Dopaminergic modulation of spontaneous activity in the brain of the crayfishCherax destructor(Decapoda, Crustacea)

Abstract

The role of dopamine in the crayfish (Cherax destructor) brain was studied in an isolated head preparation by means of extracellular recordings from unidentified neurons located in the circumoesophageal connectives. Perfusion of dopamine and the dopamine receptor agonist (±)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide into the brain induced excitatory as well as inhibitory modulation of spontaneous activity. The physiological effects of both drugs were reversible and showed concentration dependency in the concentration range 10−7to 10−3 M. Two vertebrate-derived dopamine receptor antagonists, chlorpromazine and fluphenazine, reversibly blocked the action of dopamine (10−5 M). The threshold for antagonistic blockade by chlorpromazine and fluphenazine occurred at a relatively low concentration (10−7 M) and was concentration dependent. These data collectively suggest that dopamine plays a physiological role in the crayfish brain, stimulating putative dopamine receptor(s) to alter neuronal activity.