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Purpose: Although recent literature provides increasing evidence concerning urinary bladder innervation by vagal afferents, the functional aspects and the conditions at which these afferents are recruited are still unclear., Methods: In the present study, the neuronal responses of nodose ganglion following cystometry, under different models of rat's urinary bladder irritation, cyclophosphamide (CYP), cyclophosphamide with cervical vagotomy (Vx), chronic HCl, and acute HCl, were investigated using c-fos immunohistochemistry., Results: The c-fos expression in the nodose ganglion, following cystometry, was increased significantly in the CYP and chronic-HCl groups compared to the intact, Vx, and acute-HCl groups. In addition, the acute-HCl group showed a significant increase compared to intact animals. Following cervical vagotomy, the expression in the Vx group decreased significantly compared to the CYP group, but was significantly higher than that in the intact group., Conclusion: The results of this study demonstrate the innervation of the vagus afferents to the urinary bladder. This innervation is activated under urinary bladder irritation conditions, which may indicate a possible role of the vagus nerve during urinary bladder pathology., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

The cross talk between external genitalia and urinary bladder could be used as part of management to certain pathological conditions affecting urinary bladder. Since urinary bladder function is also affected by pathologies of other organs (e.g., colon and esophagus), the effect of genitalia stimuli on parameters of bladder function in normal or under different pathological conditions needs to be characterized. Cystometry recordings in male rats were used to examine the effect of low-threshold (LT) and high-threshold (HT) stimulation of the scrotum and penis on urinary bladder function. These effects were studied in intact, colon irritation (CI), and esophagus irritation (EI) groups. Although HT penile stimulation had a significant inhibitory effect on micturition reflex in all groups, CI hypersensitized the penile-bladder inhibitory reflex. In addition, LT penile stimulation had a significant inhibitory effect on micturition, which was significant in CI group only. On the other hand, HT penile stimulation in CI group significantly increased the timing parameters of cystometry. Whereas LT and HT penile stimuli in EI group had a significantly increasing effect on all pressure parameters of cystometry. The scrotal stimuli had minimal effect on bladder function in all groups except for HT scrotal stimulation in the CI group, where it had a significant inhibitory effect on micturition reflex and significantly increased the maximum pressure and pressure amplitude of micturition cycles. These results show that CI and EI exacerbate the effects of genitalia stimuli, especially penile stimuli, on urinary bladder function.

The coexistence of different visceral pathologies in patients suffering from irritable bowel syndrome, interstitial cystitis, and other pathologies, necessitates the study of these pathologies under complicated conditions. In the present study, cystometry recordings were used to investigate the effect of distal esophageal chemical irritation on the urinary bladder interaction with distal colon distention, distal esophageal distention, and electrical stimulation of abdominal branches of vagus nerve. Distal esophageal chemical irritation significantly decreased the intercontraction time via decreasing the voiding time. Also, distal esophageal chemical irritation significantly decreased the pressure amplitude by decreasing the maximum pressure. Following distal esophageal chemical irritation, distal esophageal distention was able to significantly decrease the intercontraction time by decreasing the storage time. However, 3 mL distal colon distention significantly increased the intercontraction time by increasing the storage time. On the other hand, following distal esophageal chemical irritation, electrical stimulation of abdominal branches of vagus nerve did not have any significant effect on intercontraction time. However, electrical stimulation of abdominal branches of vagus nerve significantly increased the pressure amplitude by increasing the maximum pressure. The results of this study demonstrate that urinary bladder function and interaction of bladder with other viscera can be affected by chemical irritation of distal esophagus.

The co-occurrence of multiple pathologies in the pelvic viscera in the same patient, such as, irritable bowel syndrome and interstitial cystitis, indicates the complexity of viscero-visceral interactions and the necessity to study these interactions under multiple pathological conditions. In the present study, the effect of distal colon irritation (DCI) on the urinary bladder interaction with distal esophagus distention (DED), distal colon distention (DCD), and electrical stimulation of the abdominal branches of vagus nerve (abd-vagus) were investigated using cystometry parameters. The DCI significantly decreased the intercontraction time (ICT) by decreasing the storage time (ST); nonetheless, DED and Abd-vagus were still able to significantly decrease the ICT and ST following DCI. However, DCD had no effect on ICT following the DCI. The DCI, also, significantly decreased the Intravesical pressure amplitude (P-amplitude) by increasing the resting pressure (RP). Although DED has no effect on the P-amplitude, both in the intact and the irritated animals, the abd-vagus significantly increased the P-amplitude following DCI by increasing the maximum pressure (MP). In the contrary, 3mL DCD significantly increased the P-amplitude by increasing the MP and lost that effect following the DCI. Concerning the pressure threshold (PT), none of the stimuli had any significant changes in the intact animals. However, DCI significantly decreased the PT, also, the abd-vagus and 3mL DCD significantly decreased the PT. The results of this study indicate that chemical irritation of colon complicates the effects of mechanical irritation of esophagus and colon on urinary bladder function.

Purpose: Many studies have demonstrated the convergence of vagal inputs into brainstem centers with inputs from the urinary bladder and colon, as well as the convergence of vagal inputs into other centers controlling the urinary bladder and colon reflexes. However, the effect of the vagal inputs on the interaction between the urinary bladder and other pelvic organs has not been studied. In this study, the effect of bilateral cervical vagotomy on the distal colon to urinary bladder reflex was examined., Methods: Changes to cystometry parameters in response to increased distal colon distensions (1, 2, and 3 ml) were tested in urethane-anesthetized male rats with or without bilateral cervical vagotomy., Results: In animals with intact vagus nerves, 1 and 2 ml distal colon distentions had no significant effects on micturition frequency; however, 3 ml distal colon distention significantly decreased the frequency of micturition cycles. Also, 3 ml distal colon distention inhibited micturition cycles in 37.5 % of these animals. On the other hand, following cervical vagotomy, 1 ml distal colon distention was enough to significantly decrease the frequency of micturition cycles and to inhibit the cycles in 75 % of the animals., Conclusion: These results demonstrate the presence of supraspinal inhibitory regulation, via the vagus nerve, over the distal colon to urinary bladder inhibitory reflex.

Aims: Micturition process is a spinobulbospinal reflex that is affected by the viscero-visceral interactions due to convergent inputs into spinal and/or supraspinal centers controlling that reflex. Although interaction between bladder and other pelvic organs, such as colon, are well studied, the viscero-visceral interaction between urinary bladder and internal organs in other regions are rarely studied., Methods: In the present study, continuous filling cystometry recordings, in male rats, were used to investigate the effects of mechanical stimulation of distal-esophagus (distention), as well as, electrical stimulation of abdominal branches of the vagus nerve on urinary bladder micturition cycles., Results: Distal esophagus distention and electrical stimulation of the vagus nerve significantly increased the micturition frequency through decreasing the time of the storage phase of the micturition cycle. However, bilateral cervical vagotomy eliminated the effects of distal esophagus distention and electrical stimulation of vagus nerve on micturition cycles., Conclusions: The results of this study indicate that there is a viscero-visceral interaction between esophagus and urinary bladder, which is mediated through vagal afferents. Understanding the properties of the viscero-visceral interactions affecting the urinary bladder will help in the diagnosis and management of micturition problems., (Copyright © 2011 Wiley Periodicals, Inc.)

A number of clinical studies indicate the coexistence of multiple chronic pelvic diseases and pain syndromes. An association between various conditions related to the pelvic viscera may relate to a high degree of central visceral convergence, which is a requisite for the cross-organ coordination that is necessary for their normal functions. In the present study, a population of neurons receiving a high degree of somatovisceral convergence (those in the medullary reticular formation--MRF) was targeted in order to examine the effect of infusing a chemical irritant into one organ on the responsiveness of convergent inputs from various visceral and somatic regions of the body, using electrophysiological techniques. Acute irritation of the urinary bladder (UB) with 2% acetic acid significantly decreased the percentage of convergent MRF neuronal responses to UB distention and urethral infusion and significantly increased the percentage responding to whole body, mainly due to stimulation of the face. Irritation also produced a significant increase in the response duration of MRF neurons to distention of colon as well as the bladder (for those few UB responses that still remained). These results indicate that a pelvic/visceral pathology confined to one organ can affect at least some of the convergent responses from other regions of the body. The findings suggest that MRF neurons contribute to the cross-talk between different regions of the body under both normal and pathological conditions.