Distribution of calcitonin gene related peptide positive neurofibers in local skin tissues of "Neiting"(ST 44), "Zusanli" (ST 36) and "Futu" (ST 32) regions in the rat

Abstract

To observe the distribution of calcitonin gene related peptide (CGRP)-positive neurofibers in local tissues of "Neiting"(ST 44), "Zusanli" (ST 36) and "Futu" (ST 32) regions in the hind limbs of rats. Five adult male SD rats were used in the present study. The local skin tissues of acupoint "Neiting" (ST 44), "Zusanli" (ST 36) and "Futu" (ST 32) regions were dissected from the rat that underwent transcardiac perfusion with 4% paraformaldehyde, and cut into sections (20 microm in thickness), followed by staining with CGRP fluorescent immunohistochemical method and with phalloidin and DAPI, respectively. After that, CGRP-positive neurofibers of the samples were observed and recorded using a laser confocal microscope. CGRP-positive nerve fibers were found to distribute in the dermis and subcutaneous layers of local tissues of acupoint ST 44, ST 36 and ST 32, mainly concentrating around the vessel-like structure. The number and length of CGRP-positive nerve fibers were most in the ST 44 region, more in the ST 36 region and fewer in the ST 32 region, in turn (P<0.01). The distribution of the vessel-like structure also presented a decreasing trend in the above-mentioned three acupoint regions in turn. CGRP-positive neurofibers are an important element in the local tissues of acupoint ST 44, ST 36 and ST 32 regions, and present a decreasing tendency in the number from the distal to the proximal part of the hind-limb, showing a similar tendency of needling sensation in the human body in which a more hypersensitivity exists in the distal part of the limb.