  Instanton effects can give large contribution to strong interacting
processes, especially at the energy scale where perturbative QCD is no longer
valid. However instanton contribution to the gluon contribution in constituent
quark and nucleon has never been calculated before. Based on both the
constituent quark picture and the instanton model for QCD vacuum, we calculate
the unpolarized and polarized gluon distributions in the constituent quark and
in the nucleon for the first time. We find that the pion field plays an
important role in producing both the unpolarized and the polarized gluon
distributions.
