Intrathecal oxytocin facilitates the spinal nociceptive flexor reflex in the rat.

We examined the effects of intrathecal oxytocin over a wide dose range (10 ng to 10 micrograms) on the spinal nociceptive flexor reflex in decerebrate, spinalized, unanaesthetized rats. Oxytocin facilitated the flexor reflex at all doses. The duration, but not magnitude, of facilitation was dose-related. No reflex depression was observed with intrathecal oxytocin at any dose. It is suggested that activation of spinal oxytocin receptors excites the spinal cord and therefore intrathecal oxytocin is unlikely to be an analgesic agent.