Figure 8
From: Impact of Bioelectronic Medicine on the Neural Regulation of Pelvic Visceral Function
Model showing putative circuitry and neurotransmitters involved in the inhibition of reflex bladder overactivity elicited by pudendal nerve stimulation (PNS) in an acute spinal cord transected cat (T9/T10). Bladder overactivity was elicited by intravesical infusion of dilute acetic acid. Pudendal nerve afferents (right side) activate a GABA inhibitory interneuron via the release of glutamate and stimulation of metabotropic glutamate receptor 5 (mGluR5). The GABA interneuron can suppress the C-fiber afferent-mediated spinal micturition reflex by inhibiting transmission at the level of an excitatory interneuron or the preganglionic neuron. Note the supraspinal micturition reflex activated by Aδ afferents is eliminated by spinal cord transection. GABA activates GABAA receptors, which are blocked by picrotoxin. Excitatory glutamatergic transmission at the pudendal afferent terminal or in the micturition reflex pathway (*) is blocked by MTEP an mGluR5 antagonist.