  Within the standard cosmological scenario the Universe is found to be filled
by obscure components (dark matter and dark energy) for ~95% of its energy
budget. In particular, almost all the matter content in the Universe is given
by dark matter, which dominates the mass budget and drives the dynamics of
galaxies and clusters of galaxies. Unfortunately, dark matter and dark energy
have not been detected and no direct or indirected observations have allowed to
prove their existence and amount. For this reason, some authors have suggested
that a modification of Einstein Relativity or the change of the Newton's
dynamics law (within a relativistic and classical framework, respectively)
could allow to replace these unobserved components. We will start discussing
the role of dark matter in the early-type galaxies, mainly in their central
regions, investigating how its content changes as a function of the mass and
the size of each galaxy and few considerations about the stellar Initial mass
function have been made. In the second part of the paper we have described, as
examples, some ways to overcome the dark matter hypothesis, by fitting to the
observations the modified dynamics coming out from general relativistic
extended theories and the MOdyfied Newtonian dynamics (MOND).
