Efficacy of combined administration of select neuroprotective estrogens within CEE against glutamate-induced toxicity in basal forebrain neurons. Three-day-old basal forebrain neurons were pretreated with either single estrogens or combinations of estrogens followed by a 5 min exposure to 200 μM glutamate. Both LDH release into the medium and the intracellular ATP level were measured 24 hr later. Data are represented as mean ± SEM (n = 8 – 12 from 3 experiments). * P < 0.05, ** P < 0.01 and *** P < 0.001 compared to glutamate alone-treated cultures.