Stimulation of either cholecystokinin receptor subtype reduces while antagonists potentiate or sensitize a morphine-induced excitatory response - Felicio, Luciano Freitas; Mazzini, Betania K.; Cacheiro, Renata G. R.; Cruz, Thais N.; Flório, Jorge Camilo; Nasello, Antônia Gladys (Peptides, 2001)