OLFACTORY DISTURBANCE INDUCED BY DEAFFERENTATION OF SEROTONERGIC FIBERS IN THE OLFACTORY-BULB
OLFACTORY DISTURBANCE INDUCED BY DEAFFERENTATION OF SEROTONERGIC FIBERS IN THE OLFACTORY-BULB
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DOI：
10.1016/0306-4522(94)90396-4
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发表时间：
1994-08-01
期刊：
影响因子：
3.3
通讯作者：
MIWA, T
中科院分区：
文献类型：
--
作者：
MORIIZUMI, T;TSUKATANI, T;MIWA, T
脑干的多巴胺能神经元广泛投射到整个中枢神经系统，嗅球是5-羟色胺上行通路的主要前脑靶点之一。(13根据生理学研究，（3，5）嗅球神经元的自发放电率被麻醉性应用的5-羟色胺降低。然而，延髓5-羟色胺在嗅觉中的作用仍然没有答案。在本研究中，我们发现，使用5，7-二羟色胺，一个特定的神经毒素的5-羟色胺，条件大鼠学习，以避免一个驱避剂的嗅觉失去了辨别能力，通过去传入的延髓神经元能纤维。这种嗅觉功能障碍并没有发生在早期阶段（注射毒素后三天），当嗅球中的嗅神经能纤维消失时，但在几周后发展。有趣的是，组织学检查显示，球肾小球的显着收缩，这是一个主要的终止网站的球顶肾上腺素能纤维，也是一个突触部位的嗅觉受体细胞和延髓输出神经元。结果表明，大鼠嗅球中的肾上腺素能纤维的缺失导致肾小球萎缩和嗅觉障碍。
The serotonergic neurons of the brain stem project widely throughout the central nervous system, and the olfactory bulb is one of the major forebrain targets of the ascending serotonin pathway.(13,16) According to physiological studies,(3,5) neurons of the olfactory bulb were found to reduce their spontaneous discharge rates by electrophoretically applied serotonin. However, roles of the bulbar serotonin in the sense of smell remain unanswered. In the present study, using 5,7-dihydroxytryptamine, a specific neurotoxin for serotonin, we found that the conditioned rats who learned to avoid a repellent by olfaction lost ability of discrimination by deafferentation of the bulbar serotonergic fibers. Such olfactory dysfunction did not occur in the early stage (three days after injection of the toxin) when the serotonergic fibers disappeared in the bulb, but developed a few weeks later. Interestingly, histological examination revealed marked shrinkage of the bulbar glomerulus which is a major termination site of the bulbopetal serotonergic fibers, and also a synaptic site of olfactory receptor cells and bulbar output neurons. The results indicate that depletion of the serotonergic fibers in the olfactory bulb causes glomerular atrophy and olfactory disturbance in the rat.