Expression of pannexin1 in the CNS of adult mouse: Cellular localization and effect of 4-aminopyridine-induced seizures

Zappalà, Agata; Cicero, Deborah; Serapide, Maria Francesca; Paz, Carlos; Catania, Maria Vincenza; Falchi, Mario; Parenti, Rosalba; Pantò, Maria Rosita; Delia, Francesco La; Cicirata, F

doi:10.1016/j.neuroscience.2006.03.053

Cited by 71 publications

(79 citation statements)

References 36 publications

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“…The inhibitory nature of PC-PC synapses could contribute to sharpen the boundaries of such PC domains. Gap junctions may also contribute to synchronization because connexins and pannexins are expressed in PCs (43,44). PC-PC synapses could also be implicated in oscillatory activity.…”

Section: Discussionmentioning

confidence: 99%

Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells

Orduz

Llano

2007

Proc. Natl. Acad. Sci. U.S.A.

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Morphological studies have provided ample evidence for synaptic connections between cerebellar Purkinje cells (PCs), but the functional properties of these synapses remain elusive. We report on direct recordings of synaptically connected PCs in mice cerebellar slices. In PCs filled with a fluorescent dye to aid axon visualization and postsynaptic target identification, presynaptic action potentials elicited unitary inhibitory postsynaptic currents in neighboring PCs in 10% of potential connections tested. In 11 pairs, postsynaptic currents had a delay onset of 1.62 ؎ 0.16 ms with respect to the presynaptic spike, a 10 -90% rise time of 2.20 ؎ 0.33 ms, and a monoexponential decay with a time constant of 13.3 ؎ 1.7 ms. Average values for peak current and variance-to-mean ratio were 55 ؎ 14 and 30 ؎ 3 pA, respectively. In contrast to the depressing nature of the synapse between PCs and deep cerebellar nuclei neurons, PC-PC synapses exhibited strong facilitation operating within a time window of a few milliseconds; paired-pulse ratios for 3-and 20-ms intervals were 1.79 ؎ 0.18 and 1.01 ؎ 0.14, respectively (n ‫؍‬ 6). The facilitation is of presynaptic nature because it is accompanied by a decrease in failure rate. Trains of action potentials evoked in presynaptic varicosities volume-averaged calcium transients whose peak increased 1.7-fold as the frequency increased from 50 to 166 Hz. We suggest that PC-PC synapses are tuned for high fidelity of transmission during bursts of PC activity and that their operation in the cerebellar circuit modulates synchronized PC firing.presynaptic calcium ͉ cerebellum ͉ synaptic plasticity ͉ GABA ͉ calcium binding protein M ore than a century has elapsed since classical anatomical studies by Golgi revealed a surprising feature of Purkinje cells (PCs), namely the formation by their axon collaterals of profuse ramifications along the parasagittal plane extending from the granule cell layer into the PC layer of the cerebellar cortex (reviewed in ref. 1). The nature of this cortical plexus has since been the subject of many studies. Ramon y Cajal (2), based on light microscopy of mammalian and bird cerebellum, suggested that PC axon collaterals terminate in PCs and in other neurons of the molecular layer. In rodents, more recent work has described the development of the plexus (3-5) and provided ultrastructural evidence for the synaptic nature of the contacts made by PC collaterals (refs. 6 and 7 and see review in ref. 1). For PC-PC synapses some uncertainty remains as to the cellular compartment targeted by the collaterals. In mice, synaptic boutons were found on PC dendrites but not over PC somata (6), whereas in rat both PC regions receive PC synapses and clusters of boutons occur over PC somata (7). The boutons are large, up to 3 m in diameter in adult mice, but quantification on the number of release sites per bouton is not available. A distinctive feature of PC-PC contacts is their wide synaptic cleft, 2-fold larger than the usual value of 125 Å (7).Despite the precocity and abund...

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Section: Discussionmentioning

confidence: 99%

Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells

Orduz

Llano

2007

Proc. Natl. Acad. Sci. U.S.A.

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“…Unlike connexins, which form intercellular gap junction channels, there is no in vivo evidence for the existence of Panx1-based intercellular channels (15,16). In the central nervous system, Panx1 is expressed in many neuronal populations, including the hippocampus, olfactory bulb, cortex, and cerebellum (11,17). It has been reported that Panx1 activation in the brain plays a role in the development of epilepsy (18) and headache (9).…”

mentioning

confidence: 99%

Pannexin-1 Up-regulation in the Dorsal Root Ganglion Contributes to Neuropathic Pain Development

Zhang

Laumet

Chen

et al. 2015

Journal of Biological Chemistry

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Background: Pannexin-1 can release many signaling molecules, and blocking pannexin-1 at the spinal cord level reduces chronic pain. Results: Nerve injury increases pannexin-1 expression in primary sensory neurons via histone modifications. Pannexin-1 knockdown reduces pain hypersensitivity. Conclusion: Pannexin-1 up-regulation in primary sensory neurons contributes to neuropathic pain. Significance: Understanding the molecular mechanism of neuronal plasticity will improve treatments for neuropathic pain.

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“…This indicates that if pannexins are indeed expressed in glial cells, their expression could be location-specific. Recently, study of Zappala et al, 2006 revealed expression of Panx1 in Bergmann glial cells of the cerebellum, where it was co-localized with GFAP antibody [120]. As Panx1 expression is already proven for Purkinje cells, these findings make Panx1 an attractive candidate for recently found GJs between Bergmann glia and Purkinje cells [121].…”

Section: Expression Of Pannexins In Cerebellummentioning

confidence: 98%

“…These findings are consistent with the hypothesis that pannexins are involved in electrical coupling of principal neurons since the changes in the levels of corresponding mRNAs may lead to a variation of the composition of Panx1/Panx2 channels and may modulate their coupling strength [35]. However, another recent study which exploited 4-aminopyridine-induced seizures in mice as a model of stimulation of GJ expression in hippocampus, revealed about 1.4-fold decrease in Cx36 expression 4 hours after seizures, and 3 to 5-fold decrease 8 hours after seizures by both RT-PCR and Western blot, while no change in Panx1 expression was found at any time point tested [120]. The difference in the results of these two studies could be explained by using the different animal model also differing in age: 3-4 weeks old rat vs. adult mice, and different stimulation paradigm: application of 4-aminopyridine to hippocampal slices to induce epileptiform activity vs. induction of seizures in live animals via intraperitoneal injection.…”

Section: Panx1mentioning

confidence: 99%

“…Hovewer, differences are striking in the principal cells of hippocampus and cerebellum, where Panx1 and Panx2 are abundantly expressed, while Cx36 is absent. Investigation of the cellular localization of Panx1 protein in the principal cells of hippocampus and cerebellum revealed puncta on the cellular membrane, obviously suggestive of putative GJs [120]. Among suggested roles of pannexins in nervous systems are sensory processing, hippocampal plasticity, synchronization between hippocampus and cortex, neurosecretion and the coordination of the calcium waves supported by glial cells.…”

Section: Conclusion That Could Be Made From Observation Of Pannexinsmentioning

confidence: 99%

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What is hidden in the pannexin treasure trove: the sneak peek and the guesswork

Litvin¹

2006

J Cell Mol Med

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Connexins had been considered to be the only class of the vertebrate proteins capable of gap junction formation; however, new candidates for this function with no homology to connexins, termed pannexins were discovered. So far three pannexins were described in rodent and human genomes: Panx1, Panx2 and Panx3. Expressions of pannexins can be detected in numerous brain structures, and now found both in neuronal and glial cells. Hypothetical roles of pannexins in the nervous system include participating in sensory processing, hippocampal plasticity, synchronization between hippocampus and cortex, and propagation of the calcium waves supported by glial cells, which help maintain and modulate neuronal metabolism. Pannexin also may participate in pathological reactions of the neural cells, including their damage after ischemia and subsequent cell death. Recent study revealed non-gap junction function of Panx1

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Expression of pannexin1 in the CNS of adult mouse: Cellular localization and effect of 4-aminopyridine-induced seizures

Cited by 71 publications

References 36 publications

Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells

Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells

Pannexin-1 Up-regulation in the Dorsal Root Ganglion Contributes to Neuropathic Pain Development

What is hidden in the pannexin treasure trove: the sneak peek and the guesswork

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