Malkusz Danielle C, Yenko Ira, Rotella Francis M, Banakos Theodore, Olsson Kerstin, Dindyal Trisha, Vig Vishal, Bodnar Richard J
Behavioral and Cognitive Neuroscience Cluster, Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, United States.
Department of Psychology, Queens College, City University of New York, New York, NY, United States.
Brain Res. 2015 Jan 30;1596:116-25. doi: 10.1016/j.brainres.2014.11.028. Epub 2014 Nov 20.
Systemic dopamine (DA) D1 (SCH23390: SCH) and D2 (raclopride: RAC) antagonists blocked fructose-conditioned flavor preference (CFP) acquisition and expression. Fructose-CFP acquisition was eliminated by medial prefrontal cortex (mPFC) SCH and mPFC or amygdala (AMY) RAC. Fructose-CFP expression was reduced following SCH or RAC in AMY or nucleus accumbens (NAc). The present study examined fructose-CFP acquisition and expression following SCH and RAC in the medial orbital frontal cortex (MOFC), another ventral tegmental area DA target. For fructose-CFP acquisition, five groups of rats received vehicle, SCH (24 or 48 nmol) or RAC (24 or 48 nmol) in the MOFC 0.5h prior to 8 training sessions with one flavor (CS+/Fs) mixed in 8% fructose and 0.2% saccharin, and another flavor (CS-/s) mixed in 0.2% saccharin. In six 2-bottle choice tests in 0.2% saccharin, similar fructose-CFP preferences occurred in groups trained with vehicle (76-77%), SCH24 (69-78%), SCH48 (70-74%) and RAC48 (85-92%). RAC24-trained rats displayed significant CS+ preferences during the first (79%) and third (71%), but not second (58%) test pair. For fructose-CFP expression, rats similarly trained with CS+/Fs and CS- solutions received 2-bottle choice tests following MOFC injections of SCH or RAC (12-48 nmol). CS+ preference expression was significantly reduced by RAC (48 nmol: 58%), but not SCH relative to vehicle (78%). A control group receiving RAC in the dorsolateral prefrontal cortex displayed fructose-CFP expression similar to vehicle. These data demonstrate differential frontal cortical DA mediation of fructose-CFP with mPFC D1 and D2 signaling exclusively mediating acquisition, and MOFC D2 signaling primarily mediating expression.
全身性多巴胺（DA）D1（SCH23390：SCH）和D2（雷氯必利：RAC）拮抗剂可阻断果糖条件性味觉偏好（CFP）的获得和表达。内侧前额叶皮质（mPFC）的SCH以及mPFC或杏仁核（AMY）的RAC可消除果糖-CFP的获得。在杏仁核或伏隔核（NAc）中注射SCH或RAC后，果糖-CFP的表达降低。本研究检测了在眶额内侧皮质（MOFC）（腹侧被盖区DA的另一个靶点）注射SCH和RAC后果糖-CFP的获得和表达情况。对于果糖-CFP的获得，五组大鼠在进行8次训练前0.5小时，于MOFC中接受溶剂、SCH（24或48 nmol）或RAC（24或48 nmol）注射，训练内容为一种味道（条件刺激+/果糖）与8%果糖和0.2%糖精混合，另一种味道（条件刺激-/糖精）与0.2%糖精混合。在0.2%糖精的六次双瓶选择测试中，接受溶剂训练的组（76 - 77%）、接受24 nmol SCH训练的组（69 - 78%）、接受48 nmol SCH训练的组（70 - 74%）以及接受48 nmol RAC训练的组（85 - 92%）出现了相似的果糖-CFP偏好。接受24 nmol RAC训练的大鼠在第一次（79%）和第三次（71%）测试对中表现出显著的条件刺激+偏好，但在第二次测试对中（58%）未表现出偏好。对于果糖-CFP的表达，用条件刺激+/果糖和条件刺激-溶液进行类似训练的大鼠在MOFC注射SCH或RAC（12 - 48 nmol）后接受双瓶选择测试。与溶剂组（78%）相比，48 nmol RAC显著降低了条件刺激+偏好的表达（48 nmol：58%），但SCH未产生此效果。在背外侧前额叶皮质接受RAC注射的对照组表现出与溶剂组相似的果糖-CFP表达。这些数据表明，额叶皮质DA对果糖-CFP的调节存在差异，mPFC的D1和D2信号专门介导获得过程，而MOFC的D2信号主要介导表达过程。
