Meeting Abstract
Oxytocin and related peptides are present in animals from most phyla including Annelida. In the earthworm Eisenia fetida annetocin excites the isolated crop-gizzard. Our lab showed that this peptide and other oxytocin related peptides also stimulated the crop-gizzard of Lumbricus terrestris. Two oxytocin related peptides are predicted in the genes of the earthworm of Lumbricus rubellus, Lumbricus 1 and 2. Therefore, we tested Lumbricus 1 on the crop-gizzard of the related species L. terrestris. The crop-gizzard was removed from the animal, placed in a tissue bath filled with earthworm saline, and attached to a force transducer, which was connected to a computer using Iworx software to record the contractions. Increasing concentrations of peptide were injected into the tissue bath and the resulting changes in contraction rate and amplitude were used to create log-concentration response curves. Lumbricus 1 may cause an increase in contraction rate and a biphasic response in contraction amplitude. Of the nine trials, five showed an increase in rate with Lumbricus 1, however the variability of the data led to large standard error bars when graphing the average response. The contraction amplitude data exhibited too much variability between each trial to determine any effect. Throughout each of the trials, a biphasic response was observed, but no persistent nature was seen between them. Since oxytocin was excitatory on all preparations tested in the past, we are currently challenging the same crop-gizzard preparations with alternating, increasing doses of oxytocin and Lumbricus 1. This regimen should clarify the effects of Lumbricus 1 on the isolated earthworm crop-gizzard.
