Peroxisome proliferation activation receptor alpha modulation of Ca2+-regulated exocytosis via arachidonic acid in guinea-pig antral mucous cells.
Indomethacin (IDM, 10 microm), not aspirin (ASA; 10 microm), enhanced the Ca(2+)-regulated exocytosis stimulated by 1 microm acetylcholine (ACh) in guinea-pig antral mucous cells. Indomethacin inhibits prostaglandin G/H (PGG/H) and 15R-hydroperoxy-eicosatetraenoic acid (15R-HPETE) production from arachidonic acid (AA), while ASA inhibits PGG/H production but accelerates 15R-HPETE production. This suggests that IDM accumulates AA. Arachidonic acid (2 microm) enhanced Ca(2+)-regulated exocytosis in antral mucous cells to a similar extent to IDM. Moreover, a stable analogue of AA, arachidonyltrifluoromethyl ketone (AACOCF(3)), also enhanced Ca(2+)-regulated exocytosis, indicating that AA, not products from AA, enhances Ca(2+)-regulated exocytosis. We hypothesized that AA activates peroxisome proliferation activation receptor alpha (PPARalpha), because AA is a natural ligand for PPARalpha. A PPARalpha agonist (WY14643; 1 microm) enhanced Ca(2+)-regulated exocytosis, and a PPARalpha blocker (MK886; 50 microm) abolished the enhancement of Ca(2+)-regulated exocytosis induced by AA, IDM, AACOCF(3) and WY14643. Western blotting and immunohistochemical examinations demonstrated that PPARalpha exists in antral mucous cells. Moreover, MK886 decreased the frequency of Ca(2+)-regulated exocytosis activated by 1 microm ACh or 2 microm thapsigargin alone by 25-30%. Thus, ACh stimulates AA accumulation via an [Ca(2+)](i) increase, which activates PPARalpha, leading to enhancement of Ca(2+)-regulated exocytosis in antral mucous cells. A novel autocrine mechanism mediated via PPARalpha enhances Ca(2+)-regulated exocytosis in guinea-pig antral mucous cells.
Sawabe
Yukinori
Y
Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Shimamoto
Chikao
C
Sakai
Akiko
A
Kuwabara
Hiroko
H
Saad
Adel H
AH
Nakano
Takashi
T
Takitani
Kimitaka
K
Tamai
Hiroshi
H
Mori
Hiroshi
H
Marunaka
Yoshinori
Y
Nakahari
Takashi
T
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism* / Q000494:pharmacology; D001095:Arachidonic Acids / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D005089:Exocytosis / Q000187:drug effects* / Q000502:physiology; D005753:Gastric Mucosa / Q000187:drug effects; D006168:Guinea Pigs; D007211:Indoles / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology*; D008297:Male; D047493:PPAR alpha / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D011706:Pyloric Antrum / Q000187:drug effects*; D011743:Pyrimidines / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D002722:Chlorobenzenes
D000109:Acetylcholine; D016718:Arachidonic Acid; D001095:Arachidonic Acids; D001241:Aspirin; D002118:Calcium; D007211:Indoles; D007213:Indomethacin; D047493:PPAR alpha; D011743:Pyrimidines; D019284:Thapsigargin; C081565:arachidonyltrifluoromethane; C060893:MK-886; D002722:Chlorobenzenes; C006253:pirinixic acid