Effect of Gentamicin Intoxication on Frog Behavior

Abstract

Eighty ug of Gentamicin were injected into bull frogs' perilymphatic cistern for 3 days. Behavioral changes were evaluated together with morphology of the semicircular canal crista and the utricular macula. The behaviors evaluated were posture, walking, head stability, jumping and swimming. The earliest change of behavior was noticed one day after the last injection, and the changes tended to develop over the following 1 to 2 weeks. When the utricular macula was damaged, the frog tilted toward the damaged side. No tilting was observed when bilateral utricles were intact, or when bilateral utricles were equally damaged. Damage of the posterior (p.v.c.) and anterior vertical canal (a.v.c.) cristae resulted in instability of the head. Jumping ability also deteriorated when the p.v.c. and a.v.c. were damaged. These results indicate that p.v.c. and a.v.c. are involved in head stability and jumping function, while the utricle contributes to perception of gravity.

Key Words:

• Gentamicin
• ototoxicity
• frog motor function
• utricle