Changes in Tracheal Respiratory Mucosa After Thyroidectomy: A Rat Model

Abstract

Background/Aim: This study aimed to investigate changes in the tracheal mucosa after thyroidectomy, that can be a cause of post-thyroidectomy discomfort. Materials and Methods: Forty rats were divided into normal controls and 3 surgical groups: (i) thyroid isthmectomy with cauterization, (ii) isthmectomy by a cold instrument without hemostasis, and (iii) sham (exposure of the trachea and thyroid gland without thyroidectomy by dissection through pretracheal fascia). Animals were euthanized at 1 and 4 weeks. Mucosal edema and glandular hyperplasia were measured. Mucin production and basal cell activities were evaluated by mucin 5AC (MUC5AC) and keratin 5 (KRT5) using immunofluorescence staining. Results: Larger mucosal areas were observed in all surgical groups at 1 and 4 weeks. More submucosal glandular hyperplasia was noted in the group with isthmectomy without hemostasis. MUC5AC and KRT5 expressions were significantly higher in the surgical groups. Conclusion: The tracheal mucosa may change after surgery, which could explain postoperative discomfort after thyroidectomy.

Restoration of Homeostasis in the Tracheal Mucosa After Thyroid Surgery in a Rat Model

“…We reported prolonged mucosal edema and functional changes in the TM after thyroid surgery even without direct mucosal injury induced by endotracheal intubation in a previous study (5). The results of this study revealed that thyroid surgery actually led to increased mRNA and protein expression of key regulators involved in the restoration of homeostasis for a considerable period after thyroid surgery.…”

“…Since morphological and functional changes of TM tended to recover in four weeks after thyroid surgery in our previous study (5), three rats in the NC groups and five rats in each experimental group were euthanized to harvest TM at three (D3), seven (D7), and 21 (D21) days after thyroid surgery. We defined D3 as the early phase, D7 as the intermediate phase, and D21 as the late phase postthyroid surgery.…”

“…Surgical procedures and histological evaluation. The surgical procedure was generally carried out as described in a previous study (5). All rats in both NC and experimental groups were anesthetized using an intramuscular injection containig 0.1 mg/kg of tiletamine hydrochloride/zolazepam hydrochloride (Zoletil 50, Vibac Laboratories, Carros, France) and 0.1 mg/kg xylazine (Rompun, Bayer, Leverkusen, Germany).…”

“…We previously reported mucosal thickening with submucosal glandular hyperplasia in tracheal mucosa (TM) combined with fibrin deposition following thyroid surgery, resulting in increased mucus production and basal cell activation (5). Since the blood and lymphatic fluid of the TM drain into the deep neck space via the connected vessels is located around the thyroid glands (6,7), we suggested that edema induced by thyroid surgery might be one of the mechanisms underlying changes in TM, resulting in delayed homeostatic restoration of the TM (5). Although TM changes following thyroid surgery are expected to eventually restore homeostasis, these changes are similar to those observed in remodeling of small airway.…”

“…Although TM changes following thyroid surgery are expected to eventually restore homeostasis, these changes are similar to those observed in remodeling of small airway. Incomplete recovery of TM can cause prolonged discomfort of throat known as postthyroidectomy syndrome (5).…”