Tokyo stocks ended slightly lower Wednesday as investors cautiously awaited the outcome of the U.S. Federal Reserve monetary policy meeting later in the day. The 225-issue Nikkei Stock Average ended down 131.61 points, or 0.34 percent, from Tuesday at 38,274.05. The broader Topix index finished 13.77 points, or 0.50 percent, lower at 2,729.40. On the top-tier Prime Market, decliners were led by marine transportation, securities, and oil and coal product issues. The U.S. dollar was firm in the upper 157 yen range in Tokyo as the currency was bought on expectations that the Fed would keep intere…