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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

Effects of knee derangement on differential hind limb weight distribution in the incapacitance test.The percentage of weight bearing of the right hind limb (ipsilateral) was compared between one day before surgery (baseline) and 4 weeks after surgery. In each scatter plot, the mean (horizontal line) is superimposed. After confirming that the data was normally distributed, paired t-test was used in the comparison. Significant difference in the percentage of weight bearing of the right hind limb between OA and control rats was found at 4 weeks after surgery.
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pone-0036854-g002: Effects of knee derangement on differential hind limb weight distribution in the incapacitance test.The percentage of weight bearing of the right hind limb (ipsilateral) was compared between one day before surgery (baseline) and 4 weeks after surgery. In each scatter plot, the mean (horizontal line) is superimposed. After confirming that the data was normally distributed, paired t-test was used in the comparison. Significant difference in the percentage of weight bearing of the right hind limb between OA and control rats was found at 4 weeks after surgery.

Mentions: Baseline readings taken before surgery demonstrated equal weight distribution on both hind limbs in both groups of animals and there was no difference between the groups. There was also no difference in the percentage of weight bearing on either leg in control animals after 4 weeks of housing (data not shown). However, at four weeks after surgery in model animals, just before they were used in the acute in vivo electrophysiological experiments, 47.9±0.19% of the total hind limb load was placed on the ipsilateral hind limb (N = 9). This percentage was significantly less compared to the baseline values in this group before model induction (49.2±0.46%; N = 9; paired t-test, P = 0.02; Figure 2). Before model induction, these model animals almost placed equal weight on both limbs, although slightly more weight either on the left or right hind limb was recorded, but this was randomly distributed. After model induction these model animals consistently placed more weight on the left (contralateral) hind limb. The weight bearing difference between two limbs was significantly increased to 7.5±0.54 gram after knee surgery, which was significant either compared to the baseline value before knee surgery (2.2±1.35 gram, N = 9; P = 0.002) or compared to the value in a group of control animals with similar age and body weight (1.9±1.46 gram, N = 6; P = 0.001).


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

Wu Q, Henry JL - PLoS ONE (2012)

Effects of knee derangement on differential hind limb weight distribution in the incapacitance test.The percentage of weight bearing of the right hind limb (ipsilateral) was compared between one day before surgery (baseline) and 4 weeks after surgery. In each scatter plot, the mean (horizontal line) is superimposed. After confirming that the data was normally distributed, paired t-test was used in the comparison. Significant difference in the percentage of weight bearing of the right hind limb between OA and control rats was found at 4 weeks after surgery.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0036854-g002: Effects of knee derangement on differential hind limb weight distribution in the incapacitance test.The percentage of weight bearing of the right hind limb (ipsilateral) was compared between one day before surgery (baseline) and 4 weeks after surgery. In each scatter plot, the mean (horizontal line) is superimposed. After confirming that the data was normally distributed, paired t-test was used in the comparison. Significant difference in the percentage of weight bearing of the right hind limb between OA and control rats was found at 4 weeks after surgery.
Mentions: Baseline readings taken before surgery demonstrated equal weight distribution on both hind limbs in both groups of animals and there was no difference between the groups. There was also no difference in the percentage of weight bearing on either leg in control animals after 4 weeks of housing (data not shown). However, at four weeks after surgery in model animals, just before they were used in the acute in vivo electrophysiological experiments, 47.9±0.19% of the total hind limb load was placed on the ipsilateral hind limb (N = 9). This percentage was significantly less compared to the baseline values in this group before model induction (49.2±0.46%; N = 9; paired t-test, P = 0.02; Figure 2). Before model induction, these model animals almost placed equal weight on both limbs, although slightly more weight either on the left or right hind limb was recorded, but this was randomly distributed. After model induction these model animals consistently placed more weight on the left (contralateral) hind limb. The weight bearing difference between two limbs was significantly increased to 7.5±0.54 gram after knee surgery, which was significant either compared to the baseline value before knee surgery (2.2±1.35 gram, N = 9; P = 0.002) or compared to the value in a group of control animals with similar age and body weight (1.9±1.46 gram, N = 6; P = 0.001).

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