Ito H, Matsuda K, Sato A, Tohgi H
Department of Physiology, Tokyo Metropolitan Institute of Gerontology, Japan.
Jpn J Physiol. 1987;37(6):1005-17. doi: 10.2170/jjphysiol.37.1005.
The present experiment was performed to investigate the effect of stimulating the parasympathetic superior laryngeal nerve (SLN) on thyroid blood flow and its mediator substances in urethane-chloralose anesthetized rats. Thyroid blood flow was measured by counting number of blood drops from a thin catheter inserted into the thyroid vein. SLNs were cut bilaterally and their peripheral portions were electrically stimulated. Electrical stimulations (intensity, 10 V; pulse duration, 0.5 ms) of SLNs increased thyroid blood flow in a frequency-dependent manner as stimulus frequencies increased from 2 to 40 Hz. The intravenous administration of atropine (0.5 mg/kg) reduced these responses, but did not abolish them. The basal secretion rate of vasoactive intestinal peptide (VIP) from thyroid glands in the resting state was nearly zero (0.25 +/- 0.14 pg/(kg.min)). SLN stimulation increased markedly the VIP secretion rate to 3.40 +/- 0.64 pg/(kg.min). The VIP secretion responses evoked by SLN stimulation remained in atropinized rats. Furthermore, exogenously applied VIP increased the thyroid blood flow dose-dependently. These results suggest that SLN stimulation increases the thyroid blood flow by dilating thyroid blood vessels via activation of cholinergic and non-cholinergic (probably VIP-containing) nerve fibers. Thus, these parasympathetic vasodilation systems may play a supplementary role in regulating the secretion of thyroid hormone by changing the thyroid blood flow in addition to the role of hormonal regulation by the thyroid stimulating hormone (TSH).
本实验旨在研究刺激副交感神经喉上神经（SLN）对乌拉坦-氯醛糖麻醉大鼠甲状腺血流及其介质物质的影响。通过计算插入甲状腺静脉的细导管的血滴数来测量甲状腺血流。双侧切断SLN，并对其外周部分进行电刺激。当刺激频率从2Hz增加到40Hz时，SLN的电刺激（强度10V；脉冲持续时间0.5ms）以频率依赖的方式增加甲状腺血流。静脉注射阿托品（0.5mg/kg）可降低这些反应，但并未消除它们。在静息状态下，甲状腺血管活性肠肽（VIP）的基础分泌率几乎为零（0.25±0.14pg/（kg·min））。SLN刺激可使VIP分泌率显著增加至3.40±0.64pg/（kg·min）。SLN刺激引起的VIP分泌反应在阿托品化的大鼠中仍然存在。此外，外源性应用VIP可剂量依赖性地增加甲状腺血流。这些结果表明，SLN刺激通过激活胆碱能和非胆碱能（可能含VIP）神经纤维使甲状腺血管扩张，从而增加甲状腺血流。因此，除了促甲状腺激素（TSH）的激素调节作用外，这些副交感神经血管舒张系统可能通过改变甲状腺血流在调节甲状腺激素分泌方面发挥辅助作用。
