  The magnetization M(H) has been measured in the weakly helimagnetic itinerant
compound MnSi under high pressure up to 10.2 kbar and high magnetic field up to
9 Tesla. We interpret the simultaneous decrease under pressure of the saturated
magnetization, $p_s$, and the Curie temperature, $% T_c$ in the frame of the
self-consistent renormalization theory (SCR) of spin fluctuations. From the
analysis of the so-called Arrot-plot ($H/p [ H,T ] $ versus $p^2[ H,T ] $) and
the respective volume dependence of $p_s$ and $T_c$, we estimate the evolution
of the characteristic spin fluctuation temperatures, $T_0$ and $T_A$ when the
system approaches its critical pressure, $P_c$=15 kbar, corresponding to the
disappearance of the long range magnetic order at T=0.
