The underestimated role of a somatosensory neural network on thyroid gland morphology: an experimental subarachnoid hemorrhage model study

Authors : Cengiz ÖZTÜRK, Mehmet Nuri KOÇAK, Tuba DEMİRCİ, İsmail MALKOÇ, Mehmet Dumlu AYDIN

Pages : 155-162

View : 19 | Download : 10

Publication Date : 2019-12-31

Article Type : Research Paper

Abstract :Objectives: Innervation of the thyroid gland has been attributed to the autonomic nervous system. Although peripheral sympathetic and parasympathetic innervations of the thyroid gland are well known, little is known about the somatosensory innervation of the thyroid gland. In this study, alterations on the somatosensory neural network of the thyroid gland following an experimental subarachnoid hemorrhage were investigated in rabbits. Methods: Experiments were conducted on 23 rabbits under no medical intervention. Five rabbits were used as control group. Five rabbits were used as the sham group and serum physiologic insert ignore into journalissuearticles values(SF); was injected into their cisterna magna. The remaining 13 animals were used as the subarachnoid hemorrhage insert ignore into journalissuearticles values(SAH); group; their own blood insert ignore into journalissuearticles values(1 ml); was re-injected into the cisterna magna. Thyroid hormone levels of animals were measured at the end of one month. Then, histological sections of the middle parts of the thyroid glands were stained with haematoxylin-eosin insert ignore into journalissuearticles values(H&E); for investigation of SAH-related damage. The total follicle volume insert ignore into journalissuearticles values(TFV); per cubic millimeter of the thyroid gland was estimated by stereological methods. Comparison of degenerated neuronal density insert ignore into journalissuearticles values(DND); in the C4 dorsal root ganglia insert ignore into journalissuearticles values(DRG); was examined bilaterally using H&E and TUNEL stainings. Results: Following SAH, neuronal degeneration in the cervical DRG caused somatic innervation deficiency, follicular atrophy and thyroid hormone depletion in the thyroid gland. T3 and T4 hormone levels of the SAH group insert ignore into journalissuearticles values(T3: 61±8 μg/dl; T4: 1.01±0.12 μg/dl); were significantly insert ignore into journalissuearticles values(p<0.005); lower than those of control insert ignore into journalissuearticles values(T3; 103±6 μg/dl, T4: 1.37±0.36 μg/dl); and sham insert ignore into journalissuearticles values(T3; 94±10 μg/dl; T4: 1.24±0.87 μg/dl); groups. In control groups, mean TFV was 41% / mm3 and DND of C4 DRG was 6±2 / mm3. These values were significantly lower than those in sham insert ignore into journalissuearticles values(TFV: 35%/mm3 and DND: 22±7/mm3); and experimental SAH insert ignore into journalissuearticles values(TFV: 23%/mm3 and DND: 253±49/mm3); groups insert ignore into journalissuearticles values(p<0.0005 and p<0.0001, respectively);. Conclusion: Thyroid follicle growth and its secretory activity are under the control of a quite complex, multi-originated, yet incompletely understood innervation pattern. We propose the presence of an underestimated role of a somatosensory neural network - an interganglionary link between the superior cervical, thyroid, laryngeal, nodose, trigeminal and dorsal root ganglia - on thyroid gland morphology.
Keywords : cisterna magna, dorsal root ganglion, rabbit, subarachnoid hemorrhage, thyroid gland