Figure 1.

a: Culturing adult rat neurons and checking cell viability at different time points. Rat adult neurons were obtained from the healthy 14 week old female rat. Brain tissue was harvested and processed to make neuronal culture by plating on to glass cover slips (12 mm diameter) as described in ‘Materials and Methods’. Cells were harvested every fourth day and quantitative CTG assay was performed to measure cell viability at different time points. CTG data were plotted as relative percent value of day 4. Since CTG measures ATP concentration in the cell, a significant increase in CTG (relative luminescence units, RLU) value from day 0 and 24 is suggestive of increased metabolic activity, maturation and/or numbers of neuronal and glial cells in the culture. (n=4 for each time point)

b: Viability of rat embryonic neurons at different time points. Embryonic rat neuron culture was prepared from the fetuses of the same adult female rat. Cells were plated onto poly-D-lysine coated 12-well plates, and subsequently the attached cells from four wells were dissociated and harvested every fourth day followed by the CTG assay as described in the text. CTG data were plotted as relative percent value of day 4. Data showed that the embryonic neuronal cells had the maximum viability at day 4 and the viability abruptly decreased within next 8 days. While adult neuron culture was found to be viable even at day 24, the embryonic neuronal cells died by day 20. (n=3 for each time point).