Differential modification by opioid agents of acutely enhanced noradrenaline release in discrete brain regions.

Although immobilization stress-induced increases in MHPG-SO4 level in the hypothalamus, amygdala and thalamus were enhanced by naloxone and attenuated by morphine, both agents failed to exert significant effects upon regional MHPG-SO4 levels in methamphetamine-treated rats. The results indicate that there is a differential modification by opioid agents of acutely enhanced noradrenaline release induced by physiological and by pharmacological manipulations.