Sann H, Hammer K, Hildesheim I F, Pierau F K
Max-Planck-Institut für Physiologische und Klinische Forschung, W.G. Kerckhoff-Institut, Bad Nauheim, Germany.
J Comp Neurol. 1997 Mar 31;380(1):105-18. doi: 10.1002/(sici)1096-9861(19970331)380:1<105::aid-cne8>3.0.co;2-4.
Numerous ganglia or single neurones immunoreactive to protein gene-product 9.5 (PGP) were demonstrated in the chicken ureter. Ganglia were observed in the main nerve trunks accompanying the ureter (400-2,000 cells), in the adventitia (1-45 cells; density; 79 +/- 12 ganglia/cm2; mean +/- S.E.M.), in the circular muscle (1-9 cells; 76 +/- 10 ganglia/cm2) and in the longitudinal muscle (1-8 cells; 232 +/- 41 ganglia/cm2). Most of the PGP-positive neurones in the nerve trunk ganglia (approximately 66%) and in the smooth muscle layers (85%) were encircled by a dense plexus of varicose nerve fibres containing both substance P (SP) and calcitonin gene-related peptide (CGRP). SP-positive somata were rarely observed. Immunogold electron microscopy revealed that SP- and CGRP-immunoreactivity were colocalised in the same dense core vesicles. A strong reduction of SP-positive nerve fibres was observed in organ cultures of the ureter, indicating their extrinsic origin. The fibres might originate from the dorsal root ganglia, where SP and CGRP were colocalised in 20-30% of the neurones. The sensitivity of ureteric neurones to SP and CGRP was investigated in recordings obtained from mechanosensitive nerve fibres with cell bodies located in or adjacent to the ureter (U-G units). The majority (71%) of the U-G units was excited by local application of SP in a dose-dependent manner. The SP-sensitive U-G neurones had higher mechanical thresholds (29 +/- 5 mmHg) as opposed to the SP-insensitive ones (10 +/- 3 mmHg). Repeated applications of high doses of SP to the U-G units resulted in desensitisation and reduced the response to mechanical stimuli. None of the U-G units responded to local application of CGRP, but all U-G units were excited by acetylcholine. The data support the hypothesis that SP-containing primary afferents are involved in the modulation of the activity of ureteric neurons in the chicken.
在鸡的输尿管中发现了许多对蛋白基因产物9.5（PGP）免疫反应阳性的神经节或单个神经元。在伴随输尿管的主要神经干中观察到神经节（400 - 2000个细胞），在外膜中（1 - 45个细胞；密度为79±12个神经节/cm²；平均值±标准误），在环行肌中（1 - 9个细胞；76±10个神经节/cm²）以及在纵行肌中（1 - 8个细胞；232±41个神经节/cm²）。神经干神经节中大多数PGP阳性神经元（约66%）和平滑肌层中的PGP阳性神经元（85%）被含有P物质（SP）和降钙素基因相关肽（CGRP）的曲张神经纤维密集丛包围。很少观察到SP阳性的胞体。免疫金电子显微镜显示SP和CGRP免疫反应性共定位在相同的致密核心小泡中。在输尿管的器官培养物中观察到SP阳性神经纤维显著减少，表明它们起源于外部。这些纤维可能起源于背根神经节，其中20 - 30%的神经元中SP和CGRP共定位。通过对位于输尿管内或其附近的机械敏感神经纤维（U - G单位）的记录来研究输尿管神经元对SP和CGRP的敏感性。大多数（71%）U - G单位受到局部应用SP的剂量依赖性兴奋。与对SP不敏感的U - G单位（10±3 mmHg）相比，对SP敏感的U - G神经元具有更高的机械阈值（29±5 mmHg）。对U - G单位重复应用高剂量的SP会导致脱敏并降低对机械刺激的反应。没有U - G单位对局部应用CGRP有反应，但所有U - G单位都受到乙酰胆碱的兴奋。这些数据支持了含有SP的初级传入神经参与调节鸡输尿管神经元活动的假说。
