Xu I S, Hao J X, Xu X J, Hökfelt T, Wiesenfeld-Hallin Z
Department of Medical Laboratory Sciences and Technology, Division of Clinical Neurophysiology, Karolinska Institutet, Huddinge University Hospital, Huddinge, Sweden.
Brain Res. 1999 Jul 3;833(2):251-7. doi: 10.1016/s0006-8993(99)01551-6.
We have examined the effects of intrathecal (i.t.) administration of [Leu31,Pro34]-neuropeptide Y (NPY) or NPY-(13-36), selective agonists of NPY Y1 or Y2 receptors, respectively, on the excitability of the flexor reflex in normal rats and after unilateral transection of the sciatic nerve. In rats with intact and sectioned sciatic nerves, i.t. [Leu31,Pro34]-NPY induced a similar biphasic effect on the flexor reflex with facilitation at low doses and facilitation followed by depression at high doses. In contrast, i.t. NPY-(13-36) only facilitated the flexor reflex in normal rats, and at high dose it caused ongoing discharges in the electromyogram. NPY-(13-36) caused dose-dependent depression of the flexor reflex in rats after sciatic nerve transection, in addition to its facilitatory effect. Topical application of [Leu31,Pro34]-NPY or NPY-(13-36) caused a moderate and brief reduction in spinal cord blood flow. No difference was noted between the vasoconstrictive effect of [Leu31,Pro34]-NPY and NPY-(13-36). It is suggested that activation of Y1 receptors may be primarily responsible for the reflex depressive effect of i.t. neuropeptide Y in rats with intact sciatic nerves, whereas both Y1 and Y2 receptors may be involved in mediating the depressive effect of NPY after axotomy.
我们研究了鞘内注射[Leu31,Pro34]-神经肽Y（NPY）或NPY-(13 - 36)（分别为NPY Y1或Y2受体的选择性激动剂）对正常大鼠以及坐骨神经单侧横断后屈肌反射兴奋性的影响。在坐骨神经完整和横断的大鼠中，鞘内注射[Leu31,Pro34]-NPY对屈肌反射产生类似的双相效应，低剂量时为易化作用，高剂量时先易化后抑制。相比之下，鞘内注射NPY-(13 - 36)仅在正常大鼠中易化屈肌反射，高剂量时可导致肌电图持续放电。除了易化作用外，NPY-(13 - 36)在坐骨神经横断后的大鼠中还引起屈肌反射的剂量依赖性抑制。局部应用[Leu31,Pro34]-NPY或NPY-(13 - 36)可使脊髓血流量适度短暂减少。[Leu31,Pro34]-NPY和NPY-(13 - 36)的血管收缩作用无差异。提示在坐骨神经完整的大鼠中，Y1受体的激活可能是鞘内神经肽Y反射抑制作用的主要原因，而在轴突切断后，Y1和Y2受体可能都参与介导NPY的抑制作用。
