  There is a recent proposal of identifying the Higgs particle of the Standard
Model as a pseudo Nambu-Goldstone boson. This new broken symmetry introduces
new particles and new interactions. Among these new interactions a central role
to get a new physics is played by the new neutral gauge boson. We have studied
the new neutral currents in the Littlest Higgs model and compared with other
extended models. For high energy $e^+ + e^-$ colliders we present a clear
signature for new neutral gauge bosons that can indicate the theoretical origin
of these particles. Previous analysis by other authors were done at collider
energies equal to the new gauge boson mass $M_{A_H}$. In this paper we show
that asymmetries in fermion anti-fermion production can display model
differences in the case $M_{A_H} > \sqrt{s}$. For $M_{A_H} < \sqrt{s}$ we show
that the hard photon energy distribution in $e^+ + e^- \lra \gamma + f + \bar
f$ can present a model dependence. New bounds for the new neutral gauge boson
masses are also presented.
