  In this paper we present analytical breather solutions of the
three-dimensional nonlinear generalized Gross-Pitaevskii equation. We use an
Ansatz to reduce the three-dimensional equation with space- and time-dependent
coefficients into an one-dimensional equation with constant coefficients. The
key point is to show that both the space- and time-dependent coefficients of
the nonlinear equation can contribute to modulate the breather excitations. We
briefly discuss the experimental feasibility of the results in Bose-Einstein
condensates.
