Effects of protein kinase C activation on prostaglandin production and cyclooxygenase mRNA levels in ovine astroglia.

M J Nam, C Thore, D Busija

Index: Prostaglandins 51 , 203-213, (1996)

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Abstract

We examined effects of protein kinase C (PKC) activation by phorbol dibutyrate (PDB) on prostaglandin production in astroglia. Astroglia were cultured from sheep fetal cortex and grown in Eagle's basal media supplemented with 10% fetal calf serum (BME-C). Prostaglandin F2a (PGF2 alpha) levels in media were determined at 2-24 hours after exposure to PDB. PDB increased production of PGF2 alpha at 10(-8)M and 10(-6)M. In addition, PDB increased the ratio of membrane to cytosolic PKC. Coapplication of H7 [1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine] (10(-4)M) with PDB (10(-6)M) inhibited PDB-induced PGF2a production. To investigate the role of protein synthesis in increased prostaglandin production by PDB, astroglia were coincubated with actinomycin D (1 mg/ml) or cycloheximide (10 mg/ml). At 4 hrs, both actinomycin D and cycloheximide inhibited increases in PGF2a in response to PDB application. In addition, COX-2 mRNA levels and COX activity levels were examined. PDB increased COX-2 mRNA levels by 2 hours, and COX activity tripled after 12 hr exposure to PDB. In addition, the increase in COX activity was blocked by cycloheximide. In summary, PKC activation promotes enhanced prostaglandin production via an increase in COX synthesis.