Comparative Effects of Aqueous Leaf Extracts of Thymus schimperi and Moringa stenopetala on Regional Blood Flow Velocity and Vascular Resistance of Pre-eclampsia Rat Models

Background: Pre-eclampsia (PE) is a common hypertensive disorder of pregnancy with a prevalence rate of 3-5%. There is no modern drug which cures PE so far. On the other hand, plant medicines are claimed to cure this disease. Exploring potential plant medicines for their therapeutic and/or prophylactic uses in this disease, therefore has paramount importance. In Ethiopia, there is a strong claim that leaves of Moringa stenopetala and Thymus schimperi have anti-hypertension activities. Thus, the current study was supposed to prove the potential therapeutic effects of the two plants against PE. PE reduces organ blood flow and increasesvascular resistance. Assessing these variables has widely been accepted when monitoring high-risk pregnancies and evaluating therapeutic and/or prophylactic uses of drugs. Methods: A comparative experimental case control study was employed to determine the effects of aqueous crude extracts of Thymus schimperi and Moringa stenopetala on regional blood flow velocities and vascular resistance of PE Albino-Wistar rat models induced by a potent vasoconstrictor, nitro-arginine methyl ester(L-NAME). A Doppler flow meter (Atys, Directive 93/42/EEC/CEE, Model, BASIC123LP) was used to measure the systolic and diastolic regional blood flow velocities through abdominal aorta, uterine, renal and common carotid arteries.  The peripheral vascular resistance for the respective vessels were evaluated using resistivity and pulsatility indices. Results: Aqueous leaf extracts of T. schimperi (ALETS) and M. stenopetala (ALEMS) significantly increased regional blood flow velocities and decreased peripheral vascular resistance in PE rat modelsin a dose dependent pattern compared with untreated controls. For example, ALETS treated PE groups showed increased diastolic blood velocity (DBV) (cm/sec) of uterine arteries 3.8±0.4 (p<0.05), 4.2±0.4 (p<0.01), 7.3±0.5 (p<0.01), while ALEMS treated PE group had uterine arterial DBV of 2.8±0.3 (p<0.01), 3.5±0.8 (p<0.05), 6.6±0.8 (p<0.01) with daily doses of 250 mg/kg, 500 mg/kg and 1 gm/kg, respectively. Moreover, the vascular resistances (measured by resistivity and pulsatility indices), of the respective vessels were significantly lower in a dose dependent pattern. Conclusion: Both ALETS and ALEMS could increaseregional blood flow velocities and decrease vascular resistances of PE rat models. Further investigation should, however, be carried out to confirm their therapeutic merits.