Chiaia N L, Bennett-Clarke C A, Rhoades R W
Department of Anatomy, Medical College of Ohio, Toledo 43699.
Neuroscience. 1992 Jul;49(1):141-56. doi: 10.1016/0306-4522(92)90082-d.
Histochemistry for cytochrome oxidase reveals a vibrissa-related pattern in trigeminal nucleus principalis, subnucleus interpolaris, and the magnocellular portion of subnucleus caudalis. This pattern is apparent in late fetal animals and is disrupted by transection of the infraorbital nerve on the day of birth. We recently reported results suggesting that the cytochrome oxidase pattern reflects primary afferent-induced clustering of second order neurons in all of these nuclei. If this conclusion is correct, it should follow that primary afferent lesions made after the cytochrome oxidase pattern became established in the brainstem might have little effect upon it. Accordingly, we transected the infraorbital nerve (the trigeminal branch that supplies the vibrissae) on postnatal days 0-10 and evaluated the vibrissa-related pattern in the brainstem with cytochrome oxidase histochemistry at varying intervals after these lesions. If the infraorbital nerve was sectioned on postnatal days 0-2, the vibrissa-related pattern was absent in trigeminal nucleus principalis, and both subnucleus interpolaris and caudalis. If such lesions were made after postnatal day 9, there was no appreciable effect upon the cytochrome oxidase pattern in any portion of the trigeminal brainstem complex. However, if lesions were made between postnatal days 3 and 8, the density and clarity of the cytochrome oxidase staining pattern were reduced in interpolaris and caudalis, but not in principalis. This difference was not due to differential transganglionic degeneration in these nuclei. Tracing with horseradish peroxidase demonstrated qualitatively equivalent primary afferent losses in principalis, interpolaris, and caudalis. Immunocytochemistry with a monoclonal antibody directed against parvalbumin also demonstrated a vibrissa-related pattern of cell bodies in principalis and interpolaris in rats killed on postnatal day 9 or later ages. The combination of retrograde tracing and immunocytochemistry revealed that the parvalbumin-immunoreactive neurons in principalis projected to thalamus while those in interpolaris were not labelled by tracer injections into the thalamus, midbrain, cerebellum or spinal cord. Infraorbital nerve transections made as late as postnatal day 8 resulted in a sharp decrease in the staining of parvalbumin-positive neurons in interpolaris, but not in principalis. Lesions made on postnatal day 10 had no qualitative effect upon parvalbumin-positive neurons in any portion of the trigeminal brainstem complex. The results of this study support the conclusion that the vibrissa-related cytochrome oxidase pattern in principalis becomes independent of primary afferent input at a very short interval after its initial appearance. In contrast, the patterns in more caudal portions of the trigeminal brainstem complex require maintenance of primary afferent input for a much longer postnatal period.(ABSTRACT TRUNCATED AT 400 WORDS)
细胞色素氧化酶的组织化学研究显示，在三叉神经主核、极间亚核和尾侧亚核的大细胞部分存在与触须相关的模式。这种模式在胎儿后期的动物中很明显，并且在出生当天切断眶下神经后会被破坏。我们最近报道的结果表明，细胞色素氧化酶模式反映了所有这些核中二级神经元由初级传入诱导的聚集。如果这个结论是正确的，那么在脑干中细胞色素氧化酶模式建立后进行的初级传入损伤可能对其影响很小。因此，我们在出生后0 - 10天切断眶下神经（供应触须的三叉神经分支），并在这些损伤后的不同时间间隔，用细胞色素氧化酶组织化学评估脑干中与触须相关的模式。如果在出生后0 - 2天切断眶下神经，三叉神经主核、极间亚核和尾侧亚核中与触须相关的模式均不存在。如果在出生后第9天之后进行这种损伤，对三叉神经脑干复合体的任何部分的细胞色素氧化酶模式都没有明显影响。然而，如果在出生后第3天至第8天之间进行损伤，极间亚核和尾侧亚核中细胞色素氧化酶染色模式的密度和清晰度会降低，但主核中不会。这种差异不是由于这些核中不同的跨神经节变性所致。用辣根过氧化物酶追踪显示，主核、极间亚核和尾侧亚核中初级传入损失在质量上是等效的。用针对小白蛋白的单克隆抗体进行免疫细胞化学研究也显示，在出生后第9天或更晚处死的大鼠中，主核和极间亚核中存在与触须相关的细胞体模式。逆行追踪和免疫细胞化学相结合显示，主核中表达小白蛋白的神经元投射到丘脑，而极间亚核中的神经元在向丘脑、中脑、小脑或脊髓注射示踪剂后未被标记。直到出生后第8天进行眶下神经切断，会导致极间亚核中表达小白蛋白的神经元染色急剧减少，但主核中不会。出生后第10天进行的损伤对三叉神经脑干复合体任何部分中表达小白蛋白的神经元没有定性影响。本研究结果支持这样的结论，即主核中与触须相关的细胞色素氧化酶模式在最初出现后的很短时间间隔内就变得独立于初级传入输入。相比之下，三叉神经脑干复合体更靠尾侧部分的模式在出生后的更长时期内需要初级传入输入的维持。（摘要截短至400字）
