Antacids show gastroprotective action against various irritants in experimental animals and enhance the healing of chronic
gastroduodenal ulcers in humans but the mechanisms of these effects are unknown. The present study was designed to determine whether
prostaglandin (PG) and
epidermal growth factor (
EGF), which also have protective and antiulcer properties, contribute to the action of
antacids on rat's stomach. It was found that
Maalox 70 and its active component, Al(
OH)3, enhance significantly the healing of chronic gastric and
duodenal ulcers observed during 7 and 14 days after their induction. Pretreatment with
indomethacin caused a significant prolongation of
ulcer healing, and this was accompanied by a significant reduction in PG and
EGF formation, suggesting that both factors may be involved in
ulcer healing.
Maalox and Al(
OH)3 failed to prevent the suppression of PG by
indomethacin but were equally effective in
ulcer healing in rats without and with
indomethacin administration, suggesting that endogenous PG may not play any important role in the healing process by these drugs. Removal of salivary glands, the major source of
EGF, also prolonged
ulcer healing but, again,
Maalox was as effective in
ulcer healing as in rats with intact salivary glands. Our findings that
Maalox at pH above 3.0 binds significant amounts of
EGF, enhances the binding of
EGF to the
ulcer area, and stimulates mucosal growth, suggest that
EGF may be involved in
ulcer healing; however, because
antacids are also effective after sialoadenectomy,
EGF does not seem to be the major factor in
ulcer healing by these drugs.