Memory-impairing effects of local anesthetics in an elevated plus-maze test in mice

ABSTRACT

Post-training intracerebroventricular administration of procaine (20 mug/mul) and dimethocaine (10 or 20 mug/mul), local anesthetics of the ester class, prolonged the latency(s) in the retention test of male and female 3-month-old Swiss albino mice (25-35 g body weight; N=140) in the elevated plus-maze (mean + SEM for 10 male mice control= 41.2 + 8.1; procaine = 78.5 + 10.3; 10 mug/mul dimethocaine = 58.7 + 12.3; 20 mug/mul dimethocaine = 109.6 + 5.73; for 10 female mice control = 34.8 + 5.8; procaine = 55.3 + 13.4; 10 mug/mul dimethocaine = 59.9 + 12.3 and 20 mug/mul dimethocaine = 61.3 + 11.1). However, lidocaine (10 or 20 mug/mul), an amide class type of local anesthetic, failed to influence this parameter. Local anesthetics at the dose range used did not affect the motor coordination of mice exposed to the rota-rod test. These results suggest that procaine and dimethocaine impair some memory process(es) in the plus-maze test. These findings are interpreted in terms of non-anesthetic mechanisms of action of these drugs on memory impairment and also confirm the validity of the elevated plusmaze for the evaluation of drugs effecting learning and memory in mice.