Rittenhouse P A, Marchand J E, Chen J, Kream R M, Leeman S E
Department of Pharmacology, Boston University Medical Center, MA 02118, USA.
Peptides. 1996;17(6):1017-22. doi: 10.1016/0196-9781(96)00129-5.
Major complications arising from diabetes mellitus include neuropathic pain and altered peripheral inflammatory responses. Somatostatin (SOM), calcitenin gene-related peptide (CGRP), and substance P (SP) are neuropeptides that modulate pain responses transmitted by primary sensory afferents, the cell bodies of which are located in the dorsal root ganglion (DRG). Thus, the goal of the present study was to determine whether the diabetic condition is associated with altered neuropeptide gene expression in lumbar DRG of the rat. We employed an established animal model in which streptozotocin (STZ, 55 mg/kg) is administered to 6 week-old rats. The hallmark symptoms of hyperglycemia (blood glucose > 400 mg/dl), polydipsia, polyuria, and severe weight loss were maximal at 6 weeks postadministration, at which time animals were sacrificed. For determination of peptide encoding mRNAs distributed in DRG neurons, in situ hybridization histochemistry utilizing S-end-labeled oligonucleotides complimentary to sequences of preprosomatostatin (PPSOM), preprocalcitonin gene related peptide (PPCGRP), preprotachykinin (PPT), or preproneuropeptide Y (PPNPY) mRNA was performed. Silver grains were detected overlying DRG cells by autoradiography on sections of tissue counterstained with thionin. Semiquantitative analysis of differences in silver grain signal were made using an image analysis system, which expressed signals as fCi/microns2. In diabetic rats there was a significant decrease in DRG PPSOM (54%, p < 0.01), and PPCGRP (33%. p < 0.05) mRNA hybridization from the normal values PPT mRNA hybridization signal and SP-like immunoreactivity were not significantly changed in diabetic rat DRGs compared to control. In contrast, there was an increase in the number of cells labeled with PPNPY hybridization in DRG from diabetic rats. These data suggest that CGRP and SOM synthesis in primary sensory neurons is reduced in STZ-induced diabetic rats. These changes could contribute to the painful neuropathies and altered inflammatory responses seen in diabetes mellitus.
糖尿病引发的主要并发症包括神经性疼痛和外周炎症反应改变。生长抑素（SOM）、降钙素基因相关肽（CGRP）和P物质（SP）是神经肽，可调节由初级感觉传入神经传递的疼痛反应，其细胞体位于背根神经节（DRG）。因此，本研究的目的是确定糖尿病状态是否与大鼠腰段DRG中神经肽基因表达的改变有关。我们采用了一种成熟的动物模型，向6周龄大鼠注射链脲佐菌素（STZ，55mg/kg）。高血糖（血糖>400mg/dl）、多饮、多尿和严重体重减轻的标志性症状在给药后6周时最为明显，此时处死动物。为了测定分布在DRG神经元中的肽编码mRNA，利用与前生长抑素原（PPSOM）、前降钙素基因相关肽原（PPCGRP）、前速激肽原（PPT）或前神经肽Y原（PPNPY）mRNA序列互补的S端标记寡核苷酸进行原位杂交组织化学。在用硫堇复染的组织切片上，通过放射自显影检测DRG细胞上的银颗粒。使用图像分析系统对银颗粒信号的差异进行半定量分析，信号以fCi/μm2表示。与正常大鼠相比，糖尿病大鼠DRG中的PPSOM（54%，p<0.01）和PPCGRP（33%，p<0.05）mRNA杂交显著降低。糖尿病大鼠DRG中的PPT mRNA杂交信号和SP样免疫反应性与对照组相比无显著变化。相反，糖尿病大鼠DRG中PPNPY杂交标记的细胞数量增加。这些数据表明，在STZ诱导的糖尿病大鼠中，初级感觉神经元中CGRP和SOM的合成减少。这些变化可能导致糖尿病中出现的疼痛性神经病变和炎症反应改变。
