[Participation of NMDA receptors in spontaneous burst firing of dopaminergic mesencephalic neurons].
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In the rat, somatodendritic application of the NMDA antagonist AP-5, within the Substantia Nigra Zona Compacta and Ventral Tegmental Area, either by micro-iontophoresis or pressure ejection, reduces burst firing of dopamine neurons. Similar local application of the non-NMDA antagonist CNQX does not affect their firing pattern. These results indicate that, in vivo, excitatory amino acid afferents participate through NMDA receptors in the control of the spontaneous burst firing of midbrain dopamine neurons.Keywords:
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Background. Up to the moment there is no universally accepted scheme of spatial organization of the groups of neurons of substantia nigra pars compacta of the human midbrain. A detailed study of the architectonics of this structure is necessary for pathomorphological analysis of agerelated changes in the nervous tissue and the associated neurodegenerative diseases with selective death of dopamine neurons.
Aim. To clarify the peculiarities of the morphochemical organization of the substantia nigra (SN) of a human brain and to create a threedimensional model of pars compacta.
Materials and Methods. Threedimensional reconstruction of substantia nigra pars compacta was performed on the brain autopsy material of individuals without neurological pathology (n=10, between 52 to 84 years of age) using a method of computed morphometry. Sections of the midbrain were stained by Nissl method and by an immunohistochemical method for localization of tyrosine hydroxylase – a marker of dopamine.
Results. In the SN pars compacta accumulations of neurons were identified in the form of 9 bands oriented in the rostrocaudal direction and including four areas: medial, lateral, dorsal and ventral. Morphometric analysis detected significant differences in the density of neurons and in expression of tyrosine hydroxylase between the areas of SN.
Conclusion. A model of cellular organization of SN pars compacta proposed by us on the basis of threedimensional reconstruction is characterized by a high degree of detalization as compared to similar works, and shows expressed spatial differentiation of the groups of neurons of SN which should be taken into consideration in pathomorphological examinations.
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Objective:To observe the characteristic changes of FA value of substantia nigra pars compacta in early Parkinson′s disease using 1.5T MR scanner.Methods:20patients with early Parkinson′s disease and 28cases of gender and age-matched normal volunteers had MR scanning with T2WI sequence and DTI.Taking T2WI as reference,hand-sketched region of interest(ROI)including head,body,tail as well as internal and external areas in substantia nigra were done,their FA values were measured.Statistical analysis was calculated.Results:FA values of substantia nigra pars compacta decreased significantly in early Parkinson′s disease;The FA values of the head,body,tail of substantia nigra pars compacta were lower than those of the normal control group significantly,with the head as the most obvious,which was 0.201±0.030and 0.254±0.050respectively,P0.05.When FA value of the head of substantia nigra pars compacta was less than 0.224, Parkinson′s disease should be highly suspected.Conclusion:Lowering of FA values of the head of substantia nigra pars compacta shows a certain value in the early diagnosis of Parkinson′s disease.
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to define the quantitative characteristics of cell structures in the substantia nigra pars compacta of neurologically healthy elderly people (men and women).Autopsy brain materials from neurologically healthy men and women who had died from intercurrent diseases at the age of 72 to 87 years were examined for quantitative characteristics of the substantia nigra pars compacta, by applying computed morphometric methods.In the elderly people (men and women), the compactness of arrangement of neurons, including those containing tyrosine hydroxylase (a marker of dopamine neurons), was much higher and the glial index was lower in the ventral area of the substantia nigra pars compacta than in the dorsal area. Comparing the structures in the substantia nigra pars compacta showed that the neurons were larger in the dorsal area and the variability of the compactness of their arrangement and the glial index were higher in the women than in the men.In the elderly people, the cell structures in the substantia nigra pars compacta are typified by high morphometric heterogeneity.Цель - определение количественных характеристик клеточных структур компактной части черной субстанции мозга неврологически здоровых лиц (мужчин и женщин) пожилого возраста. Материал и методы. На аутопсийном материале мозга неврологически здоровых мужчин и женщин, умерших от интеркуррентных заболеваний в возрасте от 72 до 87 лет, изучали количественные характеристики клеточных структур компактной части черной субстанции, используя методы компьютерной морфометрии. Результаты. У лиц пожилого возраста (мужчин и женщин) в вентральной области компактной части черной субстанции плотность расположения нейронов, в том числе содержащих тирозингидроксилазу (маркер дофаминовых нейронов), значительно выше, а глиальный индекс - ниже, чем в дорсальной области. Сопоставление структур компактной части черной субстанции мозга мужчин и женщин показало, что по сравнению с мужчинами у женщин в дорсальной области нейроны крупнее, а вариабельность показателя плотности их расположения и величина глиального индекса выше, чем у мужчин. Заключение. Для клеточных структур компактной части черной субстанции мозга лиц пожилого возраста характерна высокая морфометрическая гетерогенность.
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Abstract Glial cell line‐derived neurotrophic factor (GDNF) family members have been proposed as candidates for the treatment of Parkinson's disease because they protect nigral dopaminergic neurons against various types of insult. However, the efficiency of these factors depends on the availability of their receptors after damage. We evaluated the changes in the expression of c‐Ret, GFRα1, and GFRα2 in the substantia nigra pars compacta in a rat model of Parkinson's disease by in situ hybridization. Intrastriatal injection of 6‐hydroxydopamine (6‐OHDA) transiently increased c‐Ret and GFRα1 mRNA levels in the substantia nigra pars compacta at 1 day postlesion. At later time points, 3 and 6 days, the expression of c‐Ret and GFRα1 was downregulated. GFRα2 expression was differentially regulated, as it decreased only 6 days after 6‐OHDA injection. Triple‐labeling studies, using in situ hybridization for the GDNF family receptors and immunohistochemistry for neuronal or glial cell markers, showed that changes in the expression of c‐Ret, GFRα1, and GFRα2 in the substantia nigra pars compacta were localized to neurons. In conclusion, our results show that nigral neurons differentially regulate the expression of GDNF family receptors as a transient and compensatory response to 6‐OHDA lesion. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 343–351, 2002
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Background. Up to the moment there is no universally accepted scheme of spatial organization of the groups of neurons of substantia nigra pars compacta of the human midbrain. A detailed study of the architectonics of this structure is necessary for pathomorphological analysis of agerelated changes in the nervous tissue and the associated neurodegenerative diseases with selective death of dopamine neurons.
Aim. To clarify the peculiarities of the morphochemical organization of the substantia nigra (SN) of a human brain and to create a threedimensional model of pars compacta.
Materials and Methods. Threedimensional reconstruction of substantia nigra pars compacta was performed on the brain autopsy material of individuals without neurological pathology (n=10, between 52 to 84 years of age) using a method of computed morphometry. Sections of the midbrain were stained by Nissl method and by an immunohistochemical method for localization of tyrosine hydroxylase – a marker of dopamine.
Results. In the SN pars compacta accumulations of neurons were identified in the form of 9 bands oriented in the rostrocaudal direction and including four areas: medial, lateral, dorsal and ventral. Morphometric analysis detected significant differences in the density of neurons and in expression of tyrosine hydroxylase between the areas of SN.
Conclusion. A model of cellular organization of SN pars compacta proposed by us on the basis of threedimensional reconstruction is characterized by a high degree of detalization as compared to similar works, and shows expressed spatial differentiation of the groups of neurons of SN which should be taken into consideration in pathomorphological examinations.
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Human brain
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Objective:To compare the FA and T2 *values of the substantia nigra pars compacta in early Parkinson′s disease,thus to explore more accurate diagnostic method of early Parkinson′s disease.Methods:20patients with early Parkinson′s disease and 28cases of gender and age-matched normal volunteers were scanned by DTI、ESWAN and T2WI;Using T2WI image for reference,hand-sketched regions of interest in the substantia nigra were determined and FA and T2 *values of each region of interest were measured.Results:There was statistical significant difference between FA values of the rostral,middle and caudal region of substantia nigra pars compacta in early PD and FA values of those of normal control group after refining(P0.05).There was statistical significant difference between T2 *values of the rostral,middle and caudal region of substantia nigra pars compacta between T2 *values of those of normal control group after refining(P0.05). There was statistical significant difference between FA values of medial and lateral region of substantia nigra pars compacta in early PD and FA values of those in control group(P0.05),while there was no statistical significant difference of T2 * values between above mentioned groups(P0.05).There were no statistical significant difference of FA values and T2 * values between medial and lateral region of substantia nigra pars compacta in early PD(P0.05).Conclusion:FA value is more accurate than T2 *value for the diagnosis of early Parkinson′s disease.
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During aging, decline in memory and cognitive abilities as well as motor weakening is of great concern. The dopaminergic system mediates some aspects of manual dexterity, in addition to cognition and emotion, and may be especially vulnerable to aging. A common neurodegenerative disorder of this system, Parkinson's disease, is characterized by a selective, progressive loss of dopaminergic neurons in the substantia nigra pars compacta. This review includes studies quantifying age and Parkinson's-related changes of the substantia nigra, with emphasis on stereological studies performed in the substantia nigra pars compacta.
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This study used the dissector method to evaluate pigmented nigral neuronal loss in the substantia nigra pars compacta with age. Dissector counts can be used to estimate the absolute and accurate total neurone numbers. In addition, the area and diameter of the neuronal cell body was estimated by using a computerized morphometric analysis in a single section of the substantia nigra pars compacta. Brain samples from 26 people with an age range from 17 to 90 years were studied. A significant decrease in the total number of pigmented neurones ( r =−0.83, P <0.001) and their density ( r =−0.83, P <0.001) with age was found in the substantia nigra pars compacta. The number of pigmented neurones counted from a single section also showed an age‐dependent decline ( r =−0.76, P <0.001). According to the regression equations, the total number of pigmented neurones estimated by dissector counts decreased by 9.8% per decade and the neuronal density decreased by 7.4% per decade. The area of the neuronal cell body decreased by 3.2% per decade. This latter change corresponds to an approximate 4.4% decrease per decade in neuronal volume. These findings show that both the number of pigmented neurones and their size in the substantia nigra pars compacta decreases with age. However, the reductions in the total number of pigmented neurones are more dramatic than the reduction in neurone size with ageing.
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