An experimental study to determine and correlate choline acetyltransferase assay with functional muscle testing after nerve injury

Abstract

Object. Choline acetyltransferase (ChAT) is an enzyme synthesized within the body of a motor neuron whose role is to form the neurotransmitter acetylcholine. Quantification of ChAT levels in motor or mixed nerves has been proposed to provide information regarding the viability of a proximal nerve stump for motor neurotization following brachial plexus injury. To do so requires information regarding normal ChAT levels and those in injured nerves, as well as the correlation of ChAT level determined at surgery with eventual motor recovery. The purpose of this study was to determine ChAT activity in the normal and injured sciatic/peroneal nerve in a rat model, evaluate the correlation between ChAT and motor recovery, find the relationship between ChAT activity and isometric muscle force, and elucidate the parallel between ChAT activity and acetylcholinesterase (AChE) activity.Methods. Sixty animals were divided into 3 groups. The sciatic nerves in Group 1 were transected without repair. Nerves in Group 2 were transected and repaired. Nerves in Group 3 sustained a crush injury followed by transection and reconstruction. All animals were allowed 12 weeks of recovery followed by evaluation of ChAT levels in the peroneal nerve, correlated with measures of maximal isometric tibialis anterior muscle force and muscle weight (the operated side normalized to the control side). Karnovsky AChE staining of peroneal nerve segments was also compared with radiochemical assay of ChAT activity in the same nerve.Results. A significant difference in the tibialis anterior isometric tetanic force and the tibialis anterior muscle weight index (TAMI) was noted between Group 1 and Groups 2 and 3 (p < 0.0001); no significant difference was found comparing Group 2 with Group 3. The correlation between the force measurement and the TAMI was 0.382. Both AChE measurement and ChAT activity demonstrated significantly fewer fibers in the operated nerve compared with the contralateral nerve. Intergroup variability could also be illustrated using these tests. The correlation coefficient between the isometric tetanic force measurement and the ChAT analysis in Groups 1 and 2 was 0.468. The correlation for the AChE staining and the isometric tetanic force measurement was 0.111. The correlation between the TAMI and the ChAT levels was 0.773. The correlation between the TAMI and the AChE-stained fibers was 0.640. Correlating AChE staining to the ChAT analysis produced a correlation of 0.712.Conclusions. The great variability in all groups and weak correlations to the functional muscle assessments and the ChAT radiochemical assay made this technique an unreliable method of determining motor nerve viability. 1125Abbreviations used in this paper: AChE = acetylcholinesterase; ChAT = choline acetyltransferase; TAMI = tibialis anterior muscle weight index.

Identification of sensory and motor nerve fascicles by immunofluorescence staining after peripheral nerve injury

“…Although the activity of the ChAT enzyme is affected by different tissues and time points, it has been reported that the activity of ChAT is highest following axotomy and gradually declines over time [ 59 ]. We experimented with ChAT within 1 day after nerve harvest, in hopes of maximally retaining the enzymatic activity.…”

Neurobehavioral and neurochemical effects in rats offspring co-exposed to arsenic and fluoride during development

“…The striatum is one of the brain areas an exceptionally high concentration of (ACh) and its associated enzymes (Vathana et al, 2014). Cholinergic systems of the forebrain are involved in various important processes, such as attention, learning, memory and wakefulness-sleep cycle (Inglis et al, 2001).…”

“…Moreover, it is important to consider that the striatum is one of the areas in the brain with the highest concentration of acetylcholine (ACh) and its associated enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE). Acetylcholine coordinates the neuronal networks of the brain cholinergic modulation area (Vathana et al, 2014).…”