Analysis of the Mechanism of the Protective Activity of Some Sympathomimetic Amines in Experimental Ulcers

Abstract

Apomorphine administered in reserpine-induced as well as in restraint ulcers in rats, failed to afford protection. Pimozide, moperone, trifluperidol and chlorpromazine fail to influence the development of the experimental ulcers. Pimozide and moperone although antagonizing the behavioral changes of amphetamine, maintained its antiulcer activity. Amitryptiline, cocaine and morphine had a protective activity. L-Dopa afforded a significant protection which was abolished if this compound was administered together with FLA-63, a specific dopamine-β-hydroxilase inhibitor. These results were explained by admitting that not dopamine, but noradrenaline was responsible for the antiulcer activity. α-Methyl-dopa produced a significant protection in both experimental models.

Effects of α-Methyinoradrenaline and α-Methyldopamine in Reserpine-Induced Ulcers in Rats

“…The intimate mechanism of action of these compounds is still not com pletely clear. They act as 'false ncurotransmitters' as well as by the depletion o f labile noradrenaline stores [4],…”

“…Lower and higher doses were less effective. a-Methyldopamine and a-methyl noradrenaline probably act by reestablishing the normal adrenergic tone which is diminished in reserpine-induced ulcers.In a previous paper [4] it was shown that a-methyldopa (a-MD) had a quite marked antiulcer activity when tested in reserpineinduced ulcers in rats. Since it is generally accepted that a -M D acts via the so-called 'false transmitters', a-mcthyldopamine (amDA) and a-methylnoradrenaline (a-mNA) [2,3], it was thought that the investigation of the possible antiulcer effects o f a-m D A and a-m N A would be o f interest.…”

“…The number and the severity o f the lesions were assessed by means o f a magnifying glass with a ten times magnification. The following parameters were taken into account; ( 1 ) percentage o f animals having ulcers; (2) the mean numbers o f ulcers per stomach; (3) the severity o f the lesions, for this the classification mentioned in a previous paper [4] was used, the sever ity was expressed as ulcer index [4], and (4) the protec tion ratio expressed as:Ulcer index (control) -ulcer index (treated) x |qq ulcer index (control)The protection ratio was considered to be signifi cant if it exceeds 33%. it should be mentioned that only glandular ulcers were considered.…”

Ethnopharmacology as Current Strategy in the Search of Novel Anti-Ulcerogenic Drugs: Case of a Brazilian Medicinal Plant (Maytenus ilicifolia Mart. ex. Reissek)

“…These isoquinoline alkaloids occur mainly in plants belonging to families Papaveraceae, Berberidaceae and Ephedraceae (Ziegler & Facchini, 2008). In murine model of gastric damage induced by reserpine, aspirin or indomethacin, morphine and ephedrine presented significant antiulcer activity (Al-Shabanah et al, 1993;Sandor & Cuparencu, 1977). In addition, the alkaloid 7,8-dihydro-8-hydroxypalmatine obtained from the bark of Enantia chlorantha was effective to increase gastric mucus and accelerated ulcer-healing production after gastric lesions caused by acetic acid.…”

The features of reserpine-induced gastric mucosal lesions

“…It is considered that reserpine induces gastric damage by reducing sympathetic tone and increasing cholinergic tone, www.chinaphar.com Ma XJ et al Acta Pharmacologica Sinica npg which leads to excessive acid secretion [12][13][14] . In this study, vagotomy and intracerebroventricular (icv) injection of reserpine were performed to further demonstrate the role of a central vagal mechanism in reserpine-induced GMLs.…”