Mungarndee Suriyaphun S, Lundy Robert F, Norgren Ralph
Department of Neural and Behavioral Sciences, The Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA.
Physiol Behav. 2006 Mar 30;87(3):542-51. doi: 10.1016/j.physbeh.2005.12.008. Epub 2006 Feb 3.
The efficacy of two different unconditioned stimuli (US) in producing conditioned taste aversion (CTA) was tested in rats after bilateral ibotenic acid (IBO) lesions of the gustatory nucleus of thalamus (TTAx) and the medial and lateral parabrachial nuclei (mPBNx, lPBNx). An initial study determined an equivalent dose for the two USs, LiCl and cyclophosphamide (CY), using non-lesioned rats. Subsequently, using a separate set of lesioned animals and their sham controls (SHAM), injections of CY were paired 3 times with one of two taste stimuli (CSs), 0.1 M NaCl for half the rats in each group, 0.2 M sucrose for the other half. After these conditioning trials, the CS was presented twice more without the US, first in a 1-bottle test, then in a 2-bottle choice with water. The acquisition and test trials had 2 intervening water-only days to assure complete rehydration. Two weeks later, the same rats were tested again for acquisition of a CTA using LiCl as the US and the opposite CS as that used during the CY trials. The SHAM and TTAx groups learned to avoid consuming the taste associated with either CY or LiCl treatment. The two PBNx groups failed to learn an aversion regardless of the US.
在大鼠丘脑味觉核（TTAx）以及内侧和外侧臂旁核（mPBNx、lPBNx）经双侧异搏亭酸（IBO）损伤后，测试了两种不同的非条件刺激（US）产生条件性味觉厌恶（CTA）的效果。一项初步研究使用未损伤的大鼠确定了两种非条件刺激（LiCl和环磷酰胺（CY））的等效剂量。随后，使用另一组损伤动物及其假手术对照组（SHAM），将CY注射与两种味觉刺激（CSs）之一配对3次，每组一半大鼠的CS为0.1M NaCl，另一半为0.2M蔗糖。在这些条件试验后，CS在没有US的情况下再呈现两次，首先在单瓶试验中，然后在与水的两瓶选择试验中。获取试验和测试试验之间有两天只给水以确保完全补水。两周后，再次测试相同的大鼠，使用LiCl作为US，与CY试验中使用的相反CS来获取CTA。SHAM组和TTAx组学会避免摄入与CY或LiCl处理相关的味道。无论使用何种US，两个PBNx组都未能学会厌恶反应。
