Tokyo stocks opened lower Monday as investors locked in recent gains, but declines were limited following advances on Wall Street late last week amid hopes for early interest rate cuts in the United States. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 64.57 points, or 0.16 percent, from Friday to 40,847.80. The broader Topix index was down 9.44 points, or 0.33 percent, at 2,874.74. On the top-tier Prime Market, decliners were led by electric power and gas, marine transportation and insurance issues. At 9 a.m., the U.S. dollar fetched 160.63-66 yen compared with 1…