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At least 865 records · Page 48Linked to original sources
PubMed1977

Striatal lesions with kainic acid: neurochemical characteristics.

Stereotaxic injection of 2.5 microng of kainic acid, a rigid analogue of glutamate into the rat striatum caused a 70% reduction in the striatum of the cholinergic parameters, choline acetyltransferase, acetylcholine and synaptosomal uptake of choline and a similar reduction in the GABAergic parameters, glutamic acid decarboxylase, psi-aminobutyric acid (GABA) and synaptosomal uptake of GABA. In contrast, the striatal content of dopamine and the synaptosomal uptake of dopamine were unchanged, and the activity of tyrosine hydroxylase was significantly increased. Significant changes in the activity of neurotransmitter synthesizing enzymes were demonstrable within 6h after injection of 2.5 microng of kainic acid and maximal effects occurred at 48h; the activities of choline acetyltransferase and glutamic acid decarboxylase remained depressed up to 21 days after injection. The kinetic characteristics of striatal tyrosine hydroxylase were altered 48h after injection with a two-fold increase in the Vmax for tyrosine and a three-fold reduction in Km for the pteridine cofactor. In contrast to the effects of kainic acid, the injection of copper sulfate, a non-specific toxin, caused a proportionate reduction in the dopaminergic as well as the cholinergic and GABAergic presynaptic markers. The kainate lesion caused an 85% decrement in the activity of dopamine-sensitive adenylate cyclase, a 40% reduction in the specific binding of [3H]quinuclidinyl benzilate and a 195% increase in the specific binding of [3H]GABA in the striatum. The morphology of the kainate injected striatum was markedly altered with nearly a complete loss of intrinsic neurons, increased number of glial cells but intact internal capsule fibers. Intracerebral injection of nanomolar quantities of kainic acid appears to cause degeneration of neurons with cell bodies near the injection site while sparing axons terminating in or passing through the region.

Adenylyl Cyclases↗
PubMed1977

An experimental study of the efferent connections of the superior cerebellar peduncle in the rhesus monkey.

Unilateral electrolytic lesions were made in the right superior cerebellar peduncle immediately lateral of its decussation or in the dentate nucleus of 6 monkeys. The course of the contralateral ascending and descending degenerated fibers and sites of preterminal degenerated fibers were studied in material stained by Fink-Heimer, Nissl and Weil methods. Major thalamic sites of preterminal degeneration were in the rostral part of VPLo, and in VPI, VLo, VApc, CL and PCn. In other thalamic nuclei or subdivisions, no preterminal was observed or was questionable. No degenerated fibers entered the internal capsule or corpus striatum. There was abundant preterminal degeneration in the rostral part of the nucleus ruber and adjacent reticular formation. The descending degenerated fibers of the superior cerebellar peduncle led to massive preterminal degeneration in the central part of the nucleus reticularis tegmentalis and in nuclei raphe pontis and magnus. The most caudal site of preterminal degeneration (minimal) was in the nucleus reticularis gigantocellularis adjacent to the median longitudinal fasciculus.

Animals↗
PubMed1977

The internal organization of the mouse caudate nucleus: evidence for cell clustering and regional variation.

From paraffin-embedded brains of adult mice, ten-micron sections were taken through the entire-extent of the caudate nucleus. Coronal, horizontal or sagittal sections stained with cresyl violet were used to examine two aspects of the internal organization of the nucleus: regional variation and cell clustering. A core of large cells located centrally in the head of the nucleus and ventrally in the body was described. This core is bounded by zones containing medium cells. Slightly larger medium cells occur laterally in the head of the nucleus than elsewhere. Based on these results, three zones have been described in the head of the nucleus: a lateral periphery, a central core area and a medial periphery. The dorsal area of the body of the nucleus probably corresponds most nearly to the lateral periphery, and the ventral area to the central core. Cell clustering is dominant pattern of organization within each zone. Only one large cell was seen per clumped cell grouping, and this cell could occupy either a peripheral or central position in the cluster. Medium cells participated in the clumped arrangement of cells, and also formed rings around fibers of the internal capsule.

Animals↗
PubMed1978

Kainic acid lesions of the striatum: behavioural sequalae similar to Huntington's chorea.

Kainic acid (3 nmoles bilaterally) was injected into the dorsal striatum of the rat producing virtually complete destruction of cell bodies in this structure but without directly affecting the dopamine terminals ascending from the substantia nigra and terminating in the striatum. Other fibres of passage, such as the internal capsule, were also spared. The locomotor and stereotypy responses to doses of amphetamine, a dopamine releasing agent, were found to be consistently enhanced after this lesion. The stereotypy and locomotor activity in response to the direct receptor agonist, apomorphine, however were not consistently affected. The results are interpreted in terms of a functional dichotomy between dorsal and ventral striatum and in terms of previously demonstrated electrophysiological alterations in the striatonigral feedback loop after kainic acid injection. Similarities are noted with the effects of these two stimulant drugs in human patients with Huntington's disease, thus strengthening the kainic acid animal model of this disease, first proposed on biochemical grounds.

Animals↗
PubMed1979

Observations of HRP labeling following injection through a chronically implanted cannula--a method to avoid diffusion of HRP into injured fibers.

One of the limitations of the horseradish peroxidase (HRP) tracer method is the diffusion of HRP into injured axons resulting in unintended labeling of neurons not terminating in the injection area. To overcome this limitation, an experiment was designed to inject the HRP through an implanted cannula after degeneration and healing had taken place. It was shown that implantation of a cannula into the internal capsule significantly decreased the number of labeled axons in the injection site, thus limiting the unintended labeling of neurons from that injection. When injections followed implantation of the cannula by 24 h or more, fibers damaged by the cannula had healed or degenerated sufficiently that intraaxonal diffusion of HRP into those injured fibers did not occur. A significant difference between control (without the cannula) and experimental (with the cannula) injections was observed. Extensive axonal and neuronal labeling following the control injections was seen at the injection site and caudate nucleus, and in the thalamus and parietal cortex, respectively. Experimental injections resulted in sparse axonal and neuronal labeling evident mostly with the larger injections of HRP.

Amygdala↗
PubMed1979

Sensory neglect after lesions of substantia nigra or lateral hypothalamus: differential severity and recovery of function.

Sensory neglect was studied in cats after unilateral lesions of: lateral hypothalamus (LH); internal capsule (IC) adjacent to the LH; substantia nigra (SN) or the ventromedial hypothalamus (VMH). Special behavioral tests were employed to yield quantifiable data and also to exclude any confounding due to simple movement deficits. Lesions of SN or IC produced severe and enduring contralateral visual and somesthetic deficits and a facilitation of ipsilateral visual responsiveness. In contrast, LH lesions sparing the adjacent IC produced only weak and transient deficits and VMH lesions had no effects on sensory function. This suggests that lesions of the SN or its forebrain connections are important for producing sensory neglect and that sensory deficits after LH lesions are due to infringement on fibers of passage to or from the SN. Lesions which produced neglect often suppressed the amplitude of flash evoked responses in the ipsilateral caudate nucleus and visual and association cortex. However, these evoked potential effects were transient. There was no effect on the spontaneous EEG and this fails to support the hypothesis of a lack of hemispheric arousal in sensory neglect. The results are discussed in relation to nigrotectal projections and the process of attention. This lesion-behavior model is suggested for studies of recovery of function.

Animals↗
PubMed1979

A retrothalamic system of collateral fibers from the cerebral peduncle.

Ramón y Cajal described a sizeable bundle of collateral fibers from the cerebral peduncle and called it 'faisceau de Forel'. This bundle has been consistently ignored by recent authors, possibly because of the difficulty to visualize it in transversal section. It is described here as the fasciculus prerubralis, or FPR. It originates at the level of the transition from the nucleus subthalamicus to the substantia nigra. In sagittal-stained sections of the mouse brain stained with the rapid Golgi method it can be seen following an ascending and nearly vertical course. It arches caudalwards, and appears to terminate in the rostral tegmentum. In the cat, Nauta-stained material proved that the corticofugal fibers which contribute to this system originate preponderantly, if not exclusively, in the pericruciate gyrus. Following lesions in this cortical area one could observe, in addition to the degenerating fibers of this bundle, another system of degenerating direct cortico-tegmental fibers which coursed toward the rostral tegmentum. It is not clear whether this second degenerating system resulted from the encroachment of passing fibers in the subjacent internal capsule. The tegmental prerubral collateral fibers from the cerebral peduncle were observed in mouse, rat and cat. Possibly, they could represent a general feature of the mammalian nervous system.

Afferent Pathways↗
PubMed1979

Projections to the neostriatum from the cat precruciate cortex. Anatomy and physiology.

The projections to the striatum from two cytoarchitectonically and functionally distinct subdivisions of the cat precruciate motor cortex were studied using anatomical and electrophysiological techniques. Our results indicate that the medial precruciate cortex (stimulation of which leads to movements of the axial and proximal musculature) has a widespread projection to the lateral half of the caudate nucleus. The lateral precruciate cortex (stimulation of which leads to movements of the distal musculature) has a localized projection within the caudate nucleus adjacent to the internal capsule. Both medial and lateral precruciate areas project to the putamen. These results are discussed in relation to recent studies suggesting that the basal ganglia are involved in the enabling and sequencing of movements.

Afferent Pathways↗
PubMed1980

Medium spiny neuron projection from the rat striatum: an intracellular horseradish peroxidase study.

The morphological features of striatal projection neurons and the responses of these neurons to electrical stimulation of the substantia nigra were studied in rats through the methods of intracellular recording and intracellular labeling with the enzyme horseradish peroxidase. Under urethane anesthesia, single striatal neurons were first analyzed for responsiveness to nigral stimuli and then filled electrophoretically with the enzyme in order to permit subsequent serial reconstruction. The axon of the medium spiny neuron was found to form an extensive collateral plexus within the striatum before entering the globus pallidus or the internal capsule. These medium spiny projection neurons responded to nigral stimuli with monosynaptic excitation.

Animals↗
PubMed1981

Effect of oxotremorine on local cerebral glucose utilization in motor system regions of the rat brain.

The [14C]2-deoxy-D-glucose technique was used to test the effects of central muscarinic stimulation on local cerebral glucose utilization (LCGU) in rats. Systemic administration of the muscarinic agonist oxotremorine (OXO, 0.7 mg/kg, ip) increased LCGU in brain regions involved in motor function: the sensorimotor cortex; the extrapyramidal motor system, including the striatum, globus pallidus, red nucleus, substantia nigra, subthalamus and ventral nucleus of the thalamus; the cerebellar vermis, fastigial nucleus and nucleus interpositus; and the vestibular nucleus. No effects were observed in the fibers of the pyramidal tract, internal capsule, cerebellar white matter and the dentate nucleus. Increases were not affected by methylatropine (1 mg/kg sc), but were completely antagonized by scopolamine (2.5 mg/kg, ip). The anatomic distribution and magnitude of the LCGU response to OXO were not simply correlated with the reported densities of muscarinic receptors.

Animals↗
PubMed1982

Selective retrograde transport of D-aspartate in spinal interneurons and cortical neurons of rats.

Retrograde labeling of neuronal elements in the brain and spinal cord has been investigated by autoradiographic techniques following injections of D-[3H]aspartate (asp), [3H] gamma-aminobutyric acid (GABA) or horseradish peroxidase (HRP) in the medulla and spinal cord of rats. Twenty-four hours after D-[3H]asp injections focused upon the cuneate nucleus, autoradiographic labeling is present over fibers in the pyramidal tract, internal capsule and over layer V pyramids in the forelimb representation of the sensorimotor cortex. After [3H]GABA injections in the same nucleus no labeling attributable to retrograde translocation can be detected in spinal segments, brain stem or cortex. Conversely, injections of 30% HRP in the cuneate nucleus label neurons in several brain stem nuclei, in spinal gray and in layer V of the sensorimotor cortex. These observations give further support to the proposed existence of a selective retrograde transport of D-[3H]asp and are consistent with the available evidence which indicates that the corticodorsal column nuclei path use glutamate and/or aspartate as neurotransmitter(s). D-[3H]Asp injections focused on the dorsal horn at cervical segments label a fraction of perikarya of the substantia gelatinosa and a sparser population of larger neurons in laminae IV to VI for a distance of 3-5 segments above and below the injection point. No brain stem neuronal perikarya appear labeled following spinal injections of D-[3H]asp although autoradiographic grains overlie pyramidal tract fibers on the side contralateral to the injection. This labeling however has not been observed rostral to lower pontine levels nor over cortical neurons at any of the survival times used in the present experiments (6-72 h). As in cases with cuneate injections this pattern of labeling contracts with that obtained after spinal injections of either [3H]GABA or HRP. Although labeling of neocortical neurons has not been observed after spinal injections of D [3H]asp, possibly as a result of the length of corticospinal axons, retrograde labeling of these elements for at least some distance may be taken as suggestive of a special affinity of their terminals for glutamate and/or aspartate.

Animals↗
PubMed1982

Immunohistochemical localization of choline acetyltransferase in rabbit forebrain.

uinea pig antiserum specific to the purified bovine choline acetyltransferase was used to demonstrate the localization of this enzyme in rabbit forebrain by the peroxidase-antiperoxidase immunohistochemical method. Choline acetyltransferase was localized in olfactory bulb, olfactory tract, olfactory tubercle, piriform cortex, septum, diagonal band, basal ganglia, thalamus, hypothalamus, subthalamus, habenula, cerebral cortex, hippocampal region, corpus callosum, internal capsule, fornix, longitudinal striae and other areas. The findings reflect the distribution of cholinergic axons and, possibly, their terminals. These observations correlate well with biochemical determinations of choline acetyltransferase and with previously proposed cholinergic pathways.

Animals↗
PubMed1982

A re-evaluation of the question of ascending fibers in the pyramidal tract.

In 1952 we published a study in the cat with the Glees method, demonstrating the occurrence of degenerating fibers in the pyramidal tract rostral to transections of the tract in the spinal cord. These fibers were interpreted as spinocortical fibers, which have also been described in man. However, other authors have disputed the existence of such fibers. In an attempt to provide more information about this subject, multiple injections of horseradish peroxidase (free and lectin-labeled) were made in the sensorimotor cortex of 4 cats. No retrogradely labeled cells were found in the spinal cord in these cases. Our present and previously reported findings are discussed in the light of other studies of pathological changes in fiber tracts within the central nervous system. Although the present experiments were negative, the degenerating axons previously observed by us in silver sections from the pyramid, pons and internal capsule after lesions of the pyramidal tract in the spinal cord, can not be satisfactorily explained as evidence of retrograde, indirect Wallerian, degeneration of corticospinal fibers.

Animals↗
PubMed1982

GFAP immunoreactivity reveals astrogliosis in females heterozygous for jimpy.

The jimpy gene is a sex-linked recessive mutation which produces severe hypomyelination throughout the central nervous system (CNS) in affected male mice. The female carrier also expresses the mutation, but the degree of hypomyelination varies considerably among the tracts. In the optic nerve, patches of unmyelinated tissue are interspersed with myelinated zones; in the brain, myelination is retarded during development but recovers in the adult. We have previously shown, in the male mutant, that an astroglial hypertrophy is associated with the white matter. The present study was undertaken to determine the existence and extent of astrogliosis in the female carriers. In this immunocytochemical investigation using antiserum to glial fibrillary acidic protein (GFAP), we show that the optic nerve of the female carriers exhibits patches of gliosis which are similar in appearance and intensity to those found in affected males. These patches are not present in the white matter of the carriers' brain and spinal cord, but GFAP-immunoreactivity is more intense than in control females. Throughout certain fiber tracts (e.g. optic tract and internal capsule), the number of immunostained astrocytes is increased in comparison to controls; they are larger, have more processes, and are more intensely immunoreactive. The results of the present study show that the retardation of myelin formation is accompanied by an astroglial response and that the intensity of the gliosis closely parallels the extent of the hypomyelination.

Animals↗
PubMed1982

GABA-transaminase in the basal ganglia: a pharmacohistochemical study.

A pharmacohistochemical procedure to demonstrate histochemically those cells with the ability to synthesize the GABA-metabolizing enzyme GABA-transaminase has been applied to determine the localization of this enzyme in the basal ganglia. In normal, pharmacologically unmanipulated animals, strong GABA-transaminase activity is present throughout the neuropil in many nuclei of the basal ganglia. The striatum, globus pallidus, entopeduncular nucleus, subthalamic nucleus and substantia nigra are all heavily stained. White matter such as the corpus callosum and internal capsule are unstained. Pretreatment of rats with the irreversible GABA-transaminase inhibitor ethanolamine-O-sulfate resulted in a marked reduction in the general neuropil staining. At a suitable post-injection survival time, cells which had synthesized new GABa-transaminase molecules could be detected. Small, positive neurons were present in the striatum and entopeduncular nucleus, while the globus pallidus, substantia nigra zona reticulata, and the ventral pallidal region contained many large, intensely GABA-transaminase-positive neurons. The results indicate that much of the GABA-transaminase in the basal ganglia is neuronal in origin. The relationship of GABA-transaminase to GABA neurons is discussed.

4-Aminobutyrate Transaminase↗
PubMed1983

Palmitate incorporation into different brain regions in the awake rat.

A quantitative method is presented to examine palmitate flux into a stable metabolic compartment in individual brain regions of awake rats. Following the i.v. injection of [14C]palmitate, brain radioactivity rose and then fell until, at 4 h, a stable concentration was reached that was maintained for up to 24 h. The flux of plasma palmitate into this 4 h compartment was calculated by dividing regional brain radioactivity at 4 h, as determined by quantitative autoradiography, by the integral of the plasma palmitate specific activity. Palmitate flux varied from 2.0 x 10(-5) mumol/g.s into the internal capsule to 9.3 x 10(-5) mumol/g.s into the arcuate nucleus, and generally was proportional to the regional cerebral metabolic rate for glucose, as measured with 2-deoxy-D-[1-14C]glucose. The results demonstrate that it is possible to determine unidirectional palmitate flux into a stable metabolic compartment in individual brain regions of awake rats, that flux into gray matter regions generally exceeds flux into white matter, and that palmitate flux is proportional to published values for regional brain oxidative metabolism.

Absorption↗
PubMed1983

Topographic organization and morphology of peripallidal and pallidal cells projecting to the striatum in cats.

Injections of small amounts of horseradish peroxidase (HRP) or HRP coupled with wheat germ agglutinin within the caudate nucleus in adult cats resulted in retrograde labeling of neurons within the globus pallidus and within the fibers of internal capsule near the globus pallidus. These triangular and fusiform neurons, measuring 27-30 micron, project topographically to the striatum. The morphology and the location of some of the labeled neurons in these cases resemble the acetylcholinesterase-positive neurons of the nucleus basalis magnocellularis described by other authors. The findings from this study support the existence of a projection from the globus pallidus and peripallidal region to the striatum in cats.

Afferent Pathways↗
PubMed1984

Brainstem projection to the hypothalamic ventromedial nucleus in the rat: a CCK-containing long ascending pathway.

In order to identify the source and topography of cholecystokinin-containing fibers innervating the hypothalamic ventromedial nucleus (VMN), radioimmunoassay, immunocytochemistry, retrograde tracing of horseradish peroxidase and anterograde degeneration techniques were used. Cholecystokinin (CCK) disappeared almost totally from the VMN following a caudal diencephalic knife cut, which transected the medial fibers of the internal capsule, and the dorsolateral portion of the medial forebrain bundle at the level of the mammillary body. A number of cells in the ipsilateral dorsal parabrachial nucleus, furthermore, showed intense CCK-like immunoreactivity. The ascending CCK-containing fibers in the lateral part of the medial forebrain bundle reach the VMN from the lateral side. Neither the fibers of the stria terminalis, nor of the medial corticohypothalamic tract seem to carry any significant amount of CCK to the VMN.

Afferent Pathways↗