NOXIOUS STIMULUS-INDUCED INCREASE IN SPINAL PROSTAGLANDIN-E2 IS NORADRENERGIC TERMINAL-DEPENDENT

Prostaglandins (PGs) were measured in perfusate from the lumbar intrathecal (IT) space of pentobarbital anaesthetized rats. The level of PGE2, but not of PGF2α or 6-keto PGF1α, was increased by immersion of a hindpaw in water at a noxious temperature (50°C). No increase in PGE2 was produced by non-noxious thermal stimulation (35°C water). The noxious stimulus-evoked increase in PGE2, and increases in PGE2 during norepinephrine infusion (10 μg/ml), were significantly decreased in rats pretreated with intrathecal 6-hydroxydopamine. These data suggest that noxious stimuli induce an increase in the production of spinal PGE2 and that this production derives from, or requires the presence of noradrenergic terminals in the spinal cord. © 1990.