Cholinergic and VIPergic vasodilator actions of parasympathetic nerves on the thyroid blood flow in XXXX .

@entity4486 @entity4774 @entity3897 @entity35 @entity12180
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 @entity4774 - @entity4486 anesthetized @entity35 . 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 @entity3897 (0.5 mg/kg) reduced these responses, but did not abolish them. The basal secretion rate of vasoactive intestinal peptide ( @entity12180 ) from thyroid glands in the resting state was nearly zero (0.25 +/- 0.14 pg/(kg.min)). SLN stimulation increased markedly the @entity12180 secretion rate to 3.40 +/- 0.64 pg/(kg.min). The @entity12180 secretion responses evoked by SLN stimulation remained in atropinized @entity35 . Furthermore, exogenously applied @entity12180 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 @entity12180 -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).
