Localization of Hsp27 in the Rat Submandibular Gland Following the Application of Various Surgical Treatments

Abstract

Salivary glands repair and regenerate following various types of injuries and surgical procedures. However, the tissue responses induced in the contralateral glands have yet to be elucidated in detail. Hsp27, a member of the heat-shock protein (Hsp) family, is strongly expressed in physiological environments, particularly during development. Hsp27 was previously shown to play a role in the regulation of acinar cell proliferation and differentiation in the rat submandibular gland.The present study performed the following surgical treatments on the right submandibular glands of adult rats: 1) duct ligation followed by unligation after one week; 2) partial sialoadenectomy; and 3) total sialoadenectomy. Immunohistochemistry for Hsp27 and Ki67 was performed in the experimental and normal contralateral glands, and localization was histologically and morphometrically analyzed.The results obtained revealed the localization of Hsp27 to the intercalated duct in the submandibular glands of non-treated rats. The expression of Hsp27 was strongly induced in both the uninjured contralateral control glands as well as treated glands of experimental rats regardless of the surgical procedure performed. The number of Hsp27-immunopositive cells increased rapidly following surgery, and subsequently returned to the same level as that in non-treated rats after 4 weeks. However, no marked changes were observed in the number of Ki67-immunopositive proliferating cells. Therefore, the change in the number of Hsp27-immunopositive cells may have contributed to compensatory hypertrophy. The results of the present study indicate that the expression of Hsp27 in the intercalated duct in the submandibular gland may play a role in the differentiation of acinar cells.

Morphological Changes of Myoepithelial Cells in the Rat Submandibular Gland Following the Application of Surgical Stimuli

“…The quantitative compensation of secretory function by proliferation of acinar cells and MECs during regeneration has also been reported [15, 40, 41]. Our recent study showed that salivary gland resection induced acinar cell differentiation from the intercalated duct in the residual tissue of the operated side, as well as the NC side in adult rats [25]. An increased salivary secretion from the residual acini is necessary to complement decreased glandular tissue resulting from surgery resection.…”

“…Surgery on the submandibular gland was performed using the procedure reported by Mizobe et al [25]. Under general anesthesia with an intraperitoneal injection of 1 mL/kg pentobarbital sodium (Somnopentyl, Kyoritsu Seiyaku, Tokyo, Japan), the rat was placed in a supine position, an incision was made in the right submandibular skin, and connective tissue was dissected while avoiding damage to the surrounding tissue, including nerves and blood vessels .…”