Immunochemical evidence for met-enkephalin-like and leu-enkephalin-like peptides in tissues of the earthworm, Lumbricus terrestris

The presence of met- and leu-enkephalin-like immunoreactive materials in nerve, gut, seminal vesicle and body wall tissues of the earthworm Lumbricus terrestris has been demonstrated by means of radioimmunoassay technique. The greatest activity of met- and leu-enkephalin-like immunoreactivity in earthworm gut appears in regions of high digestive enzyme activity and gastrin-like immunoreactivity where it presumably plays a role in regulation of gut function. In all tissues studied the levels of met-enkephalin-like immunoreactivity were higher than that of leu-enkephalin-like immunoreactivity. Dual localization of met- and leu-enkephalin-like immunoreactivity in earthworm gut and nerve tissues follows the pattern observed of peptide hormones in vertebrates which are common to both endocrine and non-endocrine tissues.