The effects of bilateral microinjections of mu-opioid receptor agonist
DAMGO (0.00, 0.01, 0.1, or 1.0 mu g/side) were tested in rats for 120
min in activity monitors. The horizontal movement, rearing, and stere
otypy times in seconds were measured during 12 consecutive 10-min time
blocks. DAMGO (0.01, 0.1, and 1.0 mu g) resulted in biphasic effects,
inhibition followed by activation for each of the three measures. The
se data replicate the behavioral effects of ICV DAMGO except that the
duration of the behavioral effects were longer with Acb injections.