Cellular mechanisms of beta-carotene-induced gastric cytoprotection in indomethacin-treated rats

Involvement of serum retinoids and Leiden mutation in patients with esophageal, gastric, liver, pancreatic, and colorectal cancers in Hungary

AIM

To analyze the serum levels of retinoids and Leiden mutation in patients with esophageal, gastric, liver, pancreatic, and colorectal cancers.

METHODS

The changes in serum levels of retinoids (vitamin A, alpha- and beta-carotene, alpha- and beta-cryptoxanthin, zeaxanthin, lutein) and Leiden mutation were measured by high liquid performance chromatography (HPLC) and polymerase chain reaction (PCR) in 107 patients (70 males/37 females) with esophageal (0/8), gastric (16/5), liver (8/7), pancreatic (6/4), and colorectal (30/21 including 9 patients suffering from in situ colon cancer) cancer. Fifty-seven healthy subjects (in matched groups) for controls of serum retinoids and 600 healthy blood donors for Leiden mutation were used.

RESULTS

The serum levels of vitamin A and zeaxanthin were decreased significantly in all groups of patients with gastrointestinal (GI) tumors except for vitamin A in patients with pancreatic cancer. No changes were obtained in the serum levels of alpha- and beta-carotene, alpha- and beta-cryptoxanthin, zeaxanthin, lutein in patients with GI cancer. The prevalence of Leiden mutation significantly increased in all groups of patients with GI cancer.

CONCLUSION

Retinoids (as environmental factors) are decreased significantly with increased prevalence of Leiden mutation (as a genetic factor) in patients before the clinical manifestation of histologically different (planocellular and hepatocellular carcinoma, and adenocarcinoma) GI cancer.

Effects of indomethacin, with vitamin A or β-carotene, on the rat gastric mucosa: Extra-and intracellular membrane-bound ATP mechanisms

BACKGROUND

Indomethacin (IND) is a widely used non-steroidal anti-inflammatory agent in the treatment of various inflammatory disorders, which causes gastrointestinal injury in humans and animal experiments. Vitamin A and beta-carotene prevent the IND-induced gastric mucosal injury. These compounds modify the membrane-bound ATP-dependent energy systems. The aims of this investigation were: (1) To study the IND-induced gastric mucosal damage and its prevention by vitamin A and beta-carotene; (2) to measure the biochemical compounds of the gastric mucosa ATP, ADP, ATP/ADP, AMP, ATP+ADP+AMP, 'energy charge' (ATP + 0.5 ADP)/(ATP+ADP+AMP), cAMP, lactate under the circumstances mentioned above; (3) to analyze the extra- and intracellular regulatory mechanisms between the membrane-bound ATP-dependent energy systems.

METHODS

The observations were carried out with CFY (Sprague-Dawstrein rats, weighing 180-210 g). The gastric mucosal damage was produced by IND (20 mg/kg sc. administration) and it was prevented by vitamin A (or beta-carotene), given in doses of 0.01-0.1 to 1.0-10.0 mg/kg ig. Different biochemical compounds (ATP, ADP, AMP, cAMP, lactate) and parameters (ATP/ADP, adenylate pool, 'energy charge') were measured and calculated.

RESULTS

(1) Vitamin A and beta-carotene prevented dose-dependently the IND-induced gastric mucosal damage; (2) the extent of ATP-ADP transformation was increased significantly, while the ATP-cAMP decreased in the gastric mucosa after IND-treatment; (3) vitamin A and beta-carotene enhanced the extent of ATP-cAMP transformation, while the ATP-ADP transformation was inhibited (the actions were dose-dependent responses); (4) No change was found in 'energy charge' by IND, while its value decreased significantly with vitamin A and beta-carotene.

CONCLUSIONS

(1) A very complex extra- and intracellular feedback mechanism system exists in the gastric mucosa during IND, IND + vitamin A, and IND + beta-carotene treatments; (2) The gastric mucosal preventive effect of vitamin A and beta-carotene only partly depend on their scavenger properties.