[Secondary-reinforcing effects of opiate agonists in the mouse]

Comparative examination of secondary-reinforcing properties of opiate agonists morphine, nalorphine, pentazocine and phencyclidine was carried out on mice using procedure of place preference conditioning in an automatic shuttle-box. Morphine, phencyclidine and pentaxocine (but not nalorphine) produced strong dose-dependent secondary-reinforcing effects. Special features of behavioural manifestations of their secondary-reinforcing action were analyzed in aspect of changes in temporal asymmetry and attendant locomotor activity of animals in the shuttle-box. On the basis of the obtained and literature data, it is suggested that mu- and sigma-opiate receptors mediate secondary-reinforcing effects of opiate agonists.