Gill endocrine cells in the goldfish Carassius carassius var. auratus and their impairment following experimental lead intoxication.

The presence of endocrine cells in the gills of the goldfish Carassius carassius and the effects of lead intoxication (5 mg l(-1)) on their relative abundance and secretory activity were studied. Endocrine cells synthesizing peptido-like (met and leu-enkephalin and neuropeptide Y) and serotonin-like substances were detected in gill filaments by immunocytochemical procedures. Decreased immunoreactivity for two enkephalins and neuropeptide Y was observed after 48 and 96 h lead exposure. In contrast, increased serotonin immunoreactivity was evident after a one-week treatment. A search for Ca++-binding proteins was also carried out by immunocytochemical methods. Calbindin D-28K and S-100-like molecules were detected in gill epithelium, and their expression appeared enhanced after lead exposure.