Tokyo stocks opened lower Wednesday, as a cautious mood prevailed ahead of the release of key U.S. inflation data and the conclusion of a Federal Reserve meeting later in the day. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 236.01 points, or 0.60 percent, from Tuesday to 38,898.78. The broader Topix index was down 18.29 points, or 0.66 percent, at 2,758.51. On the top-tier Prime Market, decliners were led by securities house, pharmaceutical and precision instrument shares. At 9 a.m., the U.S. dollar fetched 157.10-13 yen compared with 157.09-19 yen in New York a…