Gene expression and pharmacology of nematode NLP-12 neuropeptides

This study examines the biology of NLP-12 neuropeptides in Caenorhabditis elegans, and in the parasitic nematodes Ascaris suum and Trichostrongylus colubriformis. DYRPLQFamide (1 nM–10 μM; n≥6) produced contraction of innervated dorsal and ventral Ascaris body wall muscle preparations (10 μM, 6.8±1.9 g; 1 μM, 4.6±1.8 g; 0.1 μM, 4.1±2.0 g; 10 nM, 3.8±2.0 g; n≥6), and also caused a qualitatively similar, but quantitatively lower contractile response (10 μM, 4.0±1.5 g, n=6) on denervated muscle strips. Ovijector muscle displayed no measurable response (10 μM, n=5). nlp-12 cDNAs were characterised from A. suum (As-nlp-12) and T. colubriformis (Tc-nlp-12), both of which show sequence similarity to C. elegans nlp-12, in that they encode multiple copies of –LQFamide peptides. In C. elegans, reverse transcriptase (RT)-PCR analysis showed that nlp-12 was transcribed throughout the life cycle, suggesting that DYRPLQFamide plays a constitutive role in the nervous system of this nematode. Transcription was also identified in both L3 and adult stages of T. colubriformis, in which Tc-nlp-12 is expressed in a single tail neurone. Conversely, As-nlp-12 is expressed in both head and tail tissue of adult female A. suum, suggesting species-specific differences in the transcription pattern of this gene.