MacLean D B, Eldridge J C, Brodish A
Department of Medicine, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27103.
Neurobiol Aging. 1988 May-Jun;9(3):273-7. doi: 10.1016/s0197-4580(88)80065-4.
The two widely distributed neuropeptides, substance P (SP) and somatostatin (SS), are synthesized in cell bodies of the sensory ganglia of the vagus and sciatic nerves and transported bidirectionally toward the central nervous system and sites of sensory innervation. In this study, the content of both peptides was measured in the vagus and sciatic nerves of Fischer 344 rats aged 4, 12 and 25 months. In addition, as an indicator of biosynthesis within the sensory ganglia, the quantity of neuropeptide transported during 22 hours in a peripheral orthograde direction was measured using the ligation technique in animals age 12, 18 and 25 months. The content and transported quantity of SP was unchanged or slightly increased in both nerves as a function of age. Somatostatin content was unchanged and transport increased in the vagus of older rats. In contrast, in the sciatic nerve, SS content was reduced by more than 30% in older rats (p less than 0.01); transported somatostatin was proportionately reduced (p less than 0.05). These findings demonstrate that neuropeptide levels in the sensory vagus are not reduced as a function of age. Somatostatinergic dorsal root ganglion neurons may be selectively vulnerable in the aging Fischer rat.
两种广泛分布的神经肽，P物质（SP）和生长抑素（SS），在迷走神经和坐骨神经感觉神经节的细胞体中合成，并双向运输至中枢神经系统和感觉神经支配部位。在本研究中，对4、12和25月龄的Fischer 344大鼠的迷走神经和坐骨神经中这两种肽的含量进行了测定。此外，作为感觉神经节内生物合成的指标，使用结扎技术对12、18和25月龄动物外周顺行方向22小时内运输的神经肽量进行了测定。SP在两条神经中的含量随年龄增长未发生变化或略有增加。生长抑素含量未变，老年大鼠迷走神经中的运输量增加。相反，在坐骨神经中，老年大鼠的SS含量降低了30%以上（p<0.01）；运输的生长抑素也相应减少（p<0.05）。这些发现表明，感觉迷走神经中的神经肽水平不会随年龄增长而降低。在衰老的Fischer大鼠中，生长抑素能背根神经节神经元可能具有选择性易损性。
