Thyroxin and calcitonin secretion into thyroid venous blood is regulated by pharyngeal mechanical stimulation in anesthetized rats复制标题

咽部机械刺激对麻醉大鼠甲状腺静脉血甲状腺素和降钙素分泌的调节作用

The autonomic nerve fbers’ distribution to widespread visceral organs contributes to the regulation of various physiological functions. Endocrine functions are not exceptional. These include catecholamine secretion from the adrenal medulla and estradiol secretion from the ovary, leading to changes depending on the eferent activity of the sympathetic adrenal or ovarian branches, respectively. The thyroid gland, a large endocrine organ attached to the larynx and the upper part of the trachea, receives innervation from sympathetic and parasympathetic thyroid branches derived from the cervical sympathetic trunks (CSTs) and the superior laryngeal nerve (SLN), respectively. Recently, we have shown, by stimulating at a supramaximal intensity the cut peripheral portion of either CSTs or SLNs, that the sympathetic (inhibitory efects) and parasympathetic (excitatory efects) eferent fbers antagonistically regulate the secretion of immunoreactive thyroxin (iT4), immunoreactive triiodothyronine (iT3), and immunoreactive calcitonin (iCT) from the thyroid gland, whereas the sympathetic nerve promotes the secretion of immunoreactive parathyroid hormone (iPTH) from the parathyroid gland. Furthermore, when intact SLNs were stimulated at lowcurrent intensity to selectively excite thick myelinated fbers, secretion of iT3, iT4, and iCT increased, but secretion of iPTH did not change; these responses were similar to those produced by stimulation of cut peripheral SLNs. The majority of myelinated fbers in the SLN are aferent fbers, and pre- and postganglionic autonomic eferent fbers are unmyelinated in rats. These fndings led us to hypothesize that excitation of sensory aferents in SLN may produce a refex increase in the eferent activity of the SLN parasympathetic thyroid branches to promote hormonal secretion into thyroid venous blood.

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