Lumbosacral spinal segmental contributions to tibial and pudendal neuromodulation of bladder overactivity in cats

Abstract

AIMS To determine the spinal segmental afferent contributions to tibial and pudendal inhibition of bladder overactivity. METHODS Intravesical infusion of 0.5% acetic acid was used to irritate the bladder and induce bladder overactivity in anesthetized cats. Tibial or pudendal nerve stimulation was used to suppress the bladder overactivity and increase bladder capacity during cystometry. L5-S3 dorsal roots ipsilateral to the stimulation were exposed by a laminectomy and transected sequentially during the experiments to determine the role of individual dorsal roots in tibial or pudendal neuromodulation. RESULTS Transection of L5 dorsal root had no effect. Transection of L6 dorsal root in four cats produced an average 18% reduction in tibial inhibition, which is not a significant change when averaged in the group of 10 cats. Transection of L7 dorsal root completely removed the tibial inhibition without changing reflex bladder activity or pudendal inhibition. Transection of S1 dorsal root reduced the pudendal inhibition, after which transection of S2 dorsal root completely removed the pudendal inhibition. Transection of S3 dorsal root had no effect. The control bladder capacity was increased only by transection of S2 dorsal root. CONCLUSIONS This study in cats revealed that tibial and pudendal neuromodulation of reflex bladder overactivity depends on activation of primary afferent pathways that project into different spinal segments. This difference may be related to the recent observation in cats that the two types of neuromodulation have different mechanisms of action.

De novo aging-related megaloneurites: alteration of NADPH diaphorase positivity in the sacral spinal cord of the aged dog

“…The dense hypertrophic megaloneurites extending from dorsal entry zone and LT through lamina along the lateral edge of the dorsal horn to the region of the sacral parasympathetic nucleus (SPN). The sacral DGC and the LCP receives terminations from the somatic and visceral afferents (Morgan et al, 1981;Thor et al, 1989;Al-Chaer et al, 1996;Bansal et al, 2017). Functionally, the sacral spinal cord is known to be associated with bowel bladder, and sexual dysfunction (Cohen et al, 1991;Ogiwara and Morota, 2014;Barbe et al, 2018).…”

“…The sacral spinal cord is more specifically related to the intestine, bladder and sexual dysfunction (Cohen et al, 1991;Ogiwara and Morota, 2014;Barbe et al, 2018). In the dorsal gray commissure (DGC) in the S1-S3 segments of the cat spinal cord, this region receives the terminals of visceral afferent fibers in the pelvic nerves and somatic afferent fibers for the pudendal nerves through the Lissauer's tract (LT) and its lateral-and medial-collateral projections (McKenna and Nadelhaft, 1986;Thor et al, 1989;Liu et al, 1998;Bansal et al, 2017). The retrograde transganglionic labeling of primary afferent fibers from the bladder (Wang et al, 1998), urethra (Vizzard et al, 1995) and external urethral sphincter (Nadelhaft and Vera, 1996), as well as from the penile nerve (McKenna and Nadelhaft, 1986) has indicated that DGC is a part of the reflex pathways that control the functions of the pelvic viscera (Palecek and Willis, 2003;Cruz et al, 2017).…”

Gentle Perineal Skin Stimulation for Control of Nocturia

“…In the CMG model, peripheral nerve stimulation to anesthetized animals prolonged the latency of urination, indicating an increased volume threshold of the micturition reflex (Su et al, ; Choudhary et al, ; Jiang et al, ; Kadow et al, ; Rogers et al, ; Bandari et al, ; Bansal et al, ; Fuller et al, ; Uy et al, ; Zhang et al, ). In the RMC model, peripheral nerve stimulation abolished periodic intravesical pressure changes, reflecting suppression of the micturition reflex at a volume that was previously supra‐threshold (Su et al, ; Kovacevic and Yoo, ; Su et al, ; Onda et al, ; Ren et al, ).…”

“…In studies examining the effects of peripheral nerve activation by electrical stimulation on urinary bladder functions, stimulation is commonly applied to the tibial nerve, pudendal nerves, or the sacral nerves (Su et al, 2013a(Su et al, , 2013b(Su et al, , 2015Kovacevic and Yoo, 2015;Choudhary et al, 2016;Jiang et al, 2016;Kadow et al, 2016;Onda et al, 2016;Ren et al, 2016;Rogers et al, 2016;Bandari et al, 2017;Bansal et al, 2017;Fuller et al, 2017;Uy et al, 2017;Zhang et al, 2017). Hence, somatic afferents sending sensory inputs to spinal levels near pelvic nerve efferent outputs innervating the bladder are generally targeted for stimulation.…”

“…Hence, somatic afferents sending sensory inputs to spinal levels near pelvic nerve efferent outputs innervating the bladder are generally targeted for stimulation. In the majority of these recent studies on anesthetized animals, relatively low-intensity stimulation (1-4 times the motor threshold intensity) was used (Snellings and Grill, 2012;Su et al, 2013aSu et al, , 2013bSu et al, , 2013cSu et al, , 2015Ferroni et al, 2015;Choudhary et al, 2016;Jiang et al, 2016;Kadow et al, 2016;Lyon et al, 2016;Rogers et al, 2016;Bansal et al, 2017;Fuller et al, 2017). Such intensities of electrical stimulation are thought to be below the Aδ fiber threshold (Tai et al, 2011).…”