Murabayashi Hiroshi, Miyakawa Kiyoshi, Tanaka Kunio, Sekikawa Mitsuo, Sasaki Motoki, Kitamura Nobuo, Oomori Yukio
Division of Anatomy and Physiology, Japanese Red Cross Hokkaido College of Nursing, Kitami, Japan.
J Vet Med Sci. 2009 Mar;71(3):325-31. doi: 10.1292/jvms.71.325.
Substance P (SP)-immunoreactive nerve fibers in the adrenal medulla was very few during postnatal day 0-5, indicating that its synthesis in the neurons and the transport to nerve endings was incomplete by the end of this period. Since the number of SP-immunoreactive nerve fibers gradually increased during postnatal week 1-2, it was hypothesized that SP was not fully transported to nerve endings until postnatal week 1-2. At postnatal week 3, numerous SP-immunoreactive nerve fibers contacted some noradrenaline (NA) cells but not adrenaline (A) cells in the medulla. From postnatal week 3 onward, the abundance and expression patterns of SP-immunoreactive nerve fibers in the medulla were similar to those in adults. At postnatal week 3, the innervation with SP-immunoreactive nerve fibers was completed indicating the possibility that SP affected on the secretory activity of NA cells but not of A cells in the medulla. The medullary SP-immunoreactive nerve fibers contacting the chromaffin cells possessed a few dense-cored vesicles in their endings at postnatal week 8. Very few SP-immunoreactive chromaffin cells were found in the medulla from postnatal day 0 onward, and SP immunoreactivity was primarily observed in granular cores of the cells suggesting that SP and catecholamine synthesized in the chromaffin cells were released from the granules by adequate stimuli. Very few or a few SP-immunoreactive nerve fibers, acting as a vasomotor effect were found around blood vessels in the superficial cortex from postnatal day 0 onward.
出生后0至5天，肾上腺髓质中P物质（SP）免疫反应性神经纤维极少，这表明在此阶段结束时，其在神经元中的合成及向神经末梢的运输尚未完成。由于出生后第1至2周期间，SP免疫反应性神经纤维数量逐渐增加，因此推测直到出生后第1至2周，SP才完全运输至神经末梢。出生后第3周，大量SP免疫反应性神经纤维与髓质中的一些去甲肾上腺素（NA）细胞接触，但不与肾上腺素（A）细胞接触。从出生后第3周起，髓质中SP免疫反应性神经纤维的丰度和表达模式与成年动物相似。出生后第3周，SP免疫反应性神经纤维的神经支配完成，这表明SP可能影响髓质中NA细胞而非A细胞的分泌活动。出生后第8周，与嗜铬细胞接触的髓质SP免疫反应性神经纤维末梢含有少量致密核心小泡。从出生后第0天起，在髓质中极少发现SP免疫反应性嗜铬细胞，且SP免疫反应性主要在细胞的颗粒核心中观察到，这表明嗜铬细胞中合成的SP和儿茶酚胺在适当刺激下从颗粒中释放出来。从出生后第0天起，在浅表皮质的血管周围极少发现或仅发现少量起血管运动作用的SP免疫反应性神经纤维。
