Renal uptake and excretion of epidermal growth factor from plasma in the rat.

The rat excretes around 2 nmol epidermal growth factor (EGF) in the urine per 24 h. The urinary EGF might be derived from plasma and/or might be synthesized in the kidneys. We have used the rat to study the renal uptake and excretion of homologous EGF from plasma. I.v. injected 125I-EGF was removed from the circulation within a few minutes. 5 min after the injection, the kidneys contained 12% of the 125I-EGF. The kidneys seemed to degrade most of the 125I-EGF which they accumulated from blood, as only 4% of the injected label was excreted as intact 125I-EGF in the urine. The amount of endogenous EGF in plasma was under the detection limit of our enzyme-linked immunosorbent assay (0.03 nmol/l) and it remained so after bilateral nephrectomy. Even if plasma EGF was 0.03 nmol/l excretion of EGF from plasma could account for less than 5% of the urinary EGF. This study shows that the kidneys are able to accumulate EGF from plasma and excrete a part of it as intact EGF in the urine. However, excretion of immunoreactive EGF from plasma can only account for a minor part of the urinary EGF.

Gastrointestinal regulatory peptides in familial adenomatous polyposis.

The etiology of adenomas in the stomach and duodenum in patients with familial adenomatous polyposis (FAP) is unknown. In this study the plasma concentration of epidermal growth factor (EGF), and other gastrointestinal polypeptides with a possible trophic effect on the gastrointestinal mucosa, was unchanged before and after meal stimulation. In 3 of 7 patients an increased EGF immunoreactivity was found in duodenal adenomas. This study has not indicated that regulatory peptides are involved in development of duodenal polyps in FAP, but suggests further studies to determine the role of EGF in FAP.

Influence of epidermal growth factor on liver regeneration after partial hepatectomy in rats.

The role of epidermal growth factor on liver regeneration after partial hepatectomy in rats was investigated. After a 70% hepatectomy in rats, the concentration of epidermal growth factor in portal venous blood was unchanged compared with unoperated controls. However, small amounts of epidermal growth factor could be identified in portal venous blood after intestinal instillation of epidermal growth factor. Brunner's glands and the submandibular glands secrete epidermal growth factor. Extirpation of Brunner's glands decreased liver regeneration, whereas removal of the submandibular glands had no effect on liver regeneration. Epidermal growth factor antiserum reduced liver regeneration significantly. Oral or s.c. administration of epidermal growth factor had no effect on liver regeneration, whereas epidermal growth factor enhanced the effect of insulin and glucagon on liver regeneration. The results suggest that endogenous epidermal growth factor participates in stimulation of liver regeneration after partial hepatectomy in rats. Epidermal growth factor given together with insulin and glucagon had a synergistic effect on liver regeneration which suggests that liver regeneration in the rat is controlled by multiple regulatory peptides.

Effect of omeprazole and cimetidine on healing of chronic gastric ulcers and gastric acid secretion in rats.

The effect of omeprazole and cimetidine on healing of chronic gastric ulcers and gastric acid secretion was investigated in rats. The effect of three doses of omeprazole given orally once daily for 25 days was investigated. In controls median ulcer healing was 19.6% after 25 days. Omeprazole increased median ulcer healing from 36% at 145 mumole/kg/day to 80% at 580 mumole/kg/day. Basal and pentagastrin stimulated gastric acid secretion decreased dose-dependently by nearly 90% at a dose of 580 mumole/kg/day 22-24 hr after the last dose of omeprazole. Cimetidine given twice daily, in a dose that initially inhibits gastric acid secretion by 95%, reduced acid secretion by only 50% 11 hr after the last dose. Median ulcer healing after treatment with cimetidine for 25 days was 41%. This study demonstrates that omeprazole has a more long-acting inhibitory effect on gastric acid secretion compared to cimetidine and accelerates healing of chronic gastric ulcers dose-dependently in rats.

Is epidermal growth factor involved in development of duodenal polyps in familial polyposis coli?

Duodenal adenomas are a frequent extracolonic manifestation in patients with familial polyposis coli (FPC). Epidermal growth factor (EGF), a polypeptide that stimulates cellular growth and differentiation, is localized in Paneth cells in the small intestine. In two patients with FPC, we found EGF immunoreactivity in duodenal adenomas. Numerous EGF immunoreactive Paneth cells were localized, not as usually, in the bottom of the crypts, but scattered along the crypts alone or in clusters. We do not know whether EGF is involved in the development of duodenal polyps in FPC patients, or whether the present findings represent secondary changes in duodenal polyps.

Role of epidermal growth factor in gastroduodenal mucosal protection.

Epidermal growth factor (EGF) is a polypeptide produced in the submandibular glands, Brunner's glands, and the kidneys. The peptide is secreted in an exocrine fashion into saliva, duodenal juice, and urine. EGF stimulates cellular growth and differentiation and inhibits gastric acid secretion. Removal of the submandibular glands decreases the amount of EGF in saliva and gastric juice and subsequently the synthesis of DNA in the gastric mucosa is reduced as well as its resistance to bile-salt-induced gastric lesions. Intragastric instillation of EGF can prevent gastric ulcerations induced by aspirin as well as cysteamine in rats. EGF also accelerates the healing of chronic gastric ulcers induced by acetic acid. Cysteamine is a duodenal ulcerogen in rats. After cysteamine administration, the secretion of EGF from Brunner's glands decreases and the glands become depleted of mucus. Intraduodenal instillation of EGF can partly prevent formation of cysteamine-induced duodenal ulcers. Oral administration of EGF can accelerate healing of chronic duodenal ulcers in rats. The beneficial effect of EGF on healing of chronic gastroduodenal ulcers is probably due to the delayed effects of EGF such as stimulation of RNA and DNA synthesis. The protective effects of EGF are probably related to the early actions of the peptide such as activation of cell surface proteins and increased glycosaminoglycan synthesis.

Adrenergic effects on secretion of amylase from the rat salivary glands.

The present study was undertaken to investigate the effect of adrenergic agents on secretion of amylase from the salivary glands in vivo. Saliva was collected from the distal oesophagus in conscious rats. Adrenaline increased the concentration of amylase in saliva and serum significantly. The result of infusion of alpha- and beta-adrenergic antagonists as well as noradrenaline and isoproterenol showed that secretion of salivary amylase is predominantly mediated by stimulation of beta-adrenergic receptors, especially of the beta 1-subtype. Investigation of the isoenzyme pattern in saliva, pancreatic juice and serum demonstrated that the major component in serum is salivary amylase. This study has shown that beta-adrenergic agents stimulate secretion of amylase from the salivary glands in rats. Though the secretion is mainly exocrine small amounts of amylase is found in serum, which seems to originate from the salivary glands.

Effect of neurotensin and neurotensin fragments on gastric acid secretion in man.

The effect of intravenous infusion of neurotensin (NT) and NT-fragments on pentagastrin stimulated gastric acid secretion was investigated in healthy subjects. Neurotensin was infused in three doses (72, 144 and 288 pmol/kg per h). An N-terminal fragment (NT 1-8), a C-terminal fragment (NT 8-13) and an NT-analogue, substituted at the C-terminal tyrosine residue (Phe11-NT) were infused in two doses (72 and 144 pmol/kg per h). Concentrations of the infused peptides were measured in peripheral venous blood by radioimmunoassay. Plasma levels of NT 1-13, NT 1-8 and Phe11-NT increased in a dose-dependent manner; NT 1-13 to 50 (34-69), 78 (54-113) and 143 (112-242) pmol/l (medians and range) at 72, 144 and 288 pmol/kg per h, NT 1-8 to 405 (340-465) and 1215 (915-1300) pmol/l, and Phe11-NT to 200 (110-245) and 390 (250-410) pmol/l at 72 and 144 pmol/kg per h, respectively. Increases in plasma levels of NT 8-13 could not be detected during the infusion, suggesting that the fragment is rapidly metabolized in man. Neurotensin 1-13 inhibited gastric acid secretion in a dose-dependent manner and the decrease in gastric acid secretion was linearly related to plasma levels of NT 1-13. Neurotensin 1-8 and NT 8-13 inhibited gastric acid secretion only at 144 pmol/kg per h, while the analogue Phe11-NT had no effect. The results showed that the inhibition of gastric acid secretion produced by NT was dose-dependent and linearly related to circulating levels of NT, and that under physiological conditions this effect presumably is elicited by the C-terminal part of the peptide.

Vasoactive intestinal polypeptide and acetylcholine stimulate exocrine secretion of epidermal growth factor from the rat submandibular gland.

The effect of vasoactive intestinal polypeptide (VIP) and acetylcholine on secretion of epidermal growth factor (EGF) from the rat salivary glands was investigated. VIP in doses of 3 X 10(-10) to 3 X 10(-8) mol/kg per h stimulated secretion of saliva and total output of EGF dose-dependently. Acetylcholine also stimulated salivation and output of EGF. VIP in a dose of 3 X 10(-11) to 3 X 10(-10) mol/kg per h enhanced the stimulatory effect of acetylcholine, but this effect disappeared when the dose of VIP was increased. Adrenalectomy decreased acetylcholine stimulated total output of EGF by approximately 50%, but only by 20% when acetylcholine plus VIP was administered. EGF was localized to the convoluted granular tubules in the submandibular gland, whereas EGF could not be detected in the remaining salivary glands. The results suggest that VIP and acetylcholine cooperate in the control of exocrine secretion from the rat salivary glands. The effect of acetylcholine, however, seems to be partly dependent on circulating catecholamines.

Effect of antisecretory agents and vagotomy on healing of "chronic" cysteamine-induced duodenal ulcers in rats.

Penetrated cysteamine-induced duodenal ulcers in rats have a very prolonged course of healing. In this study, it was investigated how much the healing of these ulcers is accelerated by some treatments. The treatments included omeprazole, cimetidine, and truncal vagotomy. In addition, the effect of omeprazole and cimetidine on gastric acid secretion was investigated in chronic gastric fistula rats. After 25 days of treatment, significantly more rats in the treated groups had healed ulcers than in the control group. There was little further improvement up to 100 days of treatment, and the difference between treated and untreated groups decreased. The morphology of healing ulcers in treated and untreated rats was also compared. In controls, there was a simultaneous regeneration of mucosa and the submucosal Brunner's glands from the edges of the ulcer, the slow proliferation rate of the latter probably being decisive for the prolonged healing. In the treated rats, the mucosa first regenerated with formation of crypts and low villi and subsequently, the Brunner's glands were formed by proliferation from the bottom of the crypts.

Oral administration of synthetic human urogastrone promotes healing of chronic duodenal ulcers in rats.

The effect of oral administration of synthetic human epidermal growth factor/urogastrone (EGF/URO) on healing of chronic duodenal ulcers induced by cysteamine in rats was investigated and compared with that of cimetidine, a H2-receptor antagonist. After 25 and 50 days of treatment, synthetic human EGF/URO significantly increased healing of chronic duodenal ulcers to the same extent as cimetidine. Combined treatment with synthetic human EGF/URO and cimetidine for 25 days was more effective than synthetic human EGF/URO given alone, whereas combined treatment for 50 days was significantly more effective than cimetidine alone. These results show that a combination of an agent inhibiting gastric acid secretion and the cytoprotective and growth-stimulating peptide EGF/URO seems to be more effective with regard to duodenal ulcer healing than individual administration of the two substances. Synthetic human EGF/URO is a potent inhibitor of gastric acid secretion when administered intravenously, but had no effect on acid secretion when given intraduodenally, which suggests that the effect of synthetic human EGF/URO is a direct action on the duodenal mucosa. In conclusion, this study showed that oral synthetic human EGF/URO has a significant effect on healing of duodenal ulcers in rats. The amount of synthetic human EGF/URO administered is comparable to that found in saliva during stimulation of the salivary glands. Our results, therefore, suggest that EGF/URO is one of the endogenous factors participating in healing of duodenal ulcers.

Adrenergic effects on renal secretion of epidermal growth factor in the rat.

Urinary epidermal growth factor (EGF) has been demonstrated recently to originate from the kidneys. The present study was undertaken to investigate the adrenergic and cholinergic influence on secretion of renal EGF. beta-Adrenergic agonists increased the level of urinary EGF, while propranolol, a beta-adrenergic blocking agent, decreased basal and beta-adrenergic stimulated total output of urinary EGF. Acetylcholine and the anticholinergic agent atropine had no effect on the output of EGF in urine. Also chemical sympathectomy induced by 6-hydroxydopamine reduced the urinary output of EGF. None of the experimental groups had a median serum concentration above the detection limit of the assay. The present study shows that secretion of renal EGF is under the influence of the sympathetic nervous system and release of EGF is stimulated by activation of beta-adrenergic receptors in the kidneys.

Renal origin of rat urinary epidermal growth factor.

The origin of rat urinary epidermal growth factor (EGF) has been investigated. Unilateral nephrectomy decreased the concentration, total output of EGF and EGF/creatinine ratio by approximately 50%, while the output of creatinine was unchanged. Removal of the submandibular glands and duodenal Brunner's glands, organs known to produce EGF, had no influence on the output of EGF in urine. Renal clearance of EGF exceeded that of creatinine, and after bilateral nephrectomy or bilateral ligation of the ureters, the concentration of creatinine in serum increased, while the concentration of EGF was below the detection limit of the assay. Renal production of EGF was confirmed by immunohistochemistry demonstrating EGF immunoreactivity in the afferent arteriole of the juxtaglomerular apparatus. EGF in the submandibular glands and in urine was found to differ with chromatofocusing and reverse-phase HPLC. At isoelectric focusing the pI of submandibular EGF was 4.8 and 5.4 while that of urinary EGF was 5.3 and 6.4. In conclusion, this study demonstrates that urinary EGF mainly originates from the kidneys and is localized to the renal juxtaglomerular apparatus.

The prophylactic effect of 5-aminosalicylic acid and salazosulphapyridine on degraded-carrageenan-induced colitis in guinea pigs.

Experimental colitis was induced in guinea pigs by administration of 5% degraded carrageenan for 5 days. The prophylactic effect of a slow-release preparation of 5-aminosalicylic acid (5-ASA; 13 mg/100 g/day) was compared with approximately equimolar amounts of salazosulphapyridine (SASP; 26 mg/100 g/day) and placebo. Treatment was started 2 days before initiation of carrageenan administration. The drugs were administered through a chronic gastric fistula. At the end of the study concentrations of 5-ASA and acetylated 5-ASA (Ac-5-ASA) in cecal contents and in plasma were determined. In the placebo group, all guinea pigs developed many small punctiform ulcerations in the cecum (median, 30/cm2). In the 5-ASA group no protective effect was demonstrated, since the number of ulcerations was 37/cm2. The difference is not statistically significant. However, the SASP group presented significantly fewer ulcerations (4/cm2). The concentrations of 5-ASA and/or its acetylated metabolite were several times higher in the cecum content and twice as high in plasma in the SASP group, indicating a difference in the absorption patterns of 5-ASA and the two drugs. These results and the etiological difference between the human ulcerative colitis and the carrageenan model may account for the lack of prophylactic effect of the slow-release 5-ASA in this experiment.

Effect of secretin and glucagon on Brunner's gland secretion in the rat.

Brunner's gland secretion in response to infusion of secretin and glucagon was studied in the rat. Secretin was infused in doses of 15, 150 and 1500 ng/kg/h. All dose significantly increased bicarbonate and protein output and depleted Brunner's glands of PAS-positive mucin. Bicarbonate secretion was related to plasma secretin concentration, and a marked stimulatory effect of secretin was found in very low, probably physiological, plasma concentrations. Maximal bicarbonate output was obtained at a plasma concentration of secretin about 20 pmol/l. Glucagon was infused at a rate of 1.0 micrograms/kg/h and did not influence secretion rate or cell morphology. Also large doses of 5.0 and 50.0 micrograms/kg/h had no effect on Brunner's gland secretion. It is concluded that secretin in very low plasma concentrations stimulates secretion of bicarbonate, protein and mucus from Brunner's glands in the rat, while glucagon has no effect, and it is suggested that secretin may be involved in the physiological regulation of Brunner's gland secretion.

Neurotensin inhibits meal-stimulated gastric acid secretion in man.

The effect of physiological doses of exogenous neurotensin on meal-stimulated gastric acid secretion and serum gastrin concentration was investigated in six healthy subjects. Acid secretion was reduced by 32% during intravenous infusion of neurotensin, the plasma neurotensin concentration being within physiological range. Serum gastrin concentration was unchanged during infusion of neurotensin. The results strongly suggest that neurotensin participates in the regulation of gastric acid secretion and support the theory that neurotensin may play a role in the intestinal phase of gastric acid secretion in man.

The mechanism of gastrin release in cysteamine-induced duodenal ulcer.

Duodenal ulcer can be induced in rats by a single dose of cysteamine. The ulcer formation is accompanied by acid hypersecretion and elevated serum gastrin levels. This study was performed to elucidate the mechanisms of gastrin release after an ulcerogenic dose of cysteamine. Cysteamine induced a rise in serum gastrin from 29 +/- 5 pg/ml to a maximum of 203 +/- 62 pg/ml after 3 h in unoperated rats, whereas no rise was seen in vagotomized or antrectomized rats. The beta-adrenergic blocking agent propranolol strongly inhibited cysteamine-induced gastrin release, whereas atropine dependent on an intact vagus and may be mediated by beta-adrenergic receptors.

Vagal control of glucagon-induced inhibition of gastric acid secretion in duodenal ulcer patients.

To study the vagal influence on the inhibitory effect of pancreatic glucagon on gastric acid secretion, the effect of exogenous pancreatic glucagon on pentagastrin-stimulated acid secretion was studied in duodenal ulcer patients before and after parietal cell vagotomy without drainage (PCV). Preoperatively, exogenous pancreatic glucagon inhibited gastric acid secretion, whereas no effect was found postoperatively. Plasma pancreatic glucagon was identical pre- and post-operatively and was within the physiological range. The study demonstrates that the inhibitory effect of pancreatic glucagon on pentagastrin-stimulated gastric acid secretion is dependent on an intact vagal innervation of the parietal cell area.

Calcium and stimulus-secretion coupling in gastric fundic mucosa. Effect of inhibition of calcium transport by verapamil on gastric acid secretion in the isolated guinea pig fundic mucosa and in healthy subjects.

The effect on gastric acid secretion of blocking transmembrane Ca2+ influx into the parietal cells has been studied in the isolated guinea pig fundic mucosa and in healthy volunteers. Verapamil inhibited in a dose-related manner histamine-stimulated acid secretion in the guinea pig mucosa, whereas stimulation with theophylline and dibutyryl cyclic-AMP was unaffected. The effect of verapamil (Isoptin, 2.0 mg/h) on acid secretion stimulated by increasing doses (50, 200, 500 ng/kg-h) of 15-leucine synthetic human gastric I was studied in seven healthy volunteers, alone and in combination with infusion of calcium gluconate (1.0 meq Ca2+/kg-h). Verapamil inhibited the acid response to the lowest dose of gastrin, resulting in a significant increase of D50 of 15-leucine synthetic human gastrin I. This effect was partly reversed by calcium infusion. It is concluded that one of the mechanisms by which extracellular calcium concentration influences acid secretion is by transmembrane influx of Ca2+ during stimulation.

The effect of cysteamine on the Brunner gland secretion in the rat.

Cysteamine in a single subcutaneous administration induces release of gastrin, acid hypersecretion, and duodenal ulcer in rats. Pentagastrin-induced acid hypersecretion has no ulcerogenic effect. The Brunner glands in the proximal duodenum have previously been shown to be an important factor in the natural defence of the duodenal mucosa, and this study has been performed to determine the effect of cysteamine and pentagastrin on the Brunner glands in the rat. The proximal duodenum was isolated in situ and drained by a polyethylene tube. The secretion was studied for two 5-h periods after administration of cysteamine or pentagastrin, and then the Brunner glands were studied histologically. Pentagastrin did not affect spontaneous Brunner gland secretion, whereas cysteamine inhibited the output approximately 50%. After cysteamine the secretory cells were low and depleted of mucus, suggesting that cysteamine interferes with the synthesis of the secretory product. The depression of the Brunner gland secretion may be an important factor in the pathogenesis of cysteamine-induced duodenal ulceration.