Immunohistochemical demonstration of keratin proteins in duct‐ligated salivary glands of mice and rats

Abstract

Immunohistochemical detection of keratin proteins in duct‐ligated submandibular glands (SMG) was carried out in mice and rats with or without testosterone administration. Keratin staining in normal salivary glands was limited to the striated duct (SD) and excretory duct (ED) cells and was usually lacking in granular convoluted tubule (GCT) cells. Following duct‐ligation, the epithelia of intercalated ducts (ICD), degranulated tubules, duct‐like structures, and dilated striated and excretory ducts showed positive keratin staining, usually in their luminal aspects. The concentration of keratin was proportional to the degree of degranulation of the GCT cells. The duct‐ligated SMGs in animals with testosterone treatment showed a comparatively higher number of granules located in the GCT cells, and degranulation was slight. Keratin staining in hormone‐treated duct‐ligated glands also occurred in ductal segments to a slight degree. Keratin was also detected in degranulated tubules, and its concentration was increased in duct‐like structures, whereas staining for EGF and NGF was decreased in degranulated tubules and lacking in duct‐like structures.

Immunoreaction of keratin, actin, S‐100 protein and rat‐EGF in ductligated rat salivary glands

“…Histologic and immunohistochemical studies of EGF and NGF following duct-ligation of SMGs in mice and rats, show initial changes include the degranulation of GCT cells and the disappearance or a reduction in staining for growth factors in GCT segments (6). It has also been reported that keratin protein is expressed in duct-Uke structures of the duct-ligated SMG, though normal GCT cells are usually devoid of keratin staining (7). In duct-ligated SMGs, immunostaining for growth factor was reduced with the simultaneous appearance of keratin staining in degranulated cells.…”

“…detected changes in keratin protein expression have been observed in experimentally obstructed salivary glands in the mouse, rat and cat (1)(2)(3)(4)(5)(6)(7). The granular convoluted tubule (GCT) cells in the mouse submandibular gland (SMG) contains a characteristic abundance of epidermal growth factor (EGF) and nerve growth factor (NGF) (8)(9)(10)(11)(12), and conspicuous changes occur in the quantity of EGF and NGF deposition following duct ligation (6).…”

Immunohistochemical observations of epidermal growth factor, keratin proteins and lectin binding on effects of testosterone administration in duct-ligated submandibular glands of mice.

“…Regarding histochemical examination of duct-ligated SMGs; in duct-ligated SMGs with testosterone treatment and in those with testosterone in castrated mice, immunohistochemically detectable EGF for marking GCT cells (1,8,9,15,17,24,26), keratin (KLIM) proteins for marking duct cells (4,6,19,23,26,27), PNA and SBA lectin binding for marking GCT cells and DBA lectin for that of acinar elements, have been reported (16,20,25,26). From both histologic and immunohistochemical features in duct-ligated SMGs and castration which treated variable regimens of testosterone treatment, biologic response to testosterone in GCT cells of duct-ligated SMGs could be obtained significantly.…”

“…It has recently been pointed out that immunohistochemically detectable epidermal growth factor (EGF) and nerve growth factor (NGF) in the GCT cells in this alterative progress of ligated SMGs were markedly reduced when followed by ligation (24), whereas keratin (KLIM) gradually developed in degranulated GCT cells, and lectin binding affinities in acinar and GCT cells were changed depending on histologic figures (26,27). GCT cells in mice submandibular glands (SMGs) are unique structures containing a lot of growth factors (EGF and NGF etc.)…”

Duct ligation/de-ligation model: exploring mechanisms for salivary gland injury and regeneration

“…Additionally, Hashimoto et al showed that the negative expression of epidermal growth factor (EGF), nerve growth factor (NGF), and S-100 protein in duct obstructions leads to a reduction or elimination of the function of granular ductal cells. The loss of S-100 and EGF expression after ligation further indicated that the granular duct had lost its ability to repair, resulting in decreased tissue regeneration ( Takai, et al, 1985 ; Takai, et al, 1986 ; Hashimoto, et al, 1992 ). Few studies have been conducted on salivary gland duct ligation injury to date, and it is unclear which signaling pathway is activated.…”