Regulation of cerebrovascular endothelial peroxisome proliferator activator receptor alpha expression and nitric oxide production by clofibrate.
BACKGROUND
Peroxisome proliferator activator receptor alpha (PPAR alpha), a member of the nuclear receptor superfamily, is known to increase nitric oxide (NO) production and the mechanisms by which PPAR alpha activation alleviates vascular dysfunction may predicate its activation and possible expression.


OBJECTIVE
We have evaluated the effects of acute clofibrate, a PPAR alpha ligand and the role of PKC on PPAR alpha expression and NO production in cultured cerebral microvascular endothelial cell (CMVEC).


METHODS
Confluent CMVEC derived from pig brain were cultured and the role of PKC in acute clofibrate-induced PPAR alpha expression and NO production was determined in the presence or absence of PKC activator phorbol myristate acetate (PMA) or inhibitor (calphostin C).


RESULTS
Incubation of CMVEC with clofibrate or PMA increased NO production by 40% or 27%, respectively, whereas co-incubation of cells with PMA and clofibrate had no effect on NO production. Incubation of cells with Calphostin C blunted PMA but not clofibrate-induced increase in NO production. L-NAME (0.1 mM), an inhibitor of NO synthase, reduced basal (47%; p<0.01) and abolished clofibrate-induced increase in NO production. Clofibrate increased PPAR alpha expression (26%; p<0.05) while PMA with or without clofibrate reduced PPAR alpha expression (p<0.01). On the other hand, calphostin C reduced basal (69%, ap<0.01) as well as clofibrate-induced increase (59%, p<0.01) in PPAR expression, and further reduced PMA-induced down regulation of PPAR expression. eNOS expression was not significantly affected by either clofibrate or PMA, alone or in combination.


CONCLUSIONS
These results show that in the brain microvascular endothelial cell, PPAR alpha activation increases NO production-independent of eNOS and PKC signaling pathways, a regulates PPAR alpha expression through a complex PKC signaling mechanism(s) as both PKC activation and inhibition reduced clofibrate-induced activation of PPAR expression (Fig. 4, Ref. 32). Full Text (Free, PDF) www.bmj.sk.
Yakubu
Momoh A
MA
Vascular Biology Unit, Center for Cardiovascular Diseases, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA. yakubu_ma@tsu.edu
Nsaif
Rami H
RH
Oyekan
Adebayo O
AO
D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000098:blood supply*; D002994:Clofibrate / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000960:Hypolipidemic Agents / Q000494:pharmacology*; D055806:Microvessels / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D047493:PPAR alpha / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000494:pharmacology; D034421:Sus scrofa; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004791:Enzyme Inhibitors; D000960:Hypolipidemic Agents; D009281:Naphthalenes; D047493:PPAR alpha; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D011493:Protein Kinase C; D002994:Clofibrate; C058819:calphostin C; D013755:Tetradecanoylphorbol Acetate; D019331:NG-Nitroarginine Methyl Ester