Archives internationales de pharmacodynamie et de thérapie
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Arch Int Pharmacodyn Ther · Nov 1989
Pirenzepine prevents cysteamine-induced formation of gastroduodenal ulcers and reduction of mesenteric circulation.
The effects of pirenzepine on gastric and duodenal ulceration and barrier mucus levels, as well as on changes of superior mesenteric artery diameter caused by cysteamine, were investigated in rats and compared with those of atropine. Cysteamine induced severe gastric and duodenal ulcers and decreased both barrier mucus levels and mesenteric blood flow. Pirenzepine reduced gastric and duodenal ulceration induced by cysteamine. ⋯ The present results are consistent with the view that pirenzepine protects against gastroduodenal ulceration caused by cysteamine by increasing blood flow at the level of the ulcerated mucosa. The higher affinity of pirenzepine for the muscarinic receptors of sympathetic ganglia may explain the difference between the effects of pirenzepine and atropine. In addition to this, the measurement of superior mesenteric artery diameter changes may represent an accurate and reproducible method, suitable for studying the gastrointestinal protective mechanisms of the drugs.
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Arch Int Pharmacodyn Ther · Nov 1989
Lack of importance of caffeine as an analgesic adjuvant of dipyrone in mice.
The analgesic effect of caffeine used alone and in combination with dipyrone and butalbital was evaluated after oral administration in mice, using two different pain tests: the hot plate test and the phenylbenzoquinone-induced writhing test. Neither caffeine (5 to 200 mg/kg) nor butalbital (10 and 20 mg/kg) (20 mg/kg was the highest dose that did not induce sleep) produced a significant antinociceptive effect, whereas dipyrone was active from 400 mg/kg in the hot plate test and from 50 mg/kg in the writhing test. The scores obtained with the combinations were not different from those of the dipyrone-treated group, except for the butalbital-dipyrone combination. Thus caffeine is not an analgesic adjuvant in mice; its presence in the combination studied appears to be justifiable only insofar as it inhibited the sedative effect of butalbital.
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Arch Int Pharmacodyn Ther · Nov 1989
Comparative StudySome effects of desmethylimipramine and amitriptyline on the schedule-controlled behavior of pigeons and rats.
The effects of desmethylimipramine and amitriptyline on schedule-controlled behavior of pigeons and rats were examined. Pigeons responded under either a multiple (mult) fixed-interval (FI) 600-sec, fixed-ratio (FR) 30-response schedule of food presentation or a mult FI 200-sec, FI 200-sec schedule, in which responding during one component was punished with electric shock. Rats responded under a mult FI 300-sec, FR 30-response schedule of food presentation. ⋯ In contrast, in the rat desmethylimipramine and amitriptyline did not differentially affect the low rates of responding at the beginning of the FI compared to the higher rates of responding at the end of the FI. Correspondingly, in the pigeon, but not in the rat, desmethylimipramine and amitriptyline decreased the fixed-interval quarter-life at relatively low doses. In the pigeon neither desmethylimipramine nor amitriptyline differentially affected the overall rate of punished as compared to unpunished responding.