascending bundles will be examined. 4--The reticular an thalamic zones (posterior ventra nucleus, mid-line and intralaminar nuclei, GMme posterior group in particular) which receive painful messages have also been studied using activation provoked by pinching, pinprick, the injection of painful substances and stimulation of the dental pulp. The possible role of the different structures thereby brought into action and the limitation of these techniques will be discussed. 5--The existence of metameric controls and controls of central origin active at a spinal, reticular and thalamic level. The absence of inhibitory controls may be responsible for the development of abnormal painful sensations which accompany certain deafferentation procedures. The reestablishment of these controls with the aid of stimulation may result and often results in the improvement of these painful syndromes. 6--Section of the dorsal routes in the chronic animal (rat and cat) may represent an experimental model for deafferentation pain seen in man.

Animals↗
PubMed1977

[Identification using glass microelectrodes of the activities recorded in the neighborhood of axons and cell bodies of the trigeminal sensory complex].

Using glass micropipettes unitary activities were recorded at the level of the trigeminal sensory complex. Iontophoresis of pontamine blue allowed us to localise the recording loci. Two types of spikes were observed, they were distinguished on the basis of their shape: one corresponds to an axon spike, the other to a cell body spike.

Action Potentials↗
PubMed1977

Mapping of the trigeminal sensory complex of the cat. Characterization of its neurons by stimulations of peripheral field, dental pulp afferents and thalamic projections.

From a new systematic investigation of the 4 divisions of the trigeminal sensory complex, the following points are emphasized: 1. The subnucleus oralis receives a large representation from the oral cavity, a region also represented in the three other divisions of the trigeminal sensory complex. 2. Units responding to noxious mechanical stimulation have been found in two different loci: the subnucleus caudalis for the whole trigeminal area, and the subnucleus oralis for the oral cavity. 3. The dental pulp projects to the four divisions of the trigeminal sensory complex, but the heaviest projection is found in its rostral part (the main nucleus and subnucleus oralis). 4. Three distinct types of responses were found following dental pulp stimulation: primary, non primary and responses strongly enhanced by an increase in stimulus parameters.

Animals↗
PubMed1977

Thalamic and mid-brain responses to dental pulp afferent messages in awake cats.

1. Central projections of messages evoked by dental pulp stimulation have been searched for in awake cats and recorded at unitary level. A head-top frame screwed to the skull served to fix the animal in the stereotaxic instrument precisely and in the usual orientation. 2. Three types of responses could be distinguished, each with characteristic thalamic localization: --one was of the specific type: it occurred at short latency, followed rapid rates of stimulation, and was localized in VPM and SG; --a second type had longer latency, did not follow rapid rates of stimulation, was frequently bilateral, and was localized in VPM, CM-Pf and Posterior Group; --the third type was a complex response, exhibiting inhibitory and excitatory phases; extremely labile, it disappeared during wakefulness; it was found in LP and CM-Pf. 3. The responses elicited by dental pulp stimulation and recorded in the periaqueductal grey matter mostly originated from face muscle messages provoked by the jaw opening reflex. 4. The possible contributions to pain perception made by each of the different thalamic responses is discussed, as well as the adequacy of dental pulp stimulation for producing a purely nociceptive signal.

Action Potentials↗
PubMed1976

[Inhibition of thalamic activity by stimulation of the inferior raphe nucleus in the chronically awake cat].

Poly U dependent polyphenylalanine synthesis from 14C phenylalanyl-tRNA, under known optimal conditions, in ribosomes obtained from NaF-treated Rabbit reticulocytes, is only slightly stimulated by the addition of ATP, GTP and UTP in the absence of phosphoenolpyruvate and pyruvate kinase. However, in the presence of the energy generating system, the stimulation by ATP far surpasses that by other nucleotides. A scheme of reactions which help explain this observation is presented.

Animals↗