Spinal pelvic-urethra reflex potentiation

Abstract

Spinal reflex potentiation (SRP) in the pelvic-urethra reflex activity is a form of activity-dependent neural plasticity, presumed to be essential for urethra contraction resulting continence under physiological conditions and also to underlie the pelvic pain caused by pathology in the pelvic cavity. Studies have demonstrated that SRP could be induced by electrical shocks, bladder distension and activation of the lumbosacral (L6-S1) spinal glutamatergic NMDA and AMPA receptors. Conversely, blockage of glutamatergic receptors using selective antagonists either attenuated or abolished the established SRP. Electrical shocks on and nicotine microinjection into the pontine tegmentum area facilitated SRP induction, but intrathecal serotonin antagonists abolished electrical stimulation- and nicotine-induced facilitation on SRP. Finally, the induction of SRP is highly estrogen-dependent, because surgical ablation of menstruation diminished the SRP which is prevented by estradiol supplements, and SRP is more significant in proestrus (high estrogen but low progesterone) than in metestrus (both estrogen and progesterone are low) of the menstrual cycle. We propose that SRP is relevant to urine continence under physiological conditions, and pathological facilitation of SRP could result in pelvic pain.