  We study the propagation of neutrinos inside dense matter under the
conditions prevailing in a proto-neutron star. Equations of state obtained with
different nuclear effective interactions (Skyrme type and Gogny type) are first
discussed. It is found that for many interactions, spin and/or isospin
instabilities occur at densities larger than the saturation density of nuclear
matter. From this study we select two representative interactions, SLy230b and
D1P. We calculate the response functions in pure neutron matter where nuclear
correlations are described at the Hartree-Fock plus RPA level. These response
functions allow us to evaluate neutrino mean free paths corresponding to
neutral current processes.
