Purkinje Cells In Cerebellar Cortex Research Articles

Upregulation of Neural Cell Adhesion Molecule 1 and Excessive Migration of Purkinje Cells in Cerebellar Cortex.

Purkinje cells (PCs) are large GABAergic projection neurons of the cerebellar cortex, endowed with elaborate dendrites that receive a multitude of excitatory inputs. Being the only efferent neuron of the cerebellar cortex, PCs project to cerebellar nuclei and control behaviors ranging from movement to cognition and social interaction. Neural cell adhesion molecule 1 (NCAM1) is widely expressed in the embryonic and postnatal development of the brain and plays essential roles in neuronal migration, axon pathfinding and synapse assembly. However, despite its high expression levels in cerebellum, little is known to date regarding the role(s) of NCAM1 in PCs development. Among other aspects, elucidating how the expression of NCAM1 in PCs could impact their postnatal migration would be a significant achievement. We analyzed the Acp2 mutant mouse (nax: naked and ataxia), which displays excessive PC migration into the molecular layer, and investigated how the excessive migration of PCs along Bergmann glia could correlate to NCAM1 expression pattern in early postnatal days. Our Western blot and RT-qPCR analysis of the whole cerebellum show that the protein and mRNA of NCAM1 in wild type are not different during PC dispersal from the cluster stage to monolayer formation. However, RT-qPCR analysis from FACS-based isolated PCs shows that Ncam1 is significantly upregulated when PCs fail to align and instead overmigrate into the molecular layer. Our results suggest two alternative interpretations: (1) NCAM1 promotes excessive PC migration along Bergmann glia, or (2) NCAM1 upregulation is an attempt to prevent PCs from invading the molecular layer. If the latter scenario proves true, NCAM1 may play a key role in PC monolayer formation.

NEURONAL DAMAGE IN BRAINS OF FIRST- AND SECOND-GENERATION PUPS BORN TO HYPOTHYROID WISTAR RATS

OBJECTIVE: To study neuronal damage in brains of first and second-generation pups, born to hypothyroid Wistar rats. METHODS: Ten female adult Wistar rats, randomized into two equal groups-propylthiouracil (Group-P) and control (Group-C) were allowed to conceive. Group-P was given oral propylthiouracil throughout gestational period and weaning until 22nd day. Nine offspring from group-C (C/FC) and group-P (P/FC) were sacrificed on 22nd day of life to collect blood and brain samples. The dams of group-P (group-PP) were allowed to conceive and continued with propylthiouracil treatment throughout gestation and weaning. Their nine offsprings (PP/FC) were sacrificed on 22nd day. Serum levels of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) were measured. Brain weight, apoptotic cell count (ACC) of Purkinje cells of cerebellar cortex and Pyramidal cells of hippocampus were documented. RESULTS: Mean TSH levels were 21±3ηg/dl, 23.3±3.5ηg/dl and 10±2.1ηg/dl in P/FC, PP/FC and C/FC respectively (p=0.003). Mean T4 was 31.7±1.2ηg/dl, 30.3±1.3ηg/dl and 36.3±0.9ηg/dl in P/FC, PP/FC and C/FC respectively (p=0.030). Mean brain weights was 1.21±0.21 mg, 1.20±0.41 mg and 1.42±0.01 mg group in P/FC, PP/FC and C/FC respectively (p>0.05). The normal Pyramidal and Purkinje cell count was low in P/FC and PP/FC groups compared to C/FC group (p<0.05). The ACC of Pyramidal and Purkinje cells was high in P/FC and PP/FC groups compared to C/FC group (p<0.05). CONCLUSION: Maternal hypothyroidism adversely affected the morphology of Pyramidal and Purkinje cells by enhancing apoptosis, which increased further in second generation pups.

Progressive limb ataxia following inferior olive lesions

Cerebellar climbing fibres originate in the inferior olive (IO). Temporary IO inactivation produces movement deficits. Does permanent inactivation produce similar deficits and, if so, do they recover? The excitotoxin, kainic acid, was injected into the rostral IO of three cats. Behaviour was measured during reaching and locomotion. Two cats were injected during the reaching task. Within minutes, grasping became difficult and the trajectories of the reaches showed higher arcing than normally seen. During locomotion, both cats showed head and trunk deviation to the injected side, walking paths curved to the injected side, and the paws were lifted higher than normal. Limbs contralateral to the injections became rigid. Within 1 day, posture had normalized, locomotion was unsteady and high lifting of the paws had reversed to a tendency to drag the dorsum of the paws. Passive body movement produced vestibular signs. Over a few days, locomotion normalized and vestibular signs disappeared. Reach trajectories were normal but grasping deficits persisted. Over the first week, the amplitude of limb lift during reaching and locomotion began to increase. The increase continued over time and, after several months, limb movements became severely ataxic. The effects followed the somatotopy of the rostral IO: a loss of cells in medial rostral IO only affected the forelimb, whereas a loss of cells in medial and lateral IO affected both forelimb and hindlimb. Deficits produced by IO lesions involve multiple mechanisms; some recover rapidly, some appear stable, and some worsen over time. The nature of the progressive deficit suggests a gradual loss of Purkinje cell inhibition on cerebellar nuclear cells.

Altered White Matter Structure of the Dentatorubrothalamic Pathway in Children with Autistic Spectrum Disorders

Neuropathological studies have demonstrated decreased Purkinje cells in cerebellar cortex and changes in the dentate nucleus of the cerebellum, the projection target for the Purkinje cells, in autistic spectrum disorders (ASD). The dentatorubrothalamic tract is formed by efferents from the dentate nucleus projecting toward the red nucleus with axon collaterals to this nucleus and continuing to innervate the ventral lateral and ventral anterior nuclei of the thalamus. In the current study, we assessed whether the dentatorubrothalamic tract is altered in ASD using Q-ball imaging (QBI). The QBI tractography was performed in 13 children with high functioning ASD (HFA), 11 children with low functioning ASD (LFA), and 14 typically developing children (TD). Regions of interest in dentate nucleus and red nucleus in both hemispheres were objectively placed to sort bilateral dorsal-rostral (DR), dorsal-caudal (DC), ventral-rostral (VR), and ventral-caudal (VC) portions of the dentatorubrothalamic pathway. Group differences in fractional anisotropy (FA), axial diffusivity, radial diffusivity, and fiber volume of individual pathways were analyzed. Significantly reduced FA was found in children with LFA and HFA, compared to the TD group in tracts originating in all four subdivisions of the right dentate nucleus. Tract-based morphometry (TBM) analysis demonstrated significant reductions of FA in caudal midbrain (p<0.0001), dorsal-caudal dentate (p=0.0013), and ventral-caudal dentate (p=0.0061) on the right in the LFA group. The FA values in TBM segments of right VR and VC pathways were significantly correlated with communication skills in the combined HFA/LFA group, while there was a significant correlation found between TBM segments of right DR pathway and daily living skills (r=0.76; p=0.004). Decreased white matter integrity in dorsal portions of the dentatorubrothalamic tract may be related to motor features in ASD, while changes in the ventral portions are related more to communication behavior.

MRI-Assessed Volume of Cerebellum Correlates with Associative Learning

Richard F. Thompson's cerebellar model of classical eyeblink conditioning highlights Purkinje cells in cerebellar cortex and principal cells in the deep cerebellar nucleus as the integrating cells for acquisition of conditioned responses (CRs). CR acquisition is significantly slower in rabbits with lesions to cerebellar cortex and in Purkinje cell-deficient mice that lose all cerebellar cortical Purkinje cells. Purkinje cells are the largest neurons in the cerebellum and contribute significantly to cerebellar volume. Magnetic resonance imaging (MRI) was used to assess cerebellar volume in humans. Cerebellar volume was related to eyeblink conditioning (400-ms delay procedure) in 8 adults (21–35 years) and compared to 8 older adults (77–95 years) tested previously (Woodruff-Pak, Goldenberg, Downey-Lamb, Boyko, & Lemieux, 2000). In the young adult sample, there was a high correlation between percentage of CRs in a session and cerebellar volume (corrected for total intracranial volume [TIV], r = .58, p = .066). There were statistically significant age differences in cerebellar volume, t(14) = 8.96, p < .001, and percentage of CRs, t(14) = 3.85, p < .002, but no age difference in TIV. Combining the young and older adult sample, the correlation between percentage of CRs and cerebellar volume (corrected for TIV) was .832 (p < .001). Cerebellar volume showed age-related deficits likely due to Purkinje cell loss. Individual differences in classical eyeblink conditioning are associated with differences in cerebellar volume, supporting Thompson's model of a cerebellar cortical role in facilitating this form of associative learning.

The existence of substance P in Purkinje cells in cerebellum of the gerbil

We performed this study to identify the characteristics of substance P localization in gerbil cerebellum by immunohistochemistry. Substance P immunoreactivity was present in Purkinje cells of cerebellar cortex but not in other structures. It is suggested that the cerebellar mechanism of gerbil may be different from that of other species.

Harmaline-induced tremor and impairment of learning are both blocked by dizocilpine in the rabbit

Harmaline is known to produce tremors and retard acquisition of the rabbit's nictitating membrane response. These actions have been demonstrated to depend on the ability of harmaline to activate the inferior olive which gives rise to climbing fibers that project directly onto Purkinje cells in cerebellar cortex. However, the precise receptor systems involved in harmaline's actions remain unknown. This study examined the role of the NMDA receptor in harmaline's actions. Harmaline (10 mg/kg, s.c.) produced intense tremors and impaired the acquisition of conditioned responses. Both of these effects of harmaline were significantly blocked by the prior administration of the noncompetitive NMDA channel blocker, dizocilpine (0.01 mg/kg, s.c., given 20 min prior to the administration of harmaline). This dose of dizocilpine had no effect on acquisition of conditioned responses when given alone. A higher dose of dizocilpine (0.1 mg/kg s.c.) completely blocked the tremorogenic effects of harmaline (10 mg/kg, s.c.). Dizocilpine had no effect on motor behavior when given alone. It was suggested that the blockade of harmaline's actions by dizocilpine may be occurring at NMDA channels within the inferior olive. Regardless of the site of action, these data demonstrate that harmaline's ability to activate the inferior olivary nucleus depends on the normal activity of the NMDA receptor.

A model of the cerebellum in adaptive control of saccadic gain. I. The model and its biological substrate.

We review data showing that the cerebellum is required for adaptation of saccadic gain to repeated presentations of dual-step visual targets and thus, presumably, for providing adaptive corrections for the brainstem saccade generator in response to any error created by the open-loop saccadic system. We model the adaptability of the system in terms of plasticity of synapses from parallel fibers to Purkinje cells in cerebellar cortex, stressing the integration of cerebellar cortex and nuclei in microzones as the units for correction of motor pattern generators. We propose a model of the inferior olive as an error detector, and use a 'window of eligibility' to insure that error signals that elicit a corrective movement are used to adjust the original movement, not the secondary movement. In a companion paper we simulate this large, realistic network of neural-like units to study the complex spatiotemporal behavior of neuronal subpopulations implicated in the control and adaptation of saccades.

Somatotopic alignment between climbing fiber input and nuclear output of the cat intermediate cerebellum.

The rostral dorsal accessory olive (rDAO) contains a detailed somatosensory map of the entire contralateral body surface. The rDAO projects to the anterior interpositus nucleus (NIA) directly as well as indirectly by way of Purkinje cells in cerebellar cortex. NIA maintains a topographic relation to different levels of the spinal cord through a relay in the magnocellular red nucleus (RNm) and, thus, contains a motor somatotopy. By using bidirectional transport of WGA-HRP, we demonstrate that the sensory somatotopy of rDAO aligns with the motor somatotopy of NIA. It is likely that rDAO information supplied to the cerebellum from a specific part of the body is used to influence movements restricted to that same body part.

Selective staining of large projection neurons by monoclonal antibody to a glycoprotein of PC12 cells

A monoclonal antibody has been produced against glycoproteins prepared from PC12 cells. This antibody stains PC12 cells in a rimlike fashion, whether they are fixed or living. When neuronally differentiated PC12 cells are used, neurites as well as somata stain. In the presence of complement, the antibody is cytotoxic to PC12 cells. These lines of evidence suggest that at least some of the binding is to an exposed component of the plasma membrane in these cells. Biochemical experiments directed at identifying the antigen(s) indicate specific recognition of glycoproteins of apparent molecular weights of approximately 160 and 95 kDa by SDS-PAGE. The antibody appears to be directed against a determinant on the protein moiety. The larger species is likely to be the same as a glycoprotein previously described (Lee et al., 1981), which has been found in PC12 cells, but not in brain. The monoclonal antibody we have produced, however, selectively stains a subset of neurons in brain. Specifically, it binds to Purkinje cells in cerebellar cortex, pyramidal cells in cerebral cortex and hippocampus, ganglion cells in retina, and some neurons, generally large, in most brain structures examined. No glia or nonneural tissues stain. We suggest that the neurons recognized by this antibody may be the projection cells of each structure. However, in contrast to PC12 cells, the antigen(s) bound in this case appears to be predominantly internal. This interpretation is supported by the appearance of stained cells in tissue; by the failure of the antibody to stain live dissociated neurons from brain; and by its failure to lyse sympathetic neurons in the presence of complement. Western immunoblots show that there is glycoprotein present in brain that is recognized by the antibody, and that it is enriched in a crude microsomal fraction prepared from that tissue. This material migrates on SDS gels as two bands of 130 and 95 kDa.

Thy-1 in developing nervous tissue.

Thy-1 is a developmentally regulated cell surface glycoprotein, found at high levels in nerve and certain other tissues. In brain its level rises nearly 100-fold during early postnatal development, but until recently the cellular basis of this, or even the distribution of Thy-1 in adult nervous tissue, has been unclear. On the other hand considerable progress has been made in elucidating the gene, and protein and carbohydrate structure of this molecule, so that the basis for its developmental regulation, and possibly its function, is beginning to emerge. In adult nervous tissues Thy-1 appears to be a surface component of most neurons, although within the CNS the density of antigen varies considerably on different cell types. Early in development, however, Thy-1 is present on only certain neurons--for instance on Purkinje cells in cerebellar cortex--and Thy-1 immunohistochemistry can demonstrate new aspects of the development of such cells. During development, previously Thy-1-negative cells can acquire high levels of Thy-1, and conversely detectable antigen can be lost from cells which at earlier stages stained intensely in Thy-1 immunohistochemistry. Such developmental changes can occur in waves of maturation which are defined spatially as well as temporally. Changing patterns of Thy-1 expression are also found at some sites in nervous tissue after axonal injury. The evidence for a role for Thy-1 in nervous system development is discussed, both in terms of its changing distribution during development and in the light of more direct attempts to define its role on the cell surface.

Thy-1 in Developing Nervous Tissue (Part 2 of 2)

Thy-1 is a developmentally regulated cell surface glycoprotein, found at high levels in nerve and certain other tissues. In brain its level rises nearly 100-fold during early postnatal development, but until recently the cellular basis of this, or even the distribution of Thy-1 in adult nervous tissue, has been unclear. On the other hand considerable progress has been made in elucidating the gene, and protein and carbohydrate structure of this molecule, so that the basis for its developmental regulation, and possibly its function, is beginning to emerge. In adult nervous tissues Thy-1 appears to be a surface component of most neurons, although within the CNS the density of antigen varies considerably on different cell types. Early in development, however, Thy-1 is present on only certain neurons – for instance on Purkinje cells in cerebellar cortex – and Thy-1 immunohistochemistry can demonstrate new aspects of the development of such cells. During development, previously Thy-1-negative cells can acquire high levels of Thy-1, and conversely detectable antigen can be lost from cells which at earlier stages stained intensely in Thy-1 immunohistochemistry. Such developmental changes can occur in waves of maturation which are defined spatially as well as temporally. Changing patterns of Thy-1 expression are also found at some sites in nervous tissue after axonal injury. The evidence for a role for Thy-1 in nervous system development is discussed, both in terms of its changing distribution during development and in the light of more direct attempts to define its role on the cell surface.

Light and electron microscopic demonstration of guanylate cyclase in rat brain

Guanylate cyclase (GTP pyrophosphate-lyase (cyclizing), EC4.6.1.2) was histochemically demonstrated in rat brain with light and electron microscopes by using a specific monoclonal antibody to soluble guanylate cyclase from rat brain. Under a light microscope, intense reactions were seen in caudate-putamen complex, neocortex and cerebellar cortex. Immunoreactive cells were mainly some types of neurons such as small neurons in caudate-putamen complex, Purkinje cells in cerebellar cortex and pyramidal cells in neocortex. Some astroglial cells were also stained. Not all neurons or glial cells exhibited the positive guanylate cyclase reactivity. Electron microscopic examination revealed that guanylate cyclase was localized within postsynaptic components (perikaryo and dendrites) in neurons and in the cytoplasma and plasma membrane of astroglia. Presynaptic terminals were free of reaction. The observation supports a possibility that cyclic GMP is involved in the postsynaptic events of neuronal transmission and the regulation of intracellular processes.

The inhibitory effect of the olivocerebellar input on the cerebellar Purkinje cells in the rat.

1. In rats under Nembutal anaesthesia the inferior olive region has been reversibly inactivated by applying a cooling probe to the ventral surface of the medulla. Simple and complex spike activity has been recorded from Purkinje cells of the cerebellar cortex.2. Following cooling of the inferior olive of one side we have observed a remarkable increase of the simple spike activity in all the twenty-two Purkinje cells, showing a disappearance of the complex spike activity.3. In some rats two Purkinje cells were recorded simultaneously from each side of the cerebellar cortex. Following cooling of the left inferior olive the effect on the Purkinje cell was observed only or predominantly on the contralateral cerebellar cortex.4. In a group of animals the inferior olive has been destroyed by 3-acetylpyridine 4-221 days before the recording session. Cooling of the inferior olive region was not accompanied by any significant and consistent increase in the spike activity of presumed Purkinje cells of the contralateral cerebellar cortex.5. These results indicate that the remarkable increase of the simple spike frequency following cooling of the inferior olive region is due specifically to the suppression of the activity of the olivocerebellar neurones.6. Only a small amount of the simple spike frequency increase is attributable to the removal of the post-climbing fibre pause.7. In some lesioned rats recording was made from Purkinje cells, which showed complex spikes due to the few surviving inferior olive cells. In these Purkinje cells cooling of the inferior olive region was accompanied by a disappearance of the complex spike and by a small increase of the simple spike frequency of discharge. Such an increase is mainly attributable to the removal of the post-climbing fibre pause.8. These results suggest that a given Purkinje cell is not only under the inhibitory influence of its own climbing fibre, but also of other olivocerebellar neurones, probably through climbing fibre collaterals to the cerebellar cortical interneurones.9. It is suggested that one role of the olivocerebellar system is to exert a powerful tonic inhibitory action on the Purkinje cells and consequently to exert a significant control on the excitability of the subcerebellar centres.

Density and relative number of granule and purkinje cells in cerebellar cortex of cat

The numerical densities of granule and Purkinje cells in the cerebellar vermis of the cat were determined using a combination of stereological and other, nonparametric, methods. The density of granule cells in our Epon-Araldite embedded material was1.75 × 10 6/mm 3 of the granular layer and did not vary with the local curvature of the cortex; the density of Purkinje cells was 364 per mm 2 of the Purkinje cell layer. The average thickness of the granular layer, determined by planimetry and curvimetry, was 0.18 mm and the ratio of the volume of the molecular layer to the volume of the granular layer was 1.50. The ratio of the number of granule cells to that of Purkinje cells was 899. A previous study using knife cut lesions and silver staining for degeneration showed that cerebellar parallel fibers were about 6 mm long, a value several times that thought previously. The present estimates of the density of granule cells and the thickness of granule and molecular layers are consistent with this average parallel fiber length of 6 mm.

Histochemical distribution of alkaline and acid phosphatase and adenosine triphosphatase in the brain of squirrel monkey (Saimiri sciureus).

The distribution of some phosphatases (alkaline and acid phosphatase and ATPase) have been studied on 15 μ thick fresh frozen serial sections in the various regions and nuclei of the squirrel monkey brain. The alkaline phosphatase activity is concentrated in the blood vessels and the peripheral part of the neurons of some nuclei (e.g., nucleus supraoptic hypothalami) and the lining cells of choroid plexus. Acid phosphatase (AC) is a cellular enzyme and is concentrated in the large neurons of nuclei basalis Meynert, diagonalis band of Broca, magnocellular hypothalamic nuclei, corpus mammillaris, large sized neurons of the thalamus (e.g., nuclei paracentralis, ventralis lateralis, ventralis posterior thalami, magnocellular part of corpus geniculatum laterale), motor neurons of cranial nerve nuclei, large neurons of the reticular formation, giant pyramidal cells of cerebral cortex and the Purkinje cells of cerebellar cortex. The AC activity does not show as much variation in the different areas of the brain as the oxidative enzymes, which may mean that AC is more related to static maintenance metabolism of cells than to dynamic functional metabolism. The ATPase activity is more pronounced in the neuropil and the blood vessels compared to the neurons. In the perikarya, ATPase is concentrated close to the cell membrane, which may be significant in molecular transport across the membrane as well as in impulse conduction and synaptic transmission. Significant ATPase activity has been observed in the nucleus caudatus and putamen, magnocellular hypothalamic nuclei, nuclei parataenialis, paraventricularis, paracentralis, ventralis anterior thalami, habenular complex and cranial nerve nuclei.