Effects of melatonin, serotonin, and naloxone on aggression in isolated cichlid fish (Aequidens pulcher).
Intracranial injections of 10 micrograms melatonin, with or without 4 micrograms naloxone, result in reduced aggressive responsiveness by the cichlid fish Aequidens pulcher to a mirror presented 20 min later. Naloxone, when administered on its own, had no behavioral effect. Intracranial injections of 25 micrograms serotonin-creatinine sulphate complex (5HT-CS) also reduced aggression. 5HT-CS's action was abolished if the injection included 10 micrograms S-adenosyl homocysteine (SAH), which inhibits the conversion of serotonin to melatonin. This suggests that the behavioral action of 5HT-CS may be mediated by its conversion to melatonin. There is inconclusive evidence to suggest that 37.5 micrograms 5HT-CS, administered in conjunction with 10 micrograms SAH, may reduce aggressiveness; injection of 50 micrograms 5HT-CS, with or without 10 micrograms SAH, induced a pronounced escape behavior which precluded any measurement of aggressiveness in the fish.
D000374:Aggression / Q000187:drug effects*; D000818:Animals; D005260:Female; D008550:Melatonin / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D010471:Perches / Q000502:physiology*; D010473:Perciformes / Q000502:physiology*; D012435:S-Adenosylhomocysteine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology
D012702:Serotonin Antagonists; D012701:Serotonin; D009270:Naloxone; D012435:S-Adenosylhomocysteine; D008550:Melatonin