title: Effects of amino acid neurotransmitters on spontaneous muscular activity of the rumen amphistome, Gastrothylax crumenifer.
abstract: Amino acid neurotransmitters play an important role in regulating neuromuscular activity of helminth parasites. The present study aimed to investigate the effects of different amino acid neurotransmitters [L-glutamate, glycine, gamma-aminobutyric acid (GABA)] on spontaneous muscular activity of isometrically mounted Gastrothylax crumenifer. L-Glutamate caused a significant increase in the amplitude and frequency of spontaneous contractions of rumen fluke at 10(-7)-10(-4) m and at 10(-5)-10(-4) m concentrations, respectively. Glycine application (10(-7)-10(-3) m) produced a significant decrease in the amplitude and frequency of spontaneous muscular contractions in a concentration-dependent manner, as compared to control amplitude (0.53 +/- 0.02 g) and frequency (51 +/- 4.65/5 min). Similarly, GABA produced a significant (P < 0.05) decrease in amplitude, baseline tension and frequency of spontaneous muscular contractions of G. crumenifer. To further substantiate the GABA effect, GABAA receptor antagonists, picrotoxin and bicuculline were applied. Picrotoxin (10(-5)-10(-3) m) caused a significant (P < 0.05) increase in amplitude, baseline tension and frequency of the rumen fluke as compared to control; whereas bicuculline did not elicit any observable effect in these attributes in isometrically mounted rumen flukes. These observations suggested that L-glutamate has an excitatory, whereas GABA and glycine have an inhibitory, effect on the spontaneous muscular activity of G. crumenifer.
authors.affiliation: Division of Pharmacology and Toxicology, Indian Veterinary Research Institute, Izatnagar, Bareilly 243 122, UP, India. drpawankv@yahoo.co.in
authors.forename: P K
authors.initials: PK
authors.lastname: Verma
authors.forename: D
authors.initials: D
authors.lastname: Kumar
authors.forename: S K
authors.initials: SK
authors.lastname: Tandan
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D006041:Goats / Q000469:parasitology*; D009434:Neural Pathways / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism / Q000469:parasitology*; D013272:Stomach Diseases / Q000469:parasitology* / Q000662:veterinary; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D018377:Neurotransmitter Agents; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005998:Glycine