Immunocytochemical Demonstration of Serotonin and Neuropeptides in the Nervous System of <i>Gyrodactylus salaris</i> (Monogenea)

Abstract

Abstract A whole mount immunocytochemical (ICC) method has been used for the investigation of immunoreactivity (IR) to the molluscan cardioactive peptide FMRF‐amide, to 9 vertebrate neuropeptides—leu‐enkephalin, growth hormone‐releasing factor (GRF), urotensin I, urotensin II, bovine pancreatic peptide (BPP), β‐endorphin, substance P, secretin and insulin—and to the bioamine 5‐HT in the nervous system (NS) of the trematode Gyrodactylus salaris belonging to the taxon Monogenea. Positive results were obtained using antisera to FMRF‐amide, leu‐enkephalin, urotensin I, GRF and to 5‐HT. The present results are the first documentation of the presence of neuroregulatory peptides and a bioamine in the nervous system (NS) of Monogenea. Differences in the distribution pattern of the IR to the different antisera indicate that different subsets of neurons are revealed. In addition, details of the basic neuroanatomical pattern in monogeneans are confirmed by the whole mount ICC method used in this study. Negative results were obtained with antisera to urotensin II, substance P, β‐endorphin, secretin, insulin and bovine pancreatic polypeptide (BPP).