A Sweet Talk: The Molecular Systems of Perineuronal Nets in Controlling Neuronal Communication

Perineuronal nets (PNNs) are mesh-like structures, composed of a hierarchical assembly of extracellular matrix molecules in the central nervous system (CNS), ensheathing neurons and regulating plasticity. The mechanism of interactions between PNNs and neurons remain uncharacterized. In this review, we pose the question: how do PNNs regulate communication to and from neurons? We provide an overview of the current knowledge on PNNs with a focus on the cellular interactions. PNNs ensheath a subset of the neuronal population with distinct molecular aspects in different areas of the CNS. PNNs control neuronal communication through molecular interactions involving specific components of the PNNs. This review proposes that the PNNs are an integral part of neurons, crucial for the regulation of plasticity in the CNS

Treatment of Early Allergic and Late Inflammatory Symptoms of Allergic Rhinitis with Petasites Hybridus Leaf Extract (Ze 339): Results of a Noninterventional Observational Study in Switzerland

The primary objective of this noninterventional, observational study was to assess the effectiveness of the Petasites hybridus leaf extract (Ze 339) on early allergic and late inflammatory symptoms of allergic rhinitis in Swiss outpatients. This study was conducted by general practitioners and allergologists. Data from 226 patients were collected during three documented visits. The intermediate visit was ideally made 2–4 weeks after the baseline visit, followed by the final visit approximately 2–4 months later. The mean study duration was 63 days, with 75% of patients being treated for at least 4 weeks. Of the patients, 58.5% started with Ze 339 monotherapy, and 41.5% received other antiallergic and/or sympathomimetic drugs. In both groups, the allergic total symptom score and the inflammatory total symptom scores were significantly (p < 0.001) reduced, and the scores for quality of life were improved. Both physicians and patients were very satisfied with the treatment and the concept of therapy, not only for short-term (seasonal) therapy but also for long-term therapy. The tolerability was good: only three mild gastrointestinal adverse events occurred. In summary, the effectiveness of P. hybridus leaf extract Ze 339 for the treatment of early allergic and late inflammatory symptoms of allergic rhinitis could be confirmed

Reorganization of Synaptic Connections and Perineuronal Nets in the Deep Cerebellar Nuclei of Purkinje Cell Degeneration Mutant Mice

The perineuronal net (PN) is a subtype of extracellular matrix appearing as a net-like structure around distinct neurons throughout the whole CNS. PNs surround the soma, proximal dendrites, and the axonal initial segment embedding synaptic terminals on the neuronal surface. Different functions of the PNs are suggested which include support of synaptic stabilization, inhibition of axonal sprouting, and control of neuronal plasticity. A number of studies provide evidence that removing PNs or PN-components results in renewed neurite growth and synaptogenesis. In a mouse model for Purkinje cell degeneration, we examined the effect of deafferentation on synaptic remodeling and modulation of PNs in the deep cerebellar nuclei. We found reduced GABAergic, enhanced glutamatergic innervations at PN-associated neurons, and altered expression of the PN-components brevican and hapln4. These data refer to a direct interaction between ECM and synapses. The altered brevican expression induced by activated astrocytes could be required for an adequate regeneration by promoting neurite growth and synaptogenesis

Synaptic coupling of inner ear sensory cells is controlled by brevican-based extracellular matrix baskets resembling perineuronal nets

Abstract Background Perineuronal nets (PNNs) are specialized aggregations of extracellular matrix (ECM) molecules surrounding specific neurons in the central nervous system (CNS). PNNs are supposed to control synaptic transmission and are frequently associated with neurons firing at high rates, including principal neurons of auditory brainstem nuclei. The origin of high-frequency activity of auditory brainstem neurons is the indefatigable sound-driven transmitter release of inner hair cells (IHCs) in the cochlea. Results Here, we show that synaptic poles of IHCs are ensheathed by basket-like ECM complexes formed by the same molecules that constitute PNNs of neurons in the CNS, including brevican, aggreccan, neurocan, hyaluronan, and proteoglycan link proteins 1 and 4 and tenascin-R. Genetic deletion of brevican, one of the main components, resulted in a massive degradation of ECM baskets at IHCs, a significant impairment in spatial coupling of pre- and postsynaptic elements and mild impairment of hearing. Conclusions These ECM baskets potentially contribute to control of synaptic transmission at IHCs and might be functionally related to PNNs of neurons in the CNS