Serotonin decreases aggression via 5-HT1A receptors in the fighting fish Betta splendens.
The role of the monoamine neurotransmitter serotonin (5-HT) in the modulation of conspecific aggression in the fighting fish (Betta splendens) was investigated using pharmacological manipulations. We used a fish's response to its mirror image as our index of aggressive behavior. We also investigated the effects of some manipulations on monoamine levels in the B. splendens brain. Acute treatment with 5-HT and with the 5-HT1A receptor agonist 8-OH-DPAT both decreased aggressive behavior; however, treatment with the 5-HT1A receptor antagonist WAY-100635 did not increase aggression. Chronic treatment with the selective serotonin reuptake inhibitor fluoxetine caused no significant changes in aggressive behavior and a significant decline in 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) concentrations. Treatment with the serotonin synthesis inhibitor p-chlorophenylalanine resulted in no change in aggression, yet serotonergic activity decreased significantly. Finally, a diet supplemented with L-tryptophan (Trp), the precursor to 5-HT, showed no consistent effects on aggressive behavior or brain monoamine concentrations. These results suggest a complex role for serotonin in the expression of aggression in teleost fishes, and that B. splendens may be a useful model organism in pharmacological and toxicological studies.
Clotfelter
Ethan D
ED
Department of Biology, Amherst College, Amherst, MA 01002, United States. edclotfelter@amherst.edu
O'Hare
Erin P
EP
McNitt
Meredith M
MM
Carpenter
Russ E
RE
Summers
Cliff H
CH
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000374:Aggression / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D004032:Diet; D004298:Dopamine / Q000378:metabolism; D010134:Fenclonine / Q000494:pharmacology; D005399:Fishes / Q000502:physiology*; D005473:Fluoxetine / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007273:Injections, Intramuscular; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D044282:Receptor, Serotonin, 5-HT1A / Q000187:drug effects*; D012701:Serotonin / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology
D015102:3,4-Dihydroxyphenylacetic Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D004298:Dopamine; D010134:Fenclonine; D005473:Fluoxetine; D006897:Hydroxyindoleacetic Acid; D010879:Piperazines; D011725:Pyridines; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D017367:Selective Serotonin Reuptake Inhibitors; D014364:Tryptophan; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide