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Exposure to reduced gravity impairs junctional transmission at the semicircular canal in the frog labyrinth.
. 2010 Feb; 298(2):R439-52.

Abstract

The effects of microgravity on frog semicircular canals have been studied by electrophysiological and morphological approaches. Reduced gravity (microG) was simulated by a random positioning machine (RPM), which continually and randomly modified the orientation in space of the anesthetized animal. As this procedure stimulates the semicircular canals, the effect of altered gravity was isolated by comparing microG-treatment with an identical rotary stimulation in the presence of normal gravity (normoG). Electrophysiological experiments were performed in the isolated labyrinth, extracted from the animals after the treatment, and mounted on a turntable. Junctional activity was measured by recording quantal events (mEPSPs) and spikes from the afferent fibers close to the junction, at rest and during rotational stimulation. MicroG-treated animals displayed a marked decrease in the frequency of resting and evoked mEPSP discharge, vs. both control and normoG (mean decrease approximately 50%). Spike discharge was also depressed: 57% of microG-treated frogs displayed no spikes at rest and during rotation at 0.1 Hz, vs. 23-31% of control or normoG frogs. Among the firing units, during one cycle of sinusoidal rotation at 0.1 Hz microG-treated units emitted an average of 41.8 + or - 8.06 spikes, vs. 77.2 + or - 8.19 in controls. Patch-clamp analysis on dissociated hair cells revealed altered Ca(2+) handling, after microG, consistent with and supportive of the specificity of microG effects. Marked morphological signs of cellular suffering were observed after microG, mainly in the central part of the sensory epithelium. Functional changes due to microgravity were reversible within a few days.

Authors+Show Affiliations

Department of Biology and Evolution, Section of Physiology and Biophysics, and National Institute of Neurosciences, Ferrara University, Ferrara, Italy. rsm@unife.itNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19955492

Citation

Rossi, Maria Lisa, et al. "Exposure to Reduced Gravity Impairs Junctional Transmission at the Semicircular Canal in the Frog Labyrinth." American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 298, no. 2, 2010, pp. R439-52.
Rossi ML, Rubbini G, Gioglio L, et al. Exposure to reduced gravity impairs junctional transmission at the semicircular canal in the frog labyrinth. Am J Physiol Regul Integr Comp Physiol. 2010;298(2):R439-52.
Rossi, M. L., Rubbini, G., Gioglio, L., Martini, M., & Fesce, R. (2010). Exposure to reduced gravity impairs junctional transmission at the semicircular canal in the frog labyrinth. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 298(2), R439-52. https://doi.org/10.1152/ajpregu.00673.2009
Rossi ML, et al. Exposure to Reduced Gravity Impairs Junctional Transmission at the Semicircular Canal in the Frog Labyrinth. Am J Physiol Regul Integr Comp Physiol. 2010;298(2):R439-52. PubMed PMID: 19955492.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Exposure to reduced gravity impairs junctional transmission at the semicircular canal in the frog labyrinth. AU - Rossi,Maria Lisa, AU - Rubbini,Gemma, AU - Gioglio,Luciana, AU - Martini,Marta, AU - Fesce,Riccardo, Y1 - 2009/12/02/ PY - 2009/12/4/entrez PY - 2009/12/4/pubmed PY - 2010/2/18/medline SP - R439 EP - 52 JF - American journal of physiology. Regulatory, integrative and comparative physiology JO - Am. J. Physiol. Regul. Integr. Comp. Physiol. VL - 298 IS - 2 N2 - The effects of microgravity on frog semicircular canals have been studied by electrophysiological and morphological approaches. Reduced gravity (microG) was simulated by a random positioning machine (RPM), which continually and randomly modified the orientation in space of the anesthetized animal. As this procedure stimulates the semicircular canals, the effect of altered gravity was isolated by comparing microG-treatment with an identical rotary stimulation in the presence of normal gravity (normoG). Electrophysiological experiments were performed in the isolated labyrinth, extracted from the animals after the treatment, and mounted on a turntable. Junctional activity was measured by recording quantal events (mEPSPs) and spikes from the afferent fibers close to the junction, at rest and during rotational stimulation. MicroG-treated animals displayed a marked decrease in the frequency of resting and evoked mEPSP discharge, vs. both control and normoG (mean decrease approximately 50%). Spike discharge was also depressed: 57% of microG-treated frogs displayed no spikes at rest and during rotation at 0.1 Hz, vs. 23-31% of control or normoG frogs. Among the firing units, during one cycle of sinusoidal rotation at 0.1 Hz microG-treated units emitted an average of 41.8 + or - 8.06 spikes, vs. 77.2 + or - 8.19 in controls. Patch-clamp analysis on dissociated hair cells revealed altered Ca(2+) handling, after microG, consistent with and supportive of the specificity of microG effects. Marked morphological signs of cellular suffering were observed after microG, mainly in the central part of the sensory epithelium. Functional changes due to microgravity were reversible within a few days. SN - 1522-1490 UR - https://www.unboundmedicine.com/medline/citation/19955492/Exposure_to_reduced_gravity_impairs_junctional_transmission_at_the_semicircular_canal_in_the_frog_labyrinth_ L2 - https://journals.physiology.org/doi/10.1152/ajpregu.00673.2009?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -