Effect of 2-deoxy-D-glucose on acetylcholine and histamine levels in gastric juice of pylorus-ligated rats anesthetized with urethane

Elucidation of anti-allergic activities of curcumin-related compounds with a special reference to their anti-oxidative activities

The anti-allergic and anti-oxidative activities of curcumin-related compounds (glycosides, reductants and bis-demethoxy analogs) were investigated to elucidate the underlying active mechanisms and structural features of curcumin in exerting these activities. The anti-allergic activities were assessed by measurement of histamine release from rat basophilic leukemia cells, RBL-2H3. Curcumin and tetrahydrocurcumin (THC) caused a marked decrease in histamine release. Glycosides of curcumin, bis-demethoxycurcumin and THC also inhibited the release of histamine, though less potently than curcumin did. The anti-oxidative activities were assessed by measurement of cell-free or cellular radical scavenging. All compounds but diglycosides or bis-demethoxycurcumin analogs distinctly exerted anti-oxidative effects. The relationship between both of these activities revealed that all compounds with potent radical scavenging activities caused a definite decrease in histamine release, but some compounds with non-potent radical scavenging activities also inhibited the histamine release. These results suggest that the hydroxy groups of curcumin play a significant role in exerting both the anti-oxidative and anti-allergic activities, and that most of the compounds develop the anti-allergic activities through mechanisms related to anti-oxidative activities, but some through mechanisms unrelated to anti-oxidation activity.

Gastric antisecretory role and immunohistochemical localization of cannabinoid receptors in the rat stomach

1. The role of cannabinoid (CB) receptors in the regulation of gastric acid secretion was investigated in the rat by means of functional experiments and by immunohistochemistry. 2. In anaesthetized rats with lumen-perfused stomach, the non selective CB-receptor agonist WIN 55,212-2 (0.30 - 4.00 micromol kg(-1), i.v.) and the selective CB(1)-receptor agonist HU-210 (0.03 - 1.50 micromol kg(-1), i.v.), dose-dependently decreased the acid secretion induced by both pentagastrin (30 nmol kg(-1) h(-1)) and 2-deoxy-D-glucose (1.25 mmol kg(-1), i.v.). By contrast, neither WIN 55,212-2 (1 - 4 micromol kg(-1), i.v.) nor HU-210 (0.03 - 1.50 micromol kg(-1), i.v.) did modify histamine-induced acid secretion (20 micromol kg(-1) h(-1)). The selective CB(2)-receptor agonist JWH-015 (3 - 10 micromol kg(-1), i.v.) was ineffective. 3. The gastric antisecretory effects of WIN 55,212-2 and HU-210 on pentagastrin-induced acid secretion were prevented by the selective CB(1)-receptor antagonist SR141716A (0.65 micromol kg(-1), i.v.) and unaffected by the selective CB(2)-receptor antagonist SR144528 (0.65 - 2 micromol kg(-1), i.v.). 4. Bilateral cervical vagotomy and ganglionic blockade with hexamethonium (10 mg kg(-1), i.v., followed by continuous infusion of 10 mg kg(-1) h(-1)) significantly reduced, but not abolished, the maximal inhibitory effect of HU-210 (0.3 micromol kg(-1), i.v.) on pentagastrin-induced acid secretion; by contrast, pretreatment with atropine (1 mg kg(-1), i.v.) did not modify the antisecretory effect of HU-210. 5. Immunoreactivity to the CB(1) receptor was co-localized with that of the cholinergic marker choline acetyltransferase in neural elements innervating smooth muscle, mucosa and submucosal blood vessels of rat stomach fundus, corpus and antrum. In contrast, CB(2) receptor-like immunoreactivity was not observed. 6. These results indicate that gastric antisecretory effects of cannabinoids in the rat are mediated by suppression of vagal drive to the stomach through activation of CB(1) receptors, located on pre- and postganglionic cholinergic pathways. However, the ineffectiveness of atropine in reducing the effect of HU-210 suggests that the release of non cholinergic excitatory neurotransmitters may be regulated by CB(1) receptors.

Prolonged general anesthesia in MR studies of rats

RATIONALE AND OBJECTIVES

Magnetic resonance (MR) imaging of laboratory animals may require general anesthesia to minimize body movements over many hours. The anesthetization technique should allow physiologic parameters to remain as close to normal as possible, permit fast recovery, allow safe, repeated use, and avoid attachment of ferrous metal components to the animal. The purpose of this study was to evaluate an anesthetization technique that was developed to meet each of these qualifications.

MATERIALS AND METHODS

In 15 rats (280-483-g body weight), general anesthesia was induced (with intramuscular ketamine hydrochloride, xylazine hydrochloride, acepromazine maleate, and atropine), a tail vein catheter was inserted, and preimaging surgical procedures were performed. A face mask was applied, the animal was positioned in a dorsal recumbent position on an acrylic board, and an isothermal heating pad was placed on the ventral aspect of the abdominal wall. The rat, on the board, was then inserted into a trough that contained a custom-built, linearly polarized birdcage head coil and placed in the bore of a 4.7-T horizontal-bore magnet. The face mask was connected to a non-rebreathing gaseous anesthetic system, and anesthesia was maintained with 1.5-2.0 L/min oxygen and 0.25%-1.50% isoflurane. Oxygen saturation, heart rate, and rectal temperature were continuously monitored.

RESULTS

The duration of intramuscular anesthesia was 110 minutes +/- 12, and the duration of gaseous anesthesia was 106 minutes +/- 43. The monitoring equipment permitted display of vital signs.

CONCLUSION

The method appeared safe, was easy to perform, maintained a stable physiologic state for the parameters monitored, and could be used for repeated anesthesia in the same animal.

Inhibition of gastric acid secretion by saiboku-to, an oriental herbal medicine, in rats

Intraduodenal saiboku-to (250-1000 mg/kg) dose-dependently reduced gastric acid secretion and histamine output, without altering acetylcholine output in pylorus-ligated rats. Saiboku-to also inhibited subcutaneous bethanechol (1 mg/kg) and tetragastrin (0.3 mg/kg) -induced increases in gastric acid secretion in vagotomized pylorus-ligated rats; however, it did not inhibit subcutaneous histamine (20 mg/kg) -induced increase in acid secretion. These results, taken together, suggest a possibility that saiboku-to may inhibit histamine release. Thus, the effect of saiboku-to on histamine release was directly investigated by using anti-dinitrophenyl IgE-sensitized rat peritoneal mast cells. Antigen (dinitrophenyl)-induced histamine release from the mast cells was clearly dose-dependently inhibited by saiboku-to at concentrations of 0.1-1.0 mg/ml. These results suggest that the inhibited gastric acid secretion with saiboku-to is due to inhibited histamine release.

Effects of an oriental herbal medicine, "Saiboku-to", and its constituent herbs on Compound 48/80-induced histamine release from peritoneal mast cells in rats

Effects of a traditional oriental herbal medicine, "Saiboku-to" and its constituent herbs on Compound 48/80-induced histamine release from peritoneal mast cells in rats were investigated. Saiboku-to inhibited Compound 48/80-induced degranulation of and histamine release from the mast cells, suggesting that Saiboku-to not only possesses anti-histamine release effect from mast cells, but also contains active herbs with this effect. Significant inhibitions were found in 4 of 10 constituent herbs of Saiboku-to: Magnoliae Cortex, Perillae Herba, Bupleuri Radix and Hoelen. In the dose-response curves of the four herbs, the logarithmic linearity was observed for each herb, and 50% inhibitory concentration, the IC50 values, were calculated to be 56.8 microg/ml for Magnoliae Cortex, 175.8 microl/ml for Perillae Herba, 356.6 microg/ml for Bupleuri Radix, and 595.8 microg/ml for Hoelen. One mg/ml of Saiboku-to showing 75% inhibition of Compound 48/80-induced histamine release level from mast cells contains 88.5 microg of Magnoliae Cortex (it was estimated from the dose-response curve that this dose inhibits 62.68% of the Compound 48/80-induced histamine release level), 58.8 microg of Perillae Herba (21% inhibition), 205.9 microg of Bupleuri Radix (35.24% inhibition), and 147.1 microg of Hoelen (11.15% inhibition). From these results, it is suggested that the anti-histamine release effect of Saiboku-to, which contains 10 herbs, may be due mainly to the effect of Magnoliae Cortex and the synergism of the 3 other herbs.