More than 635 000 positional observations of planets and spacecraft of different types have been used for estimating possible changes of the gravitation constant, the solar mass, and semi-major axes of planets. The analysis of the observations has been performed on the basis of the EPM2010 ephemerides of IAA RAS in post-newtonian approximation. The estimation of the change of the geliocentric gravitation constant GM_Sun has been obtained M_Sun /GM_Sun= (-5.0 ±4.1) ·10^-14 in year (3σ). The positive annual changes of semi-major axes _i/a_i have been determined simultaneously for the planets Mercury, Venus, Mars, Jupiter, Saturn provided with high-accuracy sets of the observations, as expected if the geliocentric gravitation constant is decreasing in century wise. Taking into account the maximal limits of the possible MSun change it was found from the GM_Sun change obtained that the gravitation constant /G falls within the interval -4.2·10^-14 < /G < +7.5·10^-14 per year with 95 % probability.