Neuroplasticity is implicated in causing both NDO and AD, mediated by reformation of spinal reflex arcs and bladder
afferent neurons following SCI.
The neural circuit mediating this escape behavior is reasonably well understood, and consists of known
afferent neurons, command interneurons, central pattern generator interneurons, and efferent flexion neurons (Fig.
In 80% of trigeminal
afferent neurons originating from meninges, ASIC-like currents can be evoked at pH 6.0, and over 50% are also responsive to pH 7.0 [121].
TRPA1 and SP are expressed in intrinsic and extrinsic primary
afferent neurons; these are critical in the visceral pain and stress response (31,32).
Furthermore, local sensory neurons called intrinsic primary
afferent neurons (IPANs) regulate motility and maintain homeostasis.
Yeon et al., "Eugenol inhibits sodium currents in dental
afferent neurons," Journal of Dental Research, vol.
In neurogenic inflammation, local
afferent neurons secrete inflammatory mediators such as neurokinin A, substance P (SP), and calcitonin gene-related peptide which perpetuate inflammation.
From these studies [24-26], it can be shown that the convergence of AP signals and visceral noxious
afferent neurons in the spinal cord and the upper center is the neurobiological basis of AP for relieving visceral pain.
Synaptic connections with efferent and
afferent neurons are both observed in this the DG [10].
Regarding their function, submucosal neurons are divided into motor neurons, interneurons, intrinsic primary
afferent neurons (IPANs) and intrinsic fleeting
afferent neurons (IFANs).
During the storage phase, these
afferent neurons fire at low frequencies because the bladder wall is insufficiently stretched.
Regardless of the mechanism, damaged primary
afferent neurons undergo similar changes.
Similarly in tissue trauma or surgery, release of other mediators of pain like 5HT, along with substance P may sensitize primary
afferent neurons causing pain in cases of nerve entrapment pain or scar pain.
(1992) Central connections of trigeminal primary
afferent neurons: topographical and functional considerations.
Despite having damaged
afferent neurons, the efferent pathway is still intact allowing pupil constriction in both eyes.
