Effects of estradiol and progesterone on epidermal growth factor concentration in plasma, bile, urine, submandibular gland and kidney of the mouse

Progesterone Induces the Proliferation of Urothelial Cells in an Epidermal Growth Factor Dependent Manner

PURPOSE

We have previously reported that estrogen induced proliferation of urothelial cells is modulated by nerve growth factor (NGF). In this study we investigated whether progesterone induces urothelial cell proliferation and whether this effect is modulated by NGF or by epidermal growth factor (EGF).

MATERIALS AND METHODS

Experiments were performed using human urothelial cells immortalized by human papillomavirus E6. Cell proliferation was determined using the alamarBlue (Trek Diagnostic, Westlake, New York) assay. Human papillomavirus were seeded in 48-well plates. They were incubated with 5% alamarBlue and different concentrations of progesterone, EGF or NGF in the presence or absence of neutralizing EGF or NGF antibody, K252a (an inhibitor of trkA, the high affinity receptor for NGF), Ru-486 (an antagonist of progesterone and glucocorticoid receptor) or ZK 137 316 (a specific antagonist of progesterone receptor). Immunoblotting was performed using specific antibodies for progesterone receptor, glucocorticoid receptor or EGF receptor. EGF content in conditioned medium was determined by enzyme-linked immunosorbent assay.

RESULTS

In the presence of 10 nM to 1 microM progesterone urothelial cell proliferation was significantly increased 8.6% to 51.1%. This effect was abolished by ZK137 316 or by Ru-486. Hydrocortisone also induced urothelial cell proliferation. This effect was blocked by Ru-486 but not by ZK137 316. In addition, progesterone stimulated urothelial cell proliferation was inhibited by neutralizing EGF antibody but not by NGF antiserum or K252a. We also found that EGF synthesis and release by urothelial cells was increased by exogenous progesterone. This effect of progesterone was inhibited by ZK 137 316.

CONCLUSIONS

These findings indicate that progesterone has the capacity to induce urothelial cell proliferation through its cognate receptor and this effect is mediated by EGF but not by NGF.

Bile mediates intestinal pathology in endotoxemia in rats

Intestinal pathology frequently accompanies experimental endotoxic shock and is mediated by proinflammatory cytokines. Our hypotheses are that hepatobiliary factors operating from the luminal side of the gut make a major contribution to this damage and that tumor necrosis factor alpha (TNF-alpha) is involved in the pathology. We treated rats with lipopolysaccharide (LPS) intravenously and found that external drainage of bile totally protected the gastrointestinal tract, macroscopically and microscopically, 4 h after LPS administration and dramatically improved survival of the animals for 48 h after LPS administration. The concentration of TNF-alpha in bile increased markedly after LPS administration and was over 30 times higher in bile than in serum. Tissue damage and the biliary TNF-alpha response were abrogated when animals were pretreated with gadolinium chloride to eliminate Kupffer cells. TNF-alpha infusion into the duodenal lumen caused intestinal damage similar to that elicited by intravenous LPS. In rats treated with LPS, survival was significantly increased during the first 36 h in animals given an infusion of anti-TNF-alpha antibody into the duodenum. These results demonstrate that in endotoxemia, intestinal damage is mediated by factors derived from the bile. The findings indicate that luminally acting TNF-alpha contributes to the intestinal damage.

Regulation of expression of human intestinal bile acid-binding protein in Caco-2 cells

Molecular mechanisms of the bile acid active transport system in the ileal enterocytes remain unknown. We examined whether bile acids affect human enterocyte gene expression of intestinal bile acid-binding protein (I-BABP), a component of this transport system. Differentiated Caco-2 cells were incubated in the presence of human bile, bile acids or other lipids. The level of I-BABP expression was evaluated by Northern and Western blot analyses. A 24 h incubation of Caco-2 cells in a medium containing either bile or bile acids resulted in a remarkable 7.5-fold increase in the I-BABP mRNA level over the control level. Neither cholesterol, palmitic acid, phosphatidylcholine nor cholestyramine treated bile showed any difference in I-BABP mRNA expression from the control. Bile acid treatment increased the level of I-BABP mRNA in Caco-2 cells in a time- and dose-dependent manner. Western blot analysis showed that this induction led to increase in cytosolic I-BABP. Chenodeoxycholic acid and deoxycholic acid showed greater induction effects than other hydrophilic bile acids, including their own glycine conjugates. Pretreatment by actinomycin D or cycloheximide completely inhibited the up-regulation of I-BABP expression by bile acid. Bile acids, especially lipophilic bile acids, increase the I-BABP expression in Caco-2-cells, suggesting that luminal bile acids play an important role in regulating the I-BABP gene expression.

Effect of gonadectomy on epidermal growth factor values in the gastrointestinal tract of male and female CD-1 mice

The effects of gonadectomy on the epidermal growth factor (EGF) concentrations in the gastrointestinal tract of CD-1 mice were studied. The EGF concentrations in the gastrointestinal tissues were always higher in males than in females. Gonadectomy led to a decrease in the EGF concentration in males, and an increase in females. Gonadectomy with sialoadenectomy led to a decrease in the EGF concentrations in the gastrointestinal tract of both sexes; the most significant effect being observed in the stomach. Orchidectomy led to a decrease in total body weight, and to a significant decrease in the weight and the protein concentration (ng.g-1 wet weight of tissue) of the submandibular gland, but had no significant effect on the other tissues of the gastrointestinal tract of male mice. Body, tissue weights, and protein concentrations did not change with oophorectomy. This study shows that male and female gonads have a profound effect on the EGF content of the tissues of the gastrointestinal tract and suggests that the submandibular gland also influences the EGF concentration in gastrointestinal tissues in mice.

The impact of gender on the progression of chronic renal disease

Observations in experimental animals and in humans have shown that the rate of progression of renal disease is influenced by gender. Deterioration of renal function in patients with chronic renal disease is more rapid in men than in women, independent of differences in blood pressure or serum cholesterol levels. In addition to genetically determined differences between the sexes in renal structure and function, sex hormones may directly influence many of the processes implicated in the pathogenesis of renal disease progression. Potential mechanisms include receptor-mediated effects of sex hormones on glomerular hemodynamics and mesangial cell proliferation and matrix accumulation as well as effects on the synthesis and release of cytokines, vasoactive agents, and growth factors. In addition, estrogens may exert potent antioxidant actions in the mesangial microenvironment, which may contribute to the protective effect of female gender.

Luminal processing of epidermal growth factor in mouse gastrointestinal tract in vivo

To test the stability of epidermal growth factor (EGF) in the gastrointestinal lumen 125I-labeled EGF was administered to the lumen of isolated stomach, duodenum, jejunum, midjejunum, and ileum of anesthetized mice (14-day-old neonatals and 8-week-old adults). Radioactivity extracted from luminal contents and tissues of gastrointestinal segments was analyzed by binding to C18 isolation cartridges followed by reversed-phase high performance liquid chromatography (RP-HPLC). At 10 min, 74-97% of administered radioactivity was present in the isolated segments (luminal contents + segment tissue). Major portions (60-88%) of radioactivity recovered from luminal contents and segment tissues bound to C18 cartridges, except for lower values (40-54%) recorded in segment tissues of adult mice. RP-HPLC identified > 90% of C18-extracted radioactivity from gastric luminal contents of neonatal and adult mice as intact [125I]EGF (30-min retention time). In adult mice, 46-51% of radioactivity extracted from midjejunal luminal contents was identified as intact [125I]EGF, whereas only 3-5% was intact [125I]EGF in neonatal mice. On the contrary, in extracts of duodenal, jejunal, and ileal luminal contents, 14-30% of radioactivity was intact [125I]EGF in neonatal mice, whereas < 3% was intact [125I]EGF in adult mice. Considerable amounts of intact [125I]EGF were present in the adult mouse gastric tissue and neonatal mouse gastric and duodenal tissues. The remainder of C18-extracted radioactivity from different luminal contents and segment tissues eluted as three major C-terminally truncated EGF derivatives. These three [125]EGF derivatives, eluted with retention times of 35, 21, and 24 min, respectively, were identified as 125I-labeled EGF(1-52), EGF(1-48), and EGF(1-47).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of bile in non-specific defence mechanisms of the gut

The effect of depriving the intestine of bile for 48 hours was studied to determine any influence on various parameters of innate immunity in the gastrointestinal tract. Groups of rats were prepared by bile duct cannulation (with or without fluid replacement) or bile duct ligation. Normal and sham operated animals were used for comparing the thickness of the mucus layer and the cells contained therein, enumeration of goblet cells, and measurement of villus size. Histological examination indicated that the intestinal tissues of treated and control rats were similar. Though villus size and numbers of goblet cells were unaffected, a significant reduction occurred in the thickness of the mucus blanket in the duodenal regions of rats deprived of bile, and there were significantly lower numbers of mucus associated enterocytes and lymphocytes, suggesting a lower turnover rate of the epithelium. The balance of the bacterial populations in the caecum and intestine was altered by bile deprivation-increased numbers of coliform organisms were found in both regions. The range of factors, including antibodies and other known constituents, present in bile may contribute to the maintenance of tissue integrity and influence the balance in indigenous bacterial populations in the intestine. Disturbance of the host's biliary system and concomitant effects on the microbial flora may weaken the overall processes of defence in the intestine.

The granular convoluted tubule (GCT) cell of rodent submandibular glands

The granular convoluted tubule (GCT) is a segment of the duct system of all rodents, situated between the striated and intercalated ducts. It has the peculiar property of synthesizing a large variety of biologically active polypeptides whose role in saliva remains unknown. The literature on the fine structure of GCT cells is critically reviewed. Some recent developments on endocrine regulation of the structure and contents of rodent GCT cells are summarized, with emphasis on EGF, NGF, renin, and kallikrein proteases. A survey of the distribution of GCT cells in several vertebrate families is presented.

Epidermal growth factor modulates cholera toxin induced mammary gland development

Ovariectomized mice were either sham operated or sialoadenectomized and injected daily for 18 days with saline, estradiol + progesterone, cholera toxin or estradiol + progesterone+cholera toxin. Mammary development score and DNA were increased by estradiol + progesterone, but not by cholera toxin alone. In combination with estradiol + progesterone, cholera toxin increased mammary development score and mammary DNA. Sialoadenectomy reduced the ability of estradiol, progesterone and cholera toxin to induce mammary development. In other experiments, mice were primed with estradiol + progesterone for 10 days, and mammary tissue removed for in vitro culture with various combinations of insulin, aldosterone, cholera toxin and epidermal growth factor. In combination with insulin and aldosterone, cholera toxin increased mammary development in vitro. Sialoadenectomy reduced the ability of cholera toxin to induce mammary development in vitro. The effect of sialoadenectomy on mammary development was alleviated by adding epidermal growth factor to culture medium. Biochemical studies indicated that sialoadenectomy reduced the ability of estrogen and progesterone to induce cyclic AMP dependent protein kinase levels in mammary tissue, and also the ability of cholera toxin to induce accumulation of cyclic AMP in tissues. These effects of sialoadenectomy were reversed by addition of EGF to culture media.

The detachment cascade during metastasis

The cause of detachment of tumour cells during metastasis is still one of the most intriguing questions of tumour propagation. A hypothesis is suggested herein for lysis of extracellular matrix that could ultimately lead to the detachment and spreading of malignant cells. According to this theory a certain optimal estrogen level initiates a series of enzymatic activations that culminate in detachment and spreading of tumour cells.

EGF in breast cyst fluid: relationships with intracystic androgens, estradiol and progesterone

The relationship between intracystic levels of epidermal growth factor (EGF) and those of dehydroepiandrosterone sulphate (DHEA-S), delta-4-androstenedione (delta-4-A), 17-beta-estradiol (17-beta-E) and progesterone (PROG) have been studied in 77 breast cyst fluid (BCF) samples. EGF and all tested hormones appeared to be inversely correlated with the intracystic Na+/K+ ratio (p less than 0.001). Consequently, when the BCFs were subdivided according to the Na+/K+ ratio, significantly higher levels of EGF, DHEA-S, delta-4-A, 17-beta-E and PROG were found in Na+/K+ less than 3 BCFs compared with Na+/K+ greater than 3 BCFs (p less than 0.001 in all cases). Strong direct relationships were found among all steroid hormones when they were correlated to one another (p less than 0.001). Intracystic EGF concentration was directly and significantly correlated with each tested hormone (p less than 0.001). However, the relationship between EGF and steroid hormones appeared to be different in the 2 BCF types (Na+/K+ less than 3 or greater than 3).

Biologically active peptides in the gastrointestinal lumen

The release of a variety of biologically active peptides into the gastrointestinal lumen via gastric, duodenal and intestinal secretions, as well as in the saliva, pancreatic juice and bile, has been explored. The key features of luminal secretion of peptides such as secretion at high concentrations, neurohormonal regulation, luminal orientation of stimulated secretion, stability of peptides in the gastrointestinal lumen, altered secretion under pathophysiological conditions, and biological activity of luminally administered peptides are discussed. This review develops a detailed picture of the current understanding of luminal secretion of peptides and their possible biological functions under normal and pathophysiological conditions.

Differential distribution of an estrogen receptor in the submandibular and parotid salivary glands of female rats

The purpose of this study was to measure the availability of the estrogen receptor in submandibular and parotid salivary glands in female rats. The presence of a specific, competitive, and saturable estrogen binder in rat salivary gland tissue was determined by saturation analysis and steroid competition in cell-free homogenates of salivary gland tissue from adult ovariectomized females. Scatchard analysis of the data indicated an estrogen receptor content of 1971.1 +/- 651.4 femtomoles/gm of tissue in submandibular salivary gland. This was significantly (p less than 0.01) greater than the number of estrogen binding sites in the parotid gland (457.1 +/- 123.4 femtomoles/gm tissue). Thus, there is a differential distribution in estrogen receptor content between parotid and submandibular salivary glands. The presence of an estrogen receptor in salivary gland tissue may serve to promote gender differences in submandibular salivary gland EGF content, to mediate changes in saliva composition during the female reproductive cycle and to regulate EGF release for cyclic uterine growth.

Estrogen-androgen antagonism in the regulation of epidermal growth factor in mouse submandibular salivary gland and kidneys

To eludicate hormonal regulation of epidermal growth factor (EGF) concentration we studied the effects in adult female mice of ovariectomy and postovariectomy treatments with testosterone plus estradiol on the EGF concentrations in submandibular salivary gland (SMG), plasma, kidneys and urine. In the tissues, we also studied the location of EGF immunohistochemically and measured EGF mRNA. After ovariectomy, SMG EGF first decreased to one third of preovariectomy level. After postovariectomy day 10 it started to increase and reached by day 80 3.5-fold the preovariectomy level. Simultaneously, EGF mRNA increased. Testosterone treatment further strongly augmented the levels of both EGF mRNA and EGF. A small dose of estradiol counteracted slightly the mRNA effect of testosterone. After ovariectomy plasma EGF first increased 1.3-fold by day 10, then returned to the initial levels, and rose again 1.6-fold by day 80. Testosterone treatment induced a further 1.5-fold increase. Estradiol did not counteract this effect. Kidney EGF decreased 15% by postovariectomy day 20. This was preceded by a decrease in EGF mRNA from day 10 onwards. The EGF concentration recovered during the 80 days, but the EGF mRNA level stayed low. Testosterone treatment further reduced the levels of both EGF mRNA and EGF. This effect was counteracted by estradiol. Urine EGF increased after ovariectomy to a peak (1.7-fold) by day 40. It then returned to the preovariectomy levels by day 80. Testosterone treatment increased urinary EGF 1.9-fold; concomitant estradiol had no effect.

Epidermal growth factor concentrations in submandibular salivary gland, plasma, liver, bile, kidneys and urine of male mice: dynamics after phenylephrine injection

To elucidate the dynamics of epidermal growth factor (EGF) in mice, I studied the effects of excision of the submandibular salivary gland (SMG) and intravenous injection of phenylephrine in adult male mice on the concentration of EGF in plasma, bile, urine, the SMG, the liver and the kidneys. After excision of SMG (sx), the mean concentration of EGF in the liver decreased. Phenylephrine increased the concentrations of EGF in the plasma and liver in both intact and sx mice. In the intact mice, the EGF concentrations also increased in the bile and kidneys but not in the urine. The expected dramatic decrease occurred in the SMG EGF. I conclude that alpha-adrenergic stimulation causes 1) in intact mice release of EGF from SMG into blood, from which it is excreted into bile but not into urine, and 2) release of EGF even from tissues other than SMG.