Modulation of GABA-augmented norepinephrine release in female rat brain slices by opioids and adenosine

GABAA receptor activation augments electrically-stimulated release of norep inephrine (NE) from rat brain slices. Because this effect is not observed i n synaptoneurosomes, GABA probably acts on inhibitory interneurons to disin hibit NE release. To determine whether opioids or adenosine influence GABA- augmented NE release, hypothalamic and cortical slices from female rats wer e superfused with GABA or vehicle in the presence and absence of 10 muM mor phine or 100 muM adenosine. GABA augments [H-3]NE release in the cortex and hypothalamus. Morphine alone has no effect on [H-3]NE release, but attenua tes GABA augmentation of [H-3]NE release in both brain regions. Adenosine a lone modestly inhibits [H-3]NE release in the cortex, but not in the hypoth alamus. Adenosine inhibits GABA-augmented [H-3]NE release in both brain reg ions. The general protein kinase inhibitor H-7, augments [H-3]NE release in both brain regions and may have additive effects with GABA in cortical sli ces. These results implicate opioid and adenosine interneurons and possibly protein kinases in regulating GABAergic influences on NE transmission.