Table 1.

BrdU-positive cell number and phenotype

Group	No. with BrdU label	% NeuN+	% S100β+	% Neither	Volume, mm3
Control	1,409  ±  132	81.5  ±  2.4	5.5  ±  1.9	13.5  ±  3.2	0.438
Runner	3,746  ±  800*	92.8  ±  1.7*	1.8  ±  0.8	5.5  ±  1.6*	0.481

Controls and runners received BrdU (50 μg/g per day) from day 1 to day 10. Survival of BrdU-labeled cells was determined 2 to 4 months after the last BrdU injection. Runners (n = 8), as compared to controls (n = 8), had significantly more BrdU-positive cells (t₍₁₄₎ = 2.88, P < 0.012). The percentages of cells double-labeled for NeuN were greater in runners than in controls (t₍₁₄₎ = 3.82, P < 0.002), and a lower percentage of BrdU-positive cells that were labeled for neither S100β nor NeuN was observed in runners than in controls (t₍₁₄₎ = 2.26, P < 0.04). Means are ± SEM. *, Significantly different from controls.