Influence of thyroid function upon "Substance P" induced secretion of saliva by submaxillary glands

The effects of changes in thyroid function on the action of "Substance P" upon the secretion of saliva by the submaxillary glands was studied in male Wistar rats, with parasympathetic decentralization on the left side. The dose-response curves to increasing doses of "Substance P" showed in hyperthyroid animals increased salivary secretion while in hypothyroid animals the dose-response curve to the drug was decreased. Every animal showed supersentivity to "Substance P" in the decentralized gland. The influence of changes in thyroid function in the denervated glands was the same as that in the unoperated side, increased salivary secretion in hyperthyroidism and decreased in hypothyroidism.     

Effects of sialoadenectomy and castration in female rats

Previous work on the role of the submaxillary glands in the control of the oestrous cycle in rats has been extended to castrated rats in order to avoid the overlapping between sexual and salivary hormones. Animals were sacrificed 30 days after sialadectomy or pseudosialadectomy. The data show that simultaneous castration and sialadectomy increases significantly the glucaemia level and decreases the weight of the adrenal glands. Non-simultaneous castration and removal of the submaxillary glands decreases the weight of the parotid glands. This effect decreases when both actions are simultaneous. On the other hand, castration produces an important decrease in QO2 uptake in tested structures. Removal of submaxillary glands produces a significant increase of QO2 in hypothalamus and thyroid glands. Simultaneous castration and sialadectomy at the anterior cortex, posterior cortex and parotid gland level shows similar results with respect to desalivated rats; other structures show results similar to the castrated group values. From these results, the role played by submaxillary glands in the control of the sexual cycle of the rat and the possible relation to other structures is discussed.     

Expression and localization of immunoreactive-sialomucin complex (Muc4) in salivary glands

Sialomucin Complex (SMC; Muc4) is a heterodimeric glycoprotein consisting of two subunits, the mucin component ASGP-1 and the transmembrane subunit ASGP-2. Northern blot and immunoblot analyses demonstrated the presence of SMC/Muc4 in submaxillary, sublingual and parotid salivary glands of the rat. Immunocytochemical staining of SMC using monoclonal antisera raised against ASGP-2 and glycosylated ASGP-1 on paraffin-embedded sections of parotid, submaxillary and sublingual tissues was performed to examine the localization of the mucin in the major rat salivary glands. Histological and immunocytochemical staining of cell markers showed that the salivary glands consisted of varying numbers of serous and mucous acini which are drained by ducts. Parotid glands were composed almost entirely of serous acini, sublingual glands were mainly mucous in composition and a mixture of serous and mucous acini were present in submaxillary glands. Since immunoreactive (ir)-SMC was specifically localized to the serous cells, staining was most abundant in parotid glands, intermediate levels in submaxillary glands and least in sublingual glands. Ir-SMC in sublingual glands was localized to caps of cells around mucous acini, known as serous demilunes, which are also present in submaxillary glands. Immunocytochemical staining of SMC in human parotid glands was localized to epithelial cells of serous acini and ducts. However, the staining pattern of epithelial cells was heterogeneous, with ir-SMC present in some acinar and ductal epithelial cells but not in others. This report provides a map of normal ir-SMC/Muc4 distribution in parotid, submaxillary and sublingual glands which can be used for the study of SMC/Muc4 expression in salivary gland tumors.     

Whole body autoradiographic distribution of exogenously administered renin in mice

The distribution of exogenously administered renin was investigated using whole body autoradiography. Purified renin from mouse submaxillary gland (SR) was labeled with radioactive iodine (125I). This labeled renin (125I-SR) and Na125I were administered into the tail vein of male ddY mice, in doses of 10.2 and 16.4 mu Ci/30 g body weight, respectively. Mice were killed by an overdose of ether, and autoradiography was performed on whole body sections. To separate free 125I liberated from 125I-SR, sections were treated with perchloric acid. A major accumulation of 125I-SR, acid-insoluble, was evident in the renal cortex, whereas the hepatic accumulation of 125I-SR was minor. Radioactivity in the thyroid and submaxillary glands, in the stomach, and in urine was also apparent, but disappeared after acid treatment, except in the thyroid glands. Radioactivity in the brain, intestinal content, spleen, and adrenal glands was nil. These autoradiograms provide the first evidence that exogenously administered renin is mainly distributed in the renal cortex.     

Biosynthesis of beta nerve growth factor in mouse submaxillary glands

The biosynthesis of beta nerve growth factor (betaNGF) was studied in isolated mouse submaxillary glands incubated with L-[35S]cystine. Sodium dodecyl sulfate gels of anti-betaNGF immunoprecipitates from labeled gland homogenates showed a single major peak of radioactivity, which comigrated with purified betaNGF. This species was nearly completely precipitated by the addition of equivalent amounts of anti-betaNGF, but was absent from immunoprecipitates obtained by the addition of ferritin plus anti-ferritin. The cystine-containing tryptic peptides of the labeled species appeared identical with those of purified betaNGF. In submaxillary glands from adult male mice, labeling of betaNGF represented approximately 0.2% of the trichloroacetic acid-precipitable radioactivity. Castration reduced this value to one-third, while testosterone treatment of castrated animals restored the relative betaNGF synthesis to normal or more. No betaNGF synthesis could be detected in glands from female animals. Several tissues were examined for their ability to synthesize betaNGF in culture. Only submaxillary gland incorporated detectable amounts of radioactivity into betaNGF. Labeling of betaNGF could also be obtained by direct injection of isotope into the submaxillary gland in vivo. The results are discussed in terms of the integration of betaNGF synthesis into neuronal development and maintenance.     

Specific enkephalin-degrading aminopeptidase activity in the HPT and HPO axes of rats with breast cancer induced by N-methyl nitrosourea

State and function of breast depend on an endocrinological balance, the upsetting of which can be a factor favorable to the development of cancer. Enkephalins (ENK) have been considered as a particular form of adaptation to defense to the organism against neoplastic processes. However, ENK may modify the endocrine functions of glands such as the ovary or the thyroid through the hypothalamus-pituitary axis, acting direct or indirectly as endocrine, paracrine or autocrine stimulatory growth factors. The present work analyses enkephalin-degrading tyrosyl aminopeptidase (EDA) activity in the hypothalamus-pituitary-thyroid (HPT) and hypothalamus-pituitary-ovary (HPO) axes in a rat model of breast cancer induced by N-methyl-nitrosourea (NMU) to state the relationship between ENK levels modification through EDA activity at different neuroendocrine levels and breast cancer. Results obtained show a decrease in EDA activity in hypothalamus, anterior and posterior pituitary, thyroid and ovary, suggesting increased levels of ENK in all these locations. These ENK may induce breast cancer cell growth and progression not only at breast level, but also acting at several neuroendocrine levels such as the HPT and HPO axes, inducing an unbalance of several other hormones, which could also facilitate the progression of cancer as an undesirable concomitant effect.     

Subject index

It is the object of this report to compare the biological, biochemical activity and the immunocytochemical localization of nerve growth factor (NGF) in the submaxillary glands of Praomys (mastomys) natalensis and mouse. Biological and radioimmunoassays gave evidence of a higher NGF activity in the soluble extract of submaxillary glands of male and female mastomys than in the male mouse homologous glands. Histological and immunocytochemical studies showed that, in contrast to mouse submaxillary glands, these mastomys glands exhibit a very attenuated sexual dimorphism. Immunocytochemistry and radioimmunoassay revealed a similarity—but not identity—of mouse and mastomys NGFs.     

The submaxillary salivary glands of the African rodent Praomys (mastomys) natalensis as the richest available source of the nerve growth factor

It is the object of this report to compare the biological, biochemical activity and the immunocytochemical localization of nerve growth factor (NGF) in the submaxillary glands of Praomys (mastomys) natalensis and mouse. Biological and radioimmunoassays gave evidence of a higher NGF activity in the soluble extract of submaxillary glands of male and female mastomys than in the male mouse homologous glands. Histological and immunocytochemical studies showed that, in contrast to mouse submaxillary glands, these mastomys glands exhibit a very attenuated sexual dimorphism. Immunocytochemistry and radioimmunoassay revealed a similarity—but not identity—of mouse and mastomys NGFs.     

Verhulstian analysis of the growth of transplantable mammary tumours in sialoadenectomized mice

In this report we have analysed data published in 1989 by Inui et al. (Incidence of precancerous foci of mammary glands and growth rate of transplantable mammary cancers in sialoadenectomized mice. J. Natl Cancer Inst. 81, 1660) involving the effects of perturbation of the epidermal growth factor (EGF) status of mammary tumour-bearing mice on subsequent volumetric responses. Removal of an endogenous EGF stimulus by surgical ablation of the submaxillary glands, the major EGF-producing organ in mice, produced significantly slower growth of rodent mammary neoplasms, decreased success rate of transplantation, and an increase in the latent period before growth occurred. Administration of i.p. EGF (5 micrograms/mouse/day) to sialadectomized tumour-bearing mice would however, increase tumour growth rate. Data were analysed using the Verhulst equation which indicated that the observed effects on tumour volumetrics by either sialoadenectomy or EGF administration could be interpreted as being produced through paracrine pathways. The use of the Verhulstian analysis indicates that it is possible to analyse neoplastic responses and infer whether paracrine or autocrine pathways are involved.     

Growth-promoting actions of extracts from mouse submaxillary glands on human endothelial cells in culture.

Extracts of submaxillary glands from two different strains of inbred mice were mitogenic for human endothelial cells in culture. The mitogenic activity of extracts from glands of males of the SWR/J and C57BL/10J strains were equivalent, and the growth stimulating effect was unrelated to renin or esteroproteolytic activity. Mitogenic activity in extracts from SWR/J females was less than that from males, and extracts from C57BL/10J females were inactive. The polypeptide growth factors, epidermal (EGF) and fibroblast (FGF) growth factors, also stimulated replication of endothelial cells. Cells from either umbilical arteries or veins responded to submaxillary extracts, EGF, or FGF with a similar increase in cell number, increase in protein and enhanced uptake of 3H-thymidine. The proliferative response was associated with decreased activity of angiotensin I converting enzyme which is localized on the endothelial surface. Nerve growth factor (NGF) was not mitogenic for endothelial cells. Extracts of submaxillary glands from male mice of either strain contained approximately 20 times more EGF than extracts from females, as determined by immunodiffusion. Mitogenic activity of the extracts was completely inhibited by antiserum to EGF, suggesting that the active component of these preparations is EGF.     

Functional relationship between submaxillary gland and basal parts of intestinal cryptae and endocrine function of the pancreas]

The effect of fasting, glucose load and administration of the diabetogenic agent dithison on the cells of pancreatic islets, submaxillary glands and basal parts of intestinal cryptae was studied in rabbits by means of the histochemical dithison test. A potential relationship between these cells in realization of endocrine regulation of carbohydrate metabolism is suggested.     

Tissue distribution and characterization of peptide C-terminal alpha-amidating activity in rat

The C-terminal alpha-amide formation of peptides is one of the most important events in prohormone processing. Recently, we developed a simple and sensitive assay for detecting alpha-amidating activity in tissues by using (125I)-Ac-Tyr-Phe-Gly as a substrate. Using this assay method, we have determined the tissue distribution of alpha-amidating enzyme activity in adult male rat. High concentrations of alpha-amidating activity were found in pituitary, brain, thyroid, gastrointestinal tract, pancreas, heart, submaxillary glands and parotid glands. Alpha-amidating enzyme activities in all tissues examined exhibit very similar copper and ascorbate requirements, pH dependence, and behavior on gel-filtration.     

Enhanced differentiation of sexually dimorphic organs in L-thyroxine treated Tfm mice

Summary In the present study we examined the effects of L-thyroxine on the differentiation of three sexually dimorphic organs in mice affected by the testicular feminization mutation (Tfm): the submaxillary salivary glands, the kidneys, and the adrenal glands. In the salivary gland we compared the effects of L-thyroxine and testosterone in normal and Tfm mice on the morphology of the intercalated tubules and on the NGF content of this gland. In the kidney we examined thyroid hormone effects on the sexually dimorphic proximal convoluted tubules. In the adrenal gland we studied the effects of the same hormone on the weight of the organ and on the structure and ultrastructure of the zona reticularis in untreated and L-thyroxine treated Tfm mice. The results show that the thyroid hormone enhances differentiation of the dimorphic structures in all these organs and increases the secretory activity of the salivary and adrenal glands. The stimulatory effects of L-thyroxine are more pronounced on the weight of the adrenal than of the salivary gland and of the kidney. Our results raise the question whether the enhanced differentiation elicited by L-thyroxine in the three sexually dimorphic organs of Tfm mutants is due to a direct hormonal effect, or whether it is fully, or in part, mediated through the hypothalamo-pituitary-thyroid axis.This investigation was supported by the Progetto Finalizzato Biologia della Riproduzione of the Italian National Council of Research (CNR)     

Epidermal growth factor (EGF) expression in human salivary glands. An immunohistochemical study.

Epidermal growth factor (EGF) is a biologically active peptide involved in differentiation, growth, regeneration and repair of human and animal tissues. Quantitative biochemical studies showed in man the highest concentration of EGF in the parotid gland. The aim of the present study was to define EGF immunolocalization in the individual segments of the human major salivary glands (salivon). The material consisted of sections obtained from the surgically removed salivary glands: parotid, submaxillary and sublingual. Immunohistochemical studies were performed by PAP method using monoclonal antibody against human epidermal growth factor. EGF expression was found almost exclusively in the efferent pathways of the salivary glands, mostly in the intercalated ducts and Pflüger salivary tubules. These segments of the salivon are most developed in the parotid gland in which the staining was stronger than in other salivary glands.     

Identification of epidermal growth factor in mouse abdominal effusion

Epidermal growth factor (mEGF)-like immunoreactive material(s) was identified in mouse abdominal effusion (approximately 2.1 ng/mg protein) by our enzyme immunoassay (EIA) for mEGF. This material(s) and mEGF from the submaxillary glands of male mice were virtually equivalent with respect to the molecular weight and the antigenicity. Also, on isoelectric focusing analysis, the mEGF-like material(s) identified in abdominal effusion gave a major peak at pH 4.2 and a minor one at pH 4.5. These results demonstrate that the mEGF-like material(s) found in abdominal effusion is a molecule identical to mouse submaxillary gland EGF. Further we found that sialoadenectomy did not cause a marked decrease in the level of mEGF in abdominal effusion, suggesting that the source of mEGF found in abdominal effusion is other than the submaxillary glands.     

Development of the rat salivary glands. II. The identification of a trypsinlike protease in the submaxillary gland

Trypsinlike protease activity at pH 9.2 was measured in tissue extracts of adult rat salivary glands by using a fluorometric assay in which β-naphthylamine is released by the hydrolysis of benzylarginine β-naphthylamide. The submaxillary gland contains high levels of this activity, and the parotid and sublingual glands have a maximum of 2000-fold and 200-fold less. After polyacrylamide disc gel electrophoresis at pH 8.3, the protease activity of submaxillary extracts is associated with a major protein band. Neither this protein band nor its protease activity is detectable in extracts of parotid or sublingual glands. Homogenates of newborn submaxillary gland do not have this protease activity at detectable levels, suggesting that its major accumulation is postnatal.     

Cosmos 1887 mission overview: effects of microgravity on rat body and adrenal weights and plasma constituents

The Cosmos 1887 biosatellite carried 10 male rats and 2 rhesus monkeys on its 12.5-day mission. Upon re-entry the Vostok vehicle overshot the designated landing site, which resulted in fasting of the animals for 42 h, exposure to cage temperatures of 12-15 degrees C, and 2 days delay in death of the rats. No overt untoward effects of the delayed recovery were apparent. Tissues from the rats were harvested by Soviet scientists, appropriately preserved, and provided to U.S. investigators. Flight rats grew more slowly and had larger adrenal glands than earth gravity controls. Analysis of plasma revealed increased concentrations of hepatic alkaline phosphatase, glucose, urea nitrogen, and creatinine in flight rats. In contrast, electrolytes, total protein, albumin, corticosterone, prolactin, and immunoreactive growth hormone levels were unchanged. However, testosterone concentration was marginally decreased after flight and thyroid hormone levels were suggestive of reduced thyroid function. Due to the possible effects of reentry and the delay in recovery of the animals, it is not clear what relationship postflight levels of plasma constituents bear to their concentrations in flight.     

Comparative morphological analysis of peripheral endocrine glands in small mammals inhabiting areas with high levels of radioactive pollutants and exposed to chronic irradiation in laboratory experiments

The comparative study of cellular-tissue reactions in endocrine organs (thyroid and suprarenal glands, ovary) of rodents exposed to radiation in natural conditions (Radium station in Komi Republic and 30-km zone of Chernobyl APP) and experimental conditions modeling the chronic exposure has been conducted. There is evidence that chronic irradiation in low doses causes morphological disorders in different levels of structural organization (cellular-tissue, organism and population levels). The experimental results showed that observed variations in thyroid, suprarenal glands and ovary by morphometric parameters reflect the natural changes in their functional activity (within the physiological limits). These changes are directed at the homeostasis maintenance in changed conditions and have a compensatory and adaptation character. The effects of low dose radiation influence with combination of other agents may be amplified at the cellular-tissue reactions level. In comparison with experimental results, the natural conditions (high level of radioactivity with alpha- and beta-emitters, high natural radionuclides, toxic elements and extreme climatic factors) induce more expressed changes as a significant increasing of chromosomal and genes mutations in cells, destructive processes in organs of endocrine system and disorders of reproductive functions.