Pietersen C Y, Bosker F J, Postema F, den Boer J A
Department of Psychiatry, Medical Faculty, UMCG, The Netherlands.
Lab Anim. 2006 Apr;40(2):180-5. doi: 10.1258/002367706776319006.
Many fear conditioning studies use electric shock as the aversive stimulus. The intensity of shocks varies throughout the literature. In this study, shock intensities ranging from 0 to 1.5 mA were used, and the effects on the rats assessed by both behavioural and biochemical stress parameters. Results indicated a significant difference with respect to defaecation and freezing behaviour between controls and those animals that received a shock. Significant differences in corticosterone levels were also noted between controls and those groups that received a shock. No significant differences were found between the shock groups with regards to the stress parameters measured in our fear conditioning paradigm, indicating that the two shock groups were similarly stressed. Increased significance levels were noted for freezing behaviour as well as a lower standard error of means was found in the highest shock intensity group. We therefore recommend using the higher shock intensity (1.5 mA) as the rats in the higher shock intensity group were more homogeneously fear-conditioned and therefore the results should be more reproducible and robust than in the lower shock intensity group. This would allow for fewer rats to be used in order to gain an accurate impression of the conditioning paradigm employed.
许多恐惧条件反射研究使用电击作为厌恶刺激。在整个文献中，电击强度各不相同。在本研究中，使用了0至1.5毫安的电击强度，并通过行为和生化应激参数评估对大鼠的影响。结果表明，对照组与接受电击的动物在排便和僵住行为方面存在显著差异。对照组与接受电击的组之间在皮质酮水平上也存在显著差异。在我们的恐惧条件反射范式中测量的应激参数方面，电击组之间未发现显著差异，这表明两个电击组受到的应激相似。在最高电击强度组中，僵住行为的显著性水平增加，并且平均标准误差更低。因此，我们建议使用更高的电击强度（1.5毫安），因为在更高电击强度组中的大鼠恐惧条件反射更均匀，因此结果应该比低电击强度组更具可重复性和稳健性。这样可以使用更少的大鼠来准确了解所采用的条件反射范式。
