Esteroprotease, an androgen-dependent enzyme of the mouse submandibular gland, was increased by injection of tri-iodothyronine (T3) in mice with testicular feminization (Tfm) which are genetically deficient in androgen receptors. Histochemical and electron microscopic studies also demonstrated increases of RNA and serous-like granules in cells of the convoluted tubules of the gland. These findings suggest that the esteroprotease gene in Tfm mice is normal and that T3 can induced both esteroprotease and serous-like granules independently of androgen.
Growth hormone-releasing hormone (GHRH) is a well-known hypothalamic hormone that stimulates the synthesis and release of growth hormone (GH) as well as the proliferation of GH-producing cells in the anterior pituitary gland.Recent reports have shown GHRH synthesis in pituitary somatotroph adenomas, but GHRH immunoreactivity has not been demonstrated in the previous studies.In order to confirm the role of locally generated GHRH for the progression of somatotroph adenomas, we investigated the expression of GHRH in 25 pituitary somatotroph adenomas immunohistochemically using both conventional avidin-biotin-complex (ABC) method and novel catalyzed signal amplified (CSA) system.In addition, we investigated the expression of GHRH mRNA and GHRH receptor mRNA with in situ hybridization (ISH) using CSA system.The weak immunopositivity of GHRH were observed in only 2 adenomas (8.0%) out of 25 somatotroph adenomas using ABC method.In contrast, 15 adenomas (60.0%) out of 25 somatotroph adenomas were immunopositive for GHRH revealed by CSA system.The expression of GHRH mRNA was confirmed using CSA-ISH system in 13 adenomas (72.2%) out of 18 somatotroph adenomas.In 11 adenomas (61.1%) out of 18 somatotroph adenomas, the expression of GHRH receptor mRNA was demonstrated using CSA-ISH system.This is a first report that clarified histopathologically GHRH production in pituitary somatotroph adenomas.The demonstration of GHRH and its receptor expression is meaningful in clarifying the autocrinc or paracrine regulation of GHRH in GH production and progression of pituitary somatotroph adenomas.
We have shown the efficacy of image analysis using 3,3'-diaminobenzidine (DAB) with a metal enhancer substrate for demonstrating quantitative differences in the amount of epidermal growth factor (EGF) in the submandibular gland from normal, castrated, and testosterone propionate (TP) treated castrated rats. Immunohistochemical determination of EGF visualized by DAB-nickel reagent was performed with image analysis using a computed image analyzer system (ACAS 570). Immunohistochemistry for EGF disclosed positive staining in granular convoluted tubule cells in the tissue sections from each experimental group. Using the tools of a competent data program installed in the ACAS 570 software, we measured quantitative differences among the experimental glands examined. Castration was shown to elicit a significant reduction in the EGF-positive area and staining intensity, and administration of TP to the castrated animals restored these parameters to levels greater than those of normal rats. Our study demonstrates that a simple, inexpensive, commercially available metal enhancer substrate can be applied accurately to the computer assisted quantification of histochemical hormone-induction studies.
As an initial step to study the effect of sodium fluoride on the oral environment, we investigated how sodium fluoride (NaF) affects the branching morphogenesis of fetal mouse submandibular gland (SMG). When mouse SMG was prepared from the embryo at 13 days post prenatal stage and cultured, gradual development of branching morphogenesis was observed. Addition of NaF affected this morphological change in bimodal fashions. At a lower concentration of NaF (<2 IM), the branching morphogenesis was slightly enhanced, whereas at a higher concentration of NaF (4 ~ 8IM), it was almost completely inhibited. The inhibitory effect of NaF at the higher concentration was abrogated by stimultaneous addition of epidermal growth factor (EGF), but not by 5·- dihydrotestosterone (DHT) or insulin-like growth factor (IGF). These data demonstrate that EGF can effectively reduce the cytotoxic activity of NaF at micromolar concentration. Since 1945, when the fluoridation of the water supply was introduced, fluoride has been used not only as an additive to drinking water, but also as a mouthwash, toothpaste, and cement for dental use such as glass ionomer cement, due to its inhibitory effect on dental caries and its stimulatory effect on remineralization (1). Considering its safety, however, some researchers oppose the utilization of fluoride to prevent dental caries. Some kinds of disorders caused by excess amounts of fluoride, such as speckled tooth and early skeletal fluorisis, have been reported. In this context, the cytotoxity of fluoride has been well investigated (2-7). However, the study of its effect on the developing organ has been limited (8,9). The aim of the present study was to investigate the effect of sodium fluoride (NaF) on fetal mouse submandibular gland (SMG), a well-established organ development model. Branching morphogenesis of the mouse SMG is dependent on cell-cell interaction between and within epithelium and mesenchyme. Such an interaction is also seen in other organs including lung, kidney and pancreas. It is known that branching morphogenesis in vitro is stimulated by addition of epidermal growth factor (EGF) (10-12), insulin-like growth factor (IGF) (11) and 5·-dihydrotestosterone (DHT) (13-17). Therefore, we also tested the possibility that any of these growth factors and hormone may modify the effect of NaF on SMG.
