Figure 8.

Direct application of norepinephrine but not serotonin enhances hippocampal precursor activity in the slice-sphere assay. A, The hippocampus from a postnatal day 7 Wistar rat was dissected and cut transversely into 300 μm slices. The slices were placed on a 0.4 μm membrane filter that was bathed in 1 ml of complete serum-free NeuroCult medium in a 6-well plate. Four filters, each containing 6–7 slices, were generated from a single animal. B, The organotypic slices were cultured at a liquid-air interphase for a period of 6 d. Antidepressants or neurotransmitters were added to the medium on day 1 and half the medium was replaced with fresh medium every alternate day. C, On the sixth day, the hippocampal slices were enzymatically dissociated and cells were plated in a 96-well plate and cultured in the presence of EGF and bFGF to obtain neurospheres. D, The number of neurospheres generated was quantified after 10–12 d in culture, this being representative of the number of proliferating hippocampal precursors present in the slices. E, Serotonin (5-HT) treatment had no effect on the frequency of neurosphere formation either at 10 or 100 μm. However, direct application of NE to the slices resulted in an ∼2-fold increase in the neurosphere frequency at 1 and 10 μm, and a 3.5-fold increase at 100 μm (mean ± SEM; **p < 0.01; ***p < 0.001).