When injected at 10 μM, most Ascaris neuropeptides have potent effects on Ascaris locomotion. We have previously reported that AF1 and AF2 produce a stiffening of the body wall, decreases in body length, and a dramatic elevation in cAMP (Reinitz et al., 2000). Here we extend the list of peptides tested through both behavioral and cAMP assays, and have also assayed for changes in cGMP. Besides its effect on elevating cAMP levels, AF1 (
afp-7) also elevates cGMP. Peptides AF3,4,10,13,
and14 (encoded by
afp-1) caused increases in the number of propagating waveforms and no changes in cAMP or cGMP. AF5 (
afp-2) produced minor effects on locomotion and yet reduced cAMP. Of the peptides encoded by
afp-6, both AF21 and AF22, significantly decreased cAMP; additionally AF22 elevated cGMP, but not as dramatically as AF1 did. Afp-11 encodes 12 peptides; AF26, AF29, and AF41 decreased cAMP and interestingly AF31 elevated cAMP. The peptides AF19, AF34, and AF35 (
afp-13), produced flaccid paralysis, abolished waveforms and locomotion, however only AF19 and AF34 significantly decreased cAMP. These results indicate a correlation between flaccid relaxation and lowering of cAMP. Potentially there are two G protein coupled receptors for AF1 one leading to Gs activation of adenylate cyclase and the other leading to increased cGMP.