title: Possible serotonergic mediation of tonic immobility: effects of morphine and serotonin blockade.
abstract: Small doses of morphine, within the range of 0.02 mg/kg to 10.15 mg/kg were administered to chickens (Gallus gallus) and the effect on the fear-based tonic immobility (TI) response determined. All doses at and above 0.13 mg/kg enhanced the TI response significantly above the levels produced for the 0.2 mg/kg dose and the distilled water control group. Administration of a single large dose of p-chlorophenylalanine prevented the morphine-induced enhancement of TI. It was suggested that serotonin systems mediate morphine effects on tonic immobility in chickens.
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002645:Chickens; D004924:Escape Reaction; D005239:Fear / Q000187:drug effects*; D005260:Female; D010134:Fenclonine / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists
chemical_list: D012702:Serotonin Antagonists; D012701:Serotonin; D009020:Morphine; D010134:Fenclonine