Study on neural subtrates involved in taste-aversion learning by means of molecular biology.

学习的形成涉及到对刺激的反应中蛋白质、mrna等的产生增加。Yamamoto等人（1993）报道了大鼠对正常大鼠的各种味觉溶液的反应，以及动物学习条件性味觉（CTA）后对条件性味觉的反应，臂旁核（PBN）中的fos蛋白。在本项目中，我们参照PBN研究了CTA形成时小鼠岛叶皮层（包括味觉皮质区）FOS蛋白的产生。当小鼠饮用碱性味觉溶液时，不同味觉诱导PBN不同亚核FOS蛋白表达：NaCl、蔗糖和HCl诱导外侧中央亚核FOS阳性神经元增多，HCl也在腹侧亚核产生FOS阳性神经元。奎宁在外侧外亚核产生少量fos阳性神经元。味觉传递神经元所在的区域未发现fos阳性神经元。在大鼠中，fos阳性神经元在其他亚核中也被诱导。在岛皮层中，蔗糖诱导初级体感区和颗粒状岛皮层的fos阳性神经元较多，而包括NaCl在内的其他味觉刺激在非颗粒状岛皮层的fos阳性神经元较少。小鼠在饮用LiCl引起咸味和内脏疾病后，PBN外侧中央亚核和外侧外亚核可见fos阳性细胞。腹腔内注射仅引起内脏疾病的LiCl仅在外侧外亚核产生fos阳性神经元。在这两种情况下，fos阳性细胞均出现在颗粒异常的岛叶皮层。在小鼠通过将CTA与内脏疾病联系起来而学会了NaCl或蔗糖的CTA后，条件刺激在PBN的外侧中央和腹侧亚核以及非颗粒皮层诱导fos阳性细胞，尽管这种刺激只在PBN的外侧外核诱导fos阳性细胞。通过原位杂交观察c-fos mRNA的诱导，证实了这些发现。目前的研究结果表明，参与CTA的神经回路在小鼠和大鼠之间存在一定程度的差异。少

Formation of learning involves increase in production of protein, mRNAs and so forth in response to stimuli. Yamamoto et al. (1993) reported about FOS-protein in the parabrachial nucleus (PBN) of rats in reponse to various taste solution in normal rats, and to conditoned taste after the animal learned conditioned taste-aversion (CTA). In the present project, we studied the production of FOS protein in insular cortex including the gustatory cortical area in mice at CTA formation, in reference to that in the PBN.When mice drunk basic taste solution, different taste induced FOS protein in different subnucleus of the PBN : NaCl, sucrose snd HCl induced many FOS-positive neurons at the lateral central subnucleus, and HCl produced them at the ventral subnucleus, as well. Quinine yielded a few FOS-postive neurons at the lateral external subnucleus. No FOS-positive neuron was found at the region where taste relay neurons have been located previously. In rats, FOS-positive neurons were induced … More in some other subnucleus, as well. In the insular cortex, sucrose induced many FOS-positive neurons at primary somatosensory area and granular insular cortex, while other taste stimuli including NaCl a fewer number of such neurons in the dysgranular insular cortex. After mice received salty taste and visceral illness by drinking LiCl, FOS-posiitive cells were seen at the lateral central and lateral external subnucleus of the PBN.Intraperitoneral injection of LiCl which induces only visceral illness produced FOS-positive neurons only at the lateral external subnucleus. In both cases, FOS-positive cells were noted at the dysgranular insular cortex. After mice learned CTA to NaCl or sucrose by associating it with visceral illness, either conditioned stimulus induced FOS-positive cells at the lateral central and ventral subnucleus of the PBN,and at the dysgranular cortex, though such a stimulus induced them only at the lateral external nucleus of the PBN.These findings were confirmed by observing induction of c-fos mRNA by in situ hybridization.The present results indicate that neural circuits involved in CTA differ in some degree between mice and rats. Less