Insulin regulates P-glycoprotein in rat brain microvessel endothelial cells via an insulin receptor-mediated PKC/NF-kappaB pathway but not a PI3K/Akt pathway.
Our previous study showed that insulin restored impaired function and expression of P-glycoprotein in diabetic blood-brain barrier, and further study showed that insulin up-regulated P-glycoprotein expression and function in normal blood-brain barrier, so insulin might be one of the factors that regulated the function and expression of P-glycoprotein in blood-brain barrier of diabetes. In this study, the intracellular pathways that insulin regulated the P-glycoprotein were investigated using primarily cultured rat brain microvessel endothelial cells model. The rat brain microvessel endothelial cells were incubated in normal culture medium containing 50 mU/l insulin and different concentrations of inhibitors for 72 h. The P-glycoprotein function and expression in the rat brain microvessel endothelial cells were assessed using the uptake of P-glycoprotein substrate rhodamine 123 and western blot assay, respectively. It was found that treatment of 50 mU/l insulin significantly increased P-glycoprotein function and expression in rat brain microvessel endothelial cells. This induced effect was blocked by insulin receptor antibody, insulin receptor tyrosine kinase inhibitor I-OMe-AG538, PKC inhibitor chelerythrine and NF-kappaB inhibitor pyrrolidine dithiocarbamate ammonium (PDTC). But this induced effect was not inhibited by phosphatidylinositol 3-kinase (PI3K)/Akt inhibitor LY294002. These results indicated that insulin regulated P-glycoprotein function and expression through signal transduction pathways involving activation of PKC/NF-kappaB but not PI3K/Akt pathway.
Liu
Haiyan
H
Center of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing, China.
Yang
Huiwen
H
Wang
Dianlei
D
Liu
Yuchun
Y
Liu
Xiaodong
X
Li
Yang
Y
Xie
Lin
L
Wang
GuangJi
G
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism; D001921:Brain / Q000098:blood supply*; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D055806:Microvessels / Q000166:cytology; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000906:Antibodies; D004791:Enzyme Inhibitors; D007328:Insulin; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C