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  • 1
    Electronic Resource
    Electronic Resource
    Nigral output neurons are engaged in regulation of static fusimotor action onto flexors in cat (1981)
    Springer
    Pflügers Archiv 391 (1981), S. 255-257 
    Details
    ISSN: 1432-2013
    Keywords: muscle spindles ; fusimotoneurons ; substantia nigra ; picrotoxin ; muscimol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Picrotoxin and muscimol were unilaterally injected into the postero-lateral part of the reticular zone of substantia nigra (p1SNR) through chronically implanted guide cannulae in ketamine-anasthetized cats. Afferent activity of pretibial flexor muscle spindle primary and secondary endings was recorded before and after drug administration, and spindle sensitivity monitored during both sinusoidal and ramp stretch of the receptor-bearing muscle. From changes in spindle sensitivity after drug injection it is deduced that unilateral block by picrotoxin of the action of GABA on postsynaptic receptors in plSNR removes tonic static fusimotor action from flexor muscle spindle primary endings. Secondary endings seemed largely unaffected. The effect on primary endings is reversed by a subsequent injection of muscimol. It is concluded that the central nervous system, through GABA-modulated nigral output neurons, can control static fusimotor action onto flexor muscle spindle primary and secondary endings separately to some extent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00596180
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of muscimol and picrotoxin injections into the cat Substantia nigra (1981)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 317 (1981), S. 54-60 
    Details
    ISSN: 1432-1912
    Keywords: Substantia nigra ; GABA receptors ; Stereotypy ; Rotational behaviour ; Motor disturbances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The behaviour of cats after unilateral injections of muscimol, picrotoxin and bicuculline into the posterior and lateral parts of the substantia nigra was observed. The antagonism between muscimol and picrotoxin was limited to some effects of the drugs: (1) muscimol-induced sniffing, licking and enhanced locomotor activity was attenuated by picrotoxin in contrast to the muscimol-induced contralateral turning which was even enhanced by picrotoxin; (2) picrotoxin-induced balance disorders as well as characteristic motor disturbances in the hind legs remained unaffected following an additional treatment with muscimol. Furthermore, subcutaneously given apomorphine did not affect the picrotoxin-induced balance and hind leg disorders, although the apomorphine-induced stereotyped behaviour itself was enhanced and suppressed by intranigral administration of muscimol and picrotoxin respectively. The conclusion is reached that there are at least two distinct populations of GABA receptors within the substantia nigra: one group controlling or being controlled by dopaminergic neurons and one group operating fully independently of the former neurons. The similarities to experiments on rats are stressed. The mechanism underlying the muscimol-resistant picrotoxin-induced effects (balance disorders and motor disturbance of the hind legs) is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00506257
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  • 3
    Electronic Resource
    Electronic Resource
    3H-Spiroperidol binding to striatal membranes of mutant Han-Wistar rats which exhibit spastic paresis (1981)
    Springer
    Cellular and molecular life sciences 37 (1981), S. 490-491 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The binding of3H-spiroperidol to striatal membranes from a strain of mutant Han-Wistar rats was compared with that in normal littermate animals. The specific binding was less in the mutants than the controls. Scatchard analysis revealed that the KD- and Bmax-values for the high affinity binding sites in the mutants are greater than for those in the controls. These findings indicate that the dopamine receptors of the mutants are affected and could explain some of the previous data; it has been suggested that some of the spasticity observed in the mutants may be due to an abnormal functioning of their dopaminergic neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01986154
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  • 4
    Electronic Resource
    Electronic Resource
    Catalepsy after microinjection of haloperidol into the rat medial prefrontal cortex (1988)
    Springer
    Experimental brain research 70 (1988), S. 445-447 
    Details
    ISSN: 1432-1106
    Keywords: Catalepsy ; Dopamine ; Medial prefrontal cortex ; Neostriatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To investigate the behavioural role of mesocortical dopamine innervation we performed bilateral microinjections of haloperidol into various parts of the rat frontal cortex and into adjacent subcortical forebrain structures. Haloperidol (2.5 μg/ 0.5 μl) locally injected into the medial prefrontal cortex or into the rostral part of the neostriatum resulted in the development of catalepsy as measured in the bar test. In contrast, injections of haloperidol into the nucleus accumbens, more caudal parts of the neostriatum, anterior cingulate cortex, rostral and lateral parts of the prefrontal cortex and into the lateral ventricles failed to induce catalepsy. It is concluded that blockade of dopamine receptors located in the rostral neostriatum and in the medial prefrontal cortex contributes to the development of haloperidol induced catalepsy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248371
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  • 5
    Electronic Resource
    Electronic Resource
    The guinea-pig step cycle: X-ray cinematographic analysis of the forelimb during pharmacologically induced “stepping automatism” (1987)
    Springer
    Experimental brain research 67 (1987), S. 216-219 
    Details
    ISSN: 1432-1106
    Keywords: Stepping automatism ; Locomotion ; Step cycle ; Guinea-pig ; SIS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary “Stepping automatism” has generally been studied in mesencephalic or spinal cats and has been induced electrically with the animal on a treadmill (Shik and Orlovsky 1976). Derivatives of 4-R-2,2,5,5-tetrakis (trifluoromethyl)-imidazoline (SIS = Substances capable of Inducing Stepping) I–IV (Liu 1985, Liu et al. 1984) can induce regular “stepping automatism” in guinea pigs. The present paper concerns the guinea-pig step cycle of the forelimb during SIS II-induced “stepping automatism” analysed with the use of X-ray cinematography and electromyography (EMG) studies in suspended animals. Results show that the flexion phase (F E1) and the extension phase (E2 E3) of the SIS-induced step cycle are quite comparable to those of the normal step cycle in other quadrupedal animals walking on the ground. The excursions of elbow, shoulder and scapula joints are all in phase in F and E3, whereas the scapula is largely out of phase with the elbow and shoulder during E1 and E2. It is surprising that during SIS II-induced locomotion in guinea pigs suspended in the air, “yield” could be seen in both, the elbow and the shoulder joints.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269467
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  • 6
    Electronic Resource
    Electronic Resource
    δ-Aminovaleric acid antagonizes the pharmacological actions of baclofen in the central nervous system (1988)
    Springer
    Experimental brain research 70 (1988), S. 618-626 
    Details
    ISSN: 1432-1106
    Keywords: δ-aminovaleric acid ; Baclofen ; GABAB antagonist ; Spasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The action of δ-aminovaleric acid (AVA) on the muscle relaxant properties of baclofen, a GABAB receptor agonist, was investigated in two experimental models: (1) the pathologically increased muscle tone of the gastrocnemius muscle in spastic mutant Han-Wistar rats and (2) the Hoffmann (H)-reflex recorded from plantar foot muscles after electrical stimulation of the tibial nerve in barbiturate (60 mg/kg) anaesthetized rats. In both paradigms coadministration of AVA (500 nmol/5 μl) antagonized the muscle relaxant action of intrathecally applied baclofen (0.2–2 nmol), but failed to affect the muscle relaxant effects of intrathecally injected muscimol (2–20 nmol). In contrast, coadministration of bicuculline (1 nmol) did block the muscle relaxant action of muscimol, but failed to alter the effects of baclofen. When administered alone, bicuculline (1 nmol), or AVA (500 nmol–2 μmol) were without intrinsic action in both paradigms. In an additional series of experiments we investigated the action of AVA on a supraspinal effect of baclofen. Coadministration of AVA (12.5 nmol/0.5 μl) in the ventromedial thalamic nucleus antagonized the catalepsy induced by baclofen (ED50 10 pmol/0.5 μl), as indicated by an increase in ED50 of baclofen by a factor of 4.835 and a parallel shift of the probit-log dosage regression line to the right. The parallel shift seems to be consistent with a competitive mechanism of action of AVA. This study presents evidence that AVA antagonizes central pharmacological actions of baclofen at both spinal and supraspinal sites without affecting the actions of a GABAA agonist, muscimol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247610
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  • 7
    Electronic Resource
    Electronic Resource
    Neuromuscular responses to gait perturbations in freely moving cats (1980)
    Springer
    Experimental brain research 38 (1980), S. 109-114 
    Details
    ISSN: 1432-1106
    Keywords: Neuromuscular ; Reflexes ; Gait
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary If an obstacle impedes the forward swing of a cat's foot, the animal responds by rapidly lifting the foot over the obstacle. In freely moving cats, the electrical activity of hindlimb flexors and extensors was recorded during such reactions elicited both mechanically and electrically. The sequencing of muscle activity was more complex and longer in duration in the mechanically elicited reactions. Anaesthesia of the foot dorsum abolished responses in ankle extensors and knee flexors, and converted the responses of ankle flexors to simple stretch reflexes. Although our findings closely resemble those reported for chronic spinal kittens, there are interesting points of difference, which should be taken into account if the notion of a purely spinal mediation of the placing reaction during stepping is to be accepted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237937
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  • 8
    Electronic Resource
    Electronic Resource
    Rigidity and catalepsy after injections of muscimol into the ventromedial thalamic nucleus: an electromyographic study in the rat (1985)
    Springer
    Experimental brain research 58 (1985), S. 559-569 
    Details
    ISSN: 1432-1106
    Keywords: Catalepsy ; Electromyography ; GABA ; Limb rigidity ; Ventromedial thalamic nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cataleptic state induced by injection of the GABAmimetic drug muscimol into the rat's ventromedial thalamic nucleus (VM) was examined using an electromyographic (EMG) approach. Muscimol in doses up to 50 ng/0.5 μl injected into the VM induced a tonic EMG activity in the gastrocnemius muscle which is considered to be a measure of limb rigidity. This tonic EMG activity was found to be dose-dependent, GABA specific and locus specific. By recording EMG signals from chronically implanted electrodes in awake, unrestrained rats it was shown that muscular reactions serving to maintain the animal's static equilibrium were intact in the state of VM induced catalepsy. However, animals were unable to initiate movements or locomotion even when they were forced by strong external stimuli. It was found that the animals' immobility was due to an inability to induce a phasic activation of their muscles whereas tonic activation still occurred. It is concluded that (1) the rat's VM is part of a neuronal chain conducting information relevant for the expression of limb rigidity, (2) the VM is involved in the central mechanisms responsible for the phasic activation of a set of muscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235872
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  • 9
    Electronic Resource
    Electronic Resource
    GABAergic neurotransmission within the reticular part of the substantia nigra (SNR): role for switching motor patterns and performance of movements (1986)
    Springer
    Experimental brain research 63 (1986), S. 375-381 
    Details
    ISSN: 1432-1106
    Keywords: GABA ; Motor pattern ; Motor performance ; Substantia nigra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to investigate the role of GABAergic neurotransmission within the reticular part of substantia nigra (SNR) in the switching of motor patterns and the performance of movements, cats trained to walk on the running belt of a treadmill at constant speed were subjected to three different tests: (1) a food dispenser test measuring the animals' capacity to switch motor patterns in order to get access to food during walking; (2) an obstacle test measuring the animals' capacity to switch motor patterns in reaction to incoming obstacles; (3) EMG recording of two representative antagonistic muscles of the hindlimb during walking on the treadmill. Local injection of a moderate dose of the GABA antagonist picrotoxin (PTX; 250–500 ng/0.5 μl) into the SNR disrupted the animals' capacity to switch motor patterns in the food dispenser test, but not in the obstacle test. These animals displayed normal EMG patterns during walking. Higher doses of intranigral injections of PTX, however, impaired the execution of movements per se as detected by an increased number of ‘faults’ in the obstacle test and pathological EMG patterns during walking. These experiments support the view that (1) the SNR plays a distinct role for switching motor patterns; (2) the SNR is involved in the control of movements per se; (3) the degree of motor disorder depends on the degree of pathology within this brain structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236855
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of two isomeric 1-aminoadamantanes on the membrane anisotropy and on alpha- and gamma-motoneurones excitability (1989)
    Springer
    Journal of neural transmission 1 (1989), S. 153-164 
    Details
    ISSN: 1435-1463
    Keywords: Aminoadamantanes ; pharmacokinetics ; CNS ; membrane anisotropy ; excitability ; spinal alpha- and gamma-motoneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structure-activity relationship of two isomeric 1-aminoadamantanes, 1-C-ethylaminoadamantane (D 174) and 1-amino-3-ethyladamantane (D 175), on membrane anisotropy and the excitability of neurons was studied in the CNS of the rat and in the decerebrated cat. Mass spectrometric analysis showed that after a single, 40 mg/kg dose, D 174 and D 175 were unevenly distributed within the CNS of the rat, moreover the distribution pattern of the two substances was different. As measured by fluorescence depolarization in controls the membrane anisotropy was found to be higher in the older parts as compared with the younger parts of the CNS. After i.p. application of 40 mg/kg the membrane anisotropy was reduced in the cortex by D 174, whereas D 174 and D 175 increased the rigidity in striatal membranes. If cortical membranes were incubated with the substances, the fluidizing effect of D 174 was more prominent than that of D 175. In the decerebrated cat only D 174 in a dose of 5 mg/kg i.p. raised the discharge of spinal alpha-motoneurones significantly. The results suggest that the membrane architecture is more affected by D 174 as compared with D 175 which is reflected by a greater effect on membrane anisotropy as well as on the activity of spinal alpha-motoneurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02248665
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