Effect of partial and complete blockade of vanilloid (TRPV1-6) and ankyrin (TRPA1) transient receptor potential ion channels on urinary bladder motor activity in an experimental hyperosmolar overactive bladder rat model.

UNLABELLED: The study investigated the mechanisms through which the hyperosmolarity might induce detrusor overactivity (DO). We compared the bladder activity in response to partial and complete blockade of TRPV1-6 and TRPA1 receptors. Experiments were performed on 42 rats. DO was induced by using hyperosmolar saline. All animals were randomly divided into six groups. The measurements represent the average of five bladder micturition cycles. Hyperosmolar saline induced DO. The complete blockade of TRPV1-6 and TRPA1 prevented DO. The partial blockade of TRPV1 didn't prevented DO. In the voiding phase periodical bladder contractions complexes occurred leading to slow urine flow due to bladder distension. Ruthenium red and capsaicin resulted in complete disorganisation of detrusor muscle contractility impairing urine voiding and leading to constantly lasting urine retention in healthy rats. CONCLUSIONS: hyperosmolar-induced DO is mediated by TRPV and TRPA1 channels; the hyperosmolar stimuli of urinary bladder might be transmitted mostly via ruthenium red sensitivity pathway.

Pulsating electromagnetic field stimulation prevents cell death of puromycin treated U937 cell line.

Aim of study was to verify whether pulsating electromagnetic field (PEMF) can affect cancer cells proliferation and death. U937 human lymphoid cell line at densities starting from 1 x 10(6) cells/ml to 0.0625 x 10(6) cells/ml, were exposed to a pulsating magnetic field 50 Hz, 45+/-5 mT three times for 3 h per each stimulation with 24 h intervals. Proliferation has been studied by counting number of cells stimulated and non-stimulated by PEMF during four days of cultivation. Viability of cells was analyzed by APC labeled Annexin V and 7-AAD (7-amino-actinomycin D) dye binding and flow cytometry. Growing densities of cells increase cell death in cultures of U937 cells. PEMF exposition decreased amount of cells only in higher densities. Measurement of Annexin V binding and 7-AAD dye incorporation has shown that density-induced cell death corresponds with decrease of proliferation activity. PEMF potentiated density-induced death both apoptosis and necrosis. The strongest influence of PEMF has been found for 1 x 10(6)cells/ml and 0.5 x 10(6) cells/ml density. To eliminate density effect on cell death, for further studies density 0.25 x 10(6) cells/ml was chosen. Puromycin, a telomerase inhibitor, was used as a cell death inducer at concentration 100 microg/ml. Combined interaction of three doses of puromycin and three fold PEMF interaction resulted in a reduced of apoptosis by 24,7% and necrosis by 13%. PEMF protects U937 cells against puromycin- induced cell death. PEMF effects on the human lymphoid cell line depends upon cell density. Increased density induced cells death and on the other hand prevented cells death induced by puromycin.

Magnetically induced vagus nerve stimulation and feeding behavior in rats.

Vagus nerve (VN) contribute to the bidirectional communication between the gastrointestinal tract and the central nervous system. Stimulation of the VN by a magnetically-driven solenoid with parameters similar to those during food-induced stomach distension has been thought to mimic short-term signaling of satiety and suppress food intake. In this study, the determination of optimal parameters of vagal neuro-modulation to achieve decreased food intake with a resulting reduction in body mass of rats is explored as therapy to treat obesity. The experimental design consisted of three groups of obese adult male Wistar rats: Group 1: VEMF - with solenoid's electrodes placed on the left VN in the magnetic field exposure (MFE); Group 2: EMF - without solenoid's electrodes on the VN in MFE; Group 3: CON - without solenoid's electrodes on the VN outside the MFE. This study suggests that the rats with solenoid's electrodes placed on the left VN significantly decreased their food intake, weight gain and serum leptin concentrations when compared to that of the CON group. PP levels were found to be higher in the VEMF group when compared to the controls groups. It was found that the most effective parameters of vagal stimulation on eating behavior were 3631, 7861, 14523 A(2) x h/m(2). The magnetic field by unknown mechanisms also influences feeding behavior. This study suggests that vago-vagal reflexes are involved in the feeding homeostasis and that neuromodulation might be an effective method for managing obesity. Further studies are required to confirm these effects in humans.

Urodynamic effects of the bladder C-fiber afferent activity modulation in chronic model of overactive bladder in rats.

Previous studies have suggested that, different types of unmyelinated bladder afferent C-fibres, such as capsaicin-sensitive and capsaicin-resistant mediate the voiding reflex in overactive bladder (OAB). Considering its polymodal features, we explored the urodynamic effect of primary afferent neurons modulation on detrusor activity in normal and OAB rats. Experiments were performed on 48 female rats. OAB was induced by intraperitoneal administration of cyclophosphamide. All the surgical procedures and urodynamic studies were performed under urethane anaesthesia. Cystometry was done after a 1 h recovery period from the surgical procedure. All animals were randomly divided into six groups: control, chronic OAB, chronic OAB after capsaicin or lidocaine instillation, control capsaicin or lidocaine instillation. The measurements represent the average of five bladder micturition cycles. We analyzed: basal, threshold, micturition voiding pressure; intercontraction interval; compliance; functional bladder capacity; motility index; detrusor overactivity index. We used chronic cyclophosphamide OAB model for further investigations. In healthy rats, intravesical instillation of capsaicin caused complete inhibition of detrusor contractility preventing from proper voiding function of the bladder. Contrary, lidocaine has no influence on micturition cycles in intact animals. Also, intravesical instillation of capsaicin and lidocaine reduced the severity of detrusor overactivity of OAB rats leading to improvement of cystometric parameters.

Effect of long-term vagal stimulation on food intake and body weight during diet induced obesity in rats.

Regulation of food intake and body weight is accomplished by several mechanisms. CNS receives information from periphery and modifies food intake mainly by vagal nerves that provide the major neuroanatomical link between gastrointestinal sites stimulated during food intake and CNS sites that control feeding behavior and metabolism. Gastric mechanoreceptors and jejunal chemoreceptors activated by food or vagal nerve stimulation (VNS), which mimic the physiological input, suppress feeding within short-term regulation. Our research was aimed on determination the role of electrical VNS in long-term control of food intake and body weight in diet induced obesity fed rats. Food intake, body weight and epididymal fat pad were assessed in male Wistar rats divided into three groups (controls vs. VNS). Rats were implanted with microchip and kept during the whole study (100 days) on diet induced obesity. Vagal nerve was stimulated by electrical rectangular pulses duration 10 ms, amplitude 200 mV, frequency 0.05 Hz generated by microchip. In control group surgery produced no significant changes in meal size and body weight gain as compared to intact group. In contrast, significantly decreased epididymal fat pad weight, decreased meal size with effect on decreased weight gain was observed in VNS rats. Data support theory that VNS can increase vagal afferent signal conduct to CNS and mimics the satiety signals leading to reduce food intake and body weight gain.

Loss of interstitial cells of Cajal after pulsating electromagnetic field (PEMF) in gastrointestinal tract of the rats.

Exposure to the magnetic field has remarkably increased lately due to fast urbanization and widely available magnetic field in diagnosis and treatment. However, biological effects of the magnetic field are not well recognized. The myoelectric activity recorded from the gastrointestinal and urinary systems is generated by specialized electrically active cells called interstitial cells of Cajal (ICCs). Thus it seems rational that ICC have significant vulnerability to physical factors like an electromagnetic field. The aim of this study was to evaluate the influence of pulsating electromagnetic field (PEMF) (frequency 10 kHz, 30ms, 300 muT burst, with frequency 1Hz) on ICCs density in the rat gastrointestinal tract. Rats were divided into two groups (n=32). The first group was exposed to PEMF continuously for 1, 2, 3, and 4 weeks (n = 16), and the second group (n=16) served as a control. Tissue samples of the rat stomach, duodenum and proximal colon were fixed and paraffin embedded. The tangential sections of 5 microm thickness were stained immunohistochemically with anti-c-Kit (sc-168) antibody and visualized finally by DAB as chromogen (brown end product). C-Kit positive branched ICC-like cells were detected under the light microscope, distinguished from the c-kit-negative non-branched smooth muscle cells and from the c-kit positive but non-branched mast cells and quantitatively analyzed by MultiScan computer program. Apoptosis detection was performed with rabbit anti-Bax polyclonal antibody (Calbiochem, Germany) and LSAB 2 visualization system. The surface of c-Kit immunopositive cells decreased after exposure to PEMF in each part of the gastrointestinal tract. Reduced density of ICCs was related to exposure time. The most sensitive to PEMF were ICCs in the fundus of the stomach and in the duodenum, less sensitive were ICCs in the colon and pacemaker areas of the stomach. No marked changes in ICC density in the pyloric part of the stomach were observed. We demonstrate that the PEMF induced apoptosis dependent decrease in ICC expression.