Quipazine-induced behavior in neonatal rat pups.

Three day old Sprague-Dawley rat pups were placed in an incubator at room temperature (22 +/- 1 degrees C) or nest temperature (35 +/- 1.5 degrees C) and observed using a behavioral-time sampling procedure following injection of saline or quipazine (1, 2.5, 5, 10 mg/kg). Quipazine administration induced a marked behavioral activation that was characterized by increases in forward locomotion, wall climbing, forelimb paddling and hindlimb treading, the magnitudes of which were not dependent upon ambient temperature. In a second experiment, quipazine was also observed to induce mouthing behavior that was dependent upon the length of the mother-pup separation interval. These results suggests that administration of a serotonergic agonist can have marked behavioral effects in the neonatal rat pup, which reinforces previous neurochemical observations that have indicated the presence of ample postsynaptic serotonin substrates in neonatal rats. Possible implications of these results are discussed.