Figure 3

Oral single administration of inosine enhances cell proliferation, phosphorylation of MAPK and transcription of BDNF in the hippocampus.

(a), (b) BrdU-positive cells were increased in the DG after administration of inosine. Mice were once injected with BrdU immediately before administration of inosine (0.33 mg/g of body weight) and sacrificed by decapitation after 24 h. Brain sections were immunostained with anti-BrdU antibody. (a) Scale bar: 100 μm. The number of BrdU-positive cells in the DG was counted (n = 9–10) (b). (c) Phosphorylation of MAPK was determined at the indicated time after oral administration of inosine (0.33 mg/g of body weight). Extract of the hippocampus was analyzed by Western blotting with anti-MAPK and phosphorylated MAPK antibodies. Quantitation of the density of bands representing phosphorylated MAPK (pMAPK) was assessed by densitometric scanning and expressed relative to the band at 0 μM of inosine (n = 5–7). (d, e) BDNF transcript levels were quantified by real-time PCR coupled with reverse transcription. Total RNA was isolated from the hippocampus. Quantitation of BDNF transcript level was expressed relative to the level at 0 μM of inosine or vehicle. Mice were sacrificed at the indicated time after oral administration of inosine (0.33 mg/g of body weight) (n = 9–10) (d). DPCPX, an antagonist of adenosine A₁ receptor, was intraperitoneally administered to mice 30 min prior to the inosine administration and the hippocampus was collected 2 h after inosine administration. Vehicle (n = 7), inosine with (n = 14) or without DPCPX (n = 8) and DPCPX alone (n = 8) (e). Data represent mean ± s.e. *P < 0.05, **P < 0.01.