Figure 1.
BBB properties in the neonatal and adult in vitro BBB models.
The TEER (A), the permeability of Na-F (B) and EBA (C), and the influx (luminal-to-abluminal) and efflux (abluminal-to-luminal) of rhodamine 123 (D) in the neonatal (2 weeks, filled columns) and adult (8 weeks, open columns) BBB models. Inset in panel D shows the effect of verapamil on rhodamine 123 influx in both models. Data are means ± SEM (n = 11−12 from 3 separate experiments (A, B, and C), n = 12−19 from 3–5 separate experiments (D); n = 8−20 from 2–5 separate experiments (Fig. D inset)). ** P<0.01, significantly different from the neonatal BBB model. # P<0.05, ## P<0.01, significantly different from the influx of rhodamine 123. ++P<0.01, significantly different from each corresponding control.
Figure 2.
Expression of the tight junction-associated proteins and P-gp in the RBECs prepared from the neonatal and adult rats.
Representative images of western blots showing the expression of claudin-5, occludin, ZO-1 (top panels in A), and P-gp (top panels in B) in RBECs prepared from the neonatal (2 weeks) and adult (8 weeks) rats. β-actin is used as a loading control. Band intensities were quantified by densitometry (bottom panels in A and B) and the data are expressed as a percentage of the neonatal (2 weeks) rats. Each bar indicates mean ± SEM (n = 3 from 3 separate experiments). * P<0.05, ** P<0.01, significantly different from neonatal rats.
Figure 3.
Distribution of tight junction-associated proteins in RBECs in neonatal and adult in vitro BBB models.
Representative photographs showing immunofluorescent staining for claudin-5 (A & B), occludin (C & D) and ZO-1 (E & F) in RBECs on the inserts of neonatal (left panels) and adult (right panels) BBB models. Arrows indicate discontinuous lines and arrowheads indicate a zipper-like or zigzag shape distribution of tight junction-associated proteins. Inset panels show higher-magnification images of the squared region shown in each panel. Scale bars: 20 µm.
Figure 4.
Time-courses of the BBB permeability to valproic acid, nicotine and inulin in the neonatal and adult rats (in vivo) and the neonatal and adult BBB models (in vitro).
The time-courses of the brain/perfusate ratios of valproic acid, nicotine and inulin in the neonatal (2 weeks, filled circles) and adult (8 weeks, open circles) rats (in vivo) (left panels in A, B and C, respectively). The time-courses of the transferred volume of valproic acid, nicotine and inulin in the neonatal (2 weeks, filled circles) and adult (8 weeks, open circles) BBB models (in vitro) (right panels in A, B and C, respectively). Data are means ± SEM (n = 3−6 (in vivo) and n = 4−12 from 2–3 separate experiments (in vitro)).
Figure 5.
The influx rates of drugs in the neonatal and adult rats (in vivo) and the permeability clearance of drugs in the neonatal and adult BBB models (in vitro).
The permeability of drugs (valproic acid (A), nicotine (B), inulin (C)) is expressed as the influx rate in the neonatal (2 weeks, filled columns) and adult (8 weeks, open columns) rats (in vivo: left panels) and the permeability clearance in the neonatal (2 weeks, filled columns) and adult (8 weeks, open columns) BBB models (in vitro: right panels). The influx rate (Kin) was evaluated from the brain tracer uptake in the perfusion period of 120 s and the permeability clearance (PStrans) was evaluated from the transferred volume in the exposure periods of 10, 20, 30 and 40 min. Data are means ± SEM (n = 3−6, in vivo; and n = 4−12 from 2–3 separate experiments, in vitro). * P<0.05, ** P<0.01, significantly different from neonatal rats (in vivo) or neonatal BBB model (in vitro).