Ethyl Acetate Fraction from Trichilia catigua Confers Partial Neuroprotection in Components of the Enteric Innervation of the Jejunum in Diabetic Rats.

BACKGROUND/AIMS: Diabetes causes damage to the enteric nervous system. The enteric nervous system consists of neurons and enteric glial cells (EGCs). The present study evaluated the effects of an ethyl-acetate fraction (EAF) from Trichilia catigua (T. catigua; 200 mg/kg) on the total population of enteric neurons (HuC/D-immunoreactive [IR]) and EGCs (S100-IR and glial fibrillary acidic protein [GFAP]-IR) in the total preparation and jejunal mucosa in diabetic rats. METHODS: The animals were distributed into four groups: normoglycemic rats (N), diabetic rats (D), normoglycemic rats that received the EAF (NC), and diabetic rats that received the EAF (DC). The jejunum was processed for immunohistochemistry to evaluate HuC/D, S100, and GFAP immunoreactivity. The expression of S100 and GFAP proteins was also quantified by Western blot. RESULTS: The D group exhibited a decrease in the number of neurons and EGCs, an increase in the area of cell bodies, an increase in S100 protein expression, a decrease in GFAP protein expression, and a decrease in S100-IR and GFAP-IR EGCs in the jejunal mucosa. The DC group exhibited a decrease in the number of neurons and EGCs, a decrease in the area of cell bodies, a decrease in S100 and GFAP protein expression, and a decrease in S100-IR and GFAP-IR EGCs in the jejunal mucosa. The NC group exhibited maintenance of the number of neurons and EGCs, an increase in the area of cell bodies, and a decrease in S100 and GFAP protein expression. CONCLUSION: The EAF from T. catigua partially conferred protection against diabetic neuropathy in the enteric nervous system.

Electroacupuncture at ST25 inhibits jejunal motility: Role of sympathetic pathways and TRPV1.

AIM: To investigate whether electroacupuncture (EA) at ST25 affects jejunal motility in vivo and if so, whether a sympathetic pathway is involved. METHODS: Jejunal motility was assessed using a manometric balloon placed in the jejunum approximately about 3-5 cm away from the suspensory ligament of the duodenum in anesthetized animals. The effects of EA at ST25 were measured in male Sprague-Dawley rats, some of which were treated with propranolol or clenbuterol (EA intensities: 1, 3, 5, 7, and 9 mA), and in male transient receptor potential vanilloid-1 (TRPV1) (capsaicin receptor) knockout mice (EA intensities: 1, 2, and 4 mA). RESULTS: Anesthetized rats exhibited three types of fasting jejunal motor patterns (types A, B, and C), and only type C rats responded to EA stimulation. In type C rats, EA at ST25 significantly suppressed the motor activity of the jejunum in an intensity-dependent manner. The inhibitory effect of EA was weakened by propranolol (ß adrenoceptor antagonist) and disappeared with clenbuterol (ß adrenoceptor agonist) induced inhibition of motility, suggesting that the effect of EA on motility is mediated via a sympathetic pathway. Compared with wild-type mice, EA at ST25 was less effective in TRPV1 knockout mice, suggesting that this multi-modal sensor channel participates in the mechanism. CONCLUSION: EA at ST25 was found to inhibit jejunal motility in an intensity-dependent manner, via a mechanism in which sympathetic nerves and TRPV1 receptors play an important role.

Capsaicin alleviates abnormal intestinal motility through regulation of enteric motor neurons and MLCK activity: Relevance to intestinal motility disorders.

SCOPE: Capsaicin is an active component of chili peppers, having diverse effects. However, the effects of capsaicin on intestinal motility are still controversial. The present study aimed to investigate the effects of capsaicin on intestinal motility disorder and uncover related mechanisms. MATERIALS AND RESULTS: A rat model with intestinal motility disorder was established in vitro through adding different stimuli into tissue bath; in vivo using constipation and diarrhea model, respectively. Capsaicin exerted dual effects on intestinal motility, i.e. the relaxation and contraction of jejunum induced by corresponding stimulus were, respectively, regulated to be normal contraction by capsaicin. The mechanisms underlined capsaicin-induced dual effects were investigated using Western blotting, qRT-PCR, and whole-cell patch clamp, respectively. Results showed that cholinergic excitatory nerves, adrenergic nerves, and neurons containing nitric oxide synthase, which are the main muscle motor neurons in enteric nervous system (ENS), are involved in capsaicin-induced dual effects. The competition for regulation of Ca(2+) influx by capsaicin induced the interaction with components of the ENS. Capsaicin significantly increased myosin light chain kinase (MLCK) expression and myosin phosphorylation extent in jejunal segments of constipation-prominent rats and significantly decreased MLCK expression and myosin phosphorylation extent in jejunal segments of diarrhea-prominent rats. CONCLUSION: In summary, capsaicin alleviates abnormal intestinal motility through regulating enteric motor neurons and MLCK activity, which is beneficial for the treatment of gastrointestinal motility disorders.

Effects of ginsenoside Re on rat jejunal contractility.

Ginsenoside Re (GRe) exerts diverse effects. Based on our observations, the present study was designed to investigate GRe-exerted bidirectional regulation (BR) on the contractility of isolated jejunal segment. Six pairs of different low and high contractile states of rat jejunal segment were established and used in the study. Stimulatory effects on the contractility of jejunal segment were exerted by GRe (10.0 µM) in all 6 low contractile states, and inhibitory effects were exerted in all 6 high contractile states, indicating that GRe exerted BR on the contractility of jejunal segment. The effects of GRe on the phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK) and MLCK mRNA expression in jejunal segment in low and high contractile states were also bidirectional. GRe-exerted BR was abolished in the presence of neurotoxin tetrodotoxin or Ca2+ channel blocker verapamil or c-Kit receptor tyrosine kinase inhibitor imatinib. Atropine blocked the stimulatory effects of GRe on jejunal contractility in low-Ca2+-induced low contractile state; phentolamine, propranolol and l-NG-nitro-arginine blocked the inhibitory effects in high-Ca2+-induced high contractile state, respectively. In summary, GRe-exerted BR depends on jejunal contractile state and requires the presence of enteric nervous system, Ca2+, and interstitial cells of Cajal; the stimulatory effects of GRe on jejunal contractility are related to cholinergic stimulation and inhibitory effects are related to adrenergic activation and nitric oxide relaxing mechanisms.

Acupuncture at heterotopic acupoints enhances jejunal motility in constipated and diarrheic rats.

AIM: To investigate the effect and mechanism of acupuncture at heterotopic acupoints on jejunal motility, particularly in pathological conditions. METHODS: Jejunal motility was assessed using a manometric balloon placed in the jejunum approximately 18-20 cm downstream from the pylorus and filled with approximately 0.1 mL warm water in anesthetized normal rats or rats with diarrhea or constipation. The heterotopic acupoints including LI11 (Quchi), ST37 (Shangjuxu), BL25 (Dachangshu), and the homotopic acupoint ST25 (Tianshu), and were stimulated for 60 s by rotating acupuncture needles right and left at a frequency of 2 Hz. To determine the type of afferent fibers mediating the regulation of jejunal motility by manual acupuncture, the ipsilateral sciatic A or C fibers of ST37 were inactivated by local application of the A-fiber selective demyelination agent cobra venom or the C fiber blocker capsaicin. Methoctramine, a selective M2 receptor antagonist, was injected intravenously to identify a specific role for M2 receptors in mediating the effect of acupuncture on jejunal motility. RESULTS: Acupuncture at heterotopic acupoints, such as LI11 and ST37, increased jejunal motility not only in normal rats, but also in rats with constipation or diarrhea. In normal rats, manual acupuncture at LI11 or ST37 enhanced jejunal pressure from 7.34 ± 0.19 cmH2O to 7.93 ± 0.20 cmH2O, an increase of 9.05% ± 0.82% (P < 0.05), and from 6.95 ± 0.14 cmH2O to 8.97 ± 0.22 cmH2O, a significant increase of 27.44% ± 1.96% (P < 0.01), respectively. In constipated rats, manual acupuncture at LI11 or ST37 increased intrajejunal pressure from 8.17 ± 0.31 cmH2O to 9.86 ± 0.36 cmH2O, an increase of 20.69% ± 2.10% (P < 0.05), and from 8.82 ± 0.28 cmH2O to 10.83 ± 0.28 cmH2O, an increase of 22.81% ± 1.46% (P < 0.05), respectively. In rats with diarrhea, MA at LI11 or ST37 increased intrajejunal pressure from 11.95 ± 0.35 cmH2O to 13.96 ± 0.39 cmH2O, an increase of 16.82% ± 2.35% (P < 0.05), and tended to increase intrajejunal pressure (from 12.42 ± 0.38 cmH2O to 13.05 ± 0.38 cmH2O, an increase of 5.07% ± 1.08%, P > 0.05), respectively. In contrast, acupuncture ST25, a homotopic acupoint, decreased not only intrajejunal pressure, but also significantly decreased frequency in normal rats and rats with constipation or diarrhea. Following demyelination of Aδ fibers, acupuncture at ST37 again augmented intrajejunal pressure to 121.48% ± 3.06% of baseline. Following capsaicin application for 24 h, acupuncture at ipsilateral ST37 increased intrajejunal pressure significantly to 106.63% ± 1.26% of basal levels when compared to measurements prior to capsaicin treatment (P < 0.05). Acupuncture at LI11, ST37, or BL25 significantly rescued methoctramine-mediated inhibition of jejunal motility amplitude from 42.83% ± 1.65% to 53.43% ± 1.95% of baseline (P < 0.05), from 45.15% ± 2.22% to 70.51% ± 2.34% of baseline (P < 0.01), and from 38.03% ± 2.34% to 70.12% ± 2.22% of baseline (P < 0.01), respectively. CONCLUSION: Acupuncture at heterotopic acupoints increases the amplitude of jejunal motility in rats. C fibers and M2 receptors predominantly and partially mediate the regulation of jejunal motility by acupuncture, respectively.

Supplementation with 0.1% and 2% vitamin e in diabetic rats: analysis of myenteric neurons immunostained for myosin-V and nNOS in the jejunum / Suplementação com vitamina E 0,1% e 2% em ratos diabéticos: análise de neurônios mioentéricos imunomarcados para miosina-V e nNOS no jejuno

CONTEXT: Diabetes mellitus is a disease characterized by hyperglycemia that, when allowed to progress long-term untreated, develops vascular and neurological complications, which are responsible for the development of alterations in the enteric nervous system in diabetic patients. In the gastrointestinal tract, diabetes mellitus promotes motor and sensory changes, and in the reflex function of this system, causing gastroparesis, diarrhea, constipation, megacolon, slow gastrointestinal transit, gastric stasis and dilation with decreased or increased peristaltic contractions. Several studies have shown that oxidative stress is the main responsible for the vascular and neurological complications affecting the enteric nervous system of diabetics. OBJECTIVE: The effects of 0.1% and 2% vitamin E on myosin-V- and nNOS-immunoreactive neurons in the jejunum of diabetic rats were investigated. METHODS: Thirty rats were divided into the groups: normoglycemic, normoglycemic treated with 0.1% vitamin E, normoglycemic treated with 2% vitamin E, diabetic, diabetic treated with 0.1% vitamin E, and diabetic treated with 2% vitamin E. The neuronal density and areas of neuron cell bodies were determined. RESULTS: Diabetes (diabetic group) significantly reduced the number of myosin-V-immunoreactive neurons compared with the normoglycemic group. The diabetic treated with 0.1% vitamin E and diabetic treated with 2% vitamin E groups did not exhibit a greater density than the D group (P>0.05). Nitrergic density did not change with diabetes (P>0.05). The areas of myosin-V- and nNOS-immunoreactive neurons significantly increased in the normoglycemic treated with 2% vitamin E and diabetic groups compared with the normoglycemic group. CONCLUSION: Supplementation with 2% vitamin E had a neurotrophic effect only in the area of myosin-V-immunoreactive neurons compared with the diabetic group.

CONTEXTO: O diabetes mellitus (DM) é uma doença caracterizada pela hiperglicemia que a longo prazo, quando não tratada, desenvolve complicações vasculares e neurológicas, responsáveis pelo desenvolvimento das alterações no sistema nervoso entérico de pacientes diabéticos. Em nível gastrointestinal o DM provoca modificações motoras, sensoriais e na função reflexa desse sistema, podendo ocasionar gastroparesia, diarreia, constipação, megacólon, lentidão do trânsito gastrointestinal, estase e dilatação gástrica com diminuição ou aumento de contrações peristálticas. Diversos estudos têm evidenciado que o estresse oxidativo é o principal responsável pelas complicações vasculares e neurológicas que atingem o sistema nervoso entérico de diabéticos. OBJETIVO: O efeito da vitamina E 0,1% e 2 sobre a miosina-V e nNOS imunorreativas em neurônios do jejuno de ratos diabéticos foram investigados. MÉTODOS: Trinta ratos foram divididos em grupos: normoglicêmicos (NU), normoglicêmicos tratados com vitamina E 0,1% (NE1), normoglicêmicos tratados com vitamina E 2% (NE2), diabético (UD), diabéticos tratados com vitamina E 0,1% (DE1), e diabéticos tratados com vitamina E 2% (DE2). A densidade neuronal e áreas de corpos celulares de neurônios foram determinadas. RESULTADOS: Diabetes (UD grupo) reduziu significativamente o número de neurônios miosina-V imunorreativos quando comparado com o grupo UN. Os grupos DE1 e DE2 não exibem uma maior densidade do que o grupo D (P>0,05). Densidade nitrérgicos não se alterou com diabetes (P>0,05). As áreas dos neurônios miosina-V e nNOS imunorreativos aumentaram significativamente nos grupos NE2 e UD comparados com o grupo UN. CONCLUSÃO: A suplementação com vitamina E 2% teve um efeito neurotrófico apenas na área da miosina-V imunorreativos neurônios em comparação com o grupo UD.

Supplementation with 0.1% and 2% vitamin E in diabetic rats: analysis of myenteric neurons immunostained for myosin-V and nNOS in the jejunum.

CONTEXT: Diabetes mellitus is a disease characterized by hyperglycemia that, when allowed to progress long-term untreated, develops vascular and neurological complications, which are responsible for the development of alterations in the enteric nervous system in diabetic patients. In the gastrointestinal tract, diabetes mellitus promotes motor and sensory changes, and in the reflex function of this system, causing gastroparesis, diarrhea, constipation, megacolon, slow gastrointestinal transit, gastric stasis and dilation with decreased or increased peristaltic contractions. Several studies have shown that oxidative stress is the main responsible for the vascular and neurological complications affecting the enteric nervous system of diabetics. OBJECTIVE: The effects of 0.1% and 2% vitamin E on myosin-V- and nNOS-immunoreactive neurons in the jejunum of diabetic rats were investigated. METHODS: Thirty rats were divided into the groups: normoglycemic, normoglycemic treated with 0.1% vitamin E, normoglycemic treated with 2% vitamin E, diabetic, diabetic treated with 0.1% vitamin E, and diabetic treated with 2% vitamin E. The neuronal density and areas of neuron cell bodies were determined. RESULTS: Diabetes (diabetic group) significantly reduced the number of myosin-V-immunoreactive neurons compared with the normoglycemic group. The diabetic treated with 0.1% vitamin E and diabetic treated with 2% vitamin E groups did not exhibit a greater density than the D group (P>0.05). Nitrergic density did not change with diabetes (P>0.05). The areas of myosin-V- and nNOS-immunoreactive neurons significantly increased in the normoglycemic treated with 2% vitamin E and diabetic groups compared with the normoglycemic group. CONCLUSION: Supplementation with 2% vitamin E had a neurotrophic effect only in the area of myosin-V-immunoreactive neurons compared with the diabetic group.

Neuroprotective action of Ginkgo biloba on the enteric nervous system of diabetic rats.

AIM: To investigate the effect of Ginkgo biloba extract on the enteric neurons in the small intestine of diabetic rats. METHODS: Fifteen Wistar rats were divided into three groups: control group (C), diabetic group (D) and diabetic-treated (DT) daily with EGb 761 extract (50 mg/kg body weight) for 120 d. The enteric neurons were identified by the myosin-V immunohistochemical technique. The neuronal density and the cell body area were also analyzed. RESULTS: There was a significant decrease in the neuronal population (myenteric plexus P = 0.0351; submucous plexus P = 0.0217) in both plexuses of the jejunum in group D when compared to group C. With regard to the ileum, there was a significant decrease (P = 0.0117) only in the myenteric plexus. The DT group showed preservation of the neuronal population in the jejunum submucous plexus and in the myenteric plexus in the ileum. The cell body area in group D increased significantly (P = 0.0001) in the myenteric plexus of both segments studied as well as in the ileum submucosal plexus, when compared to C. The treatment reduced (P = 0.0001) the cell body area of the submucosal neurons of both segments and the jejunum myenteric neurons. CONCLUSION: The purified Ginkgo biloba extract has a neuroprotective effect on the jejunum submucous plexus and the myenteric plexus of the ileum of diabetic rats.

Immunohistochemical study of vasoactive intestinal peptide (VIP) enteric neurons in diabetic rats supplemented with L-glutamine.

The purpose of this work was to study the area of the varicosities of nerve fibers of myenteric neurons immunoreactive to vasoactive intestinal peptide (VIP-IR) and of the cell bodies of VIP-IR submucosal neurons of the jejunum of diabetic rats supplemented with 2% L-glutamine. Twenty male rats were divided into the following groups: normoglycemic (N), normoglycemic supplemented with L-glutamine (NG), diabetic (D) and diabetic supplemented with L-glutamine (DG). Whole-mounts of the muscle tunica and the submucosal layer were subjected to the immunohistochemical technique for neurotransmitter VIP identification. Morphometric analyses were carried out in 500 VIP-IR cell bodies of submucosal neurons and 2000 VIP-IR varicosities from each group. L-Glutamine supplementation to the normoglycemic animals caused an increase in the areas of the cell bodies (8.49%) and varicosities (21.3%) relative to the controls (P < 0.05). On the other hand, there was a decrease in the areas of the cell bodies (4.55%) and varicosities (28.9%) of group DG compared to those of group D (P < 0.05). It is concluded that L-glutamine supplementation was positive both to normoglycemic and diabetic animals.

Heparin and hyperbaric oxygenation in enteric autonomic neuron preservation for transplant.

BACKGROUND: Previous studies have suggested that the addition of heparin to a preservation solution attenuated the autonomic dysfunction observed in rat jejunum and in addition that hypothermic hyperbaric oxygenation may play a role as a preservation technique. However, these studies did not address the lesion indices of the autonomic enteric neurons. We sought to investigate whether the autonomic enteric neurons are injured during cold ischemic preservation and whether administration of heparin or hyperbaric oxygenation prevents this lesion. METHODS: Jejunal segments (2 cm; n = 20) of Wistar rats (12-16 weeks old) were maintained in lactated Ringer's solution without or with heparin (H- and H+, respectively) at 4 degrees C under normobaric conditions. Other jejunal segments (n = 10) were maintained at 4 degrees C in H- under hyperbaric oxygenation conditions (HBO). After preservation for 12 hours, H-, H+, and HBO preparations fixed in 10% formaldehyde were stained with hematoxylin and eosin. The lesion indices were expressed as the mean number of affected neurons (karyorhexis, nuclear dislocation, cytoplasmic vacuolisation) per 100 neurons present in intramural ganglia. Statistical analysis was performed using the Mann-Whitney test (P < .05). RESULTS: The histologic studies showed that enteric autonomic neurons were damaged in H- jejunal segments. The lesion indices observed were: karyorhexis 90/100, nuclear dislocation 85/100, and cytoplasmic vacuolization 82/100. The autonomic neurons in H+ and HBO segments seemed to be normal and significantly well-preserved (P < .001). CONCLUSION: Hypothermic hyperbaric oxygenation and heparin prevented lesions in cold ischemic preservation of enteric autonomic neurons.

Evaluation of the effect of Ginkgo biloba extract (EGb 761) on the myenteric plexus of the small intestine of Wistar rats.

BACKGROUND: The aging process causes a reduction in the myenteric neuronal population, related to oxidative stress, resulting in malfunctioning of the digestive tract. The purpose of this study was to evaluate the action of Ginkgo biloba extract (EGb 761), an important antioxidant drug, on the myenteric plexus of the jejunum and ileum of rats after treatment for 120 days. METHODS: Fragments of the jejunum and ileum were collected from three groups of rats: a 90-day-old group (group Y), a 210-day-old group (group A), and a 210-day-old group treated daily with the extract EGb 761 (50 mg/kg body weight) (group TA). The analysis was carried out by using the myosin-V immunohistochemical technique. Neuronal densities were estimated, and a study of the neuronal profile area of 500 neurons from each group was carried out. RESULTS: In the jejunum, there was a significant neuronal population reduction of 17% only in group A compared with group Y. In the ileum, there was a significant neuronal reduction of 36% in group A compared with group Y, and a significant reduction in group TA of 20%. The difference in the reduction between groups A and TA in the ileum was also significant. In the jejunum, only group A showed a significant increase in neuronal profile area, but in the ileum, there was a significant increase in both groups A and TA. CONCLUSIONS: A daily dose of 50 mg/kg body weight of Ginkgo biloba extract has a significant neuroprotector effect on the myenteric plexus of the ileum during the aging process in rats.

Orexins control intestinal glucose transport by distinct neuronal, endocrine, and direct epithelial pathways.

OBJECTIVE: Orexins are neuropeptides involved in energy homeostasis. We investigated the effect of orexin A (OxA) and orexin B (OxB) on intestinal glucose transport in the rat. RESEARCH DESIGN AND METHODS AND RESULTS: Injection of orexins led to a decrease in the blood glucose level in oral glucose tolerance tests (OGTTs). Effects of orexins on glucose entry were analyzed in Ussing chambers using the Na(+)-dependent increase in short-circuit current (Isc) to quantify jejunal glucose transport. The rapid and marked increase in Isc induced by luminal glucose was inhibited by 10 nmol/l OxA or OxB (53 and 59%, respectively). Response curves to OxA and OxB were not significantly different with half-maximal inhibitory concentrations at 0.9 and 0.4 nmol/l, respectively. On the one hand, OxA-induced inhibition of Isc was reduced by the neuronal blocker tetrodotoxin (TTX) and by a cholecystokinin (CCK) 2R antagonist, indicating involvement of neuronal and endocrine CCK-releasing cells. The OX(1)R antagonist SB334867 had no effect on OxA-induced inhibition, which is likely to occur via a neuronal and/or endocrine OX(2)R. On the other hand, SB334867 induced a significant right shift of the concentration-effect curve for OxB. This OxB-preferring OX(1)R pathway was not sensitive to TTX or to CCKR antagonists, suggesting that OxB may act directly on enterocytic OX(1)R. These distinct effects of OxA and OxB are consistent with the expression of OX(1)R and OX(2)R mRNA in the epithelial and nonepithelial tissues, respectively. CONCLUSIONS: Our data delineate a new function for orexins as inhibitors of intestinal glucose absorption and provide a new basis for orexin-induced short-term control of energy homeostasis.

Effects and probable mechanisms of electroacupuncture at the Zusanli point on upper gastrointestinal motility in rabbits.

BACKGROUND AND AIM: The purposes of this study were to investigate the regulative effect of acupuncture on gastrointestinal motility in rabbits and to explore the probable mechanism of electroacupuncture. METHODS: The experiment was performed on 30 rabbits implanted with three pairs of electrodes, which were equally divided into three groups: the control group, the Zusanli group, and the non-acupuncture point group. The gastrointestinal myoelectrical activity of each conscious rabbit was recorded when acupuncture was applied. Motilin in plasma, cholecystokinin (CCK) in serum, the activity of acetylcholine esterase, nitric oxide synthase (NOS), and the vesicle of nerve endings in the stomach tissue and jejunum were investigated. RESULTS: It was found that electroacupuncture did not exert much influence on the slow wave of gastrointestinal myoelectrical activity, but significantly increased the number and amplitude of spikes. In the Zusanli group, the concentration of motilin and CCK was much higher at the post-acupuncture stage than at the pre-acupuncture stage. Electroacupuncture significantly enhanced the activity of acetylcholine esterase. Moreover, we found out that in the Zusanli group, the number of vesicles without granula was significantly fewer than in the control group. The activity of NOS was less in the Zusanli group than in the control group. CONCLUSIONS: Acupuncture may enhance the gastrointestinal myoelectrical activity of conscious rabbits. The cholinergic nerve, nitric oxide, motilin, and CCK may contribute to acupuncture mechanisms.

Relationship between dietary-induced changes in intestinal commensal microflora and duodenojejunal myoelectric activity monitored by radiotelemetry in the rat in vivo.

Interdigestive intestinal motility, and especially phase III of the migrating myoelectric/motor complex (MMC), is responsible for intestinal clearance and plays an important role in prevention of bacterial overgrowth and translocation in the gut. Yet previous results from gnotobiotic rats have shown that intestinal microflora can themselves affect the characteristics of the myoelectric activity of the gut during the interdigestive state. Given that the composition of the intestinal microflora can be altered by dietary manipulations, we investigated the effect of supplementation of the diet with synbiotics on intestinal microflora structure and the duodenojejunal myoelectric activity in the rat. To reduce animal distress caused by restraint and handling, which can itself affect GI motility, we applied radiotelemetry for duodenojejunal EMG recordings in conscious, freely moving rats. Thirty 16-month-old Spraque-Dawley rats were used. The diet for 15 rats (E group) was supplemented with chicory inulin, Lactobacillus rhamnosus and Bifidobacterium lactis. The remaining 15 rats were fed control diet without supplements (C group). Three rats from each group were implanted with three bipolar electrodes positioned at 2, 14 and 28 cm distal to the pylorus. After recovery, two 6 h recordings of duodenojejunal EMG were carried out on each operated rat. Subsequently, group C rats received feed supplements and group E rats received only control diet for 1 week, and an additional two 6 h recordings were carried out on each of these rats. Non-operated C and E rats were killed and samples of GI tract were collected for microbiological analyses. Supplementation of the diet with the pro- and prebiotics mixture increased the number of bifidobacteria, whereas it decreased the number of enterobacteria in jejunum, ileum, caecum and colon. In both caecum and colon, the dietary supplementation increased the number of total anaerobes and lactobacilli. Treatment with synbiotics increased occurrence of phase III of the MMC at all three levels of the small intestine. The propagation velocity of phase III in the whole recording segment was also increased from 3.7 +/- 0.2 to 4.4 +/- 0.2 cm min(-1) by dietary treatment. Treatment with synbiotics increased the frequency of response potentials of the propagated phase III of the MMC at both levels of the jejunum, but not in the duodenum. In both parts of the jejunum, the supplementation of the diet significantly decreased the duration of phase II of the MMC, while it did not change the duration of phase I and phase III. Using the telemetry technique it was demonstrated that changes in the gastrointestinal microflora exhibited an intestinal motility response and, more importantly, that such changes can be initiated by the addition of synbiotics to the diet.

Apoptosis in rat jejunal mucosa is regulated partly through the central nervous system, which controls feeding behavior.

AIM: The aim of this study was to investigate whether central nervous system-related feeding behavior regulates mucosal apoptosis in rat small intestines. METHODS: The test solutions used in this study were an H(1) receptor antagonist (chlorpheniramine maleate), 2-deoxy-D-glucose, leptin, and 1-deoxy-D-glucosamine (2-amino-1,5-anhydro-2-deoxy-D-glucitol). Test solutions were injected into the third cerebroventricles of rats. Feeding behavior and jejunal apoptosis were evaluated both with and without truncal vagotomy. Intestinal apoptosis was evaluated by percentage fragmented DNA, electrophoresis, and TUNEL staining. RESULTS: Chlorpheniramine and 2-deoxy-D-glucose elicited feeding, whereas leptin and 1-deoxy-D-glucosamine suppressed feeding. The test solutions, which elicited feeding (0.24 and 24 micromol/rat of chlorpheniramine and 2-deoxy-D-glucose, respectively), suppressed mucosal apoptosis in the rat jejunum 1 h after cerebroventricular infusion. In contrast, the test solutions, which suppressed feeding (8 and 24 micromol/rat of leptin and 1-deoxy-D-glucosamine, respectively), induced jejunal mucosal apoptosis 3 h after infusion. The effects of the test solutions on feeding behavior and changes in apoptosis were not affected by truncal vagotomy. CONCLUSION: The central nervous system, which regulates feeding behavior, might control intestinal function through the regulation of intestinal apoptosis.

Morphometric and quantitative evaluation of the NADH-diaphorase positive myenteric neurons of the jejunum of streptozotocin-diabetic rats supplemented with acetyl-L-carnitine.

Summary In this study we investigated the effect of the acetyl-L-carnitine (ALC) supplementation on the myenteric neurons of the jejunum of rats made diabetic at the age of 105 days by streptozotocin (35 mg/kg body weight). Four groups were used: non-diabetic (C), non-diabetic supplemented with ALC (CC), diabetic (D), diabetic supplemented with ALC (DC). After 15 weeks of diabetes induction the blood was collected by cardiac puncture to evaluate glycaemia and glycated haemoglobin. Next the animals were killed and the jejunum was collected and subjected to whole-mount preparation to evidence the myenteric neurons through the histochemical technique of the NADH-diaphorase. The neuronal counts were made in 80 microscopic fields, in tissue samples of five animals of each group. The profiles of the cell bodies of 1000 neurons per group were analysed. Diabetes induced a significant increase in the area of the cell body and decrease in the number of NADH-diaphorase positive myoenteric neurons. ALC suplementation to the diabetic group promoted smaller hypertrophic effects and less neuronal loss than in the myoenteric neurons of the diabetic rats, and in addition diminished the body weight decrease and reduced the fasting glycaemia.

Truncal and hepatic vagotomy reduce suppression of feeding by jejunal lipid infusions.

Two experiments investigated mechanisms underlying the decrease in food intake produced by lipid infusions into the jejunum. In Experiment 1, male Sprague-Dawley rats with truncal abdominal vagotomy (TVx), selective hepatic-branch vagotomy (HVx), or sham vagotomy received repeated 7 h infusions of linoleic acid (LA), corn oil (CO), or saline through indwelling jejunal catheters. Cumulative food intake was measured at 1, 3, 6, and 23 h. LA and, to a lesser extent, CO suppressed food intake in excess of the caloric value of the load. This effect was eliminated by TVx, which significantly attenuated the suppression of intake produced by both lipids at 3 and 6 h and also at 23 h when LA was infused. HVx attenuated suppression at 23 h on tests with LA and at 3 and 6 h on CO tests. Experiment 2 showed that jejunal infusion of LA had no effect on multi-unit activity of afferent fibers in the left splanchnic nerve in anesthetized rats. Thus, these results provide further evidence that satiating effects of intestinal lipid infusions are mediated by the vagal fibers, some of which lie within the hepatic branch. However, because significant suppression of food intake remained after TVx, and because of the negative results of Experiment 2, these lipid infusions engage as yet unidentified mechanisms independent of the vagus.

Effect of acetyl-L-carnitine on Vip-ergic neurons in the jejunum submucous plexus of diabetic rats

The effect of the treatment with acetyl-L-carnitine (ALC) on neurons releasing the vasoactive intestinal polypeptide (VIP) of the submucous plexus in the jejunum of diabetic rats was the purpose of our investigation. Diabetes (DM) was induced by injecting streptozotocin endovenously (35mg/kg). After sacrificing the animals, the jejunum was collected and processed for VIP detection. Four groups were used: C (non-diabetic), CC (non-diabetic treated with ALC), D (diabetic), DC (diabetes treated with ALC). We analyzed the immunoreactivity and the cellular profile of 126 cell bodies. The treatment with ALC improved some aspects of DM. However, it promoted a small increase in the area of neurons from group CC, suggesting a possible neurotrophic effect. Neurons from groups D and DC showed a large increase in their cellular profile and immunoreactivity when compared to C and CC, suggesting a larger concentration of this neurotransmitter within the neurons that produce it. This observation constitutes a recurrent finding in diabetic animals, suggesting that ALC doesnot interfere in the pathophysiological mechanisms that unchain a higher production and/or neurotransmitter accumulation and increase the profile of the VIP-ergic neurons

Effect of acetyl-L-carnitine on VIP-ergic neurons in the jejunum submucous plexus of diabetic rats.

The effect of the treatment with acetyl-L-carnitine (ALC) on neurons releasing the vasoactive intestinal polypeptide (VIP) of the submucous plexus in the jejunum of diabetic rats was the purpose of our investigation. Diabetes (DM) was induced by injecting streptozotocin endoveneously (35 mg/kg). After sacrificing the animals, the jejunum was collected and processed for VIP detection. Four groups were used: C (non-diabetic), CC (non-diabetic treated with ALC), D (diabetic), DC (diabetes treated with ALC). We analyzed the immunoreactivity and the cellular profile of 126 cell bodies. The treatment with ALC improved some aspects of DM. However, it promoted a small increase in the area of neurons from group CC, suggesting a possible neurotrophic effect. Neurons from groups D and DC showed a large increase in their cellular profile and immunoreactivity when compared to C and CC, suggesting a larger concentration of this neurotransmitter within the neurons that produce it. This observation constitutes a recurrent finding in diabetic animals, suggesting that ALC does not interfere in the pathophysiological mechanisms that unchain a higher production and/or neurotransmitter accumulation and increase the profile of the VIP-ergic neurons.

Jejunal or portal vein infusions of lipids increase hepatic vagal afferent activity.

Jejunal infusions of linoleic acid, corn oil, or caprylic acid significantly increased hepatic vagal afferent activity, whereas saline infusions were ineffective. The magnitude of response was greatest with either linoleic acid or corn oil. Hepatic portal infusions of linoleic acid, Liposyn II, or caprylic acid significantly increased hepatic vagal afferent activity, whereas 5% albumin/phosphate buffer vehicle was ineffective. The magnitude of response was greatest with either linoleic acid or Liposyn II. These data show that either jejunal or portal infusions of lipids increase activity of hepatic vagal afferents and could potentially serve as a complementary and/or alternative substrate to celiac vagal afferents in mediating the effects of jejunal infusions of lipids in suppressing food intake.