Myoepithelial cells (MECs) exist on the basal surface of acini in major exocrine glands, include myofilaments and various constructive proteins, and share characteristics with smooth muscle and epithelial cells. MECs project several ramified processes to invest acini, and possibly contract to compress acini to support the secretion by the glandular cells. However, the functional roles of MECs in salivary secretion are still unclear. We investigated morphological changes in immunostained MECs using the anti-α-smooth muscle actin (αSMA) antibody in operated or non-operated contralateral (NC) submandibular glands after partial or total resection. Furthermore, we investigated and discuss other salivary glands of rats. MECs in the parotid, sublingual and submandibular gland of adult rats exhibited different shapes and localizations. After surgery, in both operated and NC glands, the number of MECs and αSMA-immunopositive areas increased significantly. Three-dimensional analysis using a confocal laser-scanning microscope revealed that substantial and significant enhancement became evident in the number, length, and thickness of MEC-processes covering acini of the operated and NC submandibular glands. The preset findings indicate that MECs alter the morphology of their processes in operated and NC glands after surgery of the partial or total resection. It is suggested that MECs promote salivary secretion using elongated, thickened, and more ramified processes.
Intravenous genistein was effective in ameliorating CPT-11-induced late-onset diarrhoea, by suppressing MRP2-mediated biliary excretion of CPT-11 and its metabolites.
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.
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