Regulation of [<SUP>3</SUP>H]Norepinephrine Release by Opioids in Human Cerebral Cortex

Regulation of [<SUP>3</SUP>H]Norepinephrine Release by Opioids in Human Cerebral Cortex

To investigate the receptors mediating the regulation of norepinephrine (NE) release in human cerebral cortex slices, we examined the effects of opioid agonists for μ-, δ-, and κ-receptors on the high potassium (15 mM)-evoked release of [<SUP>3</SUP>H]NE. [<SUP>3</SUP>H]NE release induced by high potassium was calcium-dependent and tetrodotoxin-sensitive. [D-Pen<SUP>2</SUP>, D-Pen<SUP>5</SUP>]enkephalin (DPDPE) and deltorphin II (Delt II) inhibited the stimulated release of norepinephrine in a dose-dependent manner. However, Tyr-D-Ala-Gly-(Me)Phe-Gly-ol and U69,593 did not influence the NE release. Inhibitory effect of DPDPE and Delt-II was antagonized by naloxone, naltrindole, 7-benzylidenaltrexone and naltriben. These results suggest that both δ<SUB>1</SUB> and δ<SUB>2</SUB> receptors are involved in regulation of NE release in human cerebral cortex.