Parasite manipulation of brain monoamines in California killifish (Fundulus parvipinnis) by the trematode Euhaplorchis californiensis

California killifish (Fundulus parvipinnis) infected with the brain-encysting trematode Euhaplorchis californiensis display conspicuous swimming behaviours rendering them more susceptible to predation by avian final hosts. Heavily infected killifish grow and reproduce normally, despite having thousa...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2009-03, Vol.276 (1659), p.1137-1146
Main Authors: Shaw, J.C, Korzan, W.J, Carpenter, R.E, Kuris, A.M, Lafferty, K.D, Summers, C.H, Øverli, Ø
Format: Article
Language:English
Subjects:
Animals
Average linear density
Biogenic Monoamines - metabolism
Brain
Brain - metabolism
Brain - parasitology
Density
Dopamine
Female
Fish
Fundulidae - parasitology
Infections
Male
Mechanical stress
Metacercariae
Monoamine
Parasite hosts
Parasites
Parasitism
Serotonin
Serotonin receptors
Trematoda - physiology
Trematode
Trematode Infections - metabolism
Trematode Infections - veterinary
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Summary:California killifish (Fundulus parvipinnis) infected with the brain-encysting trematode Euhaplorchis californiensis display conspicuous swimming behaviours rendering them more susceptible to predation by avian final hosts. Heavily infected killifish grow and reproduce normally, despite having thousands of cysts inside their braincases. This suggests that E. californiensis affects only specific locomotory behaviours. We hypothesised that changes in the serotonin and dopamine metabolism, essential for controlling locomotion and arousal may underlie this behaviour modification. We employed micropunch dissection and HPLC to analyse monoamine and monoamine metabolite concentrations in the brain regions of uninfected and experimentally infected fish. The parasites exerted density-dependent changes in monoaminergic activity distinct from those exhibited by fish subjected to stress. Specifically, E. californiensis inhibited a normally occurring, stress-induced elevation of serotonergic metabolism in the raphae nuclei. This effect was particularly evident in the experimentally infected fish, whose low-density infections were concentrated on the brainstem. Furthermore, high E. californiensis density was associated with increased dopaminergic activity in the hypothalamus and decreased serotonergic activity in the hippocampus. In conclusion, the altered monoaminergic metabolism may explain behavioural differences leading to increased predation of the infected killifish by their final host predators.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.2008.1597