Pattern of expression of the serotonin2C receptor messenger RNA in the basal ganglia of adult rats.

The distribution of the serotonin (5-HT) receptor 5-HT2C mRNA was examined at the single-cell level with in situ hybridization histochemistry and emulsion autoradiography in the basal ganglia and mesolimbic system of adult rats, with focus on the pallidum and the substantia nigra, which receive striatal inputs and play a critical role in basal ganglia function. 5-HT2C receptor mRNA expression was always restricted to a subpopulation of neurons in the regions examined. In the neostriatum, labeled neurons were more numerous in the rostral nucleus accumbens than in the caudal nucleus accumbens and were more numerous in the ventral and ventrolateral caudate-putamen than in the dorsal caudate-putamen, where labeled neurons were restricted to isolated clusters. In striatal target areas, dense labeling in the entopeduncular nucleus (internal pallidum, direct striatal output pathway) contrasted with an absence of labeling in the globus pallidus (external pallidum, indirect striatal output pathway). Double-label in situ hybridization in the substantia nigra revealed coexpression of 5-HT2C receptor mRNA with glutamic acid decarboxylase but not with tyrosine hydroxylase mRNA, indicating that it was restricted to gamma-aminobutyric acid (GABA)ergic neurons. In this region, dense labeling for 5-HT2C mRNA was found in half of the neurons at middle and caudal levels of both the pars compacta and the pars reticulata, with little labeling rostrally. The data suggest that drugs acting on the 5-HT2C receptor could selectively affect discrete neuronal populations in the basal ganglia and mesolimbic systems and indicate a new level of neurochemical heterogeneity among GABAergic neurons of the substantia nigra.

DNA synthesis in the Purkinje neurons.

(3H) Thymidine is incorporated into some cerebellar Purkinje cells of 6- to 30-day-old rats. The frequency of labelled neuronal nuclei was higher in the 12- to 30-day old rats than in the 6- to 10-day-old animals. The grain distribution pattern in autoradiographs was mostly nucleolar amounting to three to ten grains. Some other local labels were revealed, too. Only six Purkinje cells among 42,000 studied in 21 rats possessed heavy label (25 to 50 grains) distributed throughout the nucleus. Control estimations with deoxyribonuclease, hot perchloric acid and covering the autoradiographs again established that the Purkinje cells synthesize DNA perhaps for the purpose of DNA surplus accumulation and/or DNA repair in the neurons.

[Labelling of the nuclei of differentiated Purkinje neurons after 3H-thymidine administration to rats]. / Mechenie iader differentsirovannykh neironov Purkin'e posle vvedeniia krysam 3H-timidina.

Incorporation of 3H-thymidine into Purkinje's cells of the cerebellum of rats aged 6, 10, 12, 15 and 30 days has been demonstrated. As regards the distribution of silver granules, the nuclei can be divided into two groups--with a local label in the nucleolic zone or in the extranucleolic chromatin and with a uniform labeling. The nuclei with an intense uniform label are encountered rarely, i.e. 1-2 nuclei per 10000 cells. The frequency of the nuclei with local labeling of the nucleolus is higher than that with an extranucleolic local label. In 12--30-day-old rats, the number of labeled nuclei exceeded that in 6--10-day-old animals.

[Dynamics of quantitative RNA changes in the Purkinje cells of the rat cerebellum in various functional states]. / Dinamika kolichestvennykh izmenenii RNK v kletkakh Purkin'e mozzhechka krys pri razlichnykh funktsional'nykh sostoianiiakh.

UV cytophotometry was used to study over time the effect of vestibular stimulation on RNA content in Purkinje's cells of the rat cerebellum nodulus. The animals placed in narrow boxes were rotated horizontally (60 r.p.m.) for an hour. To evaluate partially the effects of stress and hypoxia, the content of RNA was examined in the immobilized animals placed in the same boxes without rotation. Rhythmic quantitative changes in RNA in the cytoplasm and nucleus of Purkinje cells were observed upon vestibular stimulation of cerebellum function. In the nucleolus, the changes in the content of RNA were less pronounced. The periodic quantitative changes in the content of RNA in the cytoplasm, nucleus and nucleolus of Purkinje cells were statistically significant in the majority of the animals, but weakly pronounced.

[Quantitative distribution of nucleolar nucleic acids in the Purkinje cells during vestibular stimulation and immobilization of rats]. / Raspredelenie kolichestv iadryshkovykh nukleinovykh kislot v kletkakh Purkin'e pri vestibuliarnoi stimuliatsii i immobilizatsii krys.

The content of nucleic acids in the nucleoli of Purkinje cells was studied under horizontal rotation and immobilization of rats by UV cytophotometry. The histograms of the distribution of nucleolar nucleic acids under both exposures have a common trend towards asymmetry. Unlike the immobilized animals, the rats subjected to rotation show in all the time points a correlation between changes in the total content of nucleic acids in the nucleoli and cytoplasm, and an alteration in the asymmetry of distribution of nucleolar nucleic acids. The changes in the distribution of the latter acids and cytoplasmic RNA under vestibular stimulation are also in good agreement as regards the time and pattern.

[Asymmetric histogram of nucleolar nucleic acid concentration as a potential index of ribosomal DNA amplification in rabbit cerebellar Purkinje cells]. / Nesimmetrichnaia gistogramma soderzhaniia iadryshkovykh nukleinovykh kislot kak vozmozhnyi pokazatel' amplifikatsii ribosomnoi DNK v kletkakh Purkin'e mozzhechka krysy.

Purkinje's cells from the rat cerebellum were exposed to UV cytophotometry in order to evaluate the nucleic acid content in the nucleoli and perinucleolar chromatin. The study revealed an asymmetrical histogram of RNA distribution in the Purkinje's cell nucleoli. The cells with an increased RNA content in the nucleolus displayed the elevated quantities of nucleic acids in the perinuclear chromatin. A relationship of the phenomenon under study and the hypothesis of ribosomal DNA amplification in Purkinje's cells is discussed.