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Biomedical subjects

E Jankowska

Publications and source records attributed to E Jankowska.

At least 91 records · Page 5Linked to original sources
PubMed1990

Contralaterally projecting lamina VIII interneurones in middle lumbar segments in the cat.

Peripheral input to lamina VIII interneurones was investigated by using extracellular and/or intracellular records from them. The interneurones were located in the L4-L5 spinal segments and projected to contralateral motor nuclei in the L7 segment. They constituted a non-homogeneous population but their input from muscle afferents (mainly group II afferents of quadriceps, flexor digitorum longus and pretibial flexors and group I afferents of triceps surae and hamstring nerves) and from cutaneous and joint afferents resembled the input to ipsilaterally projecting laminae V-VII interneurones of the same segments rather than the input to more caudally located lamina VIII interneurones. Since the ipsilaterally projecting laminae V-VII interneurones with such an input might be involved in locomotion, it is proposed that this is also the case for the contralaterally projecting lamina VIII midlumbar interneurones, especially those excited by stimuli applied in the cuneiform nucleus (mesencephalic locomotor region).

Animals↗
PubMed1990

Light microscopical study of dendrites and perikarya of interneurones mediating la reciprocal inhibition of cat lumbar alpha-motoneurones.

Interneurones which mediate disynaptic inhibition from la muscle spindle afferents of the quadriceps nerve to lumbar alpha-motoneurones were stained with intracellular injection of horseradish peroxidase. Seven best stained and most satisfactorily preserved cells were selected for analysis, and the light microscopic morphology of their cell bodies and dendrites were quantitatively investigated in parasagittal sections. The perikarya were located dorsal or dorso-medial to the motoneurones; they had mean diameters of 51 x 27 microns and a mean volume of 35,820 microns 3. The cells had 3 to 7 dendrites, which were arranged asymmetrically around the parent somata. The dendrites extended mainly in the dorso-ventral direction, in which the mean tip to tip distance for each cell was 1742 microns. The dendrites had few spines and they branched almost only in bifurcations. On the average, each process divided 3.5 times and in each cell they gave rise to 14.9 branching points as well as a total combined length of more than 7000 microns. Primary dendrites had a mean length of 193 microns which was generally shorter than the lengths of the branches of higher order. A more detailed analysis of two cells revealed the mean width of primary dendrites to be 5.6 microns while that of the 5th order processes was 1.5 microns. The mean tapering of individual dendritic branches per unit length was 17%, being somewhat more pronounced for the distally located segments, while at branching points the sum of daughter processes approximately equalled the diameter of the parent process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Antidepressant-like action of nicardipine, verapamil and hemicholinium-3 injected into the anterior hypothalamus in the rat forced swim test.

Male Wistar rats, chronically implanted with cannulas into the anterior hypothalamus, were acutely injected with the calcium channel inhibitors, diltiazem, nicardipine and verapamil, or the choline uptake blocker hemicholinium-3 and tested in the forced swim test. Hemicholinium-3, nicardipine and verapamil markedly increased the duration of active swimming. This antidepressant-like effect did not appear to reflect merely a hyperactive state as the drug-treated rats did not differ from vehicle-injected controls in their open field motility scores. Diltiazem failed to influence rats' performance in either test. Since nicardipine and verapamil, but not diltiazem, share choline uptake property with hemicholinium-3, it seems that this action plays a role in the antidepressant-like effect of all three drugs in the forced swim test.

Animals↗
PubMed1990

Effects of intra-amygdaloid TRH injections on motor activity and dominant-submissive behavior in rats competing for water.

The effect of thyrotropin releasing hormone (TRH) microinjections into the central amygdala (10 g in 0.5 1 into each side) on locomotor activity water intake and dominance behavior in a water competition test was investigated in male Wistar rats. TRH increased the general motility without altering the number of rearings. Intra-amygdaloid TRH injection to submissive rats resulted in a loss of subordinate position in these animals in the water competition test. A tendency to decrease dominance followed the injection of the peptide to the dominant animals. The effect of TRH in the dominance test does not appear to involve influence on the thirst drive as microinjection of the peptide did not change significantly the water consumption in thirsty rats.

Amygdala↗
PubMed1990

Murine lymph nodes in response to the local administration of dextran sulphate.

In mice a single injection of 4 mg of Dextran sulphate within a few days produces an enlargement of area draining lymph nodes and activates basophils/mast cells. This activation is manifested by many-fold increase of mast cell number per lymph node, degranulation of mast cells and appearance of young, immature mast cells capable to synthetize new granules. In contrast to the lymph nodes, the Dextran-injected connective tissue mast cells remained unchanged. This suggest that Dextran sulphate directly activates lymph node mast cells, probably by activation of T-cell suppressor or macrophages.

Animals↗
PubMed1990

[Post-traumatic chylothorax].

A case of post-traumatic chylothorax in a 84 year old man with ILD is presented. The chylothorax was successfully treated after 6 months, which was confirmed at post-mortem, during which a solitary plasmocytoma of the left kidney was also diagnosed.

Accidental Falls↗
PubMed1989

Morphology of midlumbar interneurones relaying information from group II muscle afferents in the cat spinal cord.

The morphology of midlumbar interneurones with peripheral input from group II muscle afferents was analysed after intracellular injection of horseradish peroxidase (HRP). Twenty-three interneurones were stained intrasomatically and five others intra-axonally. The majority (10 of 13) of interneurones located in lamina VII (intermediate zone and ventral horn interneurones) were found to project ipsilaterally. They had medium-sized somata and dendrites projecting radially over a distance of more than 1 mm. All of these neurones had axons that projected caudally within the ventral part of the lateral funiculus or in the lateral part of the ventral funiculus, although four had in addition an ascending secondary axonal branch. Numerous axon collaterals were given off from these axons, both before and after they left the grey matter. The collaterals arborized within laminae VII, VIII, and IX, where they covered the area of several motor nuclei. Intra-axonal labelling of five neurones with similar input and axon trajectories revealed several axon collaterals given off between the cell body and the terminal projection areas in L7 or S1 segments. Only three of the labelled interneurones located in lamina VII and displaying the same kind of input had axons with different destinations; their axons crossed to the opposite side of the spinal cord and ascended within the contralateral ventral funiculus. These were large neurones with extensive dendritic trees, which had fairly thick axons with initial axon collaterals that branched primarily ipsilaterally (within laminae V-VIII). Interneurones located in lamina V and in the bordering parts of laminae IV and VI (dorsal horn interneurones; n = 10) constituted a very nonhomogenous population. They projected either ipsilaterally or contralaterally and had either ascending or descending axons running in either the lateral or ventral funiculi. Generally, dorsal horn interneurones had cell bodies smaller than those of intermediate zone and ventral horn interneurones, and their dendrites extended less extensively and less uniformly around the soma. Their initial axon collaterals branched primarily in the dorsal horn, or in lamina VII, but not in or close to the motor nuclei. Our results support the conclusions of previous physiological studies that the intermediate zone and ventral horn midlumbar interneurones with group II input and that project to motor nuclei have collateral actions on other interneurones in the L4-L6 segments, and that dorsal horn interneurones do not project to motoneurones, but have as their targets other interneurones or ascending cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Comparison of effects of monoamines on transmission in spinal pathways from group I and II muscle afferents in the cat.

The actions of noradrenaline (NA) and 5-hydroxytryptamine (5-HT; serotonin) were compared with those of L-3,4-dihydroxyphenylalanine methyl ester (Methyl-L-DOPA) on transmission to spinal interneurones in mid-lumbar (L4 and L5) segments of the cat spinal cord. The drugs were applied ionophoretically and their effects were tested on monosynaptic field potentials evoked by nerve impulses in hindlimb group I and group II muscle afferent fibres and on responses of interneurones with synaptic input from these fibres. Of field potentials recorded at various locations, both NA and 5-HT depressed those evoked from group II fibres in the intermediate and ventral horn regions of the spinal cord but not, or only occasionally, in the dorsal horn. Field potentials of group I origin were not depressed. The tested interneurones were located where group II field potentials were affected. NA, 5-HT and Methyl-L-DOPA depressed responses to electrical stimulation of group II fibres but not responses evoked by group I fibres. The depression consisted of an increase in the latency and a decrease in the number of action potentials evoked by the stimuli. All three drugs were also found to decrease the amplitude of intracellularly recorded monosynaptic EPSPs of group II origin but not of monosynaptic EPSPs evoked in the same neurones by group I fibres. Interneuronal firing induced by DL-homocysteic acid was depressed as effectively as responses to electrical stimulation of peripheral nerves. The possibility of presynaptic and/or postsynaptic mechanisms of the selective depression of synaptic actions of group II origin are discussed.

Action Potentials↗
PubMed1989

A neuronal system of movement control via muscle spindle secondaries.

A recently discovered spinal interneuronal system of movement control is briefly described. It includes a population of midlumbar interneurones with a predominant monosynaptic input from secondary muscle spindle afferents but supplied with information via several other afferent and descending neuronal systems as well. The neurones are in direct contact with both motoneurones and other interneurones. The evidence in favour for their involvement in locomotion is briefly summarized.

Animals↗
PubMed1989

Primary afferent depolarization of central terminals of group II muscle afferents in the cat spinal cord.

1. The origin of primary afferent depolarization (PAD) of the central terminals of group II afferent fibres of tibialis anterior and extensor digitorum longus muscles has been investigated in the cat. Changes in the excitability of the terminals to intraspinal stimuli, upon application of conditioning stimuli to muscle nerves (quadriceps, sartorius, gracilis, posterior biceps-semitendinosus, anterior biceps-semimembranosus, gastrocnemius-soleus, deep peroneal), cutaneous nerves (sural, superficial peroneal) and the posterior nerve to the knee joint, were used as a measure of PAD. 2. PAD was most readily evoked by conditioning stimuli which were maximal for group II muscle afferents. However, some PAD was also evoked from group I afferents and evidence is presented that group Ia afferents contributed. Afferents of posterior biceps-semitendinosus and sartorius muscles appeared to be most effective. PAD was also evoked by stimulation of cutaneous and joint nerves, often in the same fibres which were affected by group Ia afferents. 3. It is concluded that there are several common sources of PAD of group II and group Ia afferent terminals on the one hand, and group Ib afferent terminals on the other. 4. The properties of PAD of group II afferents are discussed in relation to the problem of how PAD affects transmission from fibres with long terminal branches of small diameter.

Action Potentials↗
PubMed1989

Antibody producing cells in the spleens of mice treated with pathogenic mineral dust.

Experiments were carried out to assess the effect of intraperitoneal injection of the mineral dusts, titanium dioxide, quartz, or asbestos, on splenic lymphocyte antibody forming cells in immunised mice. Titanium dioxide and quartz caused similar, about one third, reductions in plaque forming cells; asbestos caused substantial reduction to about a quarter of the number found in control spleens. The inhibition of antibody forming cells in the spleen found with chrysotile was dose dependent and both chrysotile and crocidolite asbestos were similar in activity. Systemic immunomodulation after local deposition of mineral dust may be important to the development of disease.

Animals↗
PubMed1988

Demonstration of initial axon collaterals of cells of origin of the ventral spinocerebellar tract in the cat.

Neurones of origin of the ventral spinocerebellar tract were stained with intracellularly applied horseradish peroxidase to investigate whether they give off any initial axon collaterals. The neurones were located in the fourth and fifth lumbar segments and were identified by their antidromic activation following stimulation in the contralateral superior cerebellar peduncle. Nine of the 23 neurones with well-stained axons were found to give off axon collaterals soon after the axons crossed the midline. The collaterals entered the contralateral ventral horn and branched within lamina VII and the dorsal part of lamina VIII. Collaterals were found arising only from neurones located in the middle of lamina VII and from axons which took a mediorostral direction. In all of these neurones excitatory postsynaptic potentials were evoked from group Ia afferents of at least some nerves, in addition to such potentials from Ib or unidentified group I afferents, and inhibitory postsynaptic potentials were evoked from group I and II afferents. The area of terminal branching of the collaterals suggests that they may supply contralateral ventral spinocerebellar neurones with information from muscles and/or mediate crossed reflexes from group I afferents.

Afferent Pathways↗
PubMed1988

An investigation of local actions of ionophoretically applied DOPA in the spinal cord.

Methyl-L-DOPA (L-beta-3,4-dihydroxy-phenylalanine methyl ester, hydrochloride) was applied ionophoretically to investigate its effects on neurones at various locations in the cat spinal cord. Its actions were tested on monosynaptic field potentials evoked from group I and group II muscle afferents in midlumbar segments. Methyl-L-DOPA has been found to depress field potentials evoked from group II afferents in the ventral horn and in the intermediate zone but not in the dorsal horn, nor field potentials evoked from group I afferents. Its effects were the same as those of systemically applied L-DOPA (L-beta-3,4-dihydroxyphenylalanine), although weaker.

Action Potentials↗
PubMed1988

Inhibition of p-chlorophenylalanine-induced muricide behavior following TRH microinjection into the limbic structures in the rat.

The effect of central microinjections of thyrotropin releasing hormone (TRH) on muricide behavior was investigated in rats with chronically implanted cannulas into one of the limbic structures: the amygdala, the hippocampus or the nucleus accumbens. The rats were made aggressive by p-chlorophenylalanine administration. Saline injection did not inhibit muricide, whereas TRH (10 micrograms in 0.5 microliter per side) significantly suppressed mouse-killing reaction upon injection into each of three regions. It is suggested that the observed antiaggressive effect of TRH may involve stimulation of the central noradrenergic and/or serotonergic transmission.

Amygdala↗
PubMed1988

Information processed by dorsal horn spinocerebellar tract neurones in the cat.

1. A group of spinocerebellar tract neurones located in the dorsal horn of the mid-lumbar segments of the spinal cord but outside of Clarke's column have been investigated by intracellular and extracellular recording from their somata. The existence of these neurones has been demonstrated previously using anatomical methods, but their properties have not been investigated in detail. In contrast to the cells of Clarke's column, these neurones were found to process information from both exteroceptors and proprioceptors. 2. All of the investigated neurones were powerfully excited following stimulation of muscle nerves at strengths sufficient to activate group II afferents while there was no evidence for actions from group I afferents onto any of them. Most were excited by group II afferents from many different nerves, including those from muscles acting on different joints. The latencies and properties of the excitatory postsynaptic potentials (EPSPs) suggest that at least a large proportion of them were monosynaptically evoked. 3. All of the neurones were powerfully excited following electrical stimulation of cutaneous afferents. The most potent effects were evoked from the saphenous and sural nerves which innervate the skin of the leg and thigh. In many cases these EPSPs had latencies indicative of a monosynaptic connection. The superficial peroneal and tibial nerves which innervate the skin of the foot evoked EPSPs which were usually smaller and of longer latency. 4. Responses to adequate stimulation of cutaneous afferents were examined in twenty extracellularly recorded neurones. All but one of them could be discharged by weak mechanical stimulation of the skin over the proximal part of the leg and thigh. None were activated from the skin of the foot. 5. Some of the neurones were influenced by stimulation of the posterior knee joint or interosseous nerves. These actions were relatively weak, however, suggesting that the powerful effects seen on stimulation of muscle nerves were unlikely to have been mediated by articular or Pacinian afferents which contaminate them. 6. Excitation from group II afferents was sometimes followed by inhibition (in 27% of the neurones). In almost all cases the inhibitory postsynaptic potentials (IPSPs) were evoked from the same nerves which evoked EPSPs. The minimal latencies of the IPSPs were approximately 1.0 ms longer than those of the EPSPs, suggesting that they were evoked disynaptically. 7. The possibility that these neurones provide information regarding limb position is discussed.

Action Potentials↗
PubMed1988

Further evidence for synaptic actions of muscle spindle secondaries in the middle lumbar segments of the cat spinal cord.

1. The aim of this study has been to investigate the receptor origin of postsynaptic actions evoked by group II muscle afferents in mid-lumbar segments of the cat spinal cord. The experiments tested the hypothesis that the afferents involved were the secondary endings of muscle spindles. 2. Spindle afferents were activated by contractions of intrafusal muscle fibres which were induced by electrical stimulation of fusimotor axons in the distal parts of transected ventral roots by one to three stimuli at 150-500 stimuli/s. A separate series of experiments has shown that such stimuli are effective in activating a considerable proportion of muscle spindle secondaries when contractions of extrafusal muscle fibres are eliminated by differential fatigue of these fibres, provided that several fusimotor axons are stimulated simultaneously. 3. Extracellular field potentials were recorded in the dorsal horn, at such locations where synaptic actions were evoked by electrical stimulation of group II but not group Ia muscle spindle or group Ib tendon organ afferents of pretibial flexors. Effects of activation of spindle afferents following stimulation of fusimotor axons were then compared with effects evoked by electrical stimulation of group II afferents of anterior tibial or extensor digitorum longus nerves and by small stretches of these muscles. 4. Distinct field potentials were evoked by stimulation of ventral root fibres at all locations at which field potentials were obtained from group II afferents stimulated electrically. The latencies of these field potentials were in both cases shorter in the dorsal horn than in the ventral horn. 5. The appearance of these field potentials was not related to contractions of extrafusal muscle fibres and was also observed when these contractions were practically eliminated. Furthermore, their threshold and similar dependence on a potentiating effect of two to three stimuli, as found for single secondaries, allow them to be attributed to secondary endings of muscle spindles.

Action Potentials↗
PubMed1988

Evidence that mid-lumbar neurones in reflex pathways from group II afferents are involved in locomotion in the cat.

1. A group of interneurons in the mid-lumbar segments of the cat spinal cord which mediate disynaptic excitation or inhibition of motoneurones from group II muscle afferents have recently been described. To test the possibility that the activity of these interneurones is related to the activity in the neuronal networks which subserve locomotion we have investigated whether they are influenced by two procedures which can induce locomotion. These procedures were electrical stimulation within the cuneiform nucleus (the 'mesencephalic locomotor region') in anaesthetized preparations and systemic administration of 3,4-dihydroxyphenylalanine (DOPA) in decerebrate, spinalized, unanaesthetized preparations. The interneurones we have tested were located in the fourth lumbar (L4) segment and were excited by group II muscle afferents; more than half of them were antidromically activated from the hindlimb motor nuclei. 2. Stimuli applied in the cuneiform nucleus evoked excitatory postsynaptic potentials (EPSPs) in a high proportion of these interneurones. The stimuli also evoked distinct extracellular field potentials in the ventral horn of the L4 segment. The properties and latencies of both the intra- and extracellularly recorded potentials show that they were evoked disynaptically, via supraspinally located relay neurones and a fast-conducting descending tract. 3. Stimulation of the cortico- and rubrospinal tracts excited or inhibited some of the L4 neurones, often at latencies suggesting mono- or disynaptic coupling. The neurones which appeared to be monosynaptically excited from the cortico- and rubrospinal tracts tended to be located dorsal to the neurones which were activated from the cuneiform nucleus. 4. Systemic administration of DOPA depressed the responses evoked by stimulation of group II afferents of L4 interneurones which projected to motor nuclei. DOPA also depressed extracellular field potentials evoked by group II afferents in the intermediate zone and in the ventral horn (at the location of the interneurones) but hardly affected those in the dorsal horn. 5. By showing that both stimulation in the cuneiform nucleus and the administration of DOPA influence activity of L4 interneurones which are excited by group II afferents and which project to motor nuclei, the results of this study support the hypothesis that these neurones are in some way involved in locomotion. However, the opposing effects of DOPA administration and of stimulation in the cuneiform nucleus make the interpretation of their role in locomotion rather difficult before it is known to what extent they are active throughout the step cycle.

Action Potentials↗