Neuroprotection by pigment epithelial-derived factor against glutamate toxicity in developing primary hippocampal neurons

Pigment epithelial-derived factor (PEDF) has been shown to be a survival fa ctor for cerebellar granule neurons. Here we investigated the ability of PE DF to enhance the survival of hippocampal neurons in culture, and to protec t these neurons against acute glutamate toxicity. Hippocampal neurons prepa red from 1- to 3-day postnatal rat brain were cultured for either 7 or 14 d ays in vitro (DIV), At 13 DIV, neurons were only slightly protected (13% +/ - 4%) against 50 mu M glutamate toxicity when treated with 1 mu g/ml of PED F for 3 successive days before glutamate exposure as measured by lactate de hydrogenase (LDH) release. In comparison, basic fibroblast growth factor (b FCF) at 10 ng/ml for the same treatment period protected 58% +/- 8% of the neurons against glutamate. Using quantitative image analysis of digitized m icrographs, we found that the average size of neurons in young, developing hippocampal cultures (7 DIV), was greatly decreased by treatment with 50 gl utamate, Treatment for up to 5 successive days with 1 mu g/ml of PEDF befor e glutamate addition dramatically increased the average hippocampal neuron soma size, compared to cells treated with glutamate alone. Thus, PEDF may p romote the growth of hippocampal neurons, and, if added to developing hippo campal neurons, can also protect these cells from subsequent injury, such a s the excitotoxicity of glutamate, (C) 1999 Wiley-Liss, Inc.