Browsing by Author "Von Bernhardi, R."

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    Development and pH sensitivity of the respiratory rhythm of fetal mice in vitro
    (PERGAMON-ELSEVIER SCIENCE LTD, 2006) Eugenin, J.; Von Bernhardi, R.; Muller, K. J.; Llona, I.
    In newborn and adult mammals, chemosensory drive exerted by CO2 and H+ provides an essential tonic input: without it the rhythm of respiration is abolished. It is not known, however, whether this chemosensory drive and the respiratory rhythm appear simultaneously during development. In isolated brainstem-spinal cord preparations from fetal mice, we determined at what stage of fetal life the respiratory rhythm appeared in third to fifth cervical ventral roots (phrenic motoneurons) and whether this fetal rhythm was sensitive to chemosensory inputs. A respiratory-like rhythm consisting of short duration bursts of discharges recurring at 2-16 min(-1) was detected in two of nine embryonic day 13 fetuses; it was abolished by transection of the spinal cord between the first to second cervical segments and was phase-related to rhythmic activity from medullary units of the ventral respiratory group. At embryonic day 13, it coexisted with a slow rhythm (0.1-2.0 min(-1)) of long duration bursts of action potentials which was generated by the spinal cord. At later fetal stages, the respiratory-like rhythm became more robust and of higher frequency, while the spinal cord rhythm became less obvious. At all fetal stages, acidification of the superfusion medium from pH 7.5-7.2 or 7.4-7.3 or 7.4 to 7.2 increased the frequency of both the respiratory-like and the spinal cord rhythms. In addition, acidification reduced the amplitude of the integrated burst activity of the spinal cord rhythm of embryonic day 13-embryonic day 16 fetuses and the respiratory-like rhythm of embryonic day 17 and older fetuses. Our results indicate that the rhythms transmitted by phrenic motoneurons during fetal development are chemosensitive from early fetal stages. Through its effects on induction and patterning of the rhythm, chemosensory drive may play a role in activity-dependent formation of respiratory neural networks. (c) 2006 IBRO. Published by Elsevier Ltd. All rights reserved.
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    Scavenger receptor class A ligands induce secretion of IL1β and exert a modulatory effect on the inflammatory activation of astrocytes in culture
    (2012) Godoy, B.; Murgas, P.; Tichauer, J.; Von Bernhardi, R.
    Class-A scavenger receptor (SR-A) is expressed by microglia, and we show here that it is also expressed by astrocytes, where it participates on their inflammatory activation. Astrocytes play a key role on the inflammatory response of the central nervous system, secreting several soluble mediators like cytokines and radical species. Exposure to SR ligands activated MAPKs and NF-kappa B signaling and increased production of IL1 beta and nitric oxide (NO). IL1 beta classically an inflammatory cytokine surprisingly did not increase but inhibited LPS + IFN gamma-induced NO production by astrocytes. Our results suggest that SRs expressed by astrocytes participate in the modulation of inflammatory activation. (C) 2012 Elsevier B.V. All rights reserved.