Simple Neurobehavioral Functional Observational Battery and Objective Gait Analysis Validation by the Use of Acrylamide and Methanol with a Built-In Recovery Period

A functional observational battery (FOB) with modified objective gait analysis was validated using the neurotoxicants acrylamide and methanol. The FOB consisted of side cage observation (30 sec); open field observation (2 min); evaluation of handling, reflexes, and gait scoring; and grip strength of the fore limbs and hind limbs. Temperature and body weight were measured. Gait analysis was based on measurements of the distances and angles between sequential foot strides after walking in a corridor (90 x 10 x 10 cm). Landing foot splay was the distance between the inner surfaces of the fourth digits of each foot after the animals were dropped from a 30-cm height. Acrylamide was given at doses of 0 (saline), 20, and 40 mg/kg intraperitoneally. Days of dosing were 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19. Evaluations were done before dosing on Days 0, 2, 5, 11, 17, and 27 (for recovery). Methanol was given to another group at doses of 0 (distilled water), 3.25 (escalated to 8.5 before end of evaluation), and 6.5 ml/kg. Days of dosing were 3, 5, 7, and 10; evaluations were conducted at 0, 6, 8, and 12 days. Acrylamide at 40 mg/kg demonstrated a biologically significant increase in foot splay in males on Days 3 and 17 and was not recovered by Day 27. A significant decrease in the hind limb grip strength was seen in high-dose females, but with incomplete recovery on Day 27. Methanol (3.25/8.5 ml/kg) induced a biological decrease of activity postdosing on Days 6, 8, and 12. A significant increase in gait length was seen in females only at the 6.5 ml/kg dose at Day 12. Selected doses and schedule of observation validated the battery for screening and better quantification of acute and chronic neurotoxicity.