Artymyshyn R, Murray M
J Comp Neurol. 1985 Jan 1;231(1):78-90. doi: 10.1002/cne.902310107.
The interpeduncular nucleus (IPN) is a midbrain structure that receives its major afferents from the medial habenulae via the fasciculi retroflexi. Among the axons projecting to the IPN is a population of substance P (SP)-containing axons. The IPN has been subdivided into the central, dorsal, intermediate, rostral, and lateral subnuclei using cytoarchitectonic criteria. The distribution of SP among these subnuclei was determined by using Sternberger's ('79) peroxidase-antiperoxidase technique. In the normal IPN the rostral subnucleus can be subdivided into two sectors on the basis of SP content. The ventral sector contains a moderate amount of SP and scattered SP positive perikarya. The dorsal cap of the rostral subnucleus contains denser SP than the ventral sector and it is continuous with the SP found in the dorsal subnucleus. The lateral subnuclei contain the densest SP found in the IPN and appear as laterally placed columns that expand in size caudally. The central and intermediate subnuclei contain very sparse SP. The fasciculus retroflexus was destroyed in 30 animals unilaterally or bilaterally and animals were perfused 4 days to 3 months postoperatively. After unilateral fascicular lesion, the SP in the rostral part of the ipsilateral lateral subnucleus is almost abolished, but caudally the decrease is confined to its lateral aspect. There is no visible decrease contralateral to the lesion. SP in the rostral part of the cap of the rostral subnucleus is decreased ipsilaterally but no loss is seen contralaterally or caudally. Animals with bilateral lesions show a great decrease in staining in the dorsal cap of the rostral subnucleus and the lateral subnuclei, with no decrease seen in the central, dorsal, or intermediate subnuclei. These results confirm that the origin of most of the SP in the IPN is fasciculus retroflexus fibers, but some of the SP arises from intrinsic SP perikarya located in the ventral sector of the rostral subnucleus and some may also arise from other sources. The areas of the IPN that receive bilateral SP projections from the fasciculus retroflexus (parts of the lateral and rostral subnuclei) show evidence for replacement of SP after lesion. This replacement implies sprouting or an increase in production of SP by remaining systems.
脚间核（IPN）是一种中脑结构，它通过后屈束从内侧缰核接收主要传入纤维。投射到IPN的轴突中，有一群含有P物质（SP）的轴突。根据细胞构筑标准，IPN已被细分为中央、背侧、中间、嘴侧和外侧亚核。利用斯特恩伯格（1979年）的过氧化物酶-抗过氧化物酶技术确定了这些亚核中SP的分布。在正常的IPN中，嘴侧亚核可根据SP含量细分为两个区域。腹侧区域含有适量的SP和散在的SP阳性核周体。嘴侧亚核的背帽比腹侧区域含有更密集的SP，并且与背侧亚核中发现的SP连续。外侧亚核含有IPN中最密集的SP，呈现为侧向排列的柱状结构，向尾侧尺寸增大。中央和中间亚核含有非常稀疏的SP。在30只动物中单侧或双侧破坏后屈束，并在术后4天至3个月对动物进行灌注。单侧束状损伤后，同侧外侧亚核嘴侧部分的SP几乎消失，但在尾侧，减少仅限于其外侧部分。损伤对侧未见明显减少。嘴侧亚核帽嘴侧部分的SP同侧减少，但对侧或尾侧未见缺失。双侧损伤的动物在嘴侧亚核的背帽和外侧亚核中的染色明显减少，而中央、背侧或中间亚核未见减少。这些结果证实，IPN中大部分SP的起源是后屈束纤维，但一些SP来自位于嘴侧亚核腹侧区域的内在SP核周体，并且一些可能也来自其他来源。从后屈束接受双侧SP投射的IPN区域（外侧和嘴侧亚核的部分）在损伤后显示出SP替代的证据。这种替代意味着剩余系统的SP发芽或产生增加。
