Mycophenolate mofetil (MMF) treatment in specific time frames after injury and effects of guanosine on neuroprotective and antiproliferative properties of MMF.
(A) Treatment protocols. (B,C) Quantitative analyses of the effects of short-term MMF treatment (100 μg/ml) on neuronal survival and microglial activation in organotypic hippocampal slice cultures (OHSCs) when MMF was administered in different time windows after injury. Mean numbers of (B) propidium iodide (PI)+ degenerating neurons and (C) IB4
+ microglial cells were calculated for each experimental group, and compared with OHSCs treated with N-methyl-D-aspartate (NMDA) alone (*P < 0.05 vs. NMDA). MMF elicits strong neuroprotective effects when administered within the time frame of 4 to 48 hours or even 12 to 36 hours after injury. However, treatment within 4 to 24 hours or 24 to 48 hours after injury likewise reduced numbers of IB4
+ microglial cells. (D,E) Quantitative analyses of guanosine effects. Mean numbers of (D) PI+ degenerating neurons and (E) IB4
+ microglial cells were calculated for each experimental group and compared with matched OHSCs that did not receive guanosine (*P < 0.05). Guanosine did not affect either neuronal viability or microglial activation when applied to unlesioned control (CTL) OHSCs. In NMDA-lesioned OHSCs subjected to guanosine treatment, there was a significant reduction in the numbers of PI+ degenerating neurons, whereas the numbers of IB4
+ microglial cells were unaffected. However, application of guanosine to OHSCs that received MMF treatment within the 12 to 36 hour time window significantly reversed the antiproliferative reduction in IB4
+ microglial cells without affecting MMF-dependent neuroprotection