Effects of progesterone on T-type-Ca^(2+)-channel expression in Purkinje cells

Plasticity of cerebellar Purkinje cells(PC)is influenced by progeste rone via the classical progeste rone receptors PR-A and PR-B by stimulating dendritogenesis,spinogenesis,and synaptogenesis in these cells.Dissociated PC cultures were used to analyze progeste rone effects at a molecular level on the voltage-gated T-type-Ca^(2+)-channels Ca_(v)3.1,Ca_(v)3.2,and Ca_(v)3.3 as they helped determine neuronal plasticity by regulating Ca^(2+)-influx in neuronal cells.The results showed direct effects of progesterone on the mRNA expression of T-type-Ca^(2+)-channels,as well as on the protein kinases A and C being involved in downstream signaling pathways that play an important role in neuronal plasticity.For the mRNA expression studies of T-type-Ca^(2+)-channels and protein kinases of the signaling cascade,laser microdissection and purified PC cultures of diffe rent maturation stages were used.Immunohistochemical staining was also performed to characte rize the localization of T-type-Ca^(2+)-channels in PC.Expe rimental progesterone treatment was performed on the purified PC culture for 24 and 48 hours.Our results show that progesterone increases the expression of Ca_(v)3.1 and Ca_(v)3.3 and associated protein kinases A and Cin PC at the mRNA level within 48 hours after treatment at latest.These effects extend the current knowledge of the function of progesterone in the central nervous system and provide an explanatory approach for its influence on neuronal plasticity.

Mouse cerebellar Purkinje cell damage induced by diphenylhydantoin acute intoxication

Twenty one days old Swiss albino mice that received diphenylhydantoin(25 mg/kg,i.p.,daily for 15 days)progressively developed gait alterations,changes of behavior and cerebellar ataxia.Cerebellar slices were processed by conventional transmission electron microscopy.The body of Purkinje cells exhibited fragmented limiting plasma membranes,dilated nuclear envelopes,swelling and disassembly of nuclear pores,enlargement of rough and smooth endoplasmic reticulum and a notable detachment of membrane associated ribosomes,to-gether with distorted vacuoles of smooth endoplasmic reticulum,bizarre shaped and swollen mitochondria with dilated cristae,as well as disrupted limiting lysosomal membranes.Degenerated axosomatic synapses apparently corresponding to basket cell axonal endings were recognized.Degenerated Purkinje cell axon initial segments exhibited vacuolar degeneration of myelin sheath,dilated axoplasmic tubular bundles,fragmented axonal mem-branes,swollen mitochondria,and disassembly of cytoskeletal structures.Some edematous and clear secondary and tertiary dendrites exhibited areas of dilated cisterns of smooth endoplasmic reticulum,clear and dark mul-tivesicular bodies,and coated vesicles.Other dendritic ramifications exhibited an electron dense dendroplasm.Degenerated and large climbing fiber endings were observed making axodendritic synapses with edematous Purkinje dendrites.These presynaptic endings appeared depleted or containing few synaptic vesicles.These syn-apses did not exhibit pre-and postsynaptic densities.At the molecular layer,the edematous synaptic varicosities of parallel fibers containing pleomorphic synaptic vesicles and dense extravesicular substance were observed making asymmetric synaptic contacts with swollen Purkinje dendritic spines.These findings are postulated as pathogenic mechanisms of mouse cerebellar ataxia.

Effects of Maternal Marginal Iodine Deficiency on Interactions between Cerebellar Bergmann Glia Cells and Purkinje Cells in Rat Offspring

Iodine deficiency(ID)during early pregnancy has an adverse effect on children’s psychomotor and motor function but the mechanism has not been clarified.Therefore,our aim was to study the effect of maternal marginal ID on cerebellar neurodevelopment and the underlying mechanism.After obtaining marginal ID rats,we examined interactions between Bergmann glia cells(BGs)and Purkinje cells(PCs)using immunofluorescence

Loss of Wtap results in cerebellar ataxia and degeneration of Purkinje cells

N^(6)-methyladenosine(m^(6)A)modification,which is achieved by the METTL3/METTL14/WTAP methyltransferase complex,is the most abundant internal mRNA modification.Although recent evidence indicates that m^(6)A can regulate neurodevelopment as well as synaptic function,the roles of m^(6)A modification in the cerebellum and related synaptic connections are not well established.Here,we report that Purkinje cell(PC)-specific WTAP knockout mice display early-onset ataxia concomitant with cerebellar atrophy due to extensive PC degeneration and apoptotic cell death.Loss of Wtap also causes the aberrant degradation of multiple PC synapses.WTAP depletion leads to decreased expression levels of METTL3/14 and reduced m^(6)A methylation in PCs.Moreover,the expression of GFAP and NF-L in the degenerating cerebellum is increased,suggesting severe neuronal injuries.In conclusion,this study demonstrates the critical role of WTAP-mediated m^(6)A modification in cerebellar PCs,thus providing unique insights related to neurodegenerative disorders.

Contribution of CD3 ε Epitope and Oxidative Type of Copper-Zinc Superoxide Dismutase to the Degeneration Processes of Cerebellar Purkinje Cells in Patients with Multiple System Atrophy-Cerebellar Type (MSA-C: Olivopontocerebellar Atrophy, OPCA): An Immunohistochemical Study

Objective: This study aimed to investigate the contribution of CD3 epsilon (ε) epitope and oxidative type of copper-zinc superoxide dismutase to the degeneration processes of cerebellar Purkinje cells in patients with Multiple System Atrophy-Cerebellar type (MSA-C). Methods: This retrospective study was carried out on autopsy specimens of 17 patients with sporadic MSA-C and 10 normal individuals. Paraffin sections of autopsied cerebella and pontes were immunostained with polyclonal antibodies against CD3 ε epitope and oxidative modification to cysteine sulfonic acid of cys111 in human copper-zinc superoxide dismutase (Ox-SOD1). With respect to the areas of CD3-ε-epitope expression, the immunohistochemical study and the quantitative statistical analysis between the areas of CD3-ε-epitope expression in the surviving Purkinje cells of MSA-C patients and their disease duration were performed. Results: The cell bodies and dendritic arborization including primary, secondary, and tertiary dendrites of normal Purkinje cells were intensely immunostained by the antibody against CD3 ε epitope. Both the immunohistochemical study and the quantitative statistical analysis revealed that the areas positive for CD3 ε epitope disappeared in the order from tertiary dendrites, secondary dendrites, primary dendrites toward the cell bodies, along with the disease progression. In addition, Glial Cytoplasmic Inclusions (GCIs) and Neuronal Cytoplasmic Inclusions (NCIs) were strongly positive for CD3 ε epitope. The surviving Purkinje cells in MSA-C showed immunostaining by the anti-Ox-SOD1 antibody, although normal Purkinje cells did not. Conclusion: Based on the oxidative stress that the surviving Purkinje cells in MSA-C express Ox-SOD1, the functions of morphogenesis and morphological maintenance related to CD3-ε-epitope expression of the MSA-C Purkinje cells are impaired from the peripheral dendrites toward the cell bodies as the center of the Purkinje cell system. In addition, GCIs and NCIs that are pathological hallmarks of MSA also intensely express CD3 ε epitope.

Neuronal Activity in the Cerebellum During the Sleep-Wakefulness Transition in Mice

Cerebellar malfunction can lead to sleep disturbance such as excessive daytime sleepiness,suggesting that the cerebellum may be involved in regulating sleep and/or wakefulness.However,understanding the features of cerebellar regulation in sleep and wakefulness states requires a detailed characterization of neuronal activity within this area.By performing multiple-unit recordings in mice,we showed that Purkinje cells(PCs)in the cerebellar cortex exhibited increased firing activity prior to the transition from sleep to wakefulness.Notably,the increased PC activity resulted from the inputs of lowfrequency non-PC units in the cerebellar cortex.Moreover,the increased PC activity was accompanied by decreased activity in neurons of the deep cerebellar nuclei at the nonrapid eye-movement sleep-wakefulness transition.Our results provide in vivo electrophysiological evidence that the cerebellum has the potential to actively regulate the sleep-wakefulness transition.

The Joubert Syndrome Gene arl13b is Critical for Early Cerebellar Development in Zebrafish

Joubert syndrome is characterized by unique malformation of the cerebellar vermis.More than thirty Joubert syndrome genes have been identified,including ARL13 B.However,its role in cerebellar development remains unexplored.We found that knockdown or knockout of arl13b impaired balance and locomotion in zebrafish larvae.Granule cells were selectively reduced in the corpus cerebelli,a structure homologous to the mammalian vermis.Purkinje cell progenitors were also selectively disturbed dorsomedially.The expression of atoh1 and ptf1,proneural genes of granule and Purkinje cells,respectively,were selectively down-regulated along the dorsal midline of the cerebellum.Moreover,wnt1,which is transiently expressed early in cerebellar development,was selectively reduced.Intriguingly,activating Wnt signaling partially rescued the granule cell defects in arl13b mutants.These findings suggested that Arl13 b is necessary for the early development of cerebellar granule and Purkinje cells.The arl13b-deficient zebrafish can serve as a model organism for studying Joubert syndrome.