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PubMed1993

[The characteristics of the cholinergic mechanisms of the nucleus accumbens and the caudate nucleus in regulating an instrumental escape reflex in dogs].

We perform comparative analysis of the involvement of dorsal (Neostriatum) and ventral (Nucleus Accumbens) striatal cholinergic systems in the regulation of defensive instrumental reflex, connected with the maintenance of certain flexor posture, in dogs. The data obtained show that the carbachol microinjections (0.05 mkg) into the contralateral Head of Caudate Nucleus significantly improved instrumental reflex due to increasing of a tonic movement component and inhibition of interstimulus and phasic leg raising. In was shown that the cholinergic system of Neostriatum was of great importance for the regulation of the main component of postural adjustment: the unloading of the working limb. The same microinjections into Nucleus Accumbens significantly improved (ipsi- and contralaterally) the instrumental reflex due to prolonged increasing of a phasic component of movement and its amplitude. It can be suggested that the Neostriatum cholinergic system is structurally included into the motor components realization of instrumental reflex, connected with a certain posture maintenance. The activation of cholinergic system of Nucleus Accumbens affects this form of behavior in an excitatory way, being of nonspecific and prolonged character.

Animals↗
PubMedDate not supplied

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↗
PubMed1969

Release to the cerebral ventricles of substances with possible transmitter function in the caudate nucleus.

1. One caudate nucleus of the anaesthetized cat was superfused by perfusing the anterior horn of one lateral cerebral ventricle. The perfusates were examined for their content in acetylcholine (ACh), dopamine, homovanillic acid (HVA) and 5-hydroxytryptamine (5-HT), at rest and after a variety of stimuli.2. When prostigmine was added to the perfusion fluid, ACh appeared in the effluent; its concentration tended to rise in the course of an experiment. Various afferent stimuli, all of which caused evoked responses recorded from the contra-lateral caudate nucleus, increased the ACh content of the effluent. Effective stimuli were noise and electrical stimulation of afferent nerves or of certain regions of the brain including the ipsi-lateral substantia nigra.3. The dopamine content of the effluent was extremely low (of the order of 50 pg/min) at rest, but, on occasion, rose sharply when the substantia nigra was stimulated electrically with trains of pulses repeated once every 3 sec. The results were inconsistent.4. Since dopamine in tissue is rapidly transformed enzymically into HVA, the appearance of this acid in the perfusate was examined.5. At rest, HVA was found to appear in the effluent at a rate of 2-8 ng/min. Its concentration was rapidly depressed by increasing the depth of anaesthesia.6. Stimulation of the substantia nigra for periods of 3 or 4 min caused an increment in the HVA content of the effluent lasting 1 hr or more. It was frequently seen when two points of the substantia nigra were stimulated simultaneously, less regularly with only one stimulating electrode, and rarely if this was placed in the most caudal part of the substantia nigra.7. These results strongly support the view that there is a dopaminergic nigro-striatal pathway. The following assumption would explain the erratic appearance of dopamine and the long duration of increments in HVA: many of the axons originating in the substantia nigra end either in the putamen or in parts of the caudate nucleus which are far away from the ventricular surface; any dopamine released from these axons will not reach the ventricular surface at all, and HVA will, at best, reach it very slowly.8. Small amounts of 5-HT appeared in the ventricular perfusate, and the quantity rose after the administration of monoamine oxidase inhibitors. It was not increased by the type of stimuli used in this work to elicit the release of ACh or HVA.

Acetylcholine↗
PubMed1986

The role of the nucleus raphe pontis and the caudate nucleus in alfentanil rigidity in the rat.

Attempts to eliminate or reduce the rigidity induced with high-dose narcotic anesthesia in the operating room have been only partially successful. Previous investigations of opioid receptor sites mediating this rigidity have implicated two central regions: the nucleus raphe pontis (NRP) within the reticular formation and the caudate nucleus (CN) within the basal ganglia. The present study used systemically administered alfentanil (ALF), a potent, short-acting fentanyl analog, and intracerebrally infused methylnaloxonium (MN), a quaternary derivative of naloxone, to elucidate further the functional role of the NRP and CN in rigidity. ALF (0.5 mg/kg s.c.) produced a reliable model of rigidity, as documented by gastrocnemius electromyography. The onset of this rigidity was within 60 s of ALF administration, with a total duration of approximately 40-50 min. Intracerebroventricular (i.c.v.) injections of 2.0 or 4.0 micrograms of MN 15 min prior to ALF treatment prevented rigidity, while 0.125 or 0.5 microgram had no significant effect on rigidity. MN injected directly into the NRP at doses as low as 0.125 microgram significantly antagonized ALF-induced rigidity, while injections of MN into the caudate nucleus at doses as high as 4.0 micrograms failed to antagonize ALF-induced rigidity. These observations demonstrate that injection of MN into the NRP is at least 16-fold more effective in blocking ALF-induced rigidity than MN injected into the ventricle and, more importantly, at least 32-fold more effective than MN injected into the CN. The results suggest that the NRP may be an important site for the neural control of muscular rigidity associated with high-dose narcotic administration.

Alfentanil↗
PubMed2006

Sensory-evoked potentials recordings from the ventral tegmental area, nucleus accumbens, prefrontal cortex, and caudate nucleus and locomotor activity are modulated in dose-response characteristics by methylphenidate.

Most of the studies investigating the effects of methylphenidate (MPD) are using behavioral and biochemical approaches. There are some electrophysiological studies about the effects of MPD on spontaneous electrical activity; however, there is none about the effects of MPD on sensory inputs. The objectives of the present study were to investigate the MPD dose-response characteristics on locomotor activity and sensory inputs using acoustic stimuli. Freely behaving rats previously implanted with semi-microelectrodes were used to record from four brain areas known to be sites of psychostimulant action. For locomotor behavior assessment, rats received saline on experimental day 1 and an acute administration of MPD (0.6, 2.5, or 10.0 mg/kg, i.p.) on experimental day 2. Using an automated, computerized activity-monitoring system, locomotor behavior was recorded for 2-h postinjection on both days. For the electrophysiological experiments, animals were implanted with permanent electrodes in the ventral tegmental area (VTA), nucleus accumbens (NAc), prefrontal cortex (PFC), and caudate nucleus (CN) under general anesthesia. Five to seven days after electrode implantation, they were used to study the effects of three different MPD doses on the response to sensory inputs. The lowest dose of MPD (0.6 mg/kg, i.p.) failed to alter locomotor activity, while the two higher MPD doses (2.5 and 10.0 mg/kg) elicited increase in locomotion, with the 10.0 mg/kg dose increased at least twice as much as the 2.5 mg/kg dose. However, the same three MPD doses elicited significant attenuation of sensory inputs in dose-response characteristics, i.e., as MPD dose increased, evoked sensory inputs decreased. These opposite effects (motor activation and sensory input suppression) were further discussed.

Acoustic Stimulation↗
PubMed1977

Substantia nigra and somatosensory evoked responses in the caudate nucleus.

The nigro-caudate relationships were studied in fifteen adult anesthetized cats, paralyzed with Flaxedil. Single shocks applied to substantia nigra (SN) evoked biphasic field potentials in the ipsilateral caudate nucleus. Similar positive-negative waves were recorded in the caudate nucleus by sciatic stimulation, although with longer latencies. A triphasic field potential was also observed after cerebral peduncle stimulation. Conditioning stimuli applied to the SN at varying time intervals prior to sciatic stimulation did not modify the test response. In contrast, conditioning stimulation of the cerebral peduncle produced a marked inhibition between 25 and 100 msec. Recovery was complete after 200 msec. The present observations indicate that nigral stimulation does not influence the pool of neurons responding to sciatic nerve in the caudate nucleus. On the other hand, the cerebral peduncles exert an inhibitory action on such activity.

Animals↗
PubMed1983

Topographic changes in high-affinity glutamate uptake in the cat red nucleus, substantia nigra, thalamus, and caudate nucleus after lesions of sensorimotor cortical areas.

The distribution of presumed glutamatergic projections from sensorimotor cortical areas to the red nucleus (RN), the substantia nigra (SN), the ventrolateral thalamic complex, and the caudate nucleus (CN) was investigated in the cat. For this purpose, the changes in the sodium-dependent high-affinity glutamate uptake (HAGU) rate were measured in homogenates of tissue microdissected from various parts of these subcortical structures after chronic surgical ablation of sensorimotor cortical areas. After 8 to 10 days survival, significant reductions in HAGU activity were noted in the structures studied on the side ipsilateral to the operated cortex. Within each structure, various quantitative or qualitative changes were observed. Higher decreases in HAGU activity were found in the caudal part of the RN, the ventrolateral thalamic nucleus, and the dorsolateral part of the CN than in the other parts of these structures. The lateral part of the SN showed a large decrease in HAGU rate and its medial part a small but significant increase. Referring to the anatomic data concerning the organization of cortical projections from sensorimotor areas to the structures studied, it was shown that our results support the view that glutamate could act as a neurotransmitter along various corticosubcortical pathways.

Animals↗
PubMed1985

Effects on the caudate spindle in rats of dopamine microinjected into the caudate nucleus.

We examined the caudate spindle in control and pargyline-pretreated rats following bilateral application of 3 doses (15, 50 and 150 micrograms/site) of dopamine (DA) into the caudate nucleus. The highest dose of DA (150 micrograms) suppressed the spindle, whereas lower doses (15, 50 micrograms) enhanced the spindle in control rats. Haloperidol given into the bilateral caudate nucleus increased the spindle in control rats. In pargyline-pretreated rats, 50 and 150 micrograms DA caused marked suppression, but 15 micrograms DA caused enhancement. These findings indicate that the DA system may mediate the development of the caudate spindle. Suppression of the caudate spindle induced by intracaudate DA injection may be due to stimulation of postsynaptic DA receptors and enhancement mediated by DA autoreceptors on the DA nerve terminals in the caudate nucleus with a subsequent inhibition of DA neurotransmission.

Animals↗
PubMed1989

Effect of thalamic parafascicularis nucleus stimulation in regulation of serotoninergic transmission in the cat caudate nucleus: involvement of autoreceptors in the dorsalis raphe nucleus.

The mechanisms involved in parafascicularis nucleus control on serotoninergic neurons projecting into the caudate nucleus were investigated in "encéphale-isole" cats. The effects of unilateral stimulation of the parafascicularis nucleus on the release of newly synthesized [3H]serotonin were simultaneously determined in the ipsilateral caudate nucleus and the dorsalis raphe nucleus using push-pull cannulae. The actions of various pharmacological treatments performed either in the caudate nucleus or in the dorsalis raphe nucleus were also examined. The electrical or chemical stimulation of the parafascicularis nucleus induced a decrease in striatal [3H]serotonin release and an increase in [3H]serotonin release in the dorsalis raphe nucleus. The blockade of cholinergic (mecamylamine) and glutamatergic (PK 26124) transmissions at the striatal level did not modify the thalamic stimulation-induced effect on serotonin release in the caudate nucleus or in the dorsalis raphe nucleus. However, a decrease induced by parafascicularis nucleus stimulation in serotonin release in the caudate nucleus could not be observed when the autoreceptors present on serotoninergic nerve cell bodies localized in the dorsalis raphe nucleus were blocked by a methiothepin perfusion within the nucleus. These results indicate that the parafascicularis nucleus controls striatal serotonin transmission by inducing changes in the nerve activity of serotoninergic neurons in the dorsalis raphe nucleus via somatodendritic serotonin release and autoreceptors.

Animals↗