Dopamine in crayfish and other crustaceans: distribution in the central nervous system and physiological functions

Dopamine is widely distributed in the crustacean nervous system and has a diverse array of physiological effects. Immunocytochemical studies of several species have shown that dopamine- and/or tyrosine hydroxylase-containing cells occur in all ganglia of the central nervous system and that processes from some of these cells link ganglia of the ventral nerve cord. This study describes the distribution of tyrosine hydroxylase-containing cells in the central nervous system of a crayfish (Orconectes rusticus) and compares this information to available data from other species. The distribution of tyrosine hydroxylase (an enzyme in the synthetic pathway between tyrosine and dopamine) in O. rusticus is similar to that reported for marine species. However, differences were observed in the number of neurons in some ganglia and in the axonal projections of the L cell, which were more extensive in O. rusticus than in other species studied thus far. We also review the physiological effects of dopamine in crayfish and other crustaceans, focusing on the amine's actions in the endocrine, cardiovascular, and nervous systems, and on behavior when injected into freely-moving animals.