Aggression and defeat-induced opioid analgesia displayed by mice are modified by calcium channel antagonists and agonists.

The effects of the calcium channel antagonists diltiazem, nifedipine and verapamil and the calcium channel agonist, BAY K 8644, on offensive and defensive aggression and defeat-induced opioid analgesia were examined in male mice in resident-intruder interactions. The calcium channel antagonists decreased and the agonist increased the aggressive behaviors displayed by the mice. In addition, the calcium channel antagonists augmented, while the agonist attenuated defeat-induced analgesia displayed by the intruder mice. These results suggest that calcium channel antagonists have inhibitory influences on aggressive behavior and may facilitate endogenous opioid activity.