Decrease in aspirin-induced gastric mucosal damage in rats by oral administration of the cytotoxic drugs melphalan and methotrexate

Changes in tissue fatty acid composition in murine malignancy and following anticancer therapy

We studied the mouse NC tumour, a subcutaneously transplanted adenocarcinoma originally of mammary origin. Measurements per g tissue were made of 17 fatty acids (FAs), the combined amounts of n-3, n-6, saturated, unsaturated, and total FAs, and of various FA ratios in the tumour, mammary tissue, spleen, liver and plasma. Compared with mammary tissue from normal mice, tumours of vehicle-treated controls had less of seven of the FAs and more of two FAs. Mice bearing the NC tumour often had changed (usually decreased) amounts of FAs in the 'normal' spleen, liver and plasma, but not in mammary tissue. Treatment with methotrexate (MTX) was studied alone and with indomethacin which can potentiate MTX cytotoxicity. Indomethacin 1.25 mg kg-1 (INDO) increased the amounts of 3/17 tumours FAs and the unsaturated FAs, but reduced 9/17 FAs, the saturated and the unsaturated FAs in 'normal' mammary tissue, and usually had no effect on the FAs of other tissues. MTX 2 or 4 mg kg-1 (MTX 2 or 4 mg) +/- INDO in general partly restored (increased) the amounts of tumour FAs, and reduced the saturated/unsaturated FA ratio. In the 'normal' spleen and plasma also, but not in the liver, MTX 2 mg generally somewhat restored the FA composition. However, as in the liver, the spleen 20:4 and 22:6 (which form prostaglandins and lipid peroxides) did not increase in the presence of INDO. With MTX 4 mg, some of the plasma and liver FAs decreased, in contrast to the tumour. There was generally no evidence of MTX potentiation by INDO. These results are discussed in relation to carcinogenesis, cachexia, and the response to treatment.

Carbenoxolone and deglycyrrhized liquorice have little or no effect on prostanoid synthesis by rat gastric mucosa ex vivo

Rats were given either carbenoxolone 50 mg kg-1, deglycyrrhized liquorice 1 g kg-1 or vehicle by gastric tube. The doses were repeated 16 h later, and the stomachs removed after another 2 h. The amounts of prostaglandin E (PGE), 6-keto-PGF1 alpha and thromboxane B2, measured by radioimmunoassay in extracts of the gastric corpus and antrum mucosa, were similar in the treated animals and the controls. We conclude that in rats, carbenoxolone and deglycyrrhized liquorice may exert their anti-ulcer effect by a non-prostaglandin mechanism. This contrasts with the mechanism through to occur in man with carbenoxolone.

The role of endogenous prostaglandins in the regulation of gastric secretion in rhesus monkeys

Prostaglandins (PG) are known to alter a variety of gastrointestinal functions, but the physiological role of endogenous PG remains unclear. This experiment was designed to evaluate changes in gastric secretion following both acute and chronic inhibition of PG synthesis with indomethacin (5 mg/kg s.c.). Gastric juice was collected by continuous aspiration in 8 conscious chair-adapted male rhesus monkeys following treatment with saline or indomethacin for one or four days. The gastric juice was analyzed for H+, Na+, K+, and Cl- concentrations. The amount of soluble mucus in the gastric juice was estimated using Alcian Blue dye binding of acidic glycoproteins and Periodic Acid Schiff reaction with neutral glycoproteins. PG levels were measured in the plasma and in biopsy samples of fundus, antrum and duodenum. Both one and four days of indomethacin significantly (p less than 0.05) decreased tissue PG levels in the fundus, antrum and duodenum. Plasma levels of PGF2 alpha were significantly (p less than 0.05) decreased after both one and four days of indomethacin, while PGE2 and 6-keto PGF1 alpha were significantly inhibited only after four days of indomethacin. Both acute and chronic inhibition of PG synthesis was accompanied by a decrease in the concentration of sodium and mucus in the gastric juice but by an increase in the output and concentration of hydrogen ion. These changes suggest a possible mechanism by which endogenous PG play a role in the regulation of gastric secretion and in the protection against gastrointestinal damage.

Dose-dependent effect of calcium and magnesium etidronate on salicylic acid absorption in the rat

Disodium etidronate affected salicylic acid absorption from the rat small intestine, in-situ, when instilled into a jejunal segment for different exposure times before the salicylic acid absorption was measured. At low etidronate concentrations and short exposure times, the salicylic acid absorption rate was significantly increased compared with saline controls. At high etidronate concentrations and longer exposure times, the absorption rate was reduced. Etidronate precomplexed with calcium or magnesium ions at low concentrations still enhanced salicylic acid absorption but at high concentrations absorption of salicylic acid was close to saline controls. Intestinal mucosa exposed to high etidronate concentrations showed a progressive structural destruction but with the complexes, there was no visible alteration. It is proposed that a solubilized etidronate complex, formed either in-situ or administered as such, is responsible for enhancing salicylic acid absorption. This effect is hidden at high etidronate concentrations because of the deterioration of the mucosal surface and at high complex concentrations because these decrease the absorbing surface area and increase the viscosity of the lumen contents.

Increased survival of cancer-bearing mice treated with inhibitors of prostaglandin synthesis alone or with chemotherapy

In mice with a transplantable mammary carcinoma, treatment with the prostaglandin-synthesis inhibitors flurbiprofen or indomethacin produced various beneficial effects. Survival time after excision of the transplanted tumour was increase, particularly when the drugs were given with the chemotherapeutic agents methrotrexate and melphalan, and there were more disease-free survivors. The combined treatment with flurbiprofen also gave less tumour recurrence at the excision site. Flurbiprofen did not seem to alter the bioavailability of the chemotherapeutic agents.