Nishimura A, Ueda S, Takeuchi Y, Matsushita H, Sawada T, Kawata M
Department of Pediatrics, Kyoto Prefectural University of Medicine, Japan.
Acta Neuropathol. 1998 Dec;96(6):581-95. doi: 10.1007/s004010050939.
Distributional changes of serotonergic fibers associated with aging were demonstrated immunohistochemically. Old rat brains were morphologically characterized by the presence of peculiar features of serotonergic fibers not found in the young adult brain. In 24-month-old rats, these aberrant serotonergic fibers were subdivided into two groups according to morphological alterations: type 1 fibers consisting of thin fibers with moderately enlarged varicosities, and type 2 fibers consisting of much thicker fibers that have even larger varicosities and a tortuous course. These two types of fibers were distributed differentially in the forebrain. Type 1 fibers were found mainly in the striatum and frontoparietal cortex, whereas type 2 fibers were found in the posterior cingulate cortex and dentate gyrus of the hippocampal formation. Both types of aberrant fibers were seen in amygdala, frontoparietal cortex, hypothalamus, and thalamus. In 36-month-old rats, more highly degenerating arborizations were detected, and these aberrant ramifications were classified as follows based on shape as: type 3 fibers consisting of highly arborized thin fibers with a larger number of larger varicosities, and type 4 fibers consisting of thick fibers with abundant larger varicosities. Distributional difference indicated that type 1 fibers progress into type 3 fibers, whereas type 2 develop into type 4 fibers. These findings suggest the possibility that one set of pathological fibers emanate from the dorsal raphe nucleus and the other from the median raphe. Moreover, both two sets of serotonergic fibers show age-related aberrations in their morphology over same time course.
通过免疫组织化学方法证实了与衰老相关的5-羟色胺能纤维的分布变化。老年大鼠大脑在形态学上的特征是存在成年年轻大鼠大脑中未发现的5-羟色胺能纤维的特殊特征。在24月龄大鼠中，这些异常的5-羟色胺能纤维根据形态学改变可分为两组：1型纤维由具有中度膨大曲张的细纤维组成，2型纤维由更粗的纤维组成，这些纤维具有更大的曲张和曲折的走行。这两种类型的纤维在前脑的分布不同。1型纤维主要见于纹状体和额顶叶皮质，而2型纤维见于后扣带回皮质和海马结构的齿状回。杏仁核、额顶叶皮质、下丘脑和丘脑均可见到这两种异常纤维。在36月龄大鼠中，检测到更多高度退化的分支，这些异常分支根据形状分类如下：3型纤维由具有大量较大曲张的高度分支的细纤维组成，4型纤维由具有丰富较大曲张的粗纤维组成。分布差异表明1型纤维发展为3型纤维，而2型纤维发展为4型纤维。这些发现提示了一种可能性，即一组病理纤维起源于中缝背核，另一组起源于中缝正中核。此外，两组5-羟色胺能纤维在相同的时间进程中均表现出与年龄相关的形态异常。
