Cholinergic sensitivity and pseudoaffective visceromotor reflex response (VMR) to colorectal distention (CRD) in FSL and FRL rats

increasesvagal activity. The possible mechanism involved in the enhancement of vagal activity ~s unclear and needs further investigation.

Furthermore, the role of ICC for afferent neuron guidance has currently not been established. Aim: To evaluate the morphological differences of afferent and efferent innervation in the GI tract of wild type ( + / + ) and Ws/Wsrats. Methods: Gastric fundus and proximal jejunum of wild type (n=3) and Ws/Ws (n=3) rats weighing about 250g were observed using histochemical and immunohistochemical techniques. Frameworks of enteric nerve plexuses were visualized by protein gene product (PGP) 9.5. Acetylcholinesterase (Ach-E) was used to identify excitatory motor neurons, nNOS, NADPH diaphorase and vasoactive intestinal peptide (VIP) were used as markers for inhibitory motor neurons and calcitonin gene-related peptide (CGRP) for afferent nerves. Results: Nerve cell bodies within Auerbach's plexus and nerve fibers distributed in both the mucosa and the muscle layers were immunopositive for PGP 9.5 in both the gastric body and jejunum. Nerve fibers distributed in the inner muscle layer were strongly immunopositive for PGP 9.5 in gastric fundus and jejunum of Ws/Ws compared with wild type ( + / + ) rats. Nerve cell bodies and fibers in the inner muscle layer were intensely stained for Ach-E in Ws/Wsrats. VIP, CGRP, nNOS and NADPH diaphorasecontaining nerve fibers and cell bodies revealed no significant differences between WshYs and + / + rats in both gastric fundus and jejunum. Conclusions:WsA,Ysrats lack specific ICC populations however, enteric neurons and afferent fibers appear not to he affected in the gastric fundus or jejunum of these animals.

3868 Are There Gender Related Differences In The Neonatal Maternal Deprivation Induced Visceral Hypersensitivity in Rats? Andras Rosztoczy, Jean Fioramonti, INRA, Toulouse France; Tiber Wlttmann, Univ of Szeged, Szeged Hungary; Lionel Bueno, INRA, Toulouse France Our previous experiments shown, that in rats gender related differences can be found in the response to acute stress. We also established, that complete (type M) neonatal separation of the rat pups from their dam induces a higher degree of visceral sensitivity, than partial (type P) separation of the counterparts. In the present study we aimed to evaluate if there are gender related differences in the maternal deprivation induced visceral hyperalgesia in rats. Methods: Newborn Wistar rat pups of both sexes were submitted to different patterns of maternal deprivation. Maternal deprivation was applied for 2 hours daily, between the first and the fourteenth day of life. In "type M" deprivation all the pups were removed from the dam, while in "type P" deprivation only the half of the counterparts were separated. Pups of "untouched" families and the "non-deprived" counterparts of the "type P" families served as controls. Visceral sensitivity was tested in the young adult rats (body weight: 200-250g, age: 6-12 weeks). Progressive rectal distension was carried out by intrarectal balloon inflation (0.4-0.8-1.2 ml volumes) and abdominal contractions (AC) were recorded and counted according to our previously published protocol. Results: "Type M" deprivation induced identical grade of visceral hypersensitivity in both sexes. AC numbers were similar at all distending volumes. In contrast, 'lype P" deprived females had more AC compared to males at the higher distending volumes (O.8ml: 42.1 -+2.6 vs. 36.8-+2.3, mean+-SEM), however statistical significance was reached only at 1.2 ml (50.6-+1.9 vs. 42.4-+2.2, mean-+SEM, p
3866 Cholinergic Sensitivity and Pseudoaffective Visceromntor Reflex Response (VMR) th Colorectal Distention (CRD) in FSL and FRL Rats C Dienefeld, Ruhr Univ Bochum, Bochum Germany: L Wang, Ka Neufeld, Yk Mac, McMaster Univ, IORP, Hamilton Canada; S Hollerbach, Ruhr Univ Bochum, Bocbum Germany; G Tougas, McMaster Univ, IDRP, Hamilton Canada Background: In IBS patients, studies suggest an association between visceral hypersensitivity and cholinergic responsiveness. Flinders Sensitive Line (FSL) rats are selectively bred on the basis of increased sensitivity to cholinergic stimuli compared to their normal counterparts Flinders Resistant Line (FRL) rats. We compared pscudoaffective visceromotor responses (VMR) to CRD in FSL and FRL rats to determine if cholinerpic sensitivity can alter visceral perception. Aim: Compare the VMR to CRD in FSL and FRL rats. Methods: In male FSL and FRL rats, 2 permanent EMG electrodes were inserted into the oblique abdominal muscle. After recovery from surgery, the rats were placed in a Bollman and trained to undergo CRD using a 3 cm balloon placed 5 cm into the distal colon. VMR to CRD was recorded during an increasing phasic distention paradigm (lO-30-50-70mmHg, 30eac; 5 minutes between distention). To examine for habituation, a 12x50mmHg phasic distention paradigm was used. Changes in the VMR during CRD were expressed as % change relative to baseline abdominal EMG activity. Results: mean+-SE (n) (Table) Summary: At lOmmHg, CRD produced no distinct change in VMR in both strains. Starting at 30mmHg, FRL rats showed an increase in VMR during CRD, while FSL remained at baseline level. At 50 and 7OmmHg, a distinct pressuredependent increase in the VMR to CRD occurred in both rat strains, but the response was significantly greater in FRL than in FSL rats. Repeatedphasic distention at 50mmHg showed no habituation in both rat strains (FRL: range 344- 542% of baseline EMG activity, average 449; FSL: range 191- 448% of baseline EMG activity, average 271. p
Effects of 8atatlnum Toxin on Gastric Myoelectdcal and Vagal Activities in Dogs Zhishun Wang, Pankaj Jay Pasricha, Xiaohong Xu, Effert A. Asem, Jiande Chen, Univ of Texas Medical Branch, Galveston, TX BACKGROUND: Intramuscular injection of botulinum toxin (Botox) has been used to reduce muscle contractility and sphincter tone. The aim of this study was to investigate whether intramuscular injection of Botox in the fundus would alter autonomic and gastric functions using spectral analysis of the heart rate variability and electromyograpy, respectively. METHODS: The study was performed in six healthy female hound dogs (14.5-21.5kg) chronically implanted with four pairs of bipolar serosal electrodes on the stomach. The gastric slow wave and the electrocardiogram (ECG) were recorded for 30-min in the fasting state on the day before the Botox injection and once a week for 3 weeks after the Botox injection. The intramuscular injection of Botox (100 units) in the fundus was performed under endoscopy. Spectral analysis was applied on the gastric slow wave recording to derive the parameters including frequency and regularity of the slow wave. An advanced R-R wave extraction and heart rate variability (HRV) spectral analysis program, which was developed in our laboratory, was usedto compute the low frequency component PL(mainly sympathetic) and high frequency component PH(parasympathetic). RESULTS: 1). Gastric function: Fundic injection of Botox had no effects on gastric slow wave rhythmicity. The frequency of the gastric slow wave was 5.36 cycles/min (cpm) at baseline, and 5.28 cpm, 5.26cpm and 5.20 cpm during the 3 weeks after injection. The percentage of the normal slow waves in the 4 consecutive recording sessions was 89.9+-13.6%, 93.9+-10.4%, 92.4+-10.2%, 93.1 +-6.4%, respectively. 2) Autonomic function: In comparison with baseline (0.48+-0.13), the vogal activity after Botox injection was significantly increased during the first week (0.75-+0.10, p
_CRD Pressure (mmHg) (% of Baseline, *p<0.05 FSL vs. FRL) 10 30 50 70 FRL FSL

103_+7(10) 100~8 ( 1 1 )

124±12(10) 101±9(11)

358±13(10) 215_+15(11) *

429~22 (10) 311±13(11)*

3867 Effects Of Transcutaneous Electrical Stimulation Of Acupuncture Points On Autonomic And Gastric Functions Jieyun Yin, Hui Ouyang, Jiande Chen, Univ of Texas Medical Branch, Galveston, TX Electroacupuncture lEA) is effective for the treatment of gastrointestinal symptoms. Recently its effects on gastric emptying and myoelectrical activity have also been reported. The aim of this study was to investigate the effects of EA without needles on autonomic and gastric functions. Methods: Eight healthy volunteers (5M, 3F, 64~85kg) were enrolled in the study. Electrical stimulation was performed via two surface electrodes placed on acupuncture points, PC6. Electrical stimulus was composed of trains of pulses with a train frequency of 12 cycles/ min, a pulse frequency of 58 Hz and a pulse width of O.3ms. Gastric myoelectrical activity was recorded using noninvasive method of electrogastrography (EGG) via epigastric surface electrodes. The recordings of the electrocardiogram (ECG)and electrogastrogram (EGG) were made in the fasting state for 30-min at baseline, 30-min during stimulation and 30-rain after stimulation. The heart rate variability (HRV) signal was derived from the ECG and analyzed using spectral analysis to calculate the high frequency component (reflecting vagal activity), HF (0.15 Hz to 0.5 Hz) and the autonomic sympathovagal balance. Spectral analysis was performed on the EGG to compute the percentage of normal 2-4 cycles/min slow waves. Results: 1) The vagal activity was significantly increased (almost one-fold) with electrical stimulation (ANOVA, PO.05). 2) The stimulation, however, had no effects on the gastric slow wave measured from the EGG. The percentages of normal 2-4 cycles/min slow waves during the 3 periods were 75.2 +- 5.0 %, 79.1 -+ 6.0 % and 76.0 _+ 6.9 %, respectively (p>O.05). Conclusions: Transcutaneous electrical stimulation of acupuncture points, PC 6 without needles does not affect the gastric slow wave but substantially and significantly

3870 Vasoactive intestinal Peptide Levels Are Elevated in the Blood Plasma of Irritable Bowel Syndrome (lOS) Patients Olafur S. Palsson, Univ of North Carolina, Chapel Hill, NC; Marsha J. Turner, Michael J. Davies, David A. Johnson. Eastern Virginia Sch of Medicine, Norfolk, VA; William E. Whitehead, Univ of North Carolina, Chapel Hill, NC Background: Vasoactive intestinal peptide (VIP) is a gut hormone which modulates fluid secretion and smooth muscle activity in the human intestine. We have previously reported elevated concentrations of VIP in rectal mucosal biopsies of IBS patients (Gastroenterology 1996:109;A730). Aims: To assess (1) whether VIP concentrations are elevated in the general blood circulation of IBS patients compared to healthy controls, and (2) whether VIP plasma levels are correlated with clinical symptoms. Method: Thirty IBS patients (Rome criteria and physician diagnosis; 19 females and 11 males, mean age = 35.8 years) and 30 age- and gender-matched healthy (no gastrointestinal disorders or significant gut symptoms) control subjects gave venous blood samples. The patients also completed 14-day IBS symptom logs prior to blood collection. Blood plasma samples were acidified by adding equal volume of 1% trifluoroacetic acid, and centrifugated at 13,000 rpm for 20 minutes at 4°F. The supernatant was then loaded onto pre-treated C18 SEP-COLUMN, and washed three times with 3 ml of

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