EXPRESSION OF GLUTAMATE UPTAKE TRANSPORTERS AFTER DIBUTYRYL-CYCLIC-AMP DIFFERENTIATION AND TRAUMATIC INJURY IN CULTURED ASTROCYTES

Our findings indicate that differentiation of primary astrocytes by di butyryl cyclic adenosine monophosphate (dBcAMP) and scratch injury tog ether resulted in increased glutamate transporter gene expression. Con fluent primary cultures were prepared from cerebral cortex of normal n ew born rat pups. The primary cultures were then divided into four gro ups each: control and scratch-injured, and dBcAMP-treated control and scratch-injured cultures. Total RNA was extracted at 0, 1, 2, 4, and 7 days after injury. Expression of the electrogenic glutamate transport ers, GLAST, GLT-1, and EAAC-1, was quantitated by the reverse transcri ptase-polymerase chain reaction method (RT-PCR) and slot blot hybridiz ation followed by densitometric scanning. Triplicate cultures were ana lyzed for each time-point. Our studies indicate that all these astrocy te cultures expressed the two glial transporters, GLAST and GLT-1, whi le none of the cultures expressed the neuronal transporter, EAAC-1. Th e expression of the two transporters in the dBcAMP-treated primary cul tures were markedly increased from the non-treated cultures. The dBcAM P-treated cultures had 2- to 4-times increase in levels of GLAST and G LT-1-mRNA expression both before and after scratch injury, as compared to untreated non-injured and injured primary cultures. All of the cul tures expressed GLAST in greater proportion than GLT-1. (C) 1997 Elsev ier Science B.V.