Protective effect and possible mechanisms of ligustrazine isolated from Ligusticum wallichii on nephropathy in rats with diabetes: A preclinical systematic review and meta-analysis

Ligusticum wallichii has been used to treat renal diseases for thousands of years in China. Ligustrazine (Lig) is the active ingredient of Ligusticum wallichii that possesses a variety of biological activities against kidney disease.The purpose of this review is to further evaluate whether the supplementation with Lig has an effect on improving renal pathology, renal function indexes and blood glucose levels in animal model of diabetic nephropathy (DN). Potential mechanisms of Lig for DN as well as the existing problems regarding the modeling method and limitations in this area of research were also summarized.The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) checklist was used to organize the search of eight databases from inception to June 2019. We used Cochrane Collaboration's 10-item checklist and Rev-Man 5.3 software to analyze the data as well as risk of bias.The study quality scores ranged from 2 to 6 points with an average of 4.471. Compared with the control group, Lig significantly improved pathological changes of kidney including glomeruli and tubules, and induced significant decreases in levels of blood urea nitrogen, serum creatinine, 24-h urinary albumin and HbA1c, as well as increasing creatinine clearance rates. In subgroup analysis, the groups of high-dose STZ (≥60 mg/kg) and longer period of Lig treatment (>8 w) showed better results than those of the control group. No difference was seen between the high (>150 mg/kg, QD) and low (≤150 mg/kg, QD) dose of Lig treatment groups.Lig exerts renoprotective functions in an animal model of DN mediated by antioxidant action, inhibition of apoptosis, anti-inflammatory action, reduction of renal fibrosis, reduction of the proliferation of mesangial cells, inhibition of endotheliosis, inhibition of atherosclerosis and promotion of renal autophagy. The positive conclusion should be treated cautiously because of various methodological flaws. Further studies are recommended according to ARRIVE guidelines. The method of modeling with high-dose STZ should be avoided and improved STZ modeling schemes are recommended. Considering the large dosage range of Lig used clinically and in animals, the future studies on the basis of animal renal histology are urgently needed to determine the optimal dosages to delay histological changes. Nevertheless, together, our findings suggest that Lig is a renoprotective candidate drug for treatment of DN.