M.O.M. Tanira

The Effect of Rhazya stricta Decne, a Traditional Medicinal Plant, on the Forced Swimming Test in Rats

Immobility induced by forced swimming is well known as an animal model of depression. Using this paradigm, we have, in the present work, tested the possibility that the medicinal plant Rhazya stricta, which has previously been found to affect the monoamine oxidase inhibitory activity in rat brain, may have an antidepressant-like action. Rats were pretreated with various doses (0.025-6.4 g/kg) of the lyophilized extract of the plant leaves, or with desipramine (10, 20, and 40 mg/kg) and were subjected to the forced swimming test. The results indicated that the plant extract produced a biphasic (bell-shaped) effect on the immobility time. The lower doses (0.1, 0.2, and 0.4 g/kg) elicited a highly significant and inversely dose-dependent decrease in immobility time, and the higher doses (0.8, 1.6, and 6.4 g/kg) showed a dose-dependent decrease in immobility time. Under the same experimental conditions desipramine (20 and 40 mg/kg) produced dose-dependent significant decreases in immobility time. Following administration of R. stricta (6.4 g/kg) the immobility time recovered progressively with time, and 4 h after its administration the immobility time was about 70% of the control level (statistically insignificant). It is concluded that R. stricta extract [or component(s) thereof] may possess an antidepressant-like effect.

Effect of Extract of Rhazya stricta , a Traditional Medicinal Plant, on Rat Brain Tribulin

Rhazya stricta leaves, which have both antidepressant and sedative properties in animal models, are widely used in folk medicine in the Arabian peninsula. In this study, the effects of oral administration of leaf extracts on rat brain tribulin levels [endogenous monoamine oxidase (MAO) A and B inhibitory activity], were determined. In an acute study, low doses brought about an increase in MAO A inhibitory activity, while intermediate doses caused a significant reduction. The highest doses had no significant effects on activity. There were no significant effects on MAO B inhibitory activity at any dose. Subchronic administration (21 days) caused a significant decrease in MAO A inhibitory activity, most prominent at low dosage, and an increase in MAO B inhibitory activity. Acute intramuscular administration also resulted in a similar pattern. Such paradoxical effects were at least partially explained when different extracts of the leaves were used; a weakly basic chloroform fraction caused an increase in MAO A inhibitory activity, whereas butanol extracts brought about a decrease. These fractions had no significant effects on MAO B inhibitory activity. The findings show that Rhazya stricta leaves contain at least two different components that affect MAO inhibitory activity in opposite directions. It may be that the antidepressant and sedative actions of the plant are explicable in terms of these different components.

Antiinflammatory Activity of Some Medicinal Plants of the United Arab Emirates

AbstractThe antiinflammatory activity of 22 plants used in folk medicine, or indigenous in the United Arab Emirates, was tested using the carrageenan-induced rat paw edema method. Three plants (Citrullus colocynthis, Hammada elegans and Rhazya stricta) showed such activity. Activity-guided fractionation of Hammada elegans extract led to the isolation of a single active compound which was identified as piperidine hydrochloride. Citrullus colocynthis-m^aced antiinflammatory activity may by due to loss of body water.

EFFECT OF ENDOTOXIN ON GENTAMICIN PHARMACOKINETICS IN OLD AND YOUNG ADULT RATS

The effect of endotoxin administration on gentamicin pharmacokinetics in young adult (2-3 months) and old (22-24 months) rats was studied. Gentamicin (3 mg/kg, iv) was administered 24 hours after an endotoxin challenge (5 mg/kg, ip). Some blood biochemical parameters, viz. urea, AST, GGT activities in addition to PCV and Hb concentration and creatinine clearance were also measured. In young animals, endotoxin caused prolongation in gentamicin half life (t1/2), increased area under the plasma concentration-time curve (AUC) and reduced total body clearance (ClB) and volume of distribution (Vd). Endotoxin effects in the old rats were qualitatively similar to those induced in the young but were more pronounced. They included more than 10 fold increase in the t1/2 and AUC. In addition, a rising early phase in gentamicin plasma concentration was noticed in old rats treated with endotoxin which was, probably, due to an early redistribution process of gentamicin. The results indicate that aging and endotoxin, individually, can significantly alter gentamicin pharmacokinetics in the rat. These alterations were exacerbated when endotoxemia was induced in old rats.

Antioxidant action of extract of the traditional medicinal plant Rhazya stricta Decne. in rats

The effects of a leaf extract of the traditional medicinal plant Rhazya stricta (0.25, 1.0 and 4.0u2005g/kg/day for 3 days) on reduced glutathione (GSH), lipid peroxidation (LP) and ascorbic acid (AA) concentrations in the liver and kidneys were studied in rats 24u2005h after the last dose. The plant extract, at a dose of 0.25u2005g/kg, did not significantly affect the concentrations of GSH, LP or AA in the liver or kidneys. At a dose of 1.0u2005g/kg, the plant extract significantly increased the GSH concentration in the liver, but did not affect the GSH concentration in the kidneys, or LP or AA in the liver or kidneys. The plant extract (4.0u2005g/kg) significantly increased the GSH and decreased LP peroxidation, but did not affect the AA concentrations in the liver and kidneys.

Gastric cytoprotective activity of teucrium stocksianum extract in rats

AbstractThe preventive effects of Teucrium stocksianum (lyophilized water extract) on ulcer formation induced by severe, necrotizing agents such as absolute alcohol, 60% ethanol in 150mMHCl(HCl-ethanol), and 0.2NNaOH were studied in rats. T. stocksianum when given orally (p.o.) but not intraperitoneally exhibited a dose-dependent gastric cytoprotective effect to the three necrotizing agents tested. The I mucosal protective action of T. stocksianum was attenuated by pretreatment with indomethacin (5 mg/kg, subcutaneously). T. stocksianum (500 mg/kg twice per day, p.o.) had no significant effect on the healing process of ethanol-induced gastric ulcers 24, 48 and 72 h after ulcer induction. T. stocksianum (500 mg/kg, p. o.) did not afford. protection against cysteamine-induced duodenal ulcera- i Hon. In vitro studies showed that T. stocksianum dose-dependently inhibited ethanol-induced contractions, of rat fundic strip muscles. This effect was abolished by the cyclooxygenase inhibitor, indomethacin. In addit...

The effect of furazolidone and furaltadone on drug metabolism in rats

SummaryThis work examines the effect of oral treatment of rats with the nitrofuran drugs furazolidone (FZ) and furaltadone (F) at doses of 100, 200 and 400 mg/kg for 4 days, or F in the drinking water at concentrations of 0.1, 0.2 and 0.4% w/v for 14 days, on drug metabolism in vivo. FZ at doses of 200 and 400 mg/kg, and F at a dose of 400 mg/kg or at a concentration of 0.4% w/v in water depressed growth and prolonged pentobarbitone-induced sleeping time. Treatment also significantly increased the blood concentration of metronidazole when measured 30 and 40 min after metronidazole administration. Administration of tremorine (25 mg/kg, i.p.) to control vehicle-treated rats produced within 2–3 min tremors, piloerection, profuse salivation, defecation urination and chromodacryorrhesis (red tears). The onset of appearance of these signs was delayed to 7–12 min in rats pretreated with FZ or F (100 mg/kg, 4 days) or cimetidine (50 mg/kg, i.p.) given 45 min earlier. Taken together, these results suggest that FZ and F inhibit drug metabolism in rats. Treatment with these nitrofuran drugs may alter the disposition of certain drugs which may be given concomitantly with them.

The effect of gentamicin on acetylsalicylic acid-induced platelet antiaggregatory action in mouse pial arterioles

Gentamicin (G) treatment (5, 20, 40 and 80 mg kg[-1] day[-1] given intramuscularly for 6 days) was shown to cause a dose-related platelet proaggregatory effect in mouse pial microcirculation. This was associated with a reduction in mouse renal function, indicated by high plasma creatinine and urea concentrations. When G was given at the same doses but as a single injection, it caused no change in renal function or platelet aggregation. Gentamicin (20 and 80 mg kg/day, given intramuscularly for 6 days) significantly (P < 0.05) impeded the platelet antiaggregatory effect of acetylsalicylic acid (100 mg kg[-1], intraperitoneally).

The effect of chronic administration of cyclosporin A on phenytoin pharmacokinetic parameters in the rat

The potential for a drug interaction between cyclosporin A and phenytoin was investigated in rats. Rats were treated daily for 14 days with cyclosporin A (50 mg/Kg, s.c.) and on the day of the experiment phenytoin (10 mg/Kg) was administered intravenously. The mean residence time, the elimination half-life and the volume of distribution at steady state were significantly higher in the cyclosporin A-treated group than in the control group. However, total body clearance was similar in both groups. Plasma levels of urea, aspartate aminotransferase (AST) and glucose were significantly higher in the cyclosporin A-treated group than the control group. It was concluded that the observed changes could have been, at least in part, due to an inhibitory effect of cyclosporin A on liver drug metabolizing enzymes and/or liver and kidney damage.

Chronic verapamil administration alters phenytoin pharmacokinetics in the rat

The interaction of verapamil (4 and 8 mg/kg twice daily for 7 days) and i.v. phenytoin (10 mg/kg) in male Wistar rats has been studied. Increases occurred in phenytoin plasma elimination half-life (61%; p < 0.01 and 80%; p < 0.05), the area under the plasma concentration curve (32% n.s. and 48; p < 0.05) and volume of distribution (17%; p < 0.05 and 14% n.s.) after 4 and 8 mg/kg verapamil, respectively. The clearance was reduced to 75% (n.s.) and 67% (p < 0.05) of the control value; changes were not dose-dependent.