[Enhancement of NMDA receptor sensitivity by thrombin and its relationship with tissue transglutaminase]

To explore the possible relationship between the thrombin induced potentiation of rat cerebellum granular cell N-methyl-D-aspartate (NMDA) receptor function and the change of intracellular tissue transglutaminase (tTG).

Primary cultured rat cerebellum granular cells were pretreated by using thrombin (0.01 U/ml) with or without co-pretreatment of 0.5 x 10(-4) mol/L MDC (monodansylcadaverine, a tTG inhibitor) 30 minutes. Induce cells mentioned above to undergo apoptosis with different concentration of NMDA (0.1 x 10(-4) mol/L, 0.25 x 10(-4) mol/L and 0.5 x 10(-4) mol/L). Flowcytometer was applied 3 hours later to detect the changed function of NMDA receptor by counting percentage of apoptotic cells. RT-PCR was used to compare the tTG mRNA level in the cerebellum granular cells treated with NMDA of same dosage with/without thrombin pretreatment.

Thrombin pretreatment increased the percentage of apoptosis cells induced by NMDA [(8.3 +/- 0.5)% to (15.1 +/- 0.8)% at 0.1 x 10(-4) mol/L, (14.1 +/- 1.1)% to (23.8 +/- 0.7)% at 0.25 x 10(-4) mol/L, (26.8 +/- 1.9)% to (33.7 +/- 2.1)% at 0.5 x 10(-4) mol/L)]; and this effect was inhibited by co-pretreatment MDC with thrombin, cell apoptosis decreased to (5.8 +/- 1.2)%, (11.5 +/- 1.5)% and (19.0 +/- 1.7)%; Thrombin increased intracellular tTG mRNA levels comparing with those without thrombin pretreatment.

Thrombin potentiates rat cerebellum granular cell NMDA receptor function by increasing intracellular tissue transglutaminase.