Rossner S, Schliebs R, Perez-Polo J R, Wiley R G, Bigl V
Paul Flechsig Institute for Brain Research, Department of Neurochemistry, University of Leipzig, Germany.
J Neurosci Res. 1995 Jan 1;40(1):31-43. doi: 10.1002/jnr.490400105.
The aim of this study was to characterize the effects of cortical cholinergic denervation on cholinergic parameters in the cerebral cortex and basal forebrain using a novel immunotoxin (conjugate of the monoclonal antibody 192IgG against the low-affinity nerve growth factor receptor armed with cytotoxin saporin) to efficiently and selectively lesion cholinergic neurons in rat basal forebrain. Seven days following an intracerebroventricular injection of the cholinergic immunotoxin 192IgG-saporin the binding levels of nicotinic and M1- and M2-muscarinic acetylcholine receptors (mAChR), high-affinity choline uptake sites, as well as the m1-m4 mAChR mRNA were determined in coronal brain sections by both receptor autoradiography and in situ hybridization, and quantified by image analysis. Hemicholinium-3 binding to high-affinity choline uptake sites was decreased by up to 45% in all cortical regions and in the hippocampus after a single injection of the immunotoxin compared to controls. In contrast, M1-mAChR sites were increased over the corresponding control value in the anterior parts of cingulate, frontal, and piriform cortex by about 20%, in the hindlimb/forelimb areas (18%), in the parietal cortex (35%), in the occipital cortex area 2 (17%), as well as in the temporal cortex (25%) following immunolesion. M2-mAChR levels were found to be significantly increased in the posterior part of the parietal cortex area 1 (by about 22%) and in the occipital cortex area 2 (20%) only. With respect to laminar cortical localization, M2-mAChRs and choline uptake sites were altered in all cortical layers, whereas M1-mAChRs were preferentially affected in the upper cortical layers by the immunolesion. The increase in M1-mAChR binding in the temporal and occipital cortex as a consequence of the immunolesion was complemented by an increase in the amount of m1 and m3 mAChR mRNA of about 20% in these regions. The elevated levels of M2-mAChR sites in the occipital and temporal cortex following immunolesion were accompanied by an increase in the m4 (by 25%) but not m2 mAChR mRNA. There was no effect of the immunolesion on the m1-m4 mAChR mRNA in frontal cortical regions. in the basal forebrain, however, immunolesioning caused about a 40% decrease in the level of m2 mAChR mRNA in the medial and lateral septum as well as in the vertical and horizontal limb of the diagonal band, whereas M1- and M2-mAChR binding and the levels of m1, m3, and m4 mAChR mRNA were not affected by the immunolesion in any of the basal forebrain nuclei studied.(ABSTRACT TRUNCATED AT 400 WORDS)
本研究的目的是利用一种新型免疫毒素（针对低亲和力神经生长因子受体的单克隆抗体192IgG与细胞毒素皂草素的偶联物）来有效且选择性地损伤大鼠基底前脑的胆碱能神经元，从而描述皮质胆碱能去神经支配对大脑皮质和基底前脑胆碱能参数的影响。在脑室内注射胆碱能免疫毒素192IgG-皂草素7天后，通过受体放射自显影和原位杂交技术在冠状脑切片中测定烟碱型、M1和M2毒蕈碱型乙酰胆碱受体（mAChR）的结合水平、高亲和力胆碱摄取位点以及m1-m4 mAChR mRNA，并通过图像分析进行定量。与对照组相比，单次注射免疫毒素后，所有皮质区域和海马体中与高亲和力胆碱摄取位点结合的半胱氨酸-3减少了多达45%。相反，免疫损伤后，扣带回、额叶和梨状皮质前部的M1-mAChR位点比相应对照值增加了约20%，后肢/前肢区域增加了18%，顶叶皮质增加了35%，枕叶皮质2区增加了17%，颞叶皮质增加了25%。仅在顶叶皮质1区后部（约22%）和枕叶皮质2区（20%）发现M2-mAChR水平显著升高。关于皮质层定位，所有皮质层中的M2-mAChR和胆碱摄取位点均发生改变，而M1-mAChR在皮质上层受免疫损伤的影响更为明显。免疫损伤导致颞叶和枕叶皮质中M1-mAChR结合增加，这些区域中m1和m3 mAChR mRNA的量也增加了约20%。免疫损伤后枕叶和颞叶皮质中M2-mAChR位点水平升高，同时m4（增加25%）而非m2 mAChR mRNA增加。免疫损伤对额叶皮质区域的m1-m4 mAChR mRNA没有影响。然而，在基底前脑，免疫损伤导致内侧和外侧隔以及斜角带垂直和水平支中m2 mAChR mRNA水平下降约40%，而在所研究的任何基底前脑核中，M1-和M2-mAChR结合以及m1、m3和m4 mAChR mRNA水平均不受免疫损伤的影响。（摘要截取自400字）
