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Functional changes in muscle afferent neurones in an osteoarthritis model: implications for impaired proprioceptive performance.

Wu Q, Henry JL - PLoS ONE (2012)

Bottom Line: Depolarizing intracellular current injection elicited more APs in models than in naïve muscle afferent neurones (P = 0.01) indicating greater excitability.The present study demonstrates changes in hind limb stance accompanied by changes in the functional properties of muscle afferent neurones in this derangement model of OA.This may provide a possible avenue to explore mechanisms underlying the impaired proprioceptive performance and perhaps other sensory disorders in people with OA.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.

ABSTRACT

Background: Impaired proprioceptive performance is a significant clinical issue for many who suffer osteoarthritis (OA) and is a risk factor for falls and other liabilities. This study was designed to evaluate weight-bearing distribution in a rat model of OA and to determine whether changes also occur in muscle afferent neurones.

Methodology/principal findings: Intracellular recordings were made in functionally identified dorsal root ganglion neurones in acute electrophysiological experiments on the anaesthetized animal following measurements of hind limb weight bearing in the incapacitance test. OA rats but not naïve control rats stood with less weight on the ipsilateral hind leg (P = 0.02). In the acute electrophysiological experiments that followed weight bearing measurements, action potentials (AP) elicited by electrical stimulation of the dorsal roots differed in OA rats, including longer AP duration (P = 0.006), slower rise time (P = 0.001) and slower maximum rising rate (P = 0.03). Depolarizing intracellular current injection elicited more APs in models than in naïve muscle afferent neurones (P = 0.01) indicating greater excitability. Axonal conduction velocity in model animals was slower (P = 0.04).

Conclusions/significance: The present study demonstrates changes in hind limb stance accompanied by changes in the functional properties of muscle afferent neurones in this derangement model of OA. This may provide a possible avenue to explore mechanisms underlying the impaired proprioceptive performance and perhaps other sensory disorders in people with OA.

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Related in: MedlinePlus

Scatter plots of conduction velocity (A), AP duration (B), AP rise time (C), maximum rising rate (D), fall time (E) and maximum falling rate (F) of individual muscle afferent neurones in control and OA animals.In each case the median (horizontal line) is superimposed. Student’s t-tests were used in the comparisons between OA (N = 40) and control (N = 35) muscle afferent neurones, except that Mann-Whitney U-tests were used in the comparison for the AP fall time and maximum falling rate, because the control AP fall time and OA maximum falling rate data failed the D'Agostino and Pearson omnibus normality test. The data indicate slower axonal conduction velocities and slower dynamics of AP generation particularly depolarization in neurones in OA animals.
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pone-0036854-g003: Scatter plots of conduction velocity (A), AP duration (B), AP rise time (C), maximum rising rate (D), fall time (E) and maximum falling rate (F) of individual muscle afferent neurones in control and OA animals.In each case the median (horizontal line) is superimposed. Student’s t-tests were used in the comparisons between OA (N = 40) and control (N = 35) muscle afferent neurones, except that Mann-Whitney U-tests were used in the comparison for the AP fall time and maximum falling rate, because the control AP fall time and OA maximum falling rate data failed the D'Agostino and Pearson omnibus normality test. The data indicate slower axonal conduction velocities and slower dynamics of AP generation particularly depolarization in neurones in OA animals.

Mentions: In control rats, properties of muscle afferent neurones were similar to those in previous in vivo reports in guinea-pigs [37], [38], and are also within the range reported from in vitro studies [39], [40]. CVs were significantly slower in OA model rats (20.7±0.38 m/s, N = 40) compared to control rats (22.9±0.92 m/s, N = 35; Student's t-test, P = 0.04; Figure 3A).


Functional changes in muscle afferent neurones in an osteoarthritis model: implications for impaired proprioceptive performance.

Wu Q, Henry JL - PLoS ONE (2012)

Scatter plots of conduction velocity (A), AP duration (B), AP rise time (C), maximum rising rate (D), fall time (E) and maximum falling rate (F) of individual muscle afferent neurones in control and OA animals.In each case the median (horizontal line) is superimposed. Student’s t-tests were used in the comparisons between OA (N = 40) and control (N = 35) muscle afferent neurones, except that Mann-Whitney U-tests were used in the comparison for the AP fall time and maximum falling rate, because the control AP fall time and OA maximum falling rate data failed the D'Agostino and Pearson omnibus normality test. The data indicate slower axonal conduction velocities and slower dynamics of AP generation particularly depolarization in neurones in OA animals.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351471&req=5

pone-0036854-g003: Scatter plots of conduction velocity (A), AP duration (B), AP rise time (C), maximum rising rate (D), fall time (E) and maximum falling rate (F) of individual muscle afferent neurones in control and OA animals.In each case the median (horizontal line) is superimposed. Student’s t-tests were used in the comparisons between OA (N = 40) and control (N = 35) muscle afferent neurones, except that Mann-Whitney U-tests were used in the comparison for the AP fall time and maximum falling rate, because the control AP fall time and OA maximum falling rate data failed the D'Agostino and Pearson omnibus normality test. The data indicate slower axonal conduction velocities and slower dynamics of AP generation particularly depolarization in neurones in OA animals.
Mentions: In control rats, properties of muscle afferent neurones were similar to those in previous in vivo reports in guinea-pigs [37], [38], and are also within the range reported from in vitro studies [39], [40]. CVs were significantly slower in OA model rats (20.7±0.38 m/s, N = 40) compared to control rats (22.9±0.92 m/s, N = 35; Student's t-test, P = 0.04; Figure 3A).

Bottom Line: Depolarizing intracellular current injection elicited more APs in models than in naïve muscle afferent neurones (P = 0.01) indicating greater excitability.The present study demonstrates changes in hind limb stance accompanied by changes in the functional properties of muscle afferent neurones in this derangement model of OA.This may provide a possible avenue to explore mechanisms underlying the impaired proprioceptive performance and perhaps other sensory disorders in people with OA.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.

ABSTRACT

Background: Impaired proprioceptive performance is a significant clinical issue for many who suffer osteoarthritis (OA) and is a risk factor for falls and other liabilities. This study was designed to evaluate weight-bearing distribution in a rat model of OA and to determine whether changes also occur in muscle afferent neurones.

Methodology/principal findings: Intracellular recordings were made in functionally identified dorsal root ganglion neurones in acute electrophysiological experiments on the anaesthetized animal following measurements of hind limb weight bearing in the incapacitance test. OA rats but not naïve control rats stood with less weight on the ipsilateral hind leg (P = 0.02). In the acute electrophysiological experiments that followed weight bearing measurements, action potentials (AP) elicited by electrical stimulation of the dorsal roots differed in OA rats, including longer AP duration (P = 0.006), slower rise time (P = 0.001) and slower maximum rising rate (P = 0.03). Depolarizing intracellular current injection elicited more APs in models than in naïve muscle afferent neurones (P = 0.01) indicating greater excitability. Axonal conduction velocity in model animals was slower (P = 0.04).

Conclusions/significance: The present study demonstrates changes in hind limb stance accompanied by changes in the functional properties of muscle afferent neurones in this derangement model of OA. This may provide a possible avenue to explore mechanisms underlying the impaired proprioceptive performance and perhaps other sensory disorders in people with OA.

Show MeSH
Related in: MedlinePlus