Figure 4. Fewer NSCs are detected in the PVR of adult GHR^−/− mice, while an acute ICV infusion of GH into wild-type mice results in a long-term increase in endogenous NSCs.

(A) PVR cells harvested from adult GHR^−/− mice generate significantly fewer NSC-derived colonies (15.0±2.9 vs. 30.6±2.1, n = 4, p = 0.0066) and progenitor cell-derived colonies, as compared to littermate controls (158.3±5.5 vs. 266.3±25.7, n = 4, p = 0.017). (B) Cells harvested from the PVR of GH-infused mice 10 days from the onset of infusion generate a significantly greater number of stem cell-derived colonies compared to vehicle-infused control mice (17.1±3.0 vs. 7.1±1.4, n = 9, p = 0.004), with no associated change in the number of progenitor cell-derived colonies (311.6±49.5 vs. 228.8±13.8, n = 9, p = 0.127). (C) Ten days after bFGF infusion, the number of progenitor (253.9±7.2 vs. 467±37.9, n = 5, p = 0.002) and NSC-derived colonies (5.5±0.33 vs. 17.8±1.3, n = 5, p = 0.0001) was significantly increased relative to saline-infused controls. After 21 days of the bFGF infusion, however, the number of NSC-derived (4.6±0.8, p = 0.643, n = 4) and progenitor cell-derived (247±17.1, n = 4, p = 0.060) colonies returned to levels similar to that of saline-infused controls. (D) The number of NSC-derived colonies remained significantly increased at 21 days (12.8±0.7, n = 6, p = 0.009), 48 days (14.1±1.4, n = 6, p = 0.003), 60 days (13.1±1.8, n = 6, p = 0.021) and 120 days (13.6±0.7, n = 6, p = 0.004) following the onset of GH infusion as compared to vehicle-infused controls (7.1±1.4, n = 9, p = 0.0038). *p<0.05, **p<0.01, Student's t-test.