Involvement of beta-endorphin and mu-opioid receptors in mediating the aversive effect of lithium in the rat (Shippenberg 1988b)
- The apparatus consisted of shuttle boxes (30 × 60 × 30 cm, w × l × h) composed of Plexiglas and Acrylic and equipped with a loose-fitting lid.
- One compartment was white with a textured white floor.
- The other was black with a smooth black floor.
- A video camera was used for data recording.