An indirect immunocytochemical technique combined with confocal
scanning laser microscopy has been used to demonstrate immunoreactivities
to
the nonapeptide, RPPGFSPFR (bradykinin, BK) and the endogenous flatworm
regulatory
peptide, GYIRFamide in the nervous system of the monogenean, Diclidophora
merlangi. In addition, a simultaneous
double-labelling technique was employed to examine possible co-localization
of
GYIRFamide- and neuropeptide F (NPF)
immunoreactivities, using antisera to the C-terminal nonapeptide-amide
of NPF
(Moniezia expansa, FAIIGRPRF.NH2).
BK immunostaining was restricted to a small population of nerve cells and
associated fibres within the ventral nerve cords
and to 2 pairs of nerve cells innervating the cirrus and the pharynx, respectively.
No immunopositive nerve cells and fibres
were identified within the brain or in association with the female reproductive
apparatus. In contrast, GYIRFamide
staining was abundant throughout the central and peripheral nervous systems,
and appeared similar to the staining pattern
revealed using an FMRFamide antiserum. GYIRFamide immunoreactivity was
localized to nerve cells and fibres within
the paired cerebral ganglia and the longitudinal ventral, dorsal and lateral
nerve cords and their numerous interconnecting
transverse commissures. The plexuses of the buccal suckers, pharynx and
clamps
of the haptor were strongly immunopositive for GYIRFamide, as were nerve
cells
innervating the ootype, the oviduct and the vitelline reservoir of the
reproductive apparatus. Double-labelling experiments indicated an apparent
co-localization of GYIRFamide and NPF immunoreactivities.