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PubMed2003

[Morphological characteristics of Lugaro cells of the cerebellar cortex].

Two types of Lugaro cells--fusiform and triangular--were found at different levels of granular layer in the sections of cat cerebellar cortex, stained with silver nitrate using Golgi-Kopsch method. Their processes are oriented horizontally, vertically or obliquely to the folium axis, while their axons never leave the limits of cerebellar cortex, therefore these cells should be considered as interneurons. The processes of Lugaro cells have very large spatial expansion, due to which these cells form numerous axosomatic and axodendritic connections with all the neurons and fibers of the cerebellar cortex. Structural and topographic characteristics of Lugaro cells, as well as the peculiarities of their contacts with the other cells of cerebellar cortex, in combination with the data on their neurotransmitter content, indicate that these cells play the role of inhibitory interneurons.

Animals↗

PubMed1968

Responses evoked in the cerebellar cortex by stimulation of the caudate nucleus in the cat.

1. Responses evoked in the cerebellar cortex following stimulation of caudate nucleus are described.2. The evoked responses recorded from the surface of the cerebellar cortex were found to be of two types, one with a short (4-6 msec) latency and one with a longer (12-17 msec) latency.3. The short latency response was maximal in the lobulus simplex, the longer latency response was maximal in paramedian lobule.4. Following lesions in the inferior olive the longer latency response was absent.5. Recordings from within the cerebellar cortex showed that the short latency response was uniformly distributed throughout the grey matter, the longer latency response was maximal in the region of the Purkinje cell bodies.6. It was concluded that the short latency response was due to activation via the mossy fibres and the longer latency response to activation via the climbing fibres.7. It was found that responses could be evoked in the cerebellum following stimulation of only the latero-ventral part of the caudate nucleus; stimulation of the rest of the nucleus caused no response in the cerebellum. This division of the caudate nucleus into two parts is similar to the subdivision of the caudate nucleus made by other workers using different criteria.

Animals↗

PubMed1995

Localisation of dopamine D3 receptor in the rat cerebellar cortex: a light microscope autoradiographic study.

The pharmacological properties and the anatomical localisation of dopamine D3 receptor were assessed in the rat cerebellar cortex using radioligand binding techniques associated with light microscope autoradiography and 7-[3H]hydroxy-N,N-di-n-propyl-2-aminotetralin (7-[3H]OH-DPAT) as a ligand. 7-[3H]OH-DPAT was specifically bound to sections of rat cerebellar cortex with a dissociation constant (Kd) of 0.5 nM and a maximum density of binding sites (Bmax) of 97 +/- 4 fmol/mg tissue. The rank order of potency of competitors of 7-[3H]OH-DPAT binding and the observation that guanosine triphosphate did not affect radioligand binding suggest the labelling of a dopamine D3 receptor. 7-[3H]OH-DPAT binding sites are located mainly in the molecular layer and in lesser amounts in the Purkinje neuron layer, primarily within the cell body of Purkinje neurons. No specific accumulation of silver grains was observed in the granule neuron layer or in the white matter of the cerebellar cortex. The localisation of a putative dopamine D3 receptor within Purkinje neurons suggests that this site may have functional relevance in the cerebellar cortex.

Animals↗

PubMed1993

Effects of collateral inhibition in a model of the immature rat cerebellar cortex: multineuron correlations.

A model of the immature rat cerebellar cortex is used to simulate the effect of the inhibitory recurrent collateral axons of the Purkinje cells on the spike trains in the network. Inhibition induces an important overall change in the statistical characteristics of individual spike trains. It is also instrumental in producing a strong cooperativity between the different neurons. Moreover, a functional spatial anisotropy appears. A specific entropy index is used to analyze levels of information transfer between clustered and faraway neurons in the network. The formatting effect of recurrent collateral inhibition on spike trains and on network functional dynamics is studied by means of a model of the newborn rat cerebellar cortex. This immature structure has simpler morphological characteristics and fewer physiological parameters than the adult one. It is thus a good candidate for the comparison between experimental and theoretical data. The model network is made of 256 formal neurons (FN), arranged in a square lattice. Each neuron is coupled to its eight nearest neighbors by inhibitory links. All the parameters of the different elements of the model--in particular integration of inhibitory and excitatory inputs--are given anatomical and physiological values derived from biological data. Activities of single FNs and correlations between spatially distant ones are analyzed with classical statistical techniques as well as with a specific informational entropy method we introduce. Simulation results indicate that inhibition is instrumental in: (1) the transformation of the spike train characteristics. This includes a lengthening of the mean interspike interval as well as an overall change in the statistical distribution of intervals, with an emergence of long-lasting ones; (2) the functional structuration of the network. Inhibitory connections between nearest neighbors induce a strong cooperativity between FNs. Furthermore a clear spatial anisotropy occurs in the functioning of the network, with inhibitory effects extending beyond local connectivity in preferential directions. We propose an interpretation of this functional structuration in terms of the various routes followed by the inhibition, including relay effects. The parameters of the model (levels of activities, inhibition rules and connectivities) were varied in order to test the robustness of the above results. Finally, the results are compared with those obtained in an experimental situation.

Animals↗

PubMed1994

Nitric oxide-dependent efflux of cGMP in rat cerebellar cortex: an in vivo microdialysis study.

The stimulation of excitatory amino acid receptors in the cerebellar cortex results in the Ca2+/calmodulin-dependent activation of nitric oxide synthase. This leads to an increase in tissue levels of cGMP following the interaction of nitric oxide with soluble guanylyl cyclase. The cerebellar cortex has the highest levels of nitric oxide synthase and cGMP in the brain; however, the levels of guanylyl cyclase and cGMP-phosphodiesterase are remarkably low. Thus, the mechanisms regulating cGMP levels in cerebellar cells are unclear. One report has noted that cGMP can be released from cerebellar slices. We have therefore used intracerebellar microdialysis in awake, freely moving rats to test the hypothesis that activation of nitric oxide synthase in the cerebellar cortex results in the release of cGMP. Climbing fibers, which release excitatory amino acids in the cerebellum, were activated with systemic harmaline. This resulted in an immediate increase in extracellular cGMP, which was blocked by TTX or the removal of extracellular Ca2+, and attenuated by prior lesion of the climbing fibers. Blockade of N-type calcium channels with omega-conotoxin also antagonized the harmaline-induced increase. In contrast, blockade of L-type calcium channels, or inhibition of anion transport with probenecid or bromosulfophthalein, potentiated the increase in cGMP seen in response to harmaline. Inhibitors of nitric oxide synthase or guanylyl cyclase prevented the harmaline-induced increase in extracellular cGMP, while phosphodiesterase inhibitors potentiated the increase. Local application of the NMDA antagonist 2-amino-5-phosphonopentanoic acid or the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione attenuated the effect of harmaline.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗

PubMed1985

Effects of unilateral lesion of the inferior olive on L-[3H] aspartate receptors binding in synaptic membranes of cat cerebellar cortex.

In adult cats, local injection of kainic acid (KA) in the inferior olive (IO) of one side, from which the crossed olivocerebellar projection originates, produced asymmetric postural and motor deficits, attributed to selective damage of the olivary neurons. Since aspartate is one of the putative transmitters of the olivocerebellar fibers, experiments were performed to find out whether 6-8 days after injection of KA within the IO of one side produced changes in aspartate receptors binding in different zones of the cerebellar cortex. In particular, binding in the contralateral zones of the cerebellar cortex was referred to proteins contained in membrane suspensions and compared with the control values obtained in the same experiments from the ipsilateral zones. Binding of L-[3H] aspartate decreased on the average to 53.4% of the control value in the medial zone and to 86.1% of the control value in the intermediate and lateral zones of the cerebellar cortex. This reduction varied in different experiments according to the side of the injection, in agreement with the well known pattern of regional distribution of the olivocerebellar projection within the cerebellar cortex. These findings favour aspartate as the putative neurotransmitter of the climbing fibers. The demonstration that binding of aspartate decreased in the cerebellar cortex of one side, 6-8 days after injection of KA in the corresponding IO, indicates that plastic events occur at this level following destruction of the olivocerebellar pathway. In particular, the reduced binding can be attributed either to a decrease in number of the postsynaptic receptor sites for aspartate or to a decreased affinity of this amino acid for the corresponding receptors. These findings, however, do not exclude that an hypersensitivity by denervation may occur at the level of individual Purkinje cells when they are deprived of the climbing fibers input. In order to answer this question further experiments are required to find out how the binding for aspartate is modified at increasing time intervals after the olivary lesion.

Animals↗

PubMedDate not supplied

Granule cell raphes in the cerebellar cortex of chicken and mouse.

The cerebellar cortex of the chicken embryo contains parasagittal segments of Purkinje cells. At intermediate stages of development, cell-dense ribbons of migrating granule cells ("raphes") are found between the segments. The complementary pattern of granule cell raphes and Purkinje cell segments represents a basic scheme of cerebellar organization that coincides with the expression domains of various genes, such as cadherins, gene regulatory proteins, and ephrins and their receptors. We have recently found the raphe/segment pattern also in a mammalian species, the postnatal mouse. Like in the chicken, the parasagittal raphes of granule cells were observed at the boundaries of Purkinje cell segments that differentially express cadherins. The number and arrangement of the raphes in the different cerebellar lobules is roughly similar in both species. The raphe/segment pattern is thus more widely distributed in vertebrates than previously assumed.

Animals↗

PubMed1992

Cerebellar cortex: its simulation and the relevance of Marr's theory.

Marr's theory of the cerebellar cortex as an associative learning device is one of the best examples of a theory that directly relates the function of a neural system to its neural structure. However, although he assigned a precise function to each of the identified cell types of the cerebellar cortex, many of the crucial aspects of the implementation of his theory remained unspecified. We attempted to resolve these difficulties by constructing a computer simulation which contained a direct representation of the 13,000 mossy fibres and the 200,000 granule cells associated with a single Purkinje cell of the cerebellar cortex, together with the supporting Golgi, basket and stellate cells. In this paper we present a detailed explanation of Marr's theory based upon an analogy between Marr's cerebellar model and an abstract model called the associative net. Although some of Marr's assumptions contravene neuroanatomical findings, we found that in general terms his conclusion that each Purkinje cell can learn to respond to a large number of different patterns of activity in the mossy fibres is substantially correct. However, we found that this system has a lower capacity and acts more stochastically than he envisaged. The biologically realistic simulated structure that we designed can be used to assess the computational capabilities of other network theories of the cerebellum.

Animals↗

PubMed2005

Spontaneous electrical activity and structural plasticity in the mature cerebellar cortex.

The Purkinje cell of the cerebellar cortex presents two distinct dendritic domains: a distal one, with spiny branchlets and a high density of spines innervated by many parallel fibers, and a proximal one, with a few clusters of spines innervated by a single climbing fiber terminal arbor. In adult rats, after 7 days of blocked electrical activity by the administration of TTX into the cerebellar parenchyma, the proximal dendritic domain of the Purkinje cell shows a remarkable growth of new spines that are innervated by parallel fibers. At the same time, the climbing fiber terminal arbor tends to become atrophic. In contrast, in the branchlets, spine density remains unmodified. These changes are reversible when TTX is removed. TTX treatment also leads to a decrease in spine size both in the branchlets and in the new spines of the proximal dendritic compartment. Spontaneous electrical activity should therefore be regarded not simply as noise, but as a significant signal for maintaining the typical profile of afferent innervation of the Purkinje cell and for preventing spines from shrinking.

Animals↗

PubMedDate not supplied

[Ultrastructural changes in the rat cerebellar cortex in the remote periods after exposure to accelerated carbon ions].

The cerebellar cortex of rats irradiated with carbon ion fluxes of 320 Mev/nuclon and 60Co gamma-radiation was examined by light and electron microscopy 1, 3 or 6 months after exposure. Carbon ions induced the greatest pathomorphological changes. A month after exposure the changes were diffuse and reversible while 3 and, especially, 6 months after irradiation they were focal disorders, a large portion of which being irreversible. 3 and 6 months after exposure some structures of the cerebellar cortex showed destructive while others exhibited reparative changes. Structural disorders in various nerve and glial cells were of different type. Disorders of the Purkinje cells were of the dark type and those of adjacent Bergmann glial cells of the light type. In the granular layer, neurons showed light type changes and adjacent oligodendrocytes, a densely packed karyo- and cytoplasm and a higher osmiophilia. It can be assumed that the above changes are to maintain disordered neuronal functions, including cell interactions. Study of time course variations in the neuronal and glial ultrastructure of the cerebellar cortex of irradiated animals shows an increase of destructive changes with time. This investigation has demonstrated that CNS cells may be damaged long after exposure even to small fluxes of heavy charged particles.

Animals↗

PubMed1987

A study on the microvasculature of the cerebellar cortex. The fundamental architecture and its senile change in the cerebellar hemisphere.

The arterial structure of the cerebellar cortex was studied by vascular stain and in diaphanized specimens after intra-arterial barium injections. A scanning electron microscope study on the corrosion cast of the arteries was also performed. Arteries distributed in the cerebellar hemisphere are classified into cortical, subcortical, and medullary arteries. The patterns of arterial distribution are similar to those in the cerebral cortex. The cortical arteries are subclassified into superficial, middle, and deep cortical branches. The superficial branches are very fine, forming capillary networks in the molecular layer. The middle cortical branches terminate in the Purkinje cell layer, by dividing into several branches extending parallel to the plane of this layer. These branches connect with capillaries in both the molecular and the granular layers. The deep cortical branches give off some collaterals along the Purkinje cell layer and terminate in the granular layer, by breaking up into capillary networks. The Purkinje cell layer is marked by arterial branches ramified from the middle and deep cortical branches and no particular dense capillary networks are formed in the Purkinje cell layer. The brains of older patients show intertwining of the middle and deep cortical branches, some forming "rope-like" appearance. These patterns are similar to those seen in the cerebral cortex, but they were found, in older people, in the cerebrum.

Aged↗

PubMed1997

Spatial distribution of field potential profiles in the cat cerebellar cortex evoked by peripheral and central inputs.

The present study was designed to characterize the spread of excitation within the frontal plane of the cat cerebellar cortex following different types of stimuli. In particular, experiments were performed to determine whether the spread of excitation evoked by mossy fibre inputs proceeds primarily along the parallel fibres ("beam-like" spread) or whether these inputs activate non-propagated foci ("patches") in the cerebellar cortex. Field potentials were recorded within a frontal plane as a medial to lateral array at different depths in parallel tracks. The recordings were made following electrical stimulation of different forelimb nerves and functionally related areas of the sensorimotor cortex as well as during passive paw movements. The resulting spatial grid of responses provides discrete spatio-temporal information reflecting the activation of specific cerebellar afferents and the neuronal interactions they evoke. The method employed demonstrates the spatial distribution of the temporal sequence of excitability changes throughout all the cerebellar cortical layers. In general, the characteristics of the responses in the intermediate cerebellar cortex depended on the source of the signals. Activity patterns evoked by peripheral nerve stimulation showed more clustered foci compared with those following electrical stimulation of functionally related areas of the sensorimotor cortex. The centrally evoked profiles were generally more homogeneous. The largest number of foci were observed following passive movements around the wrist joint. The spread of excitation in the vertical direction was evaluated by the spatial shift of the line of reversal of the N3/P2-potential (zero-isopotential line). Lines of reversal for peripherally-evoked activity patterns were approximately 90 microns closer to the molecular layer than those evoked by central stimulation in animals in which recordings have been performed in lobule Vc. The opposite was found for recordings in lobule Vb, where potential reversals following peripheral stimulation were located 40 microns deeper than those evoked following central stimulation. Cortical inputs resulted in a more proximal activation of lobule Vc Purkinje cell dendrites than in lobule Vb. This type of input processing thus seems to be lobule dependent. A beam-like spread of excitation could not be demonstrated. For both climbing fibre and mossy fibre afferent systems multiple foci were found in the frontal plane. The foci due to mossy fibre activation arose from the granular layer and expanded vertically to the molecular layer. For the climbing fibre system the foci were restricted to the molecular layer, where they merged to form a superficial band of activation. Although the data presented in this paper favour a focal distribution of activity, they do not exclude beam-like propagation along the parallel fibres, because of the difficulty of detecting this pattern in response to the stimuli. The "beam"- and "patch"-like hypotheses need not be mutually exclusive. Each could contribute to a specific stage of the temporal-spatial processing in the cerebellar cortex in a functional and task-specific manner.

Animals↗

PubMed1979

High potassium, veratridine and electrically induced release of taurine from the cerebellar cortex.

In the in vivo superfused cerebellar cortex of anaesthetized rats, the following stimuli were effective in evoking large increases of isotopically labelled taurine from preloaded tissue: high (40 mM) K+; rectangular, 0.1 msec electrical pulses at 1.5 mA and 500 Hz; the depolarizing veratrum alkaloid, veratridine (0.5 x 10(-5) M) and scorpion venom (10(-6) g.ml-1). Both the high K+ and electrically evoked effluxes were markedly Ca2+ dependent; the veratridine response was abolished in the presence of tetrodotoxin (10(-6) g.ml-1). The data indicate that taurine is being released from excitable cells rather than neuroglia and may therefore have some neurotransmitter-like role in the cerebellum.

Animals↗

PubMed1991

Freeze-fracture organization of chromatin and cytoplasm in neurons and astroglia of rat cerebellar cortex.

The cytology of the cell nucleus and cytoplasm of neurons and astroglia of the rat cerebellar cortex has been investigated by freeze-fracture electron microscopy. The main differential characteristics in the cytoplasm of the several cell types of the cerebellar cortex were: (1) the organization of endoplasmic reticulum elements, including special configurations of lamellar bodies and hypolemmal complexes, (2) the polarity, extension and arrangement of Golgi cisterns and associated tubulovesicular elements; (3) the connection pattern among different membrane-bounded cellular compartments; and (4) the architecture of endomembranes (i.e. presence of pits and fenestrations). In the nucleus, the main differential features were the the three-dimensional view of the nuclear envelope, the distribution of nuclear pores and the aggregation pattern of chromatin, visualized as clusters of nuclear particles in cross-fractures. The quantitative analysis of chromatin revealed four peaks of nuclear particle sizes (8, 12, 17 and 21 nm) that may correspond to variable degrees of coiling of the polynucleosomal chain in the chromatin fibre. Significant differences were observed in the proportion, numerical density and size distribution of aggregated nuclear particles in heterochromatin domains among the different cell types of the cerebellar cortex. The percentage of nuclear particles in aggregates varied from 10% in Purkinje cells to 64% in granule cells. Astrocytes and Bergmann glia showed intermediate values (about 40%). The percentage of nuclear particles in aggregates showed a significant (P less than 0.05) negative linear correlation with the nuclear volume, the number of pores per unit nuclear volume and the total number of pores per nucleus. In granule cells and astroglia, heterochromatin domains had a greater percentage of large nuclear particles (greater than 10 nm) than did euchromatin domains, whereas in interneurons, Purkinje and Golgi cells heterochromatin and euchromatin showed a similar proportion of large particles. Nuclear particles in euchromatin exhibited a similar pattern of distribution in all cerebellar cells.

Animals↗

PubMed2002

Quantitative immunocytochemistry of GABA and synaptophysin in the cerebellar cortex of old ethanol-fed rats.

BACKGROUND: Ethanol-related synaptic loss, Purkinje neuron dendritic regression, and parallel fiber degeneration have been reported in the molecular layer of the adult cerebellar cortex. The known plasticity of the cerebellar cortex suggests that this region may respond to ethanol-related losses by compensatory remodeling of cerebellar circuitry. Stellate and basket interneurons may play an essential role in the remodeling process. Little is known about ethanol-related effects on cerebellar interneurons or on the GABAergic synapses that they form despite the fact that ethanol-related alterations in these components may contribute to the sensitivity of the cerebellum to ethanol. The paucity of data on GABAergic synapses extends to other synaptic components as well including synaptophysin, a glycoprotein component of synaptic vesicles and a synaptic marker. METHODS: Thirty 12-month-old F344 rats were divided into ethanol-fed, pair-fed, and chow-fed groups (10/group). Ethanol rats were treated for 40 weeks with a liquid diet in which 35% of the calories were derived from ethanol. At the end of treatment, rats were perfused, and tissue processed for quantitative immunohistochemistry of GABA and synaptophysin labels. RESULTS: Levels of GABA within inhibitory synapses formed by stellate and basket neurons and levels of synaptophysin were not altered by long-term ethanol treatment. CONCLUSIONS: Stable levels of GABA within GABAergic basket and stellate interneuron synapses suggest that interneurons in the molecular layer of the cerebellar cortex may not play a major role in remodeling of cerebellar circuitry following long-term ethanol consumption. The lack of ethanol-related alterations in synaptophysin levels reported here suggests that synaptic vesicles may be relatively insensitive to ethanol and that known ethanol-related effects on synapse number are due to other mechanisms.

Aging↗

PubMed1989

Changes in neuron number in the cerebellar cortex of the ageing mouse.

The cerebellar cortex of mice aged 6, 15, 22, 25, 28 and 31 months was examined in parasagittal sections using quantitative histological techniques. The number Purkinje cells per mm declined from 13.0 +/- 0.2 at 6 months to 9.1 +/- 0.8 at 31 months. Granule cell density remained constant (2.63 x 10(6) per mm3) between 6 and 31 months of age. The granule cell to Purkinje cell ratio increased from 132.4 +/- 4.2 at 6 months of age to 184.2 +/- 6.9 at 31 months of age. The stellate and basket cell density declined from 83.8 +/- 8.1 per 10(6) mm at 6 months to 58.4 +/- 5.7 at 31 months. The stellate and basket cell to Purkinje cell ratio remained constant at 5.0 +/- 0.1 from 6 to 31 months of age whilst the granule cell to stellate and basket cell ratio increased from 25.5 +/- 0.6 at 6 months to 35.1 +/- 0.6 at 31 months of age. Since granule cell number does not increase in the adult the increase in the granule cell to Purkinje cell and granule cell to stellate and basket cell ratios must be due to loss of Purkinje cells and stellate and basket cells with increasing age. The correlation between Purkinje cell and stellate and basket cell loss is statistically significant (P less than 0.01).

Aging↗

PubMed2000

Microanatomical localization of dopamine receptor protein immunoreactivity in the rat cerebellar cortex.

Dopamine (DA) receptor subtype localization was investigated in rat cerebellar cortex using immunohistochemical techniques with antibodies raised against D1-D5 receptor protein. A faint D1 receptor protein immunoreactivity was developed in molecular and Purkinje neurons layers. D2 receptor protein immunoreactivity was found primarily in cerebellar white matter followed by molecular and granular layers and Purkinje neurons. Antibodies against D2S receptor protein were localized in molecular layer and to a lesser extent, in granular layer. A few Purkinje neurons displayed a faint D2S receptor protein immunoreactivity. D3 receptor protein immunoreactivity was observed primarily in molecular and in Purkinje neurons layers of lobules 9 and 10. A faint D3 receptor protein immunoreactivity was also localized in Purkinje neurons and to a lesser extent, in molecular and granular layers of cerebellar lobules 1-8. D4 receptor protein immunoreactivity was found in cerebellar white matter. A pale immunostaining was also visualized in molecular layer. D5 receptor protein immunoreactivity was localized primarily in molecular and Purkinje neurons layers and to a lesser extent, in granular layer and in white matter. The above results indicate that rat cerebellar cortex expresses the DA receptor subtypes so far identified. Purkinje neurons, which are the only efferent neurons of cerebellum, are richest in DA receptor protein immunoreactivity. This suggests that dopaminergic neurotransmission may modulate efferent inputs from cerebellum. The localization of the majority of D2 and D4 and of a faint D5 protein receptor immunoreactivity in cerebellar white matter suggests that these receptors may be presynaptic and transported axonally.

Animals↗

PubMed1995

Identification of age-related changes of dopamine D1-like receptors in the rat cerebellar cortex.

The present study was designed to characterize the pharmacological profile of dopamine D1-like receptors in the rat cerebellar cortex and to assess if these receptor sites undergo age-related changes. Cerebella of young (3 months), adult (12 months), and old (27 months) male Wistar rats were examined by using radioligand binding techniques and light microscope autoradiography. The non-selective dopamine D1-like radioligand [3H]SCH 23390 was specifically bound to sections of rat cerebellum. The findings that dopamine displaced [3H]SCH 23390 binding in the submicromolar range suggest that labelling of a dopamine D5 (or D1B) receptor subtype. The affinity of [3H]SCH 23390 for dopamine D1-like receptors was similar in the cerebellar cortex of the three animal groups investigated, whereas radioligand binding techniques revealed a gradual age-related reduction of the density of binding sites. Light microscope autoradiography showed the localization of [3H]SCH 23390 binding sites primarily in the molecular layer and to a lesser extent in the Purkinje neuron layer of the cerebellar cortex. Aging was accompanied by a loss of [3H]SCH 23390 binding sites affecting mainly the molecular layer. The age-dependent loss of dopamine D1-like receptors is more pronounced if detected with radioligand binding techniques than with light microscope autoradiography. This suggests that the decrease of dopamine D1-like receptors observed in aging rat cerebellar cortex may depend in part on changes in the receptor expression and in part on cortico-cerebellar structural changes.

Age Factors↗