Gongronema latifolium Benth methanol leaf extract reduces blood pressure in L-NAME-induced hypertension in rats via modulation of aortic endothelial nitric oxide synthase

Abstract

Gongronema latifolium is a climbing shrub traditionally used in Nigerian ethnomedicine for hypertension, diabetes, malaria, digestive disorders, and as a nutrient-rich vegetable high in proteins, vitamins, and minerals. This study aimed to evaluate the effects of methanol leaf extract of G. latifolium (GLE) on blood pressure, electrocardiographic (ECG) parameters, oxidative stress, organ function, lipid profiles, histoarchitecture, and endothelial nitric oxide synthase (eNOS) expression in L-NAME-induced hypertensive rats. G. latifolium leaf was washed, dried and extracted with 70% methanol. Thirty-five male Wistar rats (150-200 g) were divided into seven groups (n=5): control (distilled water), L-NAME (40 mg/kg), GLE alone (100 mg/kg), L-NAME + GLE (50, 100, 200 mg/kg), and L-NAME + captopril (40 mg/kg). Oral treatments lasted 28 days. Non-invasive tail-cuff blood pressure, ECG, serum biomarkers (lipids, liver/kidney enzymes, electrolytes, oxidative stress markers), immunohistochemistry for eNOS, was assessed. Data were analyzed via one-way ANOVA with Tukey’s post-hoc (P < 0.05). L-NAME significantly elevated systolic/diastolic/mean arterial blood pressures, heart rate, prolonged ECG intervals (P, PR, QRS, QTc), increased MDA, liver/kidney markers, lipids (T-CHOL, TG, LDL, VLDL, CRI), and chloride, It reduced HDL, antioxidants (GSH, SOD, CAT, GST, nitrite), and eNOS expression in the aorta and heart, GLE dose-dependently reduced blood pressures, normalized most ECG parameters (except QTc prolongation at 200 mg/kg), boosted antioxidants/nitrite, normalized organ/lipid/electrolyte markers (LDL reductions 9.6-18.1%, CRI 10.6-17.6%), and upregulated aortic eNOS.