[Effect of morphine and pentazocine on emotional-behavioral and hemodynamic nociceptive reactions]

Pentazocine (5-15 mg/kg) fails to change the period of latency in the rat tail-flick reaction at thermic stimulation but suppresses to the same extent as morphine (5 mg/kg) the emotional-pain response and enhances the reactions of arterial blood pressure during mechanical stimulation. Both prazosin and naloxone (1 mg/kg) abolished the activating effect of pentazocine on the arterial blood pressure changes produced by nociceptive stimulation.