Meeting Abstract
Neuropeptides are important modulators of neural activity, allowing neural networks, such as the central pattern generators (CPGs) that control rhythmic movements, to alter their output and thus generate behavioral flexibility. Isoforms of a neuropeptide family vary in physical structure, allowing potentially distinct functional neuromodulatory effects on CPG systems. While some familial neuropeptide isoforms can differentially affect a system, others in the same family may elicit indistinguishable effects. Here, we examined the effects elicited by members of a novel family of six peptide hormone isoforms (GSEFLamides: I-, M-, AL-, AM-, AV-, and VM-GSEFLamide) on two CPG systems in the American lobster, Homarus americanus. The cardiac CPG drives rhythmic, neurogenic heart contractions, while the stomatogastric nervous system controls the gastric mill and pyloric filter regions of the foregut. Five of the six GSEFLamides elicited similar increases in contraction amplitude when perfused through the isolated lobster heart, while one (AVGSEFLamide) had virtually no effect. Although none of the peptides elicited a significant change in contraction frequency in pooled data, most of the isoforms caused changes that varied across individuals; the smallest range of changes was elicited by AVGSEFLamide. Using extracellular recordings, we found that the same five GSEFLamide isoforms enhanced the activity of the gastric mill pattern, while AVGSEFLamide did not alter the output of the gastric mill CPG. In contrast, the pyloric CPG was not modulated by any isoforms of this family.
