Background

Measurements of neuromuscular performance in laboratory animal models play an important role in pharmacological evaluations and other biomedical research protocols. A variety of techniques employed in behavioral studies provide a valuable tool for assessing the safety and effectiveness of the regimen.

Aim

The present study was designed to compare the use of a grip-strength meter with a rotametric device in assessing the effect of Pyridostigmine (PYR), a cholinesterase inhibitor that may exert a deleterious effect on the skeletal muscle, on neuromuscular performance in rats.

Methods

Male Sprague-Dawley rats (250 g) were pretreated with normal saline or PYR (7 mg/kg body weight i.p.) daily for 3 days and subjected to the following test at 0, 16 or 40 h later: (a) Grip-strength test: Fore limb grip strength was measured using a grip strength meter. The animal was placed on the electronic digital force gauge that measures the peak force exerted on it by the action of the animal. The animal was drawn along a straight line leading away from the sensor. The animal released at some point and the maximum force attained will be stored on the display. The highest reading (in Newton) of three successive trials was taken from each animal. (b) Coordination study: a rotametric device was used to examine the ability of the animal to co-ordinate while being placed on a rotating rod. The average reading (in seconds) of two successive trials was taken from each animal.

Results

Saline pre-treated rats was associated with grip-strength score of 8.3±0.3^a, 8.2±0.7 and 7.7±0.9, and rotametric score of 114±4^b, 117±3 and <120 at 0, 16 and 40 h, respectively. In contrast, the use of PYR resulted in grip-strength score of 6.3±0.3^c (a vs. c: p<0.05), 6.2±1.1, and 7.3±0.9, and rotametric score of 94±8^d (b vs. d: p<0.05), 83±17 and 87±19 at 0, 16 and 40 h, respectively.

Discussion

The short-term deleterious effect of PYR on the neuromuscular performance in rats was evidenced with the grip-strength and rotametric tests. There was a good correlation between grip-strength and rotametic scores, suggesting that both methods can be employed to determine the neuromuscular performance in laboratory animal models.