Meeting Abstract
Serotonin (5-HT) is a potent enhancer of neuromuscular signaling in decapod crustaceans. This has been studied extensively in the dactyl opener muscle of lobsters and crayfish. In that system, serotonin positively modulates neurotransmission through a combination of presynaptic and postsynaptic pathways. Some of these pathways involve an increased concentration of cyclic adenosine monophosphate (cAMP), and that in turn suggests the presence of a serotonin receptor whose activation stimulates adenylyl cyclase. In vertebrates, three known types of 5-HT receptor have this quality, namely 5-HT4, 5-HT6, and 5-HT7. Because 5-HT7 receptors have been identified in some other invertebrates, we decided to inquire whether the American lobster (Homarus americanus) dactyl opener muscle expresses a 5-HT7 receptor. Degenerate primers were designed by comparison of known or putative 5-HT7 receptors from molluscs, insects, crustaceans and annelids. Total RNA was isolated from dactyl opener muscle using Tri Reagent® and then treated with DNase to remove contaminating genomic DNA. Reverse transcription using MMLV (Clontech) yielded cDNA, and standard PCR was used to test the primers. The PCR products of expected size were cloned and sequenced, yielding one sequence which, when compared to other vertebrate and invertebrate monoamine receptors, appears to be a 5-HT7 receptor.
