Elena E. Ustinova

Convergence of Bladder and Colon Sensory Innervation Occurs at the Primary Afferent Level

Abstract Dichotomizing afferents are individual dorsal root ganglion (DRG) neurons that innervate two distinct structures thereby providing a form of afferent convergence that may be involved in pelvic organ cross‐sensitization. To determine the distribution of dichotomizing afferents supplying the distal colon and bladder of the Sprague–Dawley rat and the C57Bl/6 mouse, we performed concurrent retrograde labeling of urinary bladder and distal colon afferents using cholera toxin subunit B (CTB) fluorescent conjugates. Animals were perfused 4–5 days after sub‐serosal organ injections, and the T10‐S2 DRG were removed, sectioned, and analyzed using confocal microscopy. In the rat, CTB‐positive afferents retrogradely labeled from the bladder were nearly three times more numerous than those labeled from the distal colon, while in the mouse, each organ was equally represented. In both species, the majority of colon and bladder afferents projected from lumbosacral (LS) ganglia and secondarily from thoracolumbar (TL) ganglia. In the rat, 17% of the total CTB‐positive neurons were retrogradely labeled from both organs with 11% localized in TL, 6% in LS, and 0.8% in thoracic (TH) ganglia. In the mouse, 21% of the total CTB‐positive neurons were dually‐labeled with 12% localized in LS, 4% in TH, and 4% in TL ganglia. These findings support the existence of dichotomizing pelvic afferents, which provide a pre‐existing neuronal substrate for possible immediate and maintained pelvic organ cross‐sensitization and ultimately may play a role in the overlap of pelvic pain disorders.

Cross-Talk and Sensitization of Bladder Afferent Nerves

The coordination of pelvic physiologic function requires complex integrative sensory pathways that may converge both peripherally and/or centrally. Following a focal, acute irritative or infectious pelvic insult, these same afferent pathways may produce generalized pelvic sensitization or cross‐sensitization as we show bi‐directionally for the bladder and bowel in an animal model. Single unit bladder afferent recordings following intracolonic irritation reveal direct sensitization to both chemical and mechanical stimuli thats dependent upon both intact bladder sensory (C‐fiber) innervation and neuropeptide content. Concurrent mastocytosis (preponderantly neurogenic) likely plays a role in long‐term pelvic organ sensitization via the release of nociceptive and afferent‐modulating molecules. Prolonged pelvic sensitization as mediated by these convergent and antidromic reflexive pathway may likewise lead to chronic pelvic pain and thus the overlap of chronic pelvic pain disorders. Neurourol. Urodynam. 29: 77–81, 2010.

Gastrointestinal pain: unraveling a novel endogenous pathway through uroguanylin/guanylate cyclase-C/cGMP activation.

Summary Uroguanylin activation of the guanylate cyclase‐C/cyclic guanosine monophosphate pathway elicits analgesic effects in animal models of colonic hypersensitivity, unraveling a novel pathway to treat abdominal pain. ABSTRACT The natural hormone uroguanylin regulates intestinal fluid homeostasis and bowel function through activation of guanylate cyclase‐C (GC‐C), resulting in increased intracellular cyclic guanosine‐3′,5′‐monophosphate (cGMP). We report the effects of uroguanylin‐mediated activation of the GC‐C/cGMP pathway in vitro on extracellular cGMP transport and in vivo in rat models of inflammation‐ and stress‐induced visceral hypersensitivity. In vitro exposure of intestinal Caco‐2 cells to uroguanylin stimulated bidirectional, active extracellular transport of cGMP into luminal and basolateral spaces. cGMP transport was significantly and concentration dependently decreased by probenecid, an inhibitor of cGMP efflux pumps. In ex vivo Ussing chamber assays, uroguanylin stimulated cGMP secretion from the basolateral side of rat colonic epithelium into the submucosal space. In a rat model of trinitrobenzene sulfonic acid (TNBS)‐induced visceral hypersensitivity, orally administered uroguanylin increased colonic thresholds required to elicit abdominal contractions in response to colorectal distension (CRD). Oral administration of cGMP mimicked the antihyperalgesic effects of uroguanylin, significantly decreasing TNBS‐ and restraint stress–induced visceromotor response to graded CRD in rats. The antihyperalgesic effects of cGMP were not associated with increased colonic spasmolytic activity, but were linked to significantly decreased firing rates of TNBS‐sensitized colonic afferents in rats in response to mechanical stimuli. In conclusion, these data suggest that the continuous activation of the GC‐C/cGMP pathway along the intestinal tract by the endogenous hormones guanylin and uroguanylin results in significant reduction of gastrointestinal pain. Extracellular cGMP produced on activation of GC‐C is the primary mediator in this process via modulation of sensory afferent activity.

The role of hepatic type 1 plasminogen activator inhibitor (PAI‐1) during murine hemorrhagic shock

Hemorrhagic shock (HS) followed by resuscitation (HS‐R) is characterized by profound physiological changes. Even if the patient survives the initial blood loss, these poorly understood changes can lead to morbidity. One of the tissues most often affected is liver. We sought to recognize specific hepatic changes induced by this stressor to identify targets for therapeutic intervention. Gene array analyses using mouse liver mRNAs were used to identify candidate genes that contribute to hepatic damage. To verify the role of one of the genes identified using the arrays, mice were subjected to HS‐R, and multiple parameters were analyzed. A profound increase in plasminogen activator inhibitor type 1 (PAI‐1) mRNA was observed using hepatic mRNAs from C57Bl/6 mice after HS, both with and without resuscitation. Constitutive loss of PAI‐1 resulted in notable tissue preservation and lower (P < .05) alanine aminotransferase (ALT) levels. Fibrin degradation products (FDPs) and interleukins 6 and 10 (IL‐6 and IL‐10) were unaffected by loss of PAI‐1; however, enhanced urokinase activity, an elevation of active hepatocyte growth factor (HGF), an increase in unprocessed transforming growth factor‐β1 (TGF‐β1), and retention of ERK phosphorylation after HS‐R were associated with improved hepatic function. In conclusion, PAI‐1 protein is a negative effector of hepatic damage after HS‐R through its influence on classic regulators of hepatic growth, as opposed to its role in fibrinolysis. (HEPATOLOGY 2005;42:390–399.)

Evidence for the role of mast cells in colon–bladder cross organ sensitization

This study examined the contribution of mast cells to colon-bladder cross organ sensitization induced by colon irritation with trinitrobenzene sulfonic acid (TNBS-CI). In urethane anesthetized rats 12 days after TNBS-CI, the voiding interval was reduced from 357 s to 201 s and urothelial permeability, measured indirectly by absorption of sodium fluorescein from the bladder lumen, increased six-fold. These effects were blocked by oral administration of ketotifen (10 mg/kg, for 5 days), a mast cell stabilizing agent. TNBS-CI in wild type mice produced a similar decrease in voiding interval (from 319 s to 209 s) and a 10-fold increase in urothelial permeability; however this did not occur in KitªWª/KitªW-vª mast cell deficient mice. Contractile responses of bladder strips elicited by Compound 48/80 (50 μg/ml), a mast cell activating agent, were significantly larger in strips from rats with TNBS-CI (145% increase in baseline tension) than in control rats (55% increase). The contractions of strips from rats with TNBS-CI were reduced 80-90% by pretreatment of strips with ketotifen (20 μM), whereas contractions of strips from control animals were not significantly changed. Bladder strips were pretreated with SLIGRL-NH2 (100 μM) to desensitize PAR-2, the receptor for mast cell tryptase. SLIGRL-NH2 pretreatment reduced by 60-80% the 48/80 induced contractions in strips from rats with TNBS-CI but did not alter the contractions in strips from control rats. These data indicate that bladder mast cells contribute to the bladder dysfunction following colon-bladder cross-sensitization.

The Role of TLR4 in the Paclitaxel Effects on Neuronal Growth In Vitro

Paclitaxel (Pac) is an antitumor agent that is widely used for treatment of solid cancers. While being effective as a chemotherapeutic agent, Pac in high doses is neurotoxic, specifically targeting sensory innervations. In view of these toxic effects associated with conventional chemotherapy, decreasing the dose of Pac has been recently suggested as an alternative approach, which might limit neurotoxicity and immunosuppression. However, it remains unclear if low doses of Pac retain its neurotoxic properties or might exhibit unusual effects on neuronal cells. The goal of this study was to analyze the concentration-dependent effect of Pac on isolated and cultured DRG neuronal cells from wild-type and TLR4 knockout mice. Three different morphological parameters were analyzed: the number of neurons which developed neurites, the number of neurites per cell and the total length of neurites per cell. Our data demonstrate that low concentrations of Pac (0.1 nM and 0.5 nM) do not influence the neuronal growth in cultures in both wild type and TLR4 knockout mice. Higher concentrations of Pac (1–100 nM) had a significant effect on DRG neurons from wild type mice, affecting the number of neurons which developed neurites, number of neurites per cell, and the length of neurites. In DRG from TLR4 knockout mice high concentrations of Pac showed a similar effect on the number of neurons which developed neurites and the length of neurites. At the same time, the number of neurites per cell, indicating the process of growth cone initiation, was not affected by high concentrations of Pac. Thus, our data showed that Pac in high concentrations has a significant damaging effect on axonal growth and that this effect is partially mediated through TLR4 pathways. Low doses of Pac are devoid of neuronal toxicity and thus can be safely used in a chemomodulation mode.

The cytomorphologic spectrum of salivary gland type tumors in the lung and mediastinum: A report of 16 patients

In the lung and mediastinum, salivary gland type tumors (SGTTs) can occur as either primary tumors or metastases from tumors arising in the major or minor salivary glands. This study reviewed the cytology cases of SGTTs in the lung and mediastinum diagnosed over a six‐year period at our institution. The specimens included a total of 22 exfoliative or aspiration cytology specimens identified in 16 patients. Two of the cases were primary tumors: adenoid cystic carcinoma (ACC) of the trachea and mucoepidermoid carcinoma (MEC) of the thymus. The remaining 20 tumors were metastases from the parotid, submandibular gland, tongue, nasal cavity, or soft palate. Eight of the 16 patients (50%) had a diagnosis of ACC, four (25%) had salivary duct carcinomas, two (12.5%) had MECs, one (6.25%) was a basaloid tumor, and one (6.25%) was polymorphous low grade adenocarcinoma. In our series, these SGTTs were more commonly metastatic in the lung or mediastinum (87.5% of the patients), and the most common histological subtype was ACC, followed by SDC. This study also illustrates the cytomorphologic features and diagnostic pitfalls of these unusual SGTTs. Diagn. Cytopathol. 2012.