Inhibition of eNOS/sGC/PKG Pathway Decreases Akt Phosphorylation Induced by Kainic Acid in Mouse Hippocampus.
10.4196/kjpp.2010.14.1.37
- Author:
Sang Hyun LEE
1
;
Jong Seon BYUN
;
Pil Jae KONG
;
Hee Jae LEE
;
Duk Kyung KIM
;
Hae Sung KIM
;
Jong Hee SOHN
;
Jae Jun LEE
;
So Young LIM
;
Wanjoo CHUN
;
Sung Soo KIM
Author Information
1. Department of Pharmacology, School of Medicine, Kangwon National University, Chunchon 200-701, Korea. ksslsy@kangwon.ac.kr
- Publication Type:In Vitro ; Original Article
- Keywords:
Akt phosphorylation;
Astrocyte;
Kainic acid;
Nitric oxide
- MeSH:
Animals;
Astrocytes;
Cyclic GMP-Dependent Protein Kinases;
Endothelial Cells;
Guanylate Cyclase;
Hippocampus;
Kainic Acid;
Mice;
Nitric Oxide;
Phosphatidylinositol 3-Kinase;
Phosphorylation;
Phosphotransferases;
Receptors, Growth Factor;
Transducers
- From:The Korean Journal of Physiology and Pharmacology
2010;14(1):37-43
- CountryRepublic of Korea
- Language:English
-
Abstract:
The serine/threonine kinase Akt has been shown to play a role of multiple cellular signaling pathways and act as a transducer of many functions initiated by growth factor receptors that activate phosphatidylinositol 3-kinase (PI3K). It has been reported that phosphorylated Akt activates eNOS resulting in the production of NO and that NO stimulates soluble guanylate cyclase (sGC), which results in accumulation of cGMP and subsequent activation of the protein kinase G (PKG). It has been also reported that PKG activates PI3K/Akt signaling. Therefore, it is possible that PI3K, Akt, eNOS, sGC, and PKG form a loop to exert enhanced and sustained activation of Akt. However, the existence of this loop in eNOS-expressing cells, such as endothelial cells or astrocytes, has not been reported. Thus, we examined a possibility that Akt phosphorylation might be enhanced via eNOS/sGC/PKG/PI3K pathway in astrocytes in vivo and in vitro. Phosphorylation of Akt was detected in astrocytes after KA treatment and was maintained up to 72 h in mouse hippocampus. 2 weeks after KA treatment, astrocytic Akt phosphorylation was normalized to control. The inhibition of eNOS, sGC, and PKG significantly decreased Akt and eNOS phosphorylation induced by KA in astrocytes. In contrast, the decreased phosphorylation of Akt and eNOS by eNOS inhibition was significantly reversed with PKG activation. The above findings in mouse hippocampus were also observed in primary astrocytes. These data suggest that Akt/eNOS/sGC/PKG/PI3K pathway may constitute a loop, resulting in enhanced and sustained Akt activation in astrocytes.
