成人和大鼠阴茎包皮及包皮系带内降钙素基因相关肽免疫阳性神经末梢的分布及来源

THE DISTRIBUTION AND ORIGIN OF CGRP IMMUNOREACTIVE NERVE TERMINALS IN THE PREPUCE AND FRENULUM OF PENIS

目的探讨人和大鼠阴茎包皮和包皮系带内降钙素基因相关肽(CGRP)免疫阳性神经末梢的分布和起源。方法采用免疫组织化学法观察成人阴茎包皮和包皮系带内CGRP免疫阳性神经末梢的分布,通过荧光金(FG)逆行标记和CGRP免疫荧光标记相结合法研究大鼠包皮系带内CGRP免疫阳性神经末梢的起源。结果成人阴茎包皮及包皮系带内均有CGRP免疫阳性神经末梢存在,主要位于表皮基底层和棘细胞层内,呈树枝状或念珠状分布,大多成束走行。阴茎系带处CGRP免疫阳性神经末梢的分布密度明显大于阴茎包皮处。大鼠的阴茎包皮和包皮系带内也有类似的CGRP免疫阳性神经末梢分布,结合FG逆行标记法研究发现,神经末梢起源于第6腰髓对应的背根神经节(L6-DRG)和第1骶髓对应的背根神经节(S1-DRG)的神经元。CGRP免疫荧光标记细胞大多为中小型,呈深绿色,沿神经束成行排列或散在分布。FG/CGRP双标阳性细胞均为中小型,其数量占FG逆标阳性细胞总数的二分之一。结论人和大鼠阴茎包皮及包皮系带内存在着大量的CGRP免疫阳性神经末梢;大鼠实验表明,这些末梢来源于L6-DRG和S1-DRG,提示CGRP可能参与阴茎包皮及包皮系带感觉信息的传递。

Objective To study the distribution and origin of calcitonin gene-related peptide （CGRP） immunoreactive nerve terminals in the prepuce and frenulum of penis of human and mice. Methods The CGRP-immunoreactive nerve terminals in the prepuce and frenulum of penis were detected by the method of immunohistochemistry. The fluoro-gold （FG） retrogradely tracing and CGRP immunofluorescence were used to tracing the origin of CGRP-immtmoreactive terminals in the penile frenulum of rats. Results In the prepuce and frenulum of adult penis, CGRP-immunoreactive nerve terminals were mainly observed in the basal stratum and spinal stratum of epidermis distributing in a cluster. These nerve terminals were arburescent and beady in appearance. The density of these nerve terminals was significantly higher in frenulum than that in prepuce. The distribution of CGRP-immunoreactive nerve terminals in rats was similar to that of in adult. FG retrogradely tracing method found that the FG retrolabelled neurons were localized in L6-DRG and S1-DRG. Combined CGRP method indicated that a number of DRG neurons were showed CGRP-immunoreactive. CGRP-positive neurons were mainly moderate or small-sized, intense immunostained, bright green granules appeared as FITC fluorescence in the cytoplasm. These positive-neurons were arranged in rows or spots among nerve bundles. A half of FG-labelled neurons also showed CGRP-immunoreactive expression in L6-DRG and St-DRG respectively. All of FG/CGRP double-labelled neurons were moderate or small-sized. Conclusion Large numbers of CGRP-immunoreactive nerve terminals were observed in the penile frenulum of human and rats. These terminals were originated from the peripheral branches of CGRP-immunoreactive neurons in L6-DRG and S1-DRG of rats. It is suggested that CGRP may take part in the transmission of nociception in the prepuce and frenulum of penis.