Effect of fluphenazine on the footshock-induced opioid analgesia and leu-enkephalin concentration in the rat brain.

The effect of post-shock injection of 5 mg/kg fluphenazine on stress-induced analgesia (tail immersion test) and leu-enkephalin content in discrete brain areas (radioimmunoassay) was studied in male Wistar rats. The stress-induced analgesia, which was naloxone-reversible, was attenuated and shortened by fluphenazine, the drug also antagonized the stress-induced fall in hypothalamic leu-enkephalin content. Fluphenazine alone depressed the leu-enkephalin content in the medulla oblongata, and this effect was less marked in rats subjected to footshock.