BEHAVIORAL-EFFECTS OF OPIOID PEPTIDE AGONISTS DAMGO, DPDPE, AND DAKLION LOCOMOTOR ACTIVITIES

The effects of the mu-selective agonist DAMGO (ICV doses of 0.00, 0.01 , 0.1, or 1.0 mug), the delta-selective agonist DPDPE (ICV doses of 0. 00, 0.1, 1.0, or 10.0 mug), and the kappa-selective agonist DAKLI (ICV doses of 0.00, 0.01, 0.1, or 1.0 mug) were tested in rats for 60 min in an activity monitor. The durations in seconds of linear locomotor t ime, rearing time, stereotypy time, and margin time (thigmotaxis) were measured during six 10-min time blocks. DAMGO (0.1 and 1.0 mug) resul ted in biphasic effects, inhibition followed by hyperactivity for line ar locomotor, rearing, and stereotypy times, and an inhibition of thig motaxis. DPDPE (10.0 mug) was associated with monophasic potentiation of linear locomotor activity and mixed effects in stereotypy times. DA KLI did not effect horizontal, rearing, or margin times; only stereoty py times resulted in mixed effects of DAKLI. The differential behavior al profiles were discussed in reference to the three opioid receptor s ubtypes.