Hicks L E, Maser J D, Gallup G G, Edson P H
Psychopharmacologia. 1975 Apr 30;42(1):51-6. doi: 10.1007/BF00428825.
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.
给鸡（原鸡）注射0.02毫克/千克至10.15毫克/千克范围内的小剂量吗啡，并测定其对基于恐惧的强直性静止（TI）反应的影响。所有0.13毫克/千克及以上剂量的吗啡使TI反应显著增强，高于0.2毫克/千克剂量组和蒸馏水对照组所产生的水平。给予单次大剂量的对氯苯丙氨酸可阻止吗啡诱导的TI增强。研究表明，5-羟色胺系统介导了吗啡对鸡强直性静止的影响。
