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Neuronal distribution in caudate nucleus and reticular-caudate pathways.

Methods of quantitative stereology are employed to determine the cell body diameters and the disposition of the neurons of caudate nucleus (CN) of the cat. Large neurons are more frequent in the infero-external region in a well defined zone 16 to 18 mm ahead of the interaural plane. Silver impregnations and electron microscopy after lesions in the ponto-mesencephalic reticular formation demonstrate its direct projections on the nucleus centralis medialis thalami and on the CN. Ascending fibers run along the ventral and lateral surfaces of the thalamus, some of them penetrate to the lamina medullaris medialis making contact in intralaminar nuclei and in the nucleus centralis medialis, others continue through the internal capsule to end in the infero-external region of the CN. The reticular formation of one side projects to both CN.

Animals

Selective blockade by scopolamine of synaptic responses in cat's caudate nucleus and its modification by lesions of the substantia nigra.

Because it is commonly believed that acetylcholine is a synaptic transmitter in the caudate nucleus and that the reduction of striatal biogenic amines in Parkinson's disease leads to acetylcholine supersensitivity in the caudate nucleus, we investigated the effects of the muscarinic blocking agent scopolamine on synaptic responses of neurons in the intact feline caudate nucleus and in the caudate nucleus depleted of dopamine by long-standing nigrostriatal lesions. In the intact caudate nucleus, micro-iontophoretic application of scopolamine selectively blocked the neuronal responses to stimulation of the caudate nucleus near the recording site without affecting the responses to stimulation of the sensorimotor cortex or the substantia nigra in the same fashion. This suggests that acetylcholine is a synaptic transmitter of caudate interneurons. Responses to thalamic stimuli were also blocked by scopolamine, suggesting that acetylcholine may be a transmitter of thalamic afferents although the course of these afferents is unclear. In the dopamine-depleted caudate nucleus scopolamine was more effective than in the intact caudate nucleus blocking the neuronal responses to stimulation of the caudate nucleus. This greater blocking effect by scopolamine suggests an increased effect of endogenous acetylcholine in this response and supports previous observations of an increased excitatory effect of iontophoretic acetylcholine in the dopamine-depleted caudate nucleus. These results suggest that the acetylcholine supersensitivity which follows nigrostriatal degeneration may be due to increased effectiveness of synaptic transmission by cholinergic interneurons in the caudate nucleus.

Acetylcholine

Accumulation of apomorphine in caudate nucleus and hippocampus of the rabbit.

Apomorphine concentration was assayed in the caudate nucleus, hippocampus and cerebellum of rabbits injected with various doses of the drug 30 min earlier. Apomorphine accumulation was dose-dependent but uneven in the structures tested: the accumulation in the caudate nucleus being approx. 5 times higher than in cerebellum. Pretreatment with haloperidol significantly depressed the accumulation of apomorphine in the caudate nucleus and hippocampus, but not in the cerebellum. The amount of apomorphine displaceable by haloperidol was approx. 10 times higher in the caudate nucleus than in the hippocampus. The results suggest the existence of small number of apomorphine binding sites in the hippocampus.

Animals

[Modulation of primary and secondary endings activity of tibialis anterior muscle spindles during contraction induced by caudate nucleus stimulations].

1. Effects of repetitive stimulations of caudate nucleus were studied on static and dynamic sensitivities of contralateral flexor (tibialis anterior) muscle spindle primary and secondary endings in cats anaesthetized with Halothane (Fluothane). Fusimotor effects are interpreted in term of gamma dynamic and gamma static activation. 2. Threshold stimulation induce a gamma dynamic effect on the primary endings sensitivity. Secondary endings activity and muscle tension remainded unaltered. 3. A slight increase of the stimulus strength elicit a gamma dynamic-gamma static effect on the primary endings sensitivity. Simultaneously secondary endings activity was increased and muscle contractions induced. 4. Using graded voltage stimulation permit to increase primary and secondary endings activity without muscle contraction. 5. Two stimulations applied at sufficiently short time interval produce different fusimotor effects. The first stimulation induce the general motor effect previously obtained: gamma dynamic-gamma static modulation of primary endings sensitivity, increase of secondary endings activity, muscular contraction. The second stimulation elicit a gamma dynamic effect on primary endings sensitivity and a depressant effect on secondary endings activity during muscular contractions. 6. Tendon organs discharge during caudate nucleus stimulation was studied comparatively with the primary and secondary endings activity.

Action Potentials

[Dopamine concentration in the nigrostriatal system during electrical stimulation of the head of the caudate nucleus].

The high-frequency (50/sec) stimulation of the caudate nucleus head increases the level of dophamine in the area under stimulation with simultaneous drop of dophamine content in the rest of the nucleus. The dophamine content, however, does not change in the black substance or in the putamen. The 2/sec stimulation has no effect upon the dophamine content in the area under stimulation or in the black substance but increases its level in the rest of the caudate nucleus with simultaneous decrease of the dophamine in the putamen.

Animals

Character and origin of rotatory movements evoked by electrical stimulation of the caudate nucleus in cats.

High-frequency stimulation of the caudate nucleus in cats induces three types of rotatory responses: turning the head or stepping movements in a circle toward the side opposite to that of stimulation, psychomotor excitation with contralateral rotation, and ipsilateral turning of the head and trunk. Movements of the last type developed mainly from the ventro-lateral zones of the head of the caudate nucleus, whereas psychomotor excitation, on the other hand, developed from the dorsal zones. Rotatory movements do not depend significantly on a contribution of the internal capsule or cortex. Slow synchronized activity on the EEG at the time of rotation was abolished after curarization of the animals. Caudate rotation is partly due to activation of the globus pallidus, for electrical stimulation of that structure raises the threshold of the responses although it does not block them completely.

Animals

Alterations in [3H]spiperone binding in human caudate nucleus, substantia nigra and frontal cortex in the Shy-Drager syndrome and Parkinson's disease.

[3H]Spiperone binding was investigated in the caudate nucleus, substantia nigra (s. nigra) and frontal cortex of control subjects and of patients with Parkinson's disease and the Shy-Drager syndrome. Binding sites for [3H]spiperone were interpreted as dopamine receptors in caudate and s. nigra, and as 5-hydroxytryptamine (5-HT) receptors in frontal cortex. Scatchard analysis showed that the Bmax (maximal number of binding sites) in caudate was similar in the 3 groups, whereas in s. nigra the Bmax was reduced by approximately 60% in both Parkinsons disease and Shy-Drager syndrome. The dissociation constant (Kd) for [3H]spiperone binding in s. nigra was similar in the 3 groups. In caudate nucleus, the Kd was similar in control and Parkinson groups; however, there was a significant increase in the dissociation constant in the caudate nucleus from cases of Shy-Drager syndrome. No differences in binding characteristics were observed in the frontal cortex. These results are taken to reflect a loss of dopamine receptor sites in the s. nigra in both Parkinson's disease and Shy-Drager syndrome, and a reduced affinity of dopamine receptor sites in the caudate nucleus in Shy-Drager syndrome.

Binding Sites

Facilitation of conditioned motor suppression by microinjections of dopamine in the caudate nucleus of cats.

The effects of Caudate Nucleus (CN) injections of catecholamines on the suppression of a motor conditioned response (MCR), lever pressing, was investigated. Cats were trained to press a lever to obtain 0.5 ml of milk when a conditioned discriminative stimulus was on (CS-on-reward on, MCR) and to suppress the response when the light was off (CS-off-reward off, suppression of motor conditioned response, SMCR). The bilateral application of 5 or 10 micrograms of Dopamine (DA) through chronically implanted cannulae in the CN significantly decreased the lever pressing in the non rewarding situation without changing the MCR. Injection of 5 micrograms of L-DOPA caused very small effects assessed during the following 10 min. However, 10 micrograms of L-DOPA produced a significant decrement of lever pressing (CS-off) in two out of four injections. These findings further support the postulation that catecholamines in the CN have a behavioral inhibitory action upon a motor conditioned response.

Animals

[Effects of caudate nucleus stimulations on the primary and secondary endings activity of soleus muscle spindle].

Effects of repetitive stimulation of the contralateral caudate nucleus on the static discharge and dynamic sensitivity of soleus muscle spindle primary and secondary endings were studied in cats anaesthetized with Halothane (Fluothane). By progressive increasing the depth of anaesthesia two different fusimotor effects could be observed. 1. A static facilitatory effect; under light anaesthesia the static discharge of primary and secondary endings were strongly increased. The response of the primary endings to phasic stretch of the muscle was generaly decreased. 2. A depressant effect; under deep anaesthesia the static discharge of primary and secondary endings were decreased. The dynamic sensitivity of the primary endings was lightly increased or remained unaltered. The ventro-lateral part of the caudate nucleus is mainly responsible for these effects; Caudate nucleus fusimotor effects were compared with those induced by gamma dynamic and gamma static fibers stimulations.

Action Potentials

A direct input from amygdaloid complex to caudate nucleus of the rat.

Spontaneous unit activity was recorded from the caudate nucleus in rats anesthetized with urethane. Amygdaloid nucleus stimulation altered the spontaneous activity of 51 units (65% of the population tested); 23 units (29%) showed an increase and 28 (36%) a decrease of discharge rate. Moreover, 25 units (32%) responded to stimulation with stimulus-locked spikes. Post-stimulus time histograms revealed 7 patterns of response to amygdaloid stimulation. In 4 groups of cells, stimulus-locked spikes occurred followed by alteration of spontaneous discharge rate. In another 2 groups there was a change of spontaneous discharge without stimulus-locked spikes and in the final group no effect occurred. The possibility of mono-, oligo-, and polysynaptic connections from amygdaloid nuclear complex to caudate nucleus was discussed. It was suggested that an amygdalofugal connection to basal ganglia may provide a pathway whereby activity of the limbic system may exert a modulatory influence on somatic motor mechanisms.

Activation Analysis

"In situ" variation of folic acid and dihydrofolate reductase in the caudate nucleus in the ageing process.

In bovine caudate nucleus of young animal, a folic acid-positive reaction was found in the perikarya and in the neuroglia in parallel with a high dihydrofolate reductase activity in the nerve cells. In old animals, folic acid increased in neurons, neuroglia and some nerve cell processes; the folate enzyme was markedly decreased in neurons and increased neuroglia NADH2-cytochrom-C-reductase activity was strongly positive in nerve cells in young and old animals.

Aging

Antibodies to human caudate nucleus neurons in Huntington's chorea.

Antibodies reacting with neuronal cytoplasmic antigens present in normal human caudate and subthalamic nuclei were detected in 37 of 80 probands afflicted with Huntington's disease (HD). IgG antibodies were detected by immunofluorescence using frozen sections of unfixed normal human and rat brain. Specificity of IgG binding was confirmed using pepsin F(ab')2 fragments of IgG isolated from positive sera. In vitro complement fixation of IgG antibody was detected in 22 of 31 sera tested. Neuronal cytoplasmic antigens reacting with positive HD sera were diminished after trypsin or RNAase treatment of tissue sections but were not removed by DNAase, neuraminidase, EDTA, or dithiothreitol treatment. Antibody staining of neurons could be removed after absorption with isolated caudate nucleus neurons or by using perchloroacetic acid extracts of caudate nucleus. Prevalence of antibody reacting with neuronal cytoplasm was 3% in 60 normal controls and 6% among a wide variety of patients with diverse neurological disorders. However, one-third of 33 patients with Parkinson's disease showed presence of antineuronal antibody. Among patients with HD, a significant association was noted between duration of clinical disease greater than 7 yr and titers of antibody of 1:2 or greater (P less than 0.001). When 115 family members of HD probands were tested, 30% of unaffected spouses showed presence of antineuronal antibody. 23.2% of first-degree relatives at risk for developing HD was also positive (P less than 0.001). 10.5% of second-degree relatives showed presence of antineuronal antibody. These data may support an environmental or infectious factor somehow involved in the ultimate expression of HD.

Adult

GABA modulates the release of dopamine and acetylcholine from rat caudate nucleus slices.

The effects of GABA on depolarization-induced (26 mM K+) release of radiolabeled dopamine (DA) and acetylcholine (ACh) from slices of rat caudate nucleus were examined with a superfusion method. GABA, in concentrations of 10(-5)--10(-3) M, dose-dependently enhanced the release of DA, either accumulated by high-affinity uptake or synthesized from 14-C-tyrosine. In contrast, the release of ACh was reduced by GABA. This reduction appeared to be caused by the increase in DA-release. These effects of GABA decreased from the caudal to rostral part within the caudate nucleus, an order which parallels the distribution of endogenous GABA and glutamic acid decarboxylase. However, GABA had little, if any, effect in the nucleus accumbens. Since it was difficult to antagonize the effects of GABA on DA and ACh release with bicuculline or picrotoxin, it remains uncertain whether these effects were mediated via GABA receptors. In view of the high endogenous GABA level in the caudate nucleus it is concluded that GABA may be one of the local factors involved in the control of the amount of transmitter that will be released from dopaminergic varicosities upon depolarization.

Acetylcholine

[Effect of electric stimulation of the somatosensory cortex and caudate nucleus on extinctive inhibition of a conditioned alimentary reflex to sound].

In experiments performed on 9 dogs with alimentary method, extinctive inhibition was deepened and its elaboration was aceelerated by electrical stimulation of somatosensory and motor cortical areas and ventral segment of the caudate nucleus head. The extinction of the conditioned reflex was slowed down by stimulation of the anterolateral gyrus and the central segment of the caudate nucleus head. General motor excitation of animals during stimulation of the dorsal zone of caudate nucleus head impaired the elaboration of extinctive inhibition.

Animals

[Conditioned reflexes following unilateral damage to the premotor cortex and the dorsal portion of the head of the caudate nucleus in dogs].

The study was carried out on dogs by the secretory-motor method with a two-side reinforcement. Simultaneous and unilateral lesion of the premotor cortex and of the dorsal part of the caudate nucleus head brought about prolonged disturbances of the vegetative components (pulse and respiratory rate) and in the choice of the side of food reinforcement. The change in the magnitude of conditioned salivation, latencies of secretion and motor reaction was temporary, and by the end of the third postoperative period their initial magnitudes were restored. The duration of the disturbances of higher nervous activity depended on the localization and extent of lesion of the caudate nucleus head. Tests were made with chlorpromazine and caffeine before and after the lesion of the brain structures. The tests in the postoperative period revealed latent disturbances in the dog higher nervous activity. It is assumed that the premotor cortex and the dorsal part of the caudate nucleus head are one of the sub-systems involved in the regulation of vegetative, somatic components of unconditioned behaviour and in the analysis of conditioned stimuli.

Animals