Stressor-like effects of FG-7142 on medial prefrontal cortex self-stimulation.

The effects of uncontrollable stress and the anxiogenic beta-carboline FG-7142 were compared on rats bar-pressing for electrical stimulation of the medial prefrontal cortex (MPC). One minute of restraint stress produced an immediate 20% increase in response rates. A significant facilitation was also evident 24 and 48 h later. Similarly, FG-7142 (10 mg/kg) produced an immediate 20% elevation of self-stimulation rates and a significant facilitation 24 and 48 h following administration. Lower (3 mg/kg) and higher (20 mg/kg) doses of FG-7142 caused immediate decreases in MPC self-stimulation and no significant long-term effects. These results agree with previous findings that FG-7142, administered at certain doses, may mimic the effects of exposure to uncontrollable stress.