Limits...
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.

Show MeSH

Related in: MedlinePlus

Action potential (AP) recorded intracellularly from a muscle afferent neurone, illustrating parameters measured in each neurone studied.The AP in the upper trace was elicited in a muscle afferent neurone by electrical stimulation of the L4 dorsal root. 1, latency (by measuring the distance from the stimulating site to the centre of DRG after each experiment, the conduction velocity is calculated); 2, AP rise time; 3, AP fall time; AP duration at base (the value equals AP rise time plus AP fall time); 4, AP half width; 5, 50% afterhyperpolarization recovery time; 6, 80% afterhyperpolarization recovery time; 7, resting membrane potential; 8, AP amplitude; 9, afterhyperpolarization amplitude. Lower trace is the differentiated derivative of the upper trace recording, and plots the change of voltage over time: 10, maximum rising rate; 11, maximum falling rate.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3351471&req=5

pone-0036854-g001: Action potential (AP) recorded intracellularly from a muscle afferent neurone, illustrating parameters measured in each neurone studied.The AP in the upper trace was elicited in a muscle afferent neurone by electrical stimulation of the L4 dorsal root. 1, latency (by measuring the distance from the stimulating site to the centre of DRG after each experiment, the conduction velocity is calculated); 2, AP rise time; 3, AP fall time; AP duration at base (the value equals AP rise time plus AP fall time); 4, AP half width; 5, 50% afterhyperpolarization recovery time; 6, 80% afterhyperpolarization recovery time; 7, resting membrane potential; 8, AP amplitude; 9, afterhyperpolarization amplitude. Lower trace is the differentiated derivative of the upper trace recording, and plots the change of voltage over time: 10, maximum rising rate; 11, maximum falling rate.

Mentions: Figure 1 illustrates the electrophysiological parameters that were measured in each neurone, including resting membrane potential (resting Vm), action potential duration (APD), AP half width, AP amplitude, AP rise time, AP fall time, maximum rising rate (MRR), maximum falling rate (MFR), afterhyperpolarization (AHP) amplitude, 50% AHP recovery time (AHP50) and 80% AHP recovery time (AHP80). After each experiment the conduction distance was measured for each neurone recorded, as the distance from the centre of the DRG to the stimulation site (cathode). Conduction velocity (CV) was then calculated from this value. Analysis was done offline using the pClamp 9.2 software.


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

Wu Q, Henry JL - PLoS ONE (2012)

Action potential (AP) recorded intracellularly from a muscle afferent neurone, illustrating parameters measured in each neurone studied.The AP in the upper trace was elicited in a muscle afferent neurone by electrical stimulation of the L4 dorsal root. 1, latency (by measuring the distance from the stimulating site to the centre of DRG after each experiment, the conduction velocity is calculated); 2, AP rise time; 3, AP fall time; AP duration at base (the value equals AP rise time plus AP fall time); 4, AP half width; 5, 50% afterhyperpolarization recovery time; 6, 80% afterhyperpolarization recovery time; 7, resting membrane potential; 8, AP amplitude; 9, afterhyperpolarization amplitude. Lower trace is the differentiated derivative of the upper trace recording, and plots the change of voltage over time: 10, maximum rising rate; 11, maximum falling rate.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0036854-g001: Action potential (AP) recorded intracellularly from a muscle afferent neurone, illustrating parameters measured in each neurone studied.The AP in the upper trace was elicited in a muscle afferent neurone by electrical stimulation of the L4 dorsal root. 1, latency (by measuring the distance from the stimulating site to the centre of DRG after each experiment, the conduction velocity is calculated); 2, AP rise time; 3, AP fall time; AP duration at base (the value equals AP rise time plus AP fall time); 4, AP half width; 5, 50% afterhyperpolarization recovery time; 6, 80% afterhyperpolarization recovery time; 7, resting membrane potential; 8, AP amplitude; 9, afterhyperpolarization amplitude. Lower trace is the differentiated derivative of the upper trace recording, and plots the change of voltage over time: 10, maximum rising rate; 11, maximum falling rate.
Mentions: Figure 1 illustrates the electrophysiological parameters that were measured in each neurone, including resting membrane potential (resting Vm), action potential duration (APD), AP half width, AP amplitude, AP rise time, AP fall time, maximum rising rate (MRR), maximum falling rate (MFR), afterhyperpolarization (AHP) amplitude, 50% AHP recovery time (AHP50) and 80% AHP recovery time (AHP80). After each experiment the conduction distance was measured for each neurone recorded, as the distance from the centre of the DRG to the stimulation site (cathode). Conduction velocity (CV) was then calculated from this value. Analysis was done offline using the pClamp 9.2 software.

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