Repeated cocaine treatments induce distinct locomotor effects in crayfish.

A repeated injection of cocaine regime is known to induce complex locomotion alterations in both vertebrate and invertebrate models of drug addiction. However, the specific effect of cocaine on behaviorally distinct locomotion and non locomotion parameters is not well known. The present experiments determined whether cocaine has distinct effect on multifarious locomotor activity of crayfish (Orconectes rusticus). Following repeated injections of 2.5 μg/g or 10.0 μg/g dose of cocaine for three days, videotaped recordings of locomotion were analyzed to determine whether repeated injections of cocaine produced distinct effect on multifarious locomotor activity of crayfish. Cocaine decreased immobility in day 1 when compared with saline. Thereafter, cocaine increased immobility in days 2 and 3. Repeated injections of cocaine increased distance traveled, average speed, mobility and decreased lingering episodes. These findings indicate that cocaine has distinct action on movement and non-movement behavioral activities, suggesting that locomotion as a unitary phenomenon comprised of assemblage of multifarious components, which can be manipulated and separated by cocaine in crayfish.