针刺镇痛中大致密核心小泡非突触部位的胞吐及胞吐过程的研究

本文首次采用形态与机能相结合的方法研究了大致密核心小泡(LDV)非突触部位的胞吐和胞吐的动态过程。电镜下观察了在针刺镇痛中三叉神经尾侧脊束核胶状质亚核内出现的各阶段的胞吐影像。据此认为,胞吐是按下列过程连续进行的:1.LDV趋近并伸出一细颈与质膜接触、融合,融合后形成只有一层单位膜的隔,进而隔部分地开放,小的通道形成。2.通道进一步扩大,此时LDV是典型的“Ω”断面像,递质开始排入细胞间隙。3.随通道的进一步扩大,LDV内腔完全开放于细胞间隙,成为间隙的一部分。4.LDV的膜并入终末质膜,仅呈弧形弯曲,其凹侧仍留有少量致密物质,随胞吐物质的弥散,弯曲部分的质膜展平,胞吐的痕迹消失。在针刺镇痛过程中,实验组动物出现的非突触部位胞吐影像比对照组明显增多,两组间的差异非常显著(P<0.01),从而有力地说明与痛觉相关的神经元主要是通过非突触部位胞吐LDV内的递质而参与镇痛过程的。本研究为进一步揭示针刺镇痛机理提供了形态学依据,同时也有力地支持了LDV非突触部位胞吐可能是神经肽释放的主要方式的学说。

STUDIES OF NONSYNAPTIC EXOCYTOSIS AND EXOCYTOTIC PROCESSES OF LARGE DENSE CORED VESICLES DURING ACUPUNCTURE ANALGESIA

In the present article both the nonsynaptic exocytosis arld exocytotic dynamic proeesses were investigated by means of combining morphological with physiological techniques. Exocytotic profiles in the substantia gelatinosa of caudal spinal trigeminalnucleus were observed under the electron microscope during different stages of acupuncture analgesia. According to the captured profiles, it is suggested that the successive processes of exocytosis took place as followss 1. The large dense cored vesicle (LDV) moved toward the membrane, at the same time, a neck was stretched then it proceeded to touch and fuse with the terminal membrane, consequently a diaphragm was formed between LDV and the intercellular space, finally the diaphragm opened partly, a small channel was formed. 2. As the chanrel was expanding gradually,the LDV began to release its contents by way of the channel into intercellular space. 3. As the LDV opened up completely, the inside cavity of LDV turned out to face the intercellular space. 4. The membrane patch of LDV turned into arched profile in appearance and some dense substance remained in curvature side. At last, the dense substance diffused into the space, the trace of exocytosis was disappeared. The data collected from both experiment and control groups were processed statistically, the results showed that the exocytotic profiles increased obviously in experiment groups than in the control groups (P<0.001). As a very significant difference was present between two groups it is strongly suggested that some neurons concerned took part in acupuncture analgesia by releasing their transmitter from LDV at nonsynaptic areas. The results also provided powerful morphological evidence for the hypothesis that neuropeptides are released into intercellular space by exocytosis at the structurally nonspecialized areas.