GABA IN THE NERVOUS-SYSTEM OF PARASITIC FLATWORMS

In an immunocytochemical study, using an antiserum and a monoclonal an tibody specific for the amino acid, gamma-aminobutyric acid (GABA), GA BA-like immunoreactivity (GLIR) has been demonstrated for the first ti me in parasitic flatworms. In Moniezia expansa (Cestoda), GLIR was see n in nerve nets which were closely associated with the body wall muscu lature and in the longitudinal nerve cords. In the liver fluke Fasciol a hepatica (Trematoda), the GLIR occurred in the longitudinal nerve co rds and lateral nerves in the posterior half of the worm. GLIR was als o detected in subtegumental fibres in F. hepatica. The presence of GAB A was verified, using high-pressure liquid chromatography coupled with fluorescence detection. The concentration of GABA (mean+/-S.D.) in M. expansa anterior region was 124.8+/-15.3 picomole/mg wet weight, whil e in F. hepatica it was 16.8+/-4.9 picomole/mg. Since several insectic ides and anti-nematodal drugs are thought to interfere with GABA-recep tors, the findings indicate that GABAergic neurotransmission may be a potential target for chemotherapy in flatworms too.