In this paper, the cooperative control problem of networked Euler-Lagrange systems with parametric uncertainties and unidirectional interaction is addressed under dynamically changing topology. As the communication graph evolves over time, a distributed control law via local effective interactions is designed. Adaptive techniques are used to deal with parametric uncertainties in the dynamics. With a continuous Lyapunov function, it is obtained that synchronization can still be achieved asymptotically as long as the union graph of the switching topologies has a directed spanning tree frequently enough. Extensions to disturbance rejection problems are also addressed using simple disturbance-observer or sliding mode control scheme. Illustrative examples with comparing simulation in the context of attitude synchronization of five non-identical spacecraft are further presented to show the effectiveness of the proposed cooperative control strategy.