Van Reenen C G, Hopster H, Van der Werf J T N, Engel B, Buist W G, Jones R B, Blokhuis H J, Korte S M
Animal Sciences Group of Wageningen University and Research Centre (WUR), P.O. Box 65, 8200 AB, Lelystad, The Netherlands.
Physiol Behav. 2009 Feb 16;96(2):307-14. doi: 10.1016/j.physbeh.2008.10.016. Epub 2008 Oct 29.
The present study examined the effects of the intravenous administration of the anxiolytic drug brotizolam on the behavioral and physiological responsiveness of calves to novelty in a dose response fashion. Holstein Friesian heifer calves (39-41 weeks of age; body weight 200-300 kg) received an intravenous injection of either a vehicle control (12 calves) or one of four doses of brotizolam (8 calves per dose): 0.0125, 0.05, 0.2 and 0.8 mg/100 kg body weight. They were then individually subjected to a 'combined' test involving exposure to a novel environment (open field, OF) for 5 min followed by the sudden introduction of a novel object (NO) that remained in place for a further 10 min. Behavioral, heart rate and plasma cortisol responses were recorded in all animals. Compared to vehicle treatment, the highest dose of brotizolam dose-dependently and significantly increased the time spent in locomotion and the distance travelled near the NO, as well as the time spent in contact with the NO. In addition, post-test plasma cortisol concentrations changed in a dose-dependent manner over time: they decreased between 0 and 10 min after the test in calves that had received the two highest doses of brotizolam, whereas they increased in vehicle-treated and low-dosage calves. There were no effects of brotizolam on vocalization or locomotion during the OF phase of the test or on vocalization following introduction of the NO. These findings strongly support the notion that interaction with a novel object in a novel arena represents a behavioral index of fear and fearfulness in calves, and that vocalization and locomotion in an OF reflect other independent characteristics.
本研究以剂量反应方式，考察了静脉注射抗焦虑药物溴替唑仑对犊牛面对新事物时行为和生理反应的影响。荷斯坦弗里生小母牛犊（39 - 41周龄；体重200 - 300千克）静脉注射以下药物之一：溶媒对照剂（12头犊牛）或四种剂量的溴替唑仑之一（每剂量8头犊牛）：0.0125、0.05、0.2和0.8毫克/100千克体重。然后，将它们分别进行一项“综合”测试，包括在新环境（旷场，OF）中暴露5分钟，随后突然引入一个新物体（NO），该物体在原地再放置10分钟。记录所有动物的行为、心率和血浆皮质醇反应。与溶媒处理相比，最高剂量的溴替唑仑剂量依赖性地显著增加了在运动上花费的时间、在靠近新物体处行进的距离以及与新物体接触的时间。此外，测试后血浆皮质醇浓度随时间呈剂量依赖性变化：在接受两种最高剂量溴替唑仑的犊牛中，它们在测试后0至10分钟内下降，而在接受溶媒处理和低剂量处理的犊牛中则升高。在测试的旷场阶段，溴替唑仑对发声或运动没有影响，在引入新物体后对发声也没有影响。这些发现有力地支持了以下观点：在新环境中与新物体的互动代表了犊牛恐惧和惊恐的行为指标，而旷场中的发声和运动反映了其他独立的特征。
