Evaluation of selected protein biomarkers of renal function in rats with an experimental model of acute cyclophosphamide-induced cystitis treated with N-acetylcysteine

The administration of cyclophosphamide (CP) is associated with the risk of developing cystitis as well as kidney injury. The aim of the study was to verify the uroprotective effect of N-acetylcysteine (NAC), as well as the evaluation of renal function in the experimental model of acute CP-induced cystitis. Rats from group 1 received intraperitoneally only a single dose of 200 mg/kg b.w. of CP. Individuals from groups 2 and 3 additionally received a single dose of 200 mg/kg b.w. of NAC, respectively, orally (p.o.) and intraperitoneally (i.p.). After the administration of the drugs, animals were subject to individual monitoring in metabolic cages to assess 24-hour diuresis and basic vital signs, and then finally sacrificed for the purpose of collecting blood and organs for histopathological analysis. Classic renal parameters (creatinine, urea, uric acid, electrolytes) as well as new markers reflecting renal function, within the filtration-resorption range - cystatin C (CysC), renal tubular integrity - kidney injury molecule-1 (KIM-1) and the condition of the glomerular filtration barrier (nephrin) were determined in the obtained serum and urine samples. In group 1 histopathological development of cystitis was confirmed with the absence of significant pathomorphological disorders of the kidneys, and the initial results of the parameters determined were obtained. In both groups 2 and 3, a decrease of inflammatory changes in urinary bladder was observed, while there were still no morphological disturbances in kidneys. The administration of NAC in both groups 2 and 3 also resulted in a decrease of concentrations in urine and a reduction in 24-hour excretion with urine of all assessed proteins (CysC, KIM-1 and nephrin). NAC, thus exhibited a uroprotective effect, which was accompanied by a functional nephroprotective effect (more accentuated during intraperitoneal administration of this compound), manifested by the reduction of urinary excretion of proteins indicative of developing renal dysfunction.

Exogenous melatonin abolishes mechanical allodynia but not thermal hyperalgesia in neuropathic pain. The role of the opioid system and benzodiazepine-gabaergic mechanism

Melatonin (MT) is a neurohormone synthesized and secreted by the pineal gland. MT plays an important role in the regulation of physiological and neuroendocrine functions. The purpose of this study was to assess the overall effect of melatonin on neuropathic pain, the type of melatonin receptor involved, and potential role of the opioid system and GABA(A) receptors. The experiments were conducted by using the animal neuropathic pain model (CCI). The rats with CCI showed the characteristic for the mechanical allodynia and thermal hyperalgesia signs that were calculated by using the von Frey's and Hargreaves' tests. The conducted studies measured the effects of intraperitoneal administration of naloxone (opioid antagonist), prazosin (MT3 antagonist), luzindole (MT1/MT2 receptor antagonist), picrotoxin (GABA(A) antagonist) and flumazenil (benzodiazepine antagonist) on the antinociceptive effects caused by melatonin. Melatonin caused the increase in the pain threshold of the mechanical allodynia and the slight increase in the threshold of the thermal hyperalgesia. The pre-treatment with naloxone completely abolished the antinociceptive effects of melatonin in von Frey's test, but not thermal sensation in the Hargreaves's test. Prazosin did not have any effects, while administration of luzindole significantly suppressed the antinociceptive effect of melatonin. The antiallodynic effect of MT was also abolished by flumazenil and picrotoxin. Melatonin influences the mechanical allodynia but not thermal hyperalgesia via activation of opioid system and benzodiazepine-GABAergic pathway. Antinociceptive effects of melatonin are mostly related to the MT1/MT2 receptors interaction.

Pulsed electromagnetic field affects intrinsic and endoplasmatic reticulum apoptosis induction pathways in MonoMac6 cell line culture

Current studies were aimed to elucidate influence of pulsed electromagnetic field stimulation on cell viability and apoptosis induction pathways. For the experimental model we have chosen monocytic cell line MonoMac6 and several apoptosis inducers with different mechanism of death induction like puromycin, colchicine, cyclophosphamide, minocycline and hydrogen peroxide. MonoMac6 cell line was grown at density 1x10(5) cells/well in 96-well culture plates. To induce cell death cell cultures were treated with different apoptosis inducers like puromycin, colchicine, cyclophosphamide, minocycline, hydrogen peroxide and at the same time with pulsed electromagnetic field 50 Hz, 45±5 mT (PEMF) for 4 hour per each stimulation, three times, in 24 hours intervals. Afterwards, cells were harvested for flow cytometry analysis of cell viability measured by annexin V-APC labeled and propidium iodide staining. Expression of apoptosis related genes was evaluated by semi quantitative reverse transcription (RT)-PCR assay. NuPAGE Novex Western blot analysis was carried out for apoptosis inducing factor (AIF) abundance in cytosolic and nuclear extracts of MonoMac6 cells. Puromycin, colchicine and minocycline activated cells and simultaneously treated with PEMF have shown out diminished percentage of annexinV positive (AnV+) cells comparing to controls without PEMF stimulation. MonaMac6 cells puromycin/colchicyne and PEMF treated were to a higher extent double stained (AnV+,PI+), which means increased late apoptotic as well as necrotic (PI+) cells, than non-stimulated controls. On the other hand, minocycline activated cells prior to PEMF treatment showed diminished amount of apoptotic and necrotic (annexin V, annexin V and propidium iodide, propidium iodide positive staining) cells. The opposite effect of PEMF on the percentage of annexin V positively stained cells has been achieved after treatment of MonoMac6 culture with cyclophoshamide and hydrogen peroxide. PEMF enhanced early phase of apoptosis induced by both apoptosis inducing agents. The analysis of expression of the apoptosis related genes in MonoMac6 cultures treated with puromycin and exposed to PEMF performed in reverse transcription of polymerase chain reaction (PCR) assay has shown changes in mRNA of genes engaged in intrinsic apoptotic pathway and pathway with AIF abundance. The most influenced was expression of gene belonging to pro-apoptotic family of Bcl-2 and AIF agent. Examination of immunoblots developed with anti-AIF antibody showed that cytosol content of AIF protein was diminished after puromycin and PEMF treatment of MonoMac6 cells. The obtained results indicate that PEMF affects induction of apoptosis in MonoMac6 cells stimulated to death with inducing agents to a different extent. Main finding of the current results is that, PEMF stimulation of MonoMac6 cells simultaneously treated with puromycin caused changes in the Bcl-family genes expression as well as in caspase independent pathway of apoptosis inducing factor (AIF).

Morphological and urodynamic evaluation of urinary bladder wall regeneration: muscles guarantee contraction but not proper function--a rat model research study

BACKGROUND

Numerous studies are ungoing to develop a substitute for the native urinary bladder wall. The principals of tissue engineering approaches to urinary bladder wall augmentation require a favorable environment for smooth muscle regeneration, which is crucial for bladder function. This study was performed to evaluate bone marrow mesenchymal stem cells (BMSC) seeded on to amniotic membranes fixed to Tachosil sponges as grafts for urinary bladder muscle layer augmentation in a syngenic rat model.

MATERIALS AND METHODS

Amniotic membranes seeded with BMSC and covered by Tachosil sponges were implanted as multilayer grafts into nine rats to regenerate the urinary bladder wall. The control group consisted of 12 healthy rats. Urodynamic examinations included contraction, elasticity, compliance, and urinary bladder motor activity. Hematocylin and eosin and Masson's trichrome stains were used to evaluate muscle regeneration; histological data were digitally analyzed with the ImageJ tool.

RESULTS

The area of muscle bundles ranged from 5% to 25% or 32% to 41% in control versus reconstructed bladders, respectively. Among nine animals with reconstructed urinary bladders, urodynamic evaluation revealed bladder motor hyperactivity with regular (n = 4) or irregular (n = 1) storage and voiding phases, as well as proper bladder motor activity with a large bladder capacity (n = 1). No bladder contractility was recorded in one case and large stones developed in two animals, which made functional studies impossible.

CONCLUSIONS

Regenerated smooth muscle cells created an autonomic cell population that was poorly assimilated to the rest of the urinary bladder wall. The histological presence of a regenerated muscle layer did not guarantee proper urinary bladder function.

Pulsating electromagnetic field stimulation of urothelial cells induces apoptosis and diminishes necrosis: new insight to magnetic therapy in urology

The evidence of electromagnetic therapy (EMT) efficacy in stress and/or urge urinary incontinence, as well as in detrusor overactivity is generally lacking in the literature. The potential EMT action of neuromuscular tissue depolarization has been described. Because there is no data on the influence of pulsating electromagnetic fields (PEMF) on the urothelium, we evaluated the effect of PEMF stimulation on rat urothelial cultured cells (RUCC). In our study 15 Wistar rats were used for RUCC preparation. RUCC were exposed to PEMF (50 Hz, 45±5 mT) three times for 4 hours each with 24-hour intervals. The unexposed RUCC was in the same incubator, but in a distance of 35 cm from the PEMF generator. Annexin V-APC (AnV+) labelled was used to determine the percentage of apoptotic cells and propidium iodide (PI+), as standard flow cytometric viability probe to distinguish necrotic cells from viable ones. The results are presented in percentage values. The flow cytometric analysis was carried out on a FACS calibur flow cytometer using Cell-Quest software. In PEMF-unstimulated RUCC, the percentage of AnV+, PI+, and AnV+PI+ positive cells were 1.24±0.34%, 11.03±1.55%, and 12.43±1.96%, respectively. The percentages of AnV+, PI+, and AnV+PI+ positive cells obtained after PEMF stimulation were 1.45±0.16% (p=0.027), 7.03±1.76% (p<0.001), and 9.48±3.40% (p=0.003), respectively. The PEMF stimulation of RUCC induces apoptosis (increase of AnV+ cells) and inhibits necrosis (decrease of PI+ cells) of urothelial cells. This leads us to the conclusion that a low-frequency pulsating electromagnetic field stimulation induces apoptosis and diminishes necrosis of rat urothelial cells in culture.

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

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.

Functional, histological structure and mastocytes alterations in rat urinary bladders following acute and [corrected] chronic cyclophosphamide treatment

Neurogenic inflammation is linked to urinary bladder overactivity development. Cyclophosphamide (CYP) damages all mucosal defence lines of urinary bladder and induces cystitis with overactivity. The aim of this study was to estimate the effect of CYP on rat urinary bladder function, histological structure and mastocytes numbers following acute and chronic CYP treatment. Fourty two female rats were divided into four groups: I (control), II (acute cystitis), III (chronic cystitis), IV (sham group). Acute and chronic cystitis were induced by CYP in single dose and four doses (1(st), 3(rd), 5(th), 7(th) day), respectively. In group I-III the cystometric evaluation was performed. Sections of the bladder were stained with HE and toluidine blue for the detection of mastocytes. The severity of inflammation was examined according to mucosal abrasion, haemorrhage, leukocyte infiltration and oedema. Acute and chronic CYP treatment caused inflammatory macroscopic and microscopic changes (mucosal abrasion, haemorrhage, oedema) and increased infiltration of inflammatory cells in urinary bladder. Acute treatment induced the infiltration of mastocytes within bladder wall contrary to chronic one decrement. Acute treatment caused more severe mucosal abrasion, whereas chronic one revealed more developed haemorrhage changes. Additionally, cystometric evaluation revealed urinary bladder overactivity development in both types of cystitis. Basal pressure and detrusor overactivity index after acute treatment increased considerably in comparison with the increase obtained after chronic one. Our results proved that acute model of CYP-induced cystitis in rats is more credible for further evaluation of neurogenic inflammation response in pathogenesis of overactive bladder as compared to chronic one.

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.

The vagal afferents discharge and myoelectrical activity in the gastric hyperalgesia model in rats

A long term exposure of the gastric mucosa to inflammatory factors is suspected to alter the normal stomach motility. The consequence of it is an abnormal sensomotor response to food causing dyspeptic symptoms. Our study aimed to investigate the vagal afferents activity and the gastro-duodenal slow wave response to the mild gastric mucosa inflammation in rats. The gastric mucosal inflammation was induced by addition iodoacetamide to drinking water for 5 days. The gastro-duodenal slow wave, vagal nerve recordings and the gastric mucosa examination were performed on 6th day. The iodoacetamide irritated gastric mucosa presented the minimal inflammatory infiltration with mast cells. The vagal afferent activity was significantly increased after iodoacetamide treatment from 0.3 +/- 0.1 to 1.9 +/- 0.58 Hz, (p<0.05). The gastric slow wave accurate frequencies extracted from the fast Fourier transform spectra accelerated from 0.08 +/- 0.01 to 0.1 +/- 0.02 Hz (p<0.05). The duodenal frequencies remained unchanged (from 0.64 +/- 0.02 to 0.59 +/- 0.1 Hz). These results suggest that mild gastric mucosa irritation sensitizes vagal afferents and alters gastric but not duodenal pacemaker activity which may contribute to dyspeptic sensations.

The role of sensory C-fibers in response of vagal afferent stimulation by gastric distension in rats with experimental chronic gastric ulcer

There is growing evidence that gastric vagal afferent input may contribute to the altered sensations associated with gastrointestinal disorders. The aim of our study was to evaluate gastric vagal afferents (VA) activity in rats with experimental gastric ulcer and ulcer healing. The study was carried out on rats with gastric ulcer (GU), including, a group with perivagal capsaicin pretreatment (CAP), a group with capsaicin administration in gastric ulcer (CAP+GU) animals and control rats. In all rats electrical VA activity was recorded and analysed. In GU rats recordings were carried out in chronic ulcer and ulcer healing. In GU and CAP+GU groups gastric balloon distensions with vagal recording was performed on 3(rd) day after ulcer induction. Usually, experimental GU healed spontaneously within 2 weeks. Three days after acetic acid application when GU fully develop, the frequency of the basal VA activity was almost 3-times higher than in the control intact rats and remained elevayed until 4(th) week after ulcer induction. VA response to gastric distension increased concomitantly with increased balloon volume in both GU and control animals, but it was several times higher in GU rats. Perivagal capsaicin application decreased the frequency of spontaneous VA activity and decreased the response of VA to gastric distension. In CAP+GU, spontaneous activity as well as the response to gastric distension were higher than in CAP rats. Our study shows that GU induced inflammatory changes increase sensitivity of gastric VA. Capsaicin-sensitive vagal afferent fibers may play some role in this phenomenon. Peripheral sensitization of VA persists even when gastric ulcer is completely healed.

Melatonin and serotonin effects on gastrointestinal motility

The gastrointestinal tract represents the most important extra pineal source of melatonin. Presence of melatonin (M) suggests that this hormone is somehow involved in digestive pathophysiology. Release of GI melatonin from serotonin-rich enterochromaffin EC cells of the GI mucosa suggest close antagonistic relationship with serotonin (S) and seem to be related to periodicity of food intake. Food deprivation resulted in an increase of tissue and plasma concentrations of M. Its also act as an autocrine and paracrine hormone affecting not only epithelium and immune system but also smooth muscle of the digestive tract. Low doses M improve gastrointestinal transit and affect MMC. M reinforce MMCs cyclic pattern but inhibits spiking bowel activity. Pharmacological doses of M delay gastric emptying via mechanisms that involve CCK2 and 5HT3 receptors. M released in response to lipid infusion exerts a modulatory influence that decreases the inhibitory effects of the ileal brake on gastric emptying. On isolated bowel S induces dose dependent increase in tone and reduction in amplitude of contraction which is affected by M. M reduced the tone but not amplitude or frequency of contraction. M is a promising therapeutic agent for IBS with activities independent of its effects on sleep, anxiety or depression. Since of its unique properties M could be considered for prevention or treatment of colorectal cancer, ulcerative colitis, gastric ulcers and irritable bowel syndrome.

Dysfunction of the autonomic nervous system activity is responsible for gastric myoelectric disturbances in the irritable bowel syndrome patients

The pathogenesis of the irritable bowel syndrome (IBS) is still unsolved. Lately most attention has been focused on visceral hypersensitivity related to dysfunction of the autonomic nervous system (ANS). The aim of this study was to evaluate changes in the ANS activity and gastric motility in constipation-predominant IBS patients using the heart rate variability (HRV) and gastric myoelectric activity (EGG) recording. 23 patients (45+/-13 yrs) matching Manning criteria and 30 healthy volunteers (47+/-5 yrs) participated in the study. EGG and HRV in fasted and fed subjects with fasted serum catecholamine levels were measured in both groups. Fasting IBS pts showed gastric dysrrhythmia (29+/-14% vs. 11+/-7%), DP was 128.860 +/- 112.000 vs. 46.000+/- 23.200microV2, DF 2.37+/-0.8 vs. 2.9+/-0.2cpm. Feeding (300 kcal) improved dysrrhythmia to 20+/-13% vs. 8+/-5%, DP decreased to 74.500+/-57.720 vs. 165.600+/-89.000microV(2) and DF increased to 2.53+/-0.7 vs. 3.2+/-0.3cpm. In fasted and fed IBS pts SWC (channels 3-4) was about 60+/-11 vs. 84+/-8% and 68+/-14 vs. 92+/-8% respectively. In IBS pts resting HRV parameters were lower (LF - 650.3 vs. 811.6 ms2; HF - 508.8 vs. 854.6 ms2); with higher LF/HF ratio in IBS patients (1.52 vs. 1.2). The serum fasting level of adrenaline and noradrenaline in IBS pts were higher 1.28+/-0.06 vs. 0.65+/-0.05 nmol/L, and 3.54+/-1.2 vs. 2.89+/- 08 nmol/L, p<0.05 respectively. Increased sympathetic drive in IBS pts reflected by high catecholamine levels and LH/HF ratio is responsible for gastric dysrrhythmias and low DF and coupling. Meal has negligible effect on EGG parameters improvement. The ANS dysfunction observed in IBS patients is most probably responsible for disturbances in gastric myoelectric activity presented as gastric dysrrhythmias resulting in gastric emptying delay and dyspeptic symptoms.

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.

Helicobacter pylori infection in pathogenesis of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) refers to the very common and constantly increasing conditions where reflux of gastric contents into the esophagus leads to development of characteristic symptoms. The esophagus, LES and stomach can be envisioned as single functional unit controlled by neuro-hormonal factors. The abnormalities that contribute to GERD can start in any component of this unit, resulting particularly from disturbances in their control system. It is extremely important to identify factors and mechanisms leading to functional failure of this system so that causative therapy can be effectively applied. The key-role has been attributed to parasympathetic dysfunction, which may adversely affect motor activity of this area by increasing transient LES relaxation number and impairing LES pressure, esophageal acid clearance and motility of the proximal stomach. Recently, numerous investigations have been performed to elucidate the role of Helicobacter pylori (Hp) infection in GERD pathogenesis with the most concern given to its potency to increase gastric acid secretion. However, it appeared that this infection leads to much more complex changes in gastric mucosa including modification of afferent neural signals and specific gastric hormones release. Plasma ghrelin level is low in subjects infected and increases significantly after eradication. Since ghrelin, beside potency to increase gastric secretion has strong prokinetic action on LES functional unit, this phenomenon together with impaired vagal control may contribute to the Hp infection or eradication - related GERD development. Thus, ghrelin and vagal activity could be the missing links that partially explains relationship between GERD and Hp infection.

Peripheral mechanisms of intestinal dysmotility in rats with salsolinol induced experimental Parkinson's disease

Gastrointestinal dysmotility in Parkinson's disease (PD) has been attributed in part to peripheral neurotoxine action. Our purpose was the evaluation of the salsolinol effect on intramuscular interstitial cells of Cajal (ICC), duodenal myoelectrical activity (DMA) and vagal afferent activity (VAA) in rats with experimental PD. Twenty rats were divided into 2 equal groups. Experimental PD was produced in one group by 3 weeks of the intraperitoneal salsolinol injections (50 mg/kg/day), whereas the 2-nd group served as control. DMA and VAA were recorded in both groups during fasting and stepwise--gastric distension (GD) of 10 ml. Subsequently fragments of duodenum were removed and intramuscular ICC were assessed as c-Kit antigen percentage in the duodenal muscular zone. Analyses of the fasting DMA and VAA recordings didn't reveal differences between the compared groups. During GD increase of DMA dominant frequency (p=0.04) and VAA frequency (p<0.01) was observed in the controls whereas in the salsolinol group both parameters remained unchanged. Image analysis of duodenum revealed decreased c-Kit expression in the salsolinol-injected animals (p=0.05). The results of our study may suggest the direct effect of salsolinol on both ICC and neuronal pathways of gastro-duodenal reflexes.

Peripheral mechanisms of intestinal dysmotility in the morphine tolerant and dependent rats

Changes of intestinal motility and transit produced by tolerance to and dependence upon morphine have been partly attributed to peripheral mechanisms. We evaluated the effect of chronic peripheral morphine administration and peripheral mu-receptor blockade on vagal afferent activity (VAA) and c-Kit positive intramuscular cells of Cajal (ICCs). Ten rats were subjected to chronic subcutaneous morphine infusion for 72 h with subsequent VAA recording. Potential frequency was evaluated within recordings before and after mu receptor blockade by (D)-Phe -Cys -Tyr -(D)-Trp -Orn -Thr -Phe -Thr (CTOP) i.p. injections. Afterwards the rats were sacrificed and intramuscular c-Kit antigen expression was assessed by image analysis within removed fragments of duodenum and ascending colon. An equal group of rats served as a control for VAA and c-Kit expression. Analysis of VAA revealed similar frequencies of potentials in morphine tolerant / dependent rats before CTOP and in the controls. CTOP increased potential frequency in the morphine group which effect was visible mostly within the first 20 minutes (p=0.01). The morphine infused animals presented also higher c-Kit expression in both the duodenum (p<0.001) and the ascending colon (p<0.001) in comparison to the control group. Results of our study may indicate the involvement of both the intestinal wall and the long vago-vagal reflexes in tolerance to and dependence upon opioids.

Influence of vagal nerve stimulation on food intake and body weight--results of experimental studies

The paper reviews recent advances in vagal nerve stimulation for the control of food intake and body weight. The vagal nerves are the predominant pathway in the "brain-gut axis" responsible for short term regulation of food intake. Stimulation of afferent vagal traffic attenuates food intake by vagal projections to nucleus tractus solitarius, arcuate nucleus and its convergence's to thalamic center of satiety. A few studies have been published in this field so far. All of them are consistent and show significant decrease in body mass during vagal stimulation. Due to promising results of experimental studies, clinical trials are expected in the near future.

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.

The effects of baclofen on the feeding behaviour and body weight of vagally stimulated rats

It is hypothesised that the GABA(B) receptor agonist baclofen increases or has no effect on food intake, and electrical stimulation of vagal nerves decreases food intake. The aim of this study was to evaluate the effects of baclofen in vagally stimulated rats.

MATERIAL AND METHODS

Thirty two Wistar rats were divided into five groups: group A scheduled for microchip implantation for vagal stimulation, group B for sham operation, group C for microchip implantation and baclofen medication, group D for baclofen medication only and group E for gastric motility evaluation under influence of baclofen. The following parameters were then evaluated: food intake and body mass, gastric motility, leptin, insulin, and glucose serum levels.

RESULTS

In the comparison of groups B and A, daily food intake and body weight gain decreased by 17% (p<0.05) and by 22% (p<0.05), respectively. Baclofen alone (group D) did not significantly change either food intake nor diurnal body weight compared to the controls, but when used in conjunction with the microchip (group C) it did significantly reduce effect of vagal neuromodulation (p<0.05). Furthermore, a significant decrease in leptin and glucose levels was detected in group C: 677 to 165 pg/ml (p<0.05) and 5,93 to 4,88 mmol/l (p<0.05), respectively. The administration of baclofen stimulated significantly gastric motility and elicited irregular motor migrating complex (327+/-200 against control 255+/-52 cmH2O/s).

CONCLUSIONS

These results suggest that microchip vagal neuromodulation through increased vagal afferent activity induces an alteration in the feeding behaviour and decreases nocturnal food intake and body weight. These effects were partially attenuated by baclofen. The data suggests that GABA(B) receptors play an important role in the pathomechanism of attenuation of food intake induced by vagal nerve stimulation.

Disturbances of the parasympathetic branch of the autonomic nervous system in patients with gastroesophageal reflux disease (GERD) estimated by short-term heart rate variability recordings

Gastro-esophageal reflux disease (GERD) is the result of the acid contents regurgitation back from the stomach into the esophagus. According to the endoscopic findings, GERD can be divided into two main forms: non-erosive (NERD) and erosive reflux esophagitis. The pathogenesis of GERD is associated with the impaired function of the antireflux barrier. Disturbances of the autonomic nervous system (ANS), especially parasympathetic part of the ANS, may be also involved in the pathogenesis of this disease. The aim of our study was to establish the parasympathetic activity in patients with reflux esophagitis and in patients with symptomatic endoscopically negative reflux. Working hypothesis was the question, whether the possible parasympathetic activity disturbances, which are observed in all GERD patients, may be regarded as the primary or secondary to the esophagitis. All the participants (20 pts. with NERD, 20 pts. with reflux esophagitis and 20 healthy controls) underwent esophageal manometry, 24-hour ambulatory pH-monitoring, resting heart rate variability (HRV) recording and the deep breathing (DB) test with the continuous HRV recording. The results of the spectral analysis both of the short-term, resting HRV recordings and DB-evoked revealed the disturbances of the main power spectra components - LF and HF in both groups of patients in comparison with the control group. In our opinion, the observed HRV spectra changes in both groups of patients support the hypothesis that not only is the parasympathetic activity impairment associated with the pathogenesis of GERD but it is also the primary factor contributing to the pathophysiological mechanism of reflux.

Encoding meal in integrated vagal afferent discharge

Vagal afferents are integral part of the negative feedback loop induced by constitution and size of food stomach and jejunum. Aim of this study was to assess vagal discharge in response to food and gastric distension in rats. Electrophysiological recordings of vagal afferents in fasted (n=32), fed rats (n=20) and during gastric balloon distension (n=12) were performed. After 60 minutes of fasted nerve recording tube feeding was done. Fasted rats also underwent gastric distension via oesophagus. Vagal afferents discharges were analysed with dual time-amplitude window discriminator. Total vagal afferent discharge in fasted and fed rats revealed 0.3 +/- 0.12 vs 0.56 +/- 0.22 Hz (p<0.05). We observed two distinct discharge patterns: high amplitude low frequency (HALF) and low amplitude high frequency (LAHF). HALF spikes were observed more frequent in fasted than in fed rats (0.05 +/- 0.02 vs. 0.03 +/- 0.016 Hz (p<0.05). Conversely LAHF spikes in fed rats predominated over their occurrence in fasted rats: 0.52 +/- 0.2 vs. 0.25 +/- 0.12 Hz (p<0.05). Left vagal afferents discharge rises with gastric distension of 6, 8 and 10 ml and were: 0.46 +/- 0.22 Hz, 0.65 +/- 0.31 Hz, 0.86 +/- 0.33 Hz (p<0.05) respectively. Similar discharge showed right vagal afferents: 0.41 +/- 0.08 Hz, 0.51 +/- 0.13 Hz and 0.77 +/- 0.27 Hz (p<0.05) for 6, 8 and 10 ml of distension, respectively. We conclude that interdigestive information from gastrointestinal tract is encoded in high amplitude low frequency of spikes pattern in the vagus nerves.

Capasaicin induced deafferentation enhances the effect of electrical vagal nerve stimulation on food intake and body mass

Study was based on hypothesis that electrical stimulation (ES) with parameters obtained from analysis of vagal afferent discharge fed state may fake brain with satiety state. We evaluated effect of denervation of vagal capsaicin-sensitive afferents on food intake and body weight in rats with ES of vagal nerves using microchip (MC). Group A was scheduled to MC implantation, B to sham operation only, C to MC implantation and capsaicin vagal deafferentation, and D to capsaicin denervation only. ES lasted 24 days. MC parameters were 0.05 Hz, 0.1s, 0.55 V. ES of left vagus significantly reduced total food intake as well as the mean daily intake in groups A and C in comparison to control and D group (ANOVA, F=18.55, p=0.0038). Body weight was lower in group A (3462 g) and C (2727 g) then in control (3814 g) and D (3568 g) (F=25.68, p=0.00068). Leptin decreased in C (165 pg/mL) in comparison to A (625 pg/mL), B (677 pg/mL), and D (612 pg/mL) (p<0,05), mainly due to ES (F=7.27, p=0.019). Glucose was decreased in A (F=5.55, p=0.036) - by 11% and by 16% in C group. Proper vagal neuromodulation results in central and peripheral effects causing food intake and body weight downregulation.

History traces of gastrointestinal motility in Poland

The objectives of this chapter was to show how motility studies were developed and performed in Poland at the end of century to better understand pathophysiology and improve the clinicians ability to evaluate and treat patients with motility-related disorders. Some of the important historical points along the path to current understanding of the form and function of gastrointestinal motility are presented. Scarce information exists about other than Cracow and Wrocław motility centers in Poland in previous century. Lately sophisticated technology became available in Poland and more centers have begun to yield more effective strategies of treatment and enhanced understanding of the pathophysiologic mechanisms underlying GI motility disorders.

Effects of vagal neuromodulation and vagotomy on control of food intake and body weight in rats

Food induced neurohumoral signals are conduced to data processing brain centers mainly as vagal afferent discharge resulting in food intake regulation. The aim of this study was to evaluate effects of vagal nerve neuromodulation in control of food intake with fed-pattern microchip (MC) pacing. Experiments were performed on 60 rats divided on 5 groups: I group 0,05Hz left vagal pacing, II - pacing of both vagal nerves with MC 0,05Hz, III- left vagal MC 0,1Hz pacing, IV - pacing of both vagal nerves with MC 0,1 Hz was performed. In group V left vagal pacing was combined with right side abdominal vagotomy. Body weight and total food intake decreased by 12% and 14% (I), 26% and 30%(II), 8% and 21%(III), 14% and 30%(IV), 38% and 41%(IV), respectively (p<0.05). Effects of both vagal nerves stimulation on final body weight and food intake was significantly more effective than only single nerve MC pacing however most effective was stimulation with 0,1Hz combined with right vagotomy. We conclude that vagal stimulation reduce food intake and body weight by increasing vagal afferent signals. Our results suggest that information in vagal afferents can be modulated resulting in changes of feeding behaviour and body weight.

The role of vagal efferents in regulation of gastric emptying and motility in rats

Nonpharmacologic regulation of gastrointestinal motility may become competitive to actually applied methods in the nearest future. The Aim of this study was to evaluate effect of vagal stimulation on gastric motility and emptying. Experiments were performed on 30 male Wistar rats in vivo. Electrodes (120 um O Cr/Mo Microfil Industries) were placed on right vagal trunk below diaphragm without affecting its integrity. The fistula was implanted in gastric antrum. Stimulation parameters were: 0.3 V; 0.5 Hz, impulse duration--10 msec, time stimulation--5 min. Gastric pressure (balloon, Synectics pressure transducer, Sweden) and gastric emptying (red phenol method) were measured subsequently during and between stimulations.

RESULTS

Stimulation significantly decreased amplitude of gastric contractions about 14% (52.7 +/- +/- 24.5 vs control 66.8 +/- 15.0; p < 0.05) and increased liquid gastric emptying from isotonic solution about 10% (87.35 +/- 4.75 vs control 75.31 +/- 11.24; p < 0.001), hypertonic liquid about 15% (49.05 +/- 12.16 vs control 34.1 +/- 13.68; p < 0.001) and hypotonic liquid about 7% (83.05 +/- 8.8 vs control 76.29 +/- 11.88). The frequency of gastric contractions did not change significantly in Fast Fourier Analysis of the period of stimulations and in control group. CCK concentrations were not significantly different between stimulated and control group (0.3 +/- 0.08 vs control 0.27 +/- 0.06 pmol/L). L-NAME infusion abolished completely acceleration of gastric emptying of isotonic solution (50.38 +/- 12.66 vc control 87.82 +/- 5.49; p < 0.05), hypertonic solution (32.17 +/- 15.09 vs control 51.65 +/- 10.74; p < 0.05) and hypotonic solution (60.42 +/- 12.05 vs control 82.67 +/- 8.06; p < 0.05) during electrical stimulation.

DISCUSSION

In this experiment efferent stimulation of abdominal vagal nerve release neuromediators from afferent and efferent fibers. The main regulator seems to be nitric oxide. These results indicate the effective vagal nerve stimulation affects gastric motility and emptying. It is likely that observed effects reflect integrated response with activating vago-vagal reflexes and neurohumoral factors.

[Effect of chemical sympathectomy on myoelectric activity of the small bowel]

Central and peripheral noradrenergic system modulates myoelectric activity of the small bowel. Aim of this study was to evaluate the role of peripheral noradrenergic system in modulation of slow waves activity. Recordings of slow waves were performed on 20 conscious rats chronically fitted with 2 unipolar electrodes. After controls recording the animals were injected i.p. with 6-hydroxydopamine (6-OHDA--Sigma H8523) and the recording were performed on daily basis through the period of one month.

RESULTS

The increase of frequency slow waves during the first week after 6-OHDA from 0.61 (+/- 0.11) to 0.71 (+/- 0.03), (p. < 0.05), and amplitude from 14468 +/- 11196 to 19128 +/- 5282 (microV)2 (p > 0.05) were observed. Variability in control recording was higher (SD +/- 0.11) than after 6-OHDA (SD 0.03). Next day diarrhoea after 6-OHDA occurred, persisted despite return normal myoelectric activity. Slow waves frequency gradually returns to control value after the fourth week.

CONCLUSION

Peripheral noradrenergic system has a significant effect on the frequency and variability of slow wave and minor role on its amplitude but no on diarrhoea pattern.

[Myoelectric activity of the stomach and esophageal pH changes in reflux disease]

The oesophageal inflammation during gastrointestinal reflux disease (GERD) has been considered to be an acid and pepsine related disorder. The oesophagus remains under the prolonged exposure of gastric acid, which damages the mucosa and causes an esophagitis. Amongst the most important pathogenetic factors of GERD, the delayed gastric emptying and transient episodes of low esophageal sphincter (LES) relaxation have been described. The examinations like electrogastrography (EGG) and 24-hours pH-metry are useful for the evaluation of these disturbances.

AIM

The aim of the study was to confirm the co-existence among the abnormal gastric myoelectric activity and the esophageal pH changes in patients with GERD.

METHODS

Ten patients (8 m., 2 f.) 20-61 years of age (mean 46 +/- 15.3 years) with GERD were examined. The EGG recording lasted one hour: 30 min. in fasting state and 30 min. after a standard meal. The 24-hours pH-metry measurement, five cm above the upper edge of LES, was done on separate days. A control group, matched for number and age, for the comparison of the EGG recording, was recruited.

RESULTS

Amongst the patients suffering from GERD the results of fasting EGG showed the lower normogastria (mean 45.3 +/- 21.9% vs. 86.5 +/- 8.8%: p < 0.01) and the high dysrrhytmia time period (mean 54.7 +/- 21.9% vs. 13.5 +/- 9.6%: p < 0.01), than in the control group. After the meal, the dysrrhytmia persisted (mean 43.5 +/- 24.3% vs. 9.6 +/- 11.5%: p < 0.01). The mean increase of the slow waves amplitude after the meal was 0 +/- 55% vs. 80 +/- 146%; p < 0.05. The recording of the 24-hours pH-metry showed an increase of the pH < 4 episodes number (mean 329 +/- 246) and time percentage (mean 12.2 +/- 6.6%). The patients obtained mean 65.5 +/- 61 points in the De Meester and Johnson scoring. A significant correlation among the postprandial dysrrhytmia and reflux episodes time percentages was observed (p < 0.05).

CONCLUSIONS

The results of our studies suggest the importance of the gastric myoelectric activity disturbances in pathogenesis of GERD.

[Disturbances of the autonomic nervous system in gastroesophageal reflux disease]

GERD (Gastroesophageal Reflux Disease) is a common clinical problem, which affects the upper part of the gastrointestinal tract. The pathophysiology of GERD is associated with dysfunction of the various mechanisms called "the anti-reflux barrier". Lately, the disturbances of the autonomic nervous system (ANS) have been stressed in the pathogenesis of the different diseases (including GERD). The HRV examination (Heart Rate Variability) seems to be the best non-invasive method to evaluate the disturbances of ANS. The aim of our study was to detect possible ANS disturbances in GERD patients. 23 persons (healthy volunteers and GERD patients) took part in the examinations. 24-h-esophageal pH-metry and the resting, "deep breathing" (DB) test, as a short-term measurement of heart rate variability, were performed in every person. The results proved that the GERD patients have abnormal low values of the basic components that make up the HRV spectrum (LF and HF obtained from rest record and HF from record during DB). We demonstrated the evidence of functional ANS disturbances, which may be responsible for the changing the HRV parameters of the frequency domain analysis in GERD patients. The disturbances mentioned above are supposed to influence the normal modulation of the X (vagus) nerve, which plays an important role in the maintaining the physiological LES function.

[The role of leptin in metabolic regulation]

Leptin discovery--the hormone derived from adipose tissue became a challenging event in understanding food intake and energy balance regulation. Leptin serum level correlates with fat stores and reacts according to changes in energy balance. Although leptin is thought of as a factor preventing obesity, in most of the cases obesity develops in association with increase in serum leptin level which indicates leptin resistance. It may be possible that the primary role of leptin is to mediate the signal for the switch between the starved and fed state. There is a lot of evidence that leptin has systemic effects apart from those related to energy homeostasis, including regulation of neuroendocrine, immune and reproductive function.

[Interstitial cells of Cajal and their pacemaker function]

Interstitial cells of Cajal are known more than 100 years. These cells are proved now as slow wave pacesetters. Ultrastructure and physiologic pacemaker's activity is well described by many authors. Dysfunction of these cells is associated with different pathological states in gastrointestinal tract. Strong relationships between GI motility diseases and qualitative and quantitative changes of ICC are observed. Nowadays most of the gastroenterologists agree that evaluation of these cells should become routine diagnostic procedure. We gave a short review of recent achievements and ideas on interstitial cells of Cajal function in gastroenterology.

Pancreatic carcinoma-induced changes in gastric myoelectric activity and emptying

BACKGROUND/AIMS

Twenty patients with histologically confirmed pancreatic carcinoma without any endoscopic evidence of gastroduodenal obstruction were included in the study. The aim was to determine changes in gastric myoelectric activity and liquid/solid gastric emptying induced by pancreatic tumor.

METHODOLOGY

According to TNM/UICC classification patients were divided into two groups A (T2) and B (T3) due to extent of tumor invasion (mainly to retroperitoneum space). In all patients electrogastrography, solid and liquid gastric emptying tests were performed.

RESULTS

In the majority of patients of groups A and B the most commonly reported complaints included upper abdominal pain (60% vs. 80%) and icterus (80% vs. 60%). Dyspeptic symptoms were observed in 40% patients of group A and 90% in group B. In group electrogastrography recordings showed dysrhythmia patterns, mostly bradygastria, in 50% of group A patients and in 80% of group B. Liquid/solid gastric emptying were delayed in 20/40% of group A patients and 50/80% of group B. Disorders of gastric myoelectric activity and emptying correlated with tumor stage and location across analyzed groups but not with histology and hyperbilirubinemia levels.

CONCLUSIONS

It was observed that solid gastric emptying is affected earlier compared to liquid gastric emptying. Delayed gastric emptying may be attributed to gastric dysrhythmia and/or abdominal pain but not mechanical effects of tumor growth that occur during the course of disease.

Effects of continuous microchip (MC) vagal neuromodulation on gastrointestinal function in rats

Afferent fibers from gastrointestinal tract outnumber efferents ten times in vagal nerves. Modifying the afferent input makes possible to change discharge of vagal efferents affecting gastrointestinal functions in process known as neuromodulation (NM). Lately it has been used in the treatment of pain and hyperactive neurogenic bladder in urology. MC induced NM may therefore provide a concurrent to pharmacology tool, in treatment of gastrointestinal disorders. The aim of this study was to investigate the effects of long term neuromodulation procedure with use of MC on gastric motility, secretion and weight control in conscious rats. Experiments were performed on 30 Wistar male rats (250-350 g) divided in two groups: sham operated and microsurgically implanted with MC on left vagal nerve below diaphragm. Following stimulation parameters were used: frequency of 0.5-30 Hz, amplitude of 0.55 V, impulse duration of 10 ms in monophasic fashion. In both groups food intake and body weight were measured through the period of 2 weeks after recovery period. Then gastric fistula was implanted in gastric antrum and fasted gastric motility recorded with use of PowerLab system (Australia). Gastric emptying and secretion were also tested with use of phenol red and automatic titration methods. On the daily basis glucose level with standard test and leptin after MC implantation were measured. Recording of vagal activity in fasted rats showed burst of action potentials about 5 +/- 2.5 in period of 5000 sec, each burst with spike frequency up to 35 Hz. Food (5 ml of Intralipid--intragastrically) almost doubled amount of bursts to 12 +/- 5 in period of 5000 sec with increase in frequency at spike up to 50 Hz. MC induced vagal activity showed continuous spike activity similar to fed pattern. MC induced NM decreases daily food intake by 6% (33.6 +/- 4.8 vs control 35.5 +/- 4.8 g, p < 0.01). Body weight gain in rats before MC implantation decreased by 20% within 2 weeks after recovery (34.8 +/- 9.08 vs control 23.56 +/- 4.15 g). Fasting control glucose level also decreased of 5.5% (93.15 +/- 9.3 vs control 98.5 +/- 11.2 mg%, p < 0.05). Frequency of gastric contractions did not change significantly in MC versus control but amplitude of contractions increased of about 66.7% (2.0 +/- 0.8 vs 1.17 +/- 0.52) at the dominant frequency 0.08 Hz range and about 71.5% (1.17 +/- 0.35 vs 0.68 +/- 0.47, p < 0.05) at the frequency 0.12 Hz. in FFT analysis PowerLab (chart v = 4.01). BAO decreased by 29.25% without H+ concentration changes (0.2 +/- 0.14 vs 0.14 +/- 0.12 mmol/30 min, p < 0.05) but MAO did not change in MC rats (0.37 +/- 0.25 vs 0.42 +/- 0.28 mmol/30 min, p 0.05). Gastric emptying of isotonic solution increased by 10% (90.46 +/- 5.34 vs 80.39 +/- 9.95) percent of marker passing to duodenum/5 min, p < 0.0001). Our results suggest that MC induced NM affect brain-gut axis via influencing metabolic and gastric function and decreases body weight.

The effect of transcutaneous nerve stimulation (TENS) on gastric electrical activity

TENS became widely accepted method of treatment pain syndromes in clinical practice. Lately has been shown that its affects also gastrointestinal tract by releasing NANC neurotransmitter VIP. The aim of this study was to evaluate the effects of TENS on gastric myoelectric activities measured by electrogastrography (EGG). Eighteen healthy men (mean age 23 +/- 1.7) were included in the study. Healthy volunteers were divided on 3 groups each 6 persons: with normogastria occurring at 94.5 +/- 7% of recording time--group A, with predominant bradygastria (36.6 +/- 14%)--group B and with tachygastria (33 +/- 14%)--group C. In fasted condition EGG (Synectics, Sweden) was recorded with skin electrodes. TENS 15 min was performed with use of Sinus 5 stimulator (6 Hz, 0.1 ms duration, intensities 10-20 mA, Zimmer, Germany). Stimulating electrodes were placed on non-dominant hand.

RESULTS

None of the subjects during TENS reported any side effects or symptoms, during the all studies. In group A in the fasting recordings, after TENS, an decrease of the normal values in the range 2-4 cpm down to 78.5 +/- 21% of recording time (p = 0.03) occurred. The dominant frequency in the bradygastric region increased up to 17.7 +/- 7% of the total recording. In group B TENS decreased bradygastria level from 36.6 +/- 14% to 20.6 +/- 15% (p = 0.02). TENS did not significantly affect tachygastria in group C. Amplitude of the EGG signal after TENS in group B and C increased by 40 and 150% respectively (p < 0.05). Significant decrease of the amplitude was observed in group A (13%). We conclude that TENS by activating centrally mediated somato-visceral reflexes affects gastric electrical activity. Our results suggest that TENS may be useful in treatment of the gastric dysrhythmia.

Microchip vagal pacing reduces food intake and body mass

BACKGROUND/AIMS

Morbid obesity is an increasing problem worldwide. In many patients pharmacotherapy is ineffective and these cases are treated by surgery. Different types of gastroplasty and gastric bypasses have been described. However, all of these ablative surgical methods are irreversible and often replace obesity by other disorders. Neuromodulation of vagal activity is a method of inducing significant changes in stomach motility. We developed a pre-programmed microchip able to pace vagal afferent activity by changing current parameters. The aim of our study was to evaluate long-term effects of vagal neuromodulation on food intake and body mass in rabbits.

METHODOLOGY

Twenty-seven healthy male adult New Zealand white rabbits were included into the study and divided into three groups: A, B and C, 9 animals each. Microchips were implanted by laparotomy access. Anesthesia was obtained by continuous intravenous infusion of propofol. Microchips were fixed in the preperitoneal pocket and two electrodes were positioned on the posterior vagus in group A by forward, and in group B by backward pacing. Control group C was sham operated by laparotomy and only vagal nerves preparation was performed. The following parameters were estimated: daily solid food and liquids intake, amount of feces, body mass and heart rate.

RESULTS

Within four weeks after operation body mass in group B had decreased up to 12% (P = 0.029), whereas in group A and C changed to -3% and +2%, respectively. An 87% solid food intake was observed in group A, 60% in group B (P < 0.01), and 143% in group C, compared to preoperative period. No significant differences were observed between groups A, B and C for liquids intake. Total feces weight changes corresponded to solid food intake. Heart rate decreased intraoperatively to 78% and 74% in groups A and B, respectively.

CONCLUSIONS

Microchip mediated functional gastroplasty significantly reduces food intake and body mass. Obtained results encourage using similar treatment in morbid obesity human patients. However, further studies are required.

Immediate effects of endoscopic sphincterotomy on sphincter of Oddi motility

The evidence exists that incomplete sphincterotomy in patients with biliary tract diseases may result in early symptoms reoccurrence or lack of improvement. Sphincter of Oddi manometry (SOM) can be used to verify the completeness of the procedure. The purpose of the study was to investigate the immediate effects of biliary endoscopic sphincterotomy (BES) and common bile duct stones (CBDS) clearance on biliary sphincter of Oddi (SO) motility. Moreover the percentage of incomplete sphincterotomies was estimated. 26 patients (6 male, 20 female, 24-93 years) with confirmed choledocholithiasis were investigated. All underwent BES followed by CBDS extraction, and then SO manometry (SOM) was performed. Moreover 6 patients underwent SOM prior to BES. SOM was performed with a triple lumen 5 Fr catheter attached to the water perfused low compliance system. Immediately after sphincterotomy and extraction of the CBDS common bile duct pressure dropped from a mean of 10.9 mmHg to 2.9 mmHg (p < 0.05). Similarly basal biliary sphincter pressure decreased from 22.7 mmHg to 7.3 mmHg (p < 0.05). 20 patients presented duodeno-choledochal gradient of less than 5 mmHg. However only 10 patients had also basal sphincter pressure lower than 5 mmHg. The phasic sphincter activity was abolished in 16 patients, whereas phasic contractions persisted in 10 patients. Seven patients displayed uncoordinated, low amplitude contractility. BES significantly decreases SO and CBD pressures, but when performed for CBDS extraction, commonly does not abolish SO motor activity nor ablate choledocho-duodenal gradient. Therefore to confirm the completeness of sphincterotomy, SO manometry is recommended.

[The effect of aging on the activity of the autonomic nervous system in long distance runners]

The aim of the study was to evaluate the effect of endurance physical training on the autonomic function in runners. The study was performed on 20 long distance runners, divided into two groups. The first group of runners contained 12 young men of age of 20-24 years (age 21.75 +/- 1.4 years: mean S.D.--standard deviation). Into the second group 9 experienced runners, who practice long distance running for over 40 years, were qualified. The mean age of those runners was 52.9 +/- 7.2 years. Moreover two control groups, matched for age and gender were recruited. One of them was made up of 12 healthy volunteers (age 21.6 +/- 1.23 years), the second contained 9 men (age 52.9 +/- 7.2 years). In this study, the measurement of the cardiac autonomic nervous system, using the HRV computer assisted programme (Proster, Poland), was performed. The characteristics of the HRV (heart rate variability) were estimated. We have observed, that the RR intervals in runners were longer than in healthy volunteers (1033.5 +/- 185.4 ms vs. 888.1 +/- 115.3 ms. p < 0.01). We have observed a tendency towards increasing of the RR intervals with the increase of age, of the tested person, as well. A reverse tendency, a shortening of the RR intervals with ageing, was observed in the control groups. The standard deviation of the RR intervals in runners was higher than in the control group (p < 0.05). In the young runners we noticed the prevalence of parasympathetic activity, expressed by the HF (high frequency) spectra (875.7 ms2 vs. 816.7 ms2) in comparison with the healthy individuals. In the old runners the prevalence of sympathetic activity, expressed by LF (low frequency) spectra (1088.75 ms2 vs. 220.1 ms2, p < 0.05) and parasympathetic activity (920.38 ms2 vs. 294.25 ms2) in comparison with the control group, was observed. It was expressed by the increase of the LF/HF ratio (0.75 vs. 2.1). The results of our study indicate, that the autonomic, particularly sympathetic, activity in sportsmen is not affected by ageing up to the sixth decade of life.

[The effect of chronic alcohol use on heart rate variability]

A long lasting alcohol intake causes, amongst numerous systemic damages, also the autonomic nervous system (ANS) dysfunction, which causes the autonomic heart rate regulation disorders. The aim of the study was to evaluate the autonomic regulation of the circulation in chronic alcoholism. Seventeen alcoholics, 24-55 years of age (mean 43 +/- 5.2 years) were examined. They have been abstainers for 2-6 years. The cardiac ANS function was evaluated using the HRV measurement. The HRV was registered using V6 EKG lead. The recording was performed through the 15 min of resting conditions and 5 min of the deep breathing test. A group containing healthy volunteers, matched for age and gender, for the comparison of the HRV results was recruited. In the examined group, during the resting conditions, the significant RR period changes weren't observed (999.7 +/- 139.2 vs. 967 +/- 144.9; p > 0.05). The nonsignificant lower values of the spectral analysis parameters of HRV: LF (954.1 +/- 1162.6 vs. 1456.4 +/- 1327.1; p > 0.05) and HF (676.4 +/- 414.2 vs. 1557 +/- 1854.4; p > 0.05) and LF/HF ratio (1.5 +/- 1.14 vs. 1.38 +/- 1.28; p > 0.05) were also noticed. In response to the DB test, the mean value of the RR period wasn't significantly changed (921.4 +/- 152.3 vs. 930.6 +/- 137.8; p > 0.05). In DB test the significant decrease of LF (3465.8 +/- 2750.1 vs. 11558.6 +/- 7902.5; p < 0.001) and HF (406.1 +/- 366.8 vs. 1665 +/- 1757.1; p < 0.01) was observed. No significant change of LF/HF mean ratio (11.6 +/- 6.97 vs. 14.7 +/- 11.6; p > 0.05) was noticed. The results of our study indicate on the maintenance of the HRV disorders in chronic alcoholics, during the abstinence.

[The role of the autonomic nervous system on malfunction of gastric motor and myoelectric activity in patients with hyperthyroidism]

The aim of this study was to determine both the type of gastric mioelectric and emptying disorders in correlation to degree of severity of hyperthyroidism (clinical and thyroid hormones' blood levels) and ANS function estimated in HRV analysis. The study was performed on a group of 50 patients (35 with multinodular toxic goitre and 15 with Graves' disease, 45 females and 5 males, mean age 39.6 years, mean BMI 23.72) with newly diagnosed and so far untreated hyperthyroidism. The control group were 50 healthy volunteers age-, sex-, and BMI-matched to the studied group. Patients were studied twice, within newly diagnosed thyreotoxicosis and after treatment (Metizol) and reaching stable euthyroid state. The study consisted of: a) percutaneous EGG analysis (Synectics): 30 minutes before and after a test meal (ENRICH Liquid 250 ml), b) HRV analysis (ECG POSTER 2002): 10 minutes at rest and during deep breathing test, c) ultrasound measurement of gastric emptying by Bolondi method. Statistical analysis of collected data was performed. In hyperthyroid patients significant both preprandial and postprandial dysrhythmia (33.01% of bradygastria and 16.49% of tachygastria) was found. In some patients decrease of amplitude of EGG signal was marked as a result of antral hypomotility with coexisting significantly prolonged gastric emptying (110 min). Among severe hyperthyroid patients both the antral food distribution (antrum 35% bigger than in a control group) and impaired proximal stomach relaxation were evident. The degree of gastric mioelectric activity and emptying disorders was proportional to the degree of both severity of clinical manifestation of hyperthyroidism in Zgliczynski scale (from I degree to III degrees) and free thyroid hormones' blood levels (positive correlation). In HRV analysis at rest in hyperthyroid patients comparing to a control group the decrease of both the heart rate variability and a total power was found particularly in HF component resulting in relative sympathetic activation. In HRV analysis during deep breathing test the decrease of heart rate variability was present mostly in LF component. It indicates on reduction of vagal regulation (and vagal excitability) of sinus node and gastric pacemaker function. Coexistence of the increase and decrease of a gastric basic electrical rhythm with delay of gastric emptying indicates on a complex mechanism of their formation. Both neurogenic regulation dysfunction and primary miogenic autoregulation disorders as a result of tyreotoxicosis seem to be the possible causes. All the found changes were functional and disappeared after reaching the stable euthyroid state within 3 months of pharmacological treatment.

[Gastric motility disturbances in pancreatic cancer patients]

Eighteen patients with confirmed pancreatic carcinoma without endoscopic evidence of mechanical gastroduodenal obstruction were included in the study. Aim was to determine changes in gastric myoelectric activity and liquid emptying (LGE) induced by pancreatic tumor growth. According TNM/UICC classification patients were divided in two groups A (T2) and B (T3) due to extend of expansion. Dyspeptic symptoms were observed in 4 patients of group A and 8 in group B. In group A dysrhythmic patterns of gastric myoelectric activity mostly bradygastria type were observed in 5 of patients and 8 in group B. LGE were delayed in 2 in group A and 5 in group B respectively. Disordered gastric myoelectric activity and emptying correlated with tumor stage and location. Delayed gastric emptying may be attributed to gastric dysrhythmia and abdominal pain that occur during the course of disease due to splamchnic plex infiltration.

[Sphincter of Oddi motility disturbances--etiologic factor or the consequence of choledocholithiasis]

Choledocholithiasis is often found in patients after cholecystectomy done previously for cholelithiasis.

AIM

To evaluate the effects of cholecystectomy and common bile stones' presence on sphincter of Oddi (SO) motility.

MATERIAL

13 patients with common bile duct stones (2 men and 11 women, age 54 to 85 yrs) were studied. They were divided in two groups: A--6 pts age 54 to 85 yrs (with biliary lithiasis) and group B of 7 pts age 55-71 after cholecystectomy. Cholecystectomized group was further divided into 2 groups according to administration (B1 group) or not (B2) a premedication.

METHOD

Sphincter of Oddi manometry was done in all patients as the part of routine ERCP. A water-perfused, low-compliance, triple-lumen manometric system (Synectics Medical Sweden) was used to record the SO tonic and phasic activity. Common bile duct (CBD) pressure, basal SO pressure, SO phasic contractions frequency, duration and amplitude as well as direction of propagation peristaltic waves, motility index (MI) and AuC (area under curve) were measured.

RESULTS

The CBD pressure, the basal SO pressure and the frequency of phasic SO waves tended to be lower in patients after cholecystectomy (p > 0.05). We observed profound changes in the motility pattern of SO phasic activity. There was significantly less anterograde and more retrograde waves in patients from group B than A (18.9% vs. 68.8%; p < 0.01 and 52.4% vs. 10.4% respectively; p = 0.01). In the group B1 comparing with group B2 we found significant decrease of frequency (1.8/min +/- 0.53 vs. 3.3/min +/- 0.77; p < 0.05) and increase of the mean amplitude of phasic SO activity (223.2 mmHg +/- 22.9 vs. 137.3 mmHg +/- 25.0; p < 0.01). The duration of pressure waves was prolonged (with long "plateau" or multipeaked) with rapid pressure increase, what resulted in high AuC index (1155.61 +/- 100.42 vs. 515.23 +/- 210.9; p < 0.01). However no difference in MI was observed.

CONCLUSION

Our results confirm hypothesis that cholecystectomy influences the pattern of phasic SO motility. Moreover increased percent of retrograde propagation of SO phasic contractions probably contributes to subsequent common duct stones development rather than being the consequences of their presence.

[Autonomic nervous system and gastric myoelectric activities in type 1 and type 2 diabetes]

The aim of the study was to compare autonomic function and gastric myoelectric activity in patients with type 1 and 2 of diabetes. We used the skin electrodes for recording gastric myoelectric activity (EGG) and the heart rate variability (HRV). Patients were divided into two groups. The first group: 19 patients with IDDM. The second-16 patients with NIDDM. We made two comparative control groups, matched with age and gender. We conclude, that decrease in gastric myoelectric activity was observed in both groups of patients, mostly in 1 group (IDDM) of patients. There was increase of heart rate and reduction of spectral analysis parameters in both types of diabetic. In patients with type 1 we noticed the increase of sympathetic activity (LF/HF ratio increased). In patients with type 2 there was the non significant decrease in sympathetic activity (LF/HF ratio decreased). On the basis of our observations we confirmed the correlation among autonomic function tested by HRV and changes of stomach electric activity. Decrease in HRV and gastric myoelectric activity could be indicating damage of parasympathetic system in IDDM.

[Stomach electrostimulation--new possibility for treating gastroparesis]

This paper presents a large range of methods of human gastric pacing. Based on our own experience and literature authors discuss a variety of pacing models, current parameters and place of stimulation. We described a new method of intragastric stimulation as a method of treatment of postoperative, pharmacotherapy resistant gastroparesis. Five patients were included in to the study (3 male and 2 female). The current parameters were as follow: square profile, amplitude 2V (2mA), frequency 6 ips.p.m., duration 3 hours. Two electrodes located on nasogastric catheter (external diameter 1.5 mm) were placed in antral region of the stomach and connected to the computer preprogrammed stimulator. Electrostimulation was accompanied by the continuous cutaneous EGG monitoring (Synectics Sweden). Excellent results were obtained in 3 patients (60%) with disappearance of symptoms, rumbling, normalization in gastric myoelectric rhythm (2-4 cpm > 85%) and with increase in amplitude (average 250%). In one patient with the gastrectasia, symptoms returned next day and stimulation had to be repeated for several days. In another one results were not satisfying. Authors conclude that gastric pacing has made tremendous progress fast developing method in last decade and in most patient is efficient for treatment postoperative gastroparesis.

[The influence of aging on autonomic nervous system activity and gastric myoelectric activity in humans]

The study was performed on 84 healthy volunteers (33 women, 52 men) of age 20-71 years with no history of the circulatory or gastrointestinal system disease. The gastric myoelectrical activity (EGG) was recorded with the cutaneous electrodes--electrogastrography Synectics (Sweden). The activity of the cardiac autonomic nervous system was measured by HRV (heart rate variability) recorded with EGG and computer assisted programme Proster (Poland). Subject were divided into 5 groups according to the decade of age (20-70). Percentage of basal electrical rhythm (BER) dysrhythmias increased (1.9 +/- 0.5% vs 21.1 +/- 3.2% in fasting and 2.4 +/- 1.2% vs 24.6 +/- 5% postprandially but decrease of the EGG amplitude after the meal was observed (270 +/- 20% vs 90 +/- 7%) in youngest and oldest group respectively. With the ageing the cardiac sympathetic and parasympathetic activity (LF and HF) decreased in first and last group respectively. In the forth decade in man and women the sympathetic activity system prevalence expressed by the LF/HF rate increased (1.09 +/- 0.2 vs. 2.14 +/- 0.5) (p < 0.05). The results of our study suggest the deleterious influence of the ageing on the of autonomic system activity as shown by changes in HRV and dysrhythmia of the gastric slow waves in EGG.

[Value of electrogastrographic parameters in evaluation of gastric myoelectrical activity]

Electrogastrography (EGG) is presently the only non-invasive method for the evaluation of gastric myoelectrical activity. In relation to the more and more described disturbances of the basic electrical rhythm in different pathological units EGG has been applied on a still larger scale. However, the data obtained from the EGG record do not reflect directly the gastric motility. This method allows only to make an indirect evaluation of the gastric motor disturbances. It still entails a great number of investigations so as to attain a better precisions of the evaluations of its clinical usefulness in gastroenterological diagnostics. This thesis presents the basic information on the methodology, the parameters under evaluation and the clinical application of the EGG method.

[The effect of pentagastrin on calcium ion concentration in gastric juice]

Calcium concentration in gastric juice is lower then other electrolytes. The mechanism of its transport remained unknown. The aim of the study was to evaluate influence of pentagastrin on calcium concentration in gastric juice in humans. Ten patients were examined (4 females and 6 males, mean age 46.8 range 33-67), four with duodenal ulcer, three with achalasia cardiae and three with Addison-Biermer anemia. Pentagastrin--PG (Cambridge Laboratories, Newcastle, United Kingdom) was injected subcutaneously after overnight fast in dose of 6 micrograms/kg of body weight. Nosogastric tube was located in body of the stomach near large curvature and connected to suction of--40 mmHg pressure. Gastric juice was collected during subsequent five 15 minutes periods (first fasted and four periods after stimulation with PG). Calcium concentration was measured in each sample by fluorescentic titration method with EGTA. Statistic analysis was performed with student "t" test. Mean fasted and stimulated calcium concentrations were 0.83; 0.44; 0.54; 0.37 and 0.95 mmol/l respectively. Ca2+ concentration range in fasted state from 0.21 to 1.75 mmol/l and from 0.07 to 0.27 mmol/l by maximal stimulation. Calcium concentration decreased immediately after stimulation (significance p = 0.0025). This strong effect persisted throughout the period of stimulation. Calcium output was 0.064; 0.029; 0.032; 0.018 and 0.17 mmol/15 min respectively. Two phases of decrease of the calcium output were observed: first, fast decrease immediately after pentagastrin injection and second, slower, between 30 and 45 minute after stimulation (p < 0.01 and 0.02 respectively). Calcium concentration in gastric juice decreases after stimulation with pentagastin (p = 0.0025). Calcium concentration was lower in Addison-Biermer anemia and higher in duodenal ulcer patients then in healthy control. We conclude that calcium ions are not actively secreted by gastric mucosa. Their presence in gastric juice is a result of leak from mucosal cells and remains opposite to their metabolic activity.

Neuromodulation of vago-vagal reflex

Functional gastrointestinal disorders are poorly understood. The lack of clear classification and definition of these disturbances interferes with unsatisfying treatment. The possible explanation has been recently looked up in the changes of brain-gut axis interactions. Simultaneously microelectronics has been made tremendous progress in the cooperation with medical sciences lately. Electronic microcircuits have become widely used in neurosciences because of their many advantages compared to standard investigational devices. Implantable microchips facilitate studies of nervous system allowing carrying on chronic experiments with minimal damage to surrounding organs. Neuromodulation of autonomic nerves gives promise for treatment refractory disturbances of gut motility.

Early effects of standard and pylorus-preserving pancreatectomy on myoelectric activity and gastric emptying

BACKGROUND/AIMS

The main concern about pylorus preserving pancreatectomy (PPP) is delayed gastric emptying (GE). Both cancer and surgical procedures cause damage to the enteric nervous system and induce profound changes in gastric motility and emptying. The aim was to evaluate the effects of primary disease and type of surgical procedure used (standard pancreatoduodenectomy, SP vs. PPP) on myoelectric activity (MA), and solid and liquid GE in pancreatectomy patients.

METHODOLOGY

Twenty-eight subjects were included, 18 after Whipple (group A) and 10 after a Traverso (group B) procedure. MA was captured by cutaneous electrodes (Synectics) and simultaneously LGE tested with ultrasonography. On separate days, the SGE of a radiolabelled meal was measured. MA and GE studies were done before and within three months after surgery.

RESULTS

Before surgery LGE/SGE were delayed in 5/8 patients in group A and 2/2 in group B. Gastric dysrhythmia was observed in 6 patients in group A and 1 in group B. After PPP, the nasogastric tube was removed within 8.4+/-4.9 days and after SP within 4.6+/-4.1 days. GE studies showed accelerated LGE/SLG in 16/12 and delayed in 6/5 patients, respectively, in group A and B. Dysrhythmia was observed in 16 patients in group A and in 4 in group B. There was a strong relationship between SGE delay and dysrhythmia in patients after PPP.

CONCLUSIONS

We conclude that papilla of Vater neoplasia damages mechanisms responsible for gastric emptying to a lesser extent than pancreatic cancer. In patients after PPP, post-operative MA disturbances are partially responsible for delayed GE.

Double-blind crossover study of ranitidine and ebrotidine in gastro-esophageal reflux disease

Gastroesophageal reflux disease (GERD) is multifactorial disorder in which acid exposure has a central role in the mucosal damage, and the mainstay of medical treatment is the suppression of gastric acid secretion justifying the use of H2 receptors antagonists. In our study we compared the effects of ranitidine and ebrotidine, a novel H2 antagonist with gastroprotective properties, on the motor, pH and endoscopic aspects of GERD in randomized cross-over trial in humans. Twenty patients with endoscopic evidence of erosive esophagitis were included in the study. Esophageal manometry and 24-hour pH-metry were done with the use Synectics (Sweden) systems. The same examinations were repeated after 20 days period of treatment with either ranitidine or ebrotidine, given in single dose 300 and 800 mg (nocte) respectively. The pressure within the lower esophageal sphincter (LES) in the untreated and treated with ebrotidine or ranitidine patients remained lowered. Patients with GERD showed increase in duration and decrease in amplitude and propagation of peristaltic waves in the esophageal body which were not improved after treatment. Complete healing after 40 days of treatment was comparable with ebrotidine and ranitidine and averaged about 40%. The pH-metry showed improvement in treated patients in the reflux frequency and time pH below 4, ranitidine being more effective than ebrotidine. It can be concluded that GERD patients showed weaker primary peristalsis unrelated to LES pressure and treatment. Treatment with ebrotidine or ranitidine reduced significantly the endoscopic and self-assessment score, ebrotidine and ranitidine being equally effective in healing of esophageal mucosal lesions.

Effect of stimulation of the vagus nerves and vagotomy on myoelectric activity of small bowel

Experiments have been done on conscious dogs (6 animals) to study vagal influences on small bowel motility. First group (3 dogs) was prepared with gastric and esophageal fistulas, the second group (3 dogs) with gastric fistulas. Both groups had monopolar silver electrodes placed along small bowel. Stimulation of vagus with sham feeding (SF) increased MMC period of about 21%. Insulin and 2DG infused intravenously increased MMC period at lower dose range and in high doses induced fed-like pattern of motility. Supradiaphragmatic vagotomy done in the second group animals does not change significantly fasted as well as fed motility pattern. These data suggest that central and peripheral vagal input is required for inhibition MMC activity and development fed motility pattern.

Gastric emptying of liquids in patients with peptic ulcer disease

This study was designed to determine the rates of gastric emptying of water, saline and a 20% glucose solution in patients with gastric and duodenal ulcers. In all subjects, gastric emptying was fastest after administration of the saline, slower with water and the slowest with glucose. Significant statistical differences (p less than 0.05) in emptying rates between normal subjects and the group with duodenal ulcer were seen when water and saline but not glucose were used. We conclude that inhibitory effects of the osmotic receptors are not changed in gastric and duodenal ulcer patients. However, the emptying rates were higher when osmotic stimulus was withheld.