The Effects of Dopamine, Methylphenidate, and Dopamine and Methylphenidate Upon Excitatory Junctional Potentials at the Crayfish Neuromuscular Junction

Abstract

Ritalin (methylphenidate) is a widely prescribed, mood-altering, and controversial drug which has not been widely studied at the cellular level. Dopamine is a neurotransmitter that plays an important role in pleasure; it is also deficient in individuals with Parkinson's disease (Kandel et al. 2000). Zaczek et al. (1989) and Volkow et al. (1999) showed that methylphenidate increases dopamine concentration at synapses. To test the interaction of the two drugs, we studied the effects of dopamine alone, methylphenidate alone, and the two in combination at the crayfish neuromuscular junction. Specifically, we used standard intracellular micropipette insertion at the crayfish neuromuscular junction to measure excitatory junctional potentials (EJPs). We found that dopamine causes a significant drop in EJPs, that methylphenidate, by itself, has no significant effect upon EJPs, and that methylphenidate may reduce dopamines effect upon EJPs.