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- Author or Editor: Adrian Steiner x
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Abstract
Objective
To compare concentrations of acetic, propionic, butyric, and i- and n-valerianic acids in digesta samples obtained from the rumen, cecum, proximal loop of the ascending colon (PLAC), and rectum of healthy cows and cows with cecal dilatation or dislocation (CDD).
Animals
20 cows with CDD and 20 healthy cows.
Procedure
Samples were collected from all sites during surgical correction of CDD and also from the rectum 1, 2, and 3 days after surgery (group CDD). Samples from healthy (control) cows, matched on the basis of diet and milk yield, were obtained at a slaughterhouse. Concentrations of volatile fatty acids (VFA) were analyzed by use of gas chromatography. Absolute concentration of each VFA was additionally corrected for pH to allow calculation of the concentration of undissociated VFA.
Results
Absolute concentration and concentration of the undissociated form of all analyzed VFA were significantly increased in samples collected from the cecum and PLAC of cows in group CDD, compared with concentrations for control cows. Within 3 days after surgery, significant decreases of the absolute concentration of butyric, i- and n-valerianic acids, and undissociated i- and n-valerianic acids were evident in samples obtained from the rectum of group-CDD cows. Concentrations of VFA in samples obtained from the rectum during surgery correlated with corresponding VFA concentrations in samples obtained from the PLAC.
Conclusions
Concentrations of VFA are increased in the cecum and PLAC of cows with CDD. However, the role of increased concentrations of VFA in the etiopathogenesis of CDD is unknown. (Am J Vet Res 1999;60:1540–1545)
Abstract
Objective—To investigate the distribution of mRNA coding for 7 subtypes of 5-hydroxytryptamine receptors (5-HTRs) in the intestines of healthy dairy cows and dairy cows with cecal dilatation-dislocation (CDD).
Sample Population—Full-thickness intestinal wall biopsy specimens were obtained from the ileum, cecum, proximal loop of the ascending colon, and external loop of the spiral colon (ELSC) of 15 cows with CDD (group 1) and 15 healthy dairy cows allocated to 2 control groups (specimens collected during routine laparotomy [group 2] or after cows were slaughtered [group 3]).
Procedure—Amounts of mRNA coding for 7 subtypes of 5-HTRs (5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, and 5-HT4) were measured by quantitative real-time reverse transcriptase–PCR assay. Results were expressed as the percentage of mRNA expression of a housekeeping gene.
Results—Expression of mRNA coding for 5-HTR1B, 5-HTR2B, and 5-HTR4 was significantly lower in cows with CDD than in healthy cows. For 5-HTR2B and 5-HTR4, significant differences between cows with CDD and control cows were most pronounced for the ELSC. Expression of mRNA for 5-HTR1D, 5-HTR1F, and 5-HTR2A was extremely low in all groups, and mRNA for 5-HTR1A was not detected.
Conclusions and Clinical Relevance—Relative concentrations of mRNA coding for 5-HTR1B, 5-HT2B, and 5-HTR4 were significantly lower in the intestines of cows with CDD than in the intestines of healthy dairy cows, especially for 5-HT2B and 5-HTR4 in the ELSC. This supports the hypothesis that serotonergic mechanisms, primarily in the spiral colon, are implicated in the pathogenesis of CDD.
Abstract
Objective—To describe the distribution of mRNA that codes for 8 subtypes of 5-hydroxytryptamine receptors (5-HTRs) in the digestive tract of dairy cows.
Sample Population—Fresh full-thickness wall specimens from the abomasum (fundus, corpus, and antrum), ileum, cecum, proximal loop of ascending colon, and 4 locations of the spiral colon collected from 10 healthy cows at slaughter.
Procedure—Concentrations of mRNA that code for 5-HTR subtypes (5-HTR1A, 5-HTR1B, 5-HTR1D, 5-HTR1F, 5-HTR2A, 5-HTR2B, 5-HTR2C, and 5-HTR4) in the bovine digestive tract were measured by use of a quantitative real-time reverse transcription-polymerase chain reaction assay. Results were reported in relation to mRNA expression of the housekeeping gene glyceraldehyde phosphate dehydrogenase (GAPDH).
Results—Mean relative mRNA concentrations for 5-HTR were low (range, 0% to 1.32% of GAPDH), and mRNA that codes for 5-HTR1A was not detected. In the abomasum, mRNA expression was highest for 5-HTR1B and 5-HTR2B, followed by subtypes 1F, 2A, 1D, and 4, whereas 5-HTR2C was not detected. In intestinal samples, concentrations of subtypes 1B, 2B, and 4 were highest, followed by 1D, 1F, 2A, and 2C. Relative concentrations of mRNA that code for 5-HTR2A were significantly higher in the abomasum than the intestines, but lower for 5-HTR2B, 5-HTR2C, and 5-HTR4.
Conclusions and Clinical Relevance—Relative concentrations of mRNA that code for 5-HTRs differ among locations in the gastrointestinal tract of cattle. Understanding differences in the distribution of 5- HTRs in healthy cattle and cattle with gastrointestinal tract disease may lead to improved therapeutic approaches for abomasal and cecal motility disorders. (Am J Vet Res 2004;65:1151–1158)
Abstract
Objective—To describe the distribution of mRNA that codes for 9 subtypes of adrenergic receptors in the digestive tract of dairy cows.
Sample Population—Fresh full-thickness wall specimens from the abomasum (fundus, corpus, and antrum), ileum, cecum, proximal loop of ascending colon, and 4 locations of the spiral colon collected from 10 healthy cows at slaughter.
Procedure—Concentrations of mRNA that code for 9 subtypes of adrenergic receptors in the bovine gastrointestinal tract (α1A, α1B, α1D, α2AD, α2B, α2C, β1, β2, and β3) were measured by use of a quantitative realtime reverse transcription-polymerase chain reaction assay. Results were reported in relation to mRNA expression of the housekeeping gene glyceraldehyde phosphate dehydrogenase (GAPDH).
Results—Mean mRNA contents of adrenergic receptors in the bovine digestive tract were low (range, 0.00006% to 5.04% of GAPDH). Distribution of receptor subtypes was similar in all tissues, with lowest expression of α1D receptors, followed by α2B, α2C, β3, α1B, α1A, β1, and β2 in the abomasum, whereas α2AD and β2 in the intestines were highest. In comparison with the intestines, relative concentrations of mRNA for receptors β2 and β3 were significantly lower in the abomasum.
Conclusions and Clinical Relevance—Relative concentrations of mRNA that code for adrenergic receptors differed among receptor subtypes and among locations in the bovine gastrointestinal tract. Comparison of these values established in healthy cattle with results for cows with motility disorders, such as abomasal displacement and cecal dilatation, may lead to improved therapeutic or prophylactic approaches for these diseases. (Am J Vet Res 2004;65:1142–1150)
Abstract
Objective—To describe the distribution of muscarinic receptor subtypes M1 to M5 and interstitial cells of Cajal (ICCs) in the gastrointestinal tract of healthy dairy cows.
Sample Population—Full-thickness samples were collected from the fundus, corpus, and pyloric part of the abomasum and from the duodenum, ileum, cecum, proximal loop of the ascending colon, and both external loops of the spiral colon of 5 healthy dairy cows after slaughter.
Procedures—Samples were fixed in paraformaldehyde and embedded in paraffin. Muscarinic receptor subtypes and ICCs were identified by immunohistochemical analysis.
Results—Staining for M1 receptors was found in the submucosal plexus and myenteric plexus. Antibodies against M2 receptors stained nuclei of smooth muscle cells only. Evidence of M3 receptors was found in the lamina propria, in intramuscular neuronal terminals, on intermuscular nerve fibers, and on myocytes of microvessels. There was no staining for M4 receptors. Staining for M5 receptors was evident in the myocytes of microvessels and in smooth muscle cells. The ICCs were detected in the myenteric plexus and within smooth muscle layers. Distribution among locations of the bovine gastrointestinal tract did not differ for muscarinic receptor subtypes or ICCs.
Conclusions and Clinical Relevance—The broad distribution of M1, M3, M5, and ICCs in the bovine gastrointestinal tract indicated that these components are likely to play an important role in the regulation of gastrointestinal tract motility in healthy dairy cows. Muscarinic receptors and ICCs may be implicated in the pathogenesis of motility disorders, such as abomasal displacement and cecal dilatation-dislocation.
SUMMARY
The effect of bethanechol, neostigmine, metoclopramide, and propranolol on myoelectric activity of the ileum, cecum, and proximal loop of the ascending colon was determined in 6 healthy Jersey cows implanted with 8 pairs of bipolar electrodes. Assigned at random, each cow received each of 5 treatments in 3-day intervals. The treatments included bethanechol (0.07 mg/kg of body weight, sc), neostigmine (0.02 mg/kg, sc), metoclopramide (0.15 mg/kg, im), dl-propranolol (0.2 mg/kg, im), and 0.9% sodium chloride (NaCl) solution (20 ml, sc). All drugs were administered during early phase I of the migrating myoelectric complex in the ileum. Myoelectric activity was recorded for 4 hours after treatment, and data were analyzed for each hour separately.
Bethanechol and neostigmine significantly (P < 0.05) increased the number of cecocolic spikes per minute per electrode, duration of cecocolic spike activity (%), and number of cecocolic propagated spike sequences per 10 minutes, relative to NaCl, during 1 or more hours of the recording period. The effect of bethanechol was more pronounced on duration of spike activity and number of propagated spike sequences, whereas neostigmine mainly increased the number of (uncoordinated) spikes. Metoclopramide and propranolol had no significant effect on cecocolic myoelectric activity, relative to NaCl.
It was concluded that bethanechol and, less likely, neostigmine at the dosage used in this study may be suitable for medical treatment of cecal dilatation in cattle in which hypomotility of the cecum and proximal loop of the ascending colon has to be reversed. The potential advantage of bethanechol vs neostigmine for medical treatment of cecal dilatation is worth further evaluation.
Abstract
Objective—To compare the effect of various concentrations of sodium butyric acid and sodium valerianic acid, as well as various osmolarities, on contractility of ex-vivo intestinal wall specimens obtained from the cecum and spiral colon of each of several healthy cows.
Sample Population—Full-thickness preparations of intestinal wall, dissected parallel to the longitudinal smooth muscle layers, harvested from freshly slaughtered healthy cows.
Procedure—Specimens of intestinal wall were incubated for 5 minutes with various concentrations of sodium butyric acid and sodium valerianic acid as well as various osmolar concentrations of NaCl, using a crossover design. Isometric contractions were induced 7 times with carbachol (CH; 5 X 10–6 mol/L). Contractility was defined as the maximum amplitude of contraction and the amplitude of contraction 2 minutes after addition of CH.
Results—Repeated addition of CH did not result in a significant effect on contractility of specimens from the cecum and spiral colon. Contractility after addition of CH was not significantly affected by prior incubation with various concentrations of sodium butyric acid or sodium valerianic acid or after an increase of osmolarity. Maximum amplitude of contraction was significantly higher in specimens from the spiral colon, compared with specimens from the cecum.
Conclusions—Increases in concentrations of sodium butyric acid or sodium valerianic acid and increases in osmolarity did not inhibit contractility of intestinal wall specimens from the cecum and spiral colon of a group of healthy cows. (Am J Vet Res 2000;61: 678–683)
SUMMARY
The effect of xylazine, cisapride, and naloxone on myoelectric activity of the ileum, cecum, and proximal loop of the ascending colon (plac) was determined in 4 healthy Jersey cows implanted with 8 pairs of bipolar electrodes. A 4 × 4 Latin square design was used. The treatments included xylazine (0.04 mg/kg of body weight), cisapride (0.08 mg/kg), naloxone (0.05 mg/kg), and 0.9% sodium chloride solution (20 ml). All treatments were administered IV during early phase I of the migrating myoelectric complex in the ileum. Myoelectric activity was recorded for 4 hours after treatment, and data were analyzed for each hour separately.
Xylazine significantly (P < 0.05) increased the duration of phase I of the first migrating myoelectric complex in the ileum to 220.72 ± 26.89 minutes, compared with 30.91 ± 10.11 minutes after administration of 0.9% sodium chloride solution. The number of cecocolic spikes per minute per electrode and the duration of cecocolic spike activity (percentage of recording time) were significantly (P < 0.05) decreased for the first 3 hours, and the number of propagated spike sequences in the cecum and PLAC was significantly (P < 0.05) decreased for the first 2 hours after administration of xylazine. Significant difference was not found between control and either cisapride or naloxone treatment of healthy cows. However, during hour 1 after treatment with cisapride, number of spikes per minute, duration of spike activity, and number of propagated spike sequences were highest, compared with the other treatments.
It was concluded that naloxone at the dosage used in this study was not suitable for medical treatment of cecal dilatation in cattle, when hypomotility of the cecum and PLAC must be reversed. Xylazine should not be used for relief of signs of pain in cases of cecal dilatation, because it significantly reduced myo electric activity of the cecum and PLAC for at least 2 hours after treatment. Furthermore, results of this study indicated a trend (P > 0.05) toward increase of cecocolic myoelectric activity after administration of cisapride. It is the authors’ opinion that the potential benefit of cisapride for medical treatment of cecal dilatation in cattle needs further evaluation.
Abstract
Objective—To describe the effects of an abrupt increase of concentrates in the diet of dairy cows on myoelectric activity of the spiral colon and on fermentation patterns in the rumen and large intestine.
Animals—6 healthy lactating Simmental X Red- Holstein cows.
Procedure—The diet of 6 cows implanted with bipolar electrodes in the spiral colon was changed from hay only to a ration of 50% hay:50% starch-rich concentrates during a period of 60 hours. Myoelectric activity of the spiral colon, concentrations of absolute and undissociated volatile fatty acids (VFA), and pH of ruminal and large intestinal contents were monitored before, during, and after the dietary change.
Results—Significant changes in patterns of myoelectric activity of the spiral colon were restricted to phases III and IV of the bovine migrating myoelectric complex and to propagation velocity. Significant alterations were not observed in pH or VFA concentrations in ruminal fluid, but pH decreased and VFA concentrations increased significantly in fecal specimens after the change of diet.
Conclusion and Clinical Relevance—Although rumen fluid is of limited value for measurement of certain indicators of fermentation, fecal samples can be used for measurement of pH and VFA concentrations, which serve as indicators of fermentation patterns in the large intestine. Increased concentrations of VFA and low pH in large intestinal digesta have a minimal influence on myoelectric activity of the spiral colon. Increased luminal VFA concentrations are unlikely to play an important role in the etiopathogenesis of motility disorders of the large intestine in cattle. (Am J Vet Res 2002;63:857–867)
Abstract
Objective—To describe the in vitro effects of bethanechol on contractility of smooth muscle preparations from the small intestines of healthy cows and define the muscarinic receptor subtypes involved in mediating contraction.
Sample Population—Tissue samples from the duodenum and jejunum collected immediately after slaughter of 40 healthy cows.
Procedures—Cumulative concentration-response curves were determined for the muscarinic receptor agonist bethanechol with or without prior incubation with subtype-specific receptor antagonists in an organ bath. Effects of bethanechol and antagonists and the influence of intestinal location on basal tone, maximal amplitude (Amax), and area under the curve (AUC) were evaluated.
Results—Bethanechol induced a significant, concentration-dependent increase in all preparations and variables. The effect of bethanechol was more pronounced in jejunal than in duodenal samples and in circular than in longitudinal preparations. Significant inhibition of the effects of bethanechol was observed after prior incubation with muscarinic receptor subtype M3 antagonists (more commonly for basal tone than for Amax and AUC). The M2 receptor antagonists partly inhibited the response to bethanechol, especially for basal tone. The M3 receptor antagonists were generally more potent than the M2 receptor antagonists. In a protection experiment, an M3 receptor antagonist was less potent than when used in combination with an M2 receptor antagonist. Receptor antagonists for M1 and M4 did not affect contractility variables.
Conclusions and Clinical Relevance—Bethanechol acting on muscarinic receptor sub-types M2 and M3 may be of clinical use as a prokinetic drug for motility disorders of the duodenum and jejunum in dairy cows.