Concurrent administration of aqueous Azadirachta indica (neem) leaf extract with DOCA‐salt prevents the development of hypertension and accompanying electrocardiogram changes in the rat

The effect of concurrent administration of Azadirachta indica leaf extract with DOCA‐salt was investigated in the development of hypertension. Over 5–6 week old, inbred male Wistar rats with a starting weight of 190 g were given either: (1) twice weekly subcutaneous (s.c.) injections of vehicle (soyabean oil, 0.25 mL per animal) for the first 2 weeks, plus normal drinking water (controls); (2) twice weekly (s.c.) injections (weeks 1 and 2 only) of 15 mg/kg DOCA dissolved in vehicle, plus drinking water containing 1.0% NaCl and 0.03% KCl (DOCA‐salt group); or (3) 20 mg/kg of aqueous neem extract daily, in addition to the DOCA‐salt treatment (DOCA‐salt‐neem group). All groups (8–12 animals) received normal rat pellets ad libitum and their BP was measured weekly. Terminally, the animals were anaesthetized and ECGs recorded using s.c. pins in a lead II configuration. The mean arterial pressure was significantly lower ( p < 0.05) in the control (97 ± 3.7 mmHg) and DOCA‐salt‐neem (87 ± 3.4 mm Hg) groups than in the DOCA‐salt group (115 ± 7.1 mm Hg). PR and RR intervals and the duration of the QRS complex were shorter ( p < 0.05) in the DOCA‐salt group than in the control and DOCA‐salt‐neem groups. Amplitude of the QRS complex was increased ( p < 0.05) in the DOCA‐salt group compared with both the DOCA‐salt‐neem and the control groups. Daily administration of 20 mg/kg neem‐leaf extract concurrently with DOCA‐salt for 5 weeks, prevents the development of hypertension and the accompanying alterations in the ECG patterns seen in DOCA‐salt treated rats. Copyright © 2005 John Wiley & Sons, Ltd.