Cocaine increases synaptic transmission at the crayfish neuromuscular junction

Abstract

Cocaine is an alkaloid that stimulates the nervous system. It has high affinity for the 5-HT transporter, blocking the reuptake of serotonin. Therefore, manipulation of the serotonergic system may reveal the mechanisms of action of cocaine. We hypothesized that cocaine would increase EJPs amplitude in the neuromuscular junction of a crayfish. Moreover, we predicted that cyproheptadine hydrochloride, a 5-HT receptor antagonist, would decrease EJPs amplitude in presence of cocaine. To test our hypothesis, we exposed a crayfish tail to different solutions of 5-HT, cocaine and cyproheptadine hydrochloride and through intracellular recording we measured EJPs amplitudes. As we expected, cocaine enhanced EJPs in the neuromuscular junction of a crayfish. Moreover, we observed that when the 5-HT2C blocker was added to the solution, the EJP amplitude decreased.