Center for the Study of Emotion and Attention

描述（由申请人提供）：我们在恐惧增强惊吓试验中发现，向杏仁核内侧（Me）局部注射吗啡完全阻断条件恐惧的表达，而向中央（Ce）、基底外侧（Bla）或尾状壳核注射相同剂量的吗啡则没有效果。注射吗啡的作用被同时注射纳洛酮完全逆转。此外，局部注射纳洛酮完全阻止了全身注射吗啡阻断恐惧增强惊吓的作用。局部输注选择性阿片激动剂与吗啡的作用相似。目前还不清楚为什么局部注入吗啡能如此有效地阻止恐惧增强的惊吓，因为我们还没有发现Me的损伤会阻止恐惧增强的惊吓。虽然有报道称Me向Ce投射，但我们认为这种明显的投射可能是由于示踪剂扩散到Ce，因为我们没有发现通过将敏感的顺行示踪剂生物素化右旋糖酐离散输注到Me中，Me向Ce投射。相反，Me主要投射到终纹的前内侧床核（BNSTam），后中间BNSTpi)和下丘脑腹内侧（VMH）。因为BNST大量地投射到Ce，事实上，最严重地投射到Ce的输出区从Me到BNST再到Ce很可能参与了一个抑制回路由吗啡与Me中的受体结合而激活。或者，大脑的其他区域也可能参与这个假定的恐惧抑制回路。为了评估这一点，我们将吗啡注入脑内，然后用免疫细胞化学分析脑Fos蛋白作为神经元激活的标志。局部注射吗啡可导致脑内肌区、中隔外侧核腹侧区及bbnst邻近区域、Ce和Bla交界的嵌入细胞团和腹侧坐骨下的Fos增加。因为这些区域中的一些与恐惧的抑制有关，我们相信我们可能已经进入了一个与恐惧抑制有关的神经网络。因此，我们将确定BNST、腹侧耻骨下带、外侧隔、下丘脑腹内侧和插层细胞在吗啡局部给药的抗焦虑作用中的作用，以及吗啡、丁螺环酮和地西泮全身给药的抗焦虑作用。我们还将评估阿片受体在Me， Bla中的神经肽Y （NPY）细胞和Bla中的GABA以及上述确定的各种脑区域中的作用，在恐惧增强惊吓的消退和条件抑制中。最后，我们将对麻醉大鼠进行气味介导的恐惧保留、消退和条件抑制的脑成像，使用功能磁共振成像（fmri）在11t磁铁上测量血压

DESCRIPTION (provided by applicant): We have found in the fear potentiated startle test that bilateral local infusion of morphine into the medial nucleus of the amygdala (Me) completely blocks the expression of conditioned fear whereas infusion of comparable doses into the central (Ce), basolateral (Bla) or caudate-putamen had no effect. The effects of morphine infused into the Me were completely reversed by co-infusion of naloxone into the Me. Moreover, local infusion of naloxone into the Me completely prevented morphine, given systemically, from blocking fear potentiated startle. Local infusion of mu or delta selective opiate agonists had similar effects to morphine. At the present time it is not clear why local infusion of morphine into the Me so effectively blocks fear potentiated startle because we have not found that lesions of the Me block fear potentiated startle. Although the Me has been reported to project to the Ce we believe this apparent projection probably resulted from spread of the tracer into the Ce, because we have not found projections from the Me to the Ce using discrete infusion of the sensitive anterograde tracer biotinylated dextran into the Me. Instead, the Me projects heavily to anteriomedial bed nucleus of the stria terminalis (BNSTam) the posterior intermediate BNSTpi), and the ventromedial hypothalamus (VMH). Because the BNST projects heavily to the Ce, in fact most heavily to the output division of the Ce projections from the Me to the BNST and then to the Ce could well be involved in an inhibitory circuit activated by morphine binding to receptors in the Me. Alternatively, other brain areas might also participate in this putative fearinhibition circuit. To evaluate this, we infused morphine into the Me and then analyzed the brain using immunocytochemistry for Fos protein as a marker of neuronal activation. Local infusion of morphine into the ME led to increases in Fos in the Me, ventral lateral septal nucleus and adjacent areas of the BNST, the intercalated cell mass on the border between the Ce and Bla, and the ventral subiculum. Because some of these areas have been implicated in the inhibition of fear we believe we may have tapped into a neuronal network involved in the inhibition of fear. Hence, we will determine the role of the BNST, ventral subiculum, lateral septum, ventromedial hypothalamus and intercalated cells in the anxiolytic effects of morphine given locally into the Me, as well as the anxiolytic effects of morphine, buspirone and diazepam given systemically. We wll also evaluate the role of opiate receptors in the Me, neuropeptide Y (NPY) cells in the Bla and GABA in the Bla, as well as various brain areas identified above, in extinction and conditioned inhibition of fear potentiated startle. Finally, we will carry out brain imaging of odor-mediated fear retention, extinction, and conditioned inhibition in anesthetized rats usingfMRI in an 11 T magnet measured with blood pressure