Distribution of dopamine-like immunoreactivity suggests a role for dopamine in the courtship display behavior of the blue crab, Callinectes sapidus.

Abstract

Injection of dopamine initiates a posture in the blue crab, Callinectes sapidus, identical to courtship display behavior of the male crab. The threshold for proctolin-induced rhythmic components of courtship display is lowered in preparations when dopamine is co-applied with proctolin. To elucidate the anatomical substrate of this behavior, immunocytochemistry was used to map dopamine-immunoreactive neurons. Courtship display is sex-specific, and dependent on the hormonal, developmental, and seasonal state of the animal. We compared the distribution of dopamine-like immunoreactivity between adults and juveniles of both sexes across seasons, with hormonal alteration, and with the distribution of proctolin-like immunoreactivity. Dopamine-like immunoreactivity was found throughout the nervous system in identical patterns between the sexes and hormonal states. Differences were found between juveniles and adults that are not obviously correlated with the development of behavior. Two areas of staining were of interest: neurites that longitudinally traverse and terminate in the posterior ventral nerve cord, and a neuron in the esophageal ganglion that has projections to the pericardial organ. The results do not suggest that proctolin-like and dopamine-like immunoreactivity co-localize, but in the subesophageal ganglion there was a region of close proximity.