  In this paper, the holographic dark energy model is considered in Brans-Dicke
theory where the holographic dark energy density $\rho_{\Lambda} =3c^2
M^{2}_{pl} L^{-2}$ is replaced with $\rho_{h}=3c^2 \Phi(t)L^{-2}$. Here
$\Phi(t)=\frac{1}{8\pi G}$ is a time variable Newton constant. With this
replacement, it is found that no accelerated expansion universe will be
achieved when the Hubble horizon is taken as the role of IR cut-off. When the
event horizon is adopted as the IR cut-off, an accelerated expansion universe
is obtained. In this case, the equation of state of holographic dark energy
$w_h$ takes a modified form
$w_h=-{1/3}(1+\alpha+\frac{2}{c}\sqrt{\Omega_{h}})$. In the limit $\alpha\to
0$, the 'standard' holographic dark energy is recovered. In the holographic
dark energy dominated epoch, power-law and de Sitter time-space solutions are
obtained.

Astrophysics