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Altered host behaviour and brain serotonergic activity caused by acanthocephalans: evidence for specificity
Luke Tain1, Marie-Jeanne Perrot-Minnot, Frank Cézilly
1Equipe Ecologie Evolutive, UMR CNRS 5561 Biogéosciences, Université de Bourgogne, 6 boulevard Gabriel, 21000 Dijon, France.
Proceedings. Biological Sciences
|October 4, 2006
Summary
Parasitic manipulation alters amphipod behavior by changing serotonin levels. This study links altered serotonin (5-hydroxytryptamine, 5-HT) activity to specific behavioral changes, enhancing parasite transmission.
Area of Science:
- Ecology
- Parasitology
- Neurobiology
Background:
- Parasites can manipulate host behavior to increase transmission.
- The physiological mechanisms underlying parasite-induced behavioral changes are not fully understood.
- Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter known to influence behavior.
Purpose of the Study:
- To investigate the link between parasitic manipulation and host serotonergic activity.
- To determine if altered 5-HT levels are responsible for specific behavioral changes in Gammarus pulex infected by acanthocephalans.
- To explore the specificity of 5-HT's role in mediating parasite-induced behavioral alterations.
Main Methods:
- Infection of Gammarus pulex with different acanthocephalan species (Pomphorhynchus laevis, Pomphorhynchus tereticollis, Polymorphus minutus).
- Behavioral assays to measure phototactism and geotactism in infected and uninfected amphipods.
- Injection of serotonin (5-HT) into uninfected amphipods to mimic behavioral changes.
- Measurement of brain 5-HT immunoreactivity using immunohistochemistry.
Main Results:
- Pomphorhynchus species altered phototactism, while Polymorphus minutus altered geotactism in G. pulex.
- Serotonin injection mimicked the phototactic changes induced by Pomphorhynchus infection.
- Infected G. pulex with altered phototaxis showed increased brain 5-HT immunoreactivity.
- No difference in 5-HT immunoreactivity was observed in G. pulex infected with P. minutus (which altered geotaxis).
- 5-HT immunoreactivity correlated with the degree of manipulation in P. tereticollis-infected individuals.
Conclusions:
- Altered serotonergic (5-HT) activity is functionally linked to specific behavioral manipulations (phototaxis) by acanthocephalan parasites.
- The observed behavioral alterations are not mere by-products of infection but adaptive mechanisms for transmission.
- Different parasite species may employ distinct physiological pathways to manipulate host behavior.
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