The effect of dopamine receptor blockade on motor behavior in Aplysia californica

The mammalian D1- and D2-like receptor blockers SCH-23390 and raclopride were used to block receptors in Aplysia californica, and the effect on reflexes and escape behavior was examined. Four groups of 20 young adults were each injected with SCH-23390, raclopride, SCH-23390 + raclopride, or seawater. The drug (0.0125 mg/g of body weight) was injected 2 mm anterior to the parapodia. After the injection of either SCH-23390 or SCH-23390 + raclopride, there was a significant increase in parapodia opening (P < .001), siphon withdrawal (P < .05), and galloping following tail pinch (P < .01) compared to raclopride-injected or control animals. The data showed that blockade of receptors by SCH-23390, but not raclopride, produced significant changes in motor behavior in A. californica. (C) 2001 Elsevier Science Inc. All rights reserved.