Protective role of melatonin and the pineal gland in modulating water immersion restraint stress ulcer in rats.
We investigated the protective effect of melatonin on stress-induced gastric lesions in rats. Fasted rats were subjected to water immersion restraint stress for 4 h and the percentage of corpus mucosa containing hemorrhagic lesions was determined. Thirty minutes before restraint stress, melatonin or vehicle was administered i.p. In another experiment, pinealectomy was performed 1 week before water immersion restraint stress. Administration of melatonin at 1 and 5 mg/kg significantly decreased gastric lesions by 46 and 74%, respectively. In contrast, pinealectomy significantly enlarged the lesion area, although this effect was counteracted by melatonin at a dose of 1 mg/kg i.p. However, this protective effect of melatonin was abolished by i.p. pretreatment with indomethacin at 5 mg/kg. These results suggest that melatonin has gastroprotective properties against stress-induced gastric injury in rats and that the pineal gland contributes to gastric protection via prostaglandin-dependent mechanisms.
Kato
K
K
Department of Internal Medicine III, Nihon University School of Medicine, Tokyo, Japan.
Murai
I
I
Asai
S
S
Matsuno
Y
Y
Komuro
S
S
Kaneda
N
N
Iwasaki
A
A
Ishikawa
K
K
Nakagawa
S
S
Arakawa
Y
Y
Kuwayama
H
H
D000818:Animals; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008550:Melatonin / Q000494:pharmacology* / Q000502:physiology; D010870:Pineal Gland / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D013276:Stomach Ulcer / Q000209:etiology* / Q000517:prevention & control; D013312:Stress, Physiological / Q000150:complications*
D016861:Cyclooxygenase Inhibitors; D016166:Free Radical Scavengers; D008550:Melatonin; D007213:Indomethacin