Modulation of Calcitonin, Parathyroid Hormone, and Thyroid Hormone Secretion by Electrical Stimulation of Sympathetic and Parasympathetic Nerves in Anesthetized Rats

Abstract

The thyroid and parathyroid glands are dually innervated by sympathetic (cervical sympathetic trunk [CST]) and parasympathetic (superior laryngeal nerve [SLN]) nerve fibers. We examined the effects of electrical stimulation of efferent or afferent nerve fibers innervating the thyroid and parathyroid glands on the secretion of immunoreactive calcitonin (iCT), parathyroid hormone (iPTH), 3,3′,5-triiodothyronine (iT3), and thyroxine (iT4) from the thyroid and parathyroid glands. In anesthetized and artificially ventilated rats, thyroid venous blood was collected. The rate of hormone secretion from the glands was calculated from plasma hormone levels, measured by ELISA, and the flow rate of thyroid venous plasma. SLNs or CSTs were stimulated bilaterally with rectangular pulses with a 0.5-ms width. To define the role of unmyelinated nerve fibers (typically efferent), the cut peripheral segments were stimulated at various frequencies (up to 40 Hz) with a supramaximal intensity to excite all nerve fibers. The secretion of iCT, iT3, and iT4 increased during SLN stimulation and decreased during CST stimulation. iPTH secretion increased during CST stimulation, but was not affected by SLN stimulation. To examine the effects of selective stimulation of myelinated nerve fibers (typically afferent) in the SLN, intact SLNs were stimulated with a subthreshold intensity for unmyelinated nerve fibers. iCT, iT3, and iT4 secretion increased during stimulation of intact SLNs at 40 Hz. These results suggest that excitation of myelinated afferents induced by low intensity and high frequency stimulation of intact SLNs promotes secretion of CT and thyroid hormones from the thyroid gland, potentially via reflex activation of parasympathetic efferent nerve fibers in the SLN.

Effect of Restraint Stress on Plasma PTH Concentration and Its Molecular Targets Expressions in Wistar Rats

“…The time spent for immobile posture during a 5-minute testing period was measured. The test was performed by observers who were blinded to the groups ( 14 ).…”

“…Blood plasma was obtained by centrifugation and stored at -80°C. Plasma levels of adrenocorticotrophic hormone (ACTH) (Intra assay CV%: 10 sensitivity: 2.49 ng/L), corticosterone (CORT) (Intra assay CV%: 10 sensitivity: 2.51 ng/mL), and intact parathormone (iPTH) (Intra assay CV%: 10 sensitivity: 0.51 ng/L) in both stress and control groups were measured using commercially available ELISA kits (Shanghai YeHua Biological Technology Co., Ltd., China), according to the manufacturer’s instructions ( 14 ).…”

Chronic Electrical Stimulation of the Superior Laryngeal Nerve in the Rat: A Potential Therapeutic Approach for Postmenopausal Osteoporosis

“…Secondly, cuffs were placed on the SLNs of the anterior cervical region approximately 8 mm lateral from the thyroid (as shown in Figure 1C of our previous study [5]). To expose the SLN, the ventral neck muscles were separated without transection.…”

“…We recently showed in anesthetized and artificially ventilated rats that electrical stimulation of the superior laryngeal nerve (SLN) innervating the thyroid gland increases immunoreactive CT (iCT) secretion into thyroid venous blood [5]. In this study, firstly to examine the effect of efferent nerve stimulation, the SLN was cut and supramaximal electrical stimulation applied to the cut peripheral end of the nerve, with iCT secretion being increased at 40 Hz.…”

Design and Analysis of a Whole-Body Noncontact Electromagnetic Subthreshold Stimulation Device with Field Modulation Targeting Nonspecific Neuropathic Pain

“…Lowfield magnetic stimulation of depression is an active area of research [48][49][50][51][52][53][54]. The subthreshold technique is also a modern research direction in spinal cord stimulation [55][56][57][58][59], as it eliminates noxious and off-target paresthesia, while being efficient, as well as in vagus [60], occipital [61], proximal [62], and parasympathetic [63] nerve stimulation, and in neuromuscular stimulation [64]. Electrocutaneous subthreshold stimulation has been found to improve sleep and reduce reactive anxiety/depression [65].…”