In total, 1975 relevant studies were retrieved from eight databases, 1015 duplicate records were removed, and 960 articles remained. After screening the titles and abstracts, 832 articles were eliminated and 128 citations entered the full-text reading stage, from which 106 articles were excluded. Ultimately, 22 studies were included in the data syntheses and meta-analysis. The flow diagram of the study selection process is shown in Fig. 1.

Flowchart of literature selection process and screening results

Twenty-two studies with a total of 747 rats were included; 266 rats were in treatment groups and 481 rats in control groups. These studies were published from 2000 to 2022, of which 15 were in Chinese and 7 in English. The species of experimental animals in the included studies were Sprague Dawley or Wistar rats. Fifteen studies [24,25,26, 30,31,32,33,34,35,36,37,38,39,40,41] included only male animals, two [42, 43] included only female, and five [44,45,46,47,48] included equal numbers of each sex. For modelling VaD, eight studies [24,25,26, 30, 32,33,34,35] used the bilateral common carotid artery ligation (AL) method, two [31, 40] used bilateral internal carotid AL method, one [43] used middle cerebral AL method, one [42] used the bilateral common carotid intermittent artery clamp (AC) method, six [36, 41, 45,46,47,48] used the 4-vessel occlusion (4-VO) method, and four [37,38,39, 44] used the thromboembolus method (TM). Only two studies [33, 38] reported treatment by a licensed acupuncturist. No one reported the adverse acupuncture reactions.

In terms of acupuncture stimulation methods, MA was utilized in 12 studies [24,25,26, 30, 33, 34, 36,37,38,39, 44, 45] and EA in 10 studies [31, 32, 35, 40,41,42,43, 46,47,48]. Among them, nine studies [31, 32, 40,41,42,43, 46,47,48] reported the parameters of EA, 4 studies [31, 32, 40, 47] used disperse-dense wave, and 5 studies [41,42,43, 46, 48] used continuous wave. Nine [31, 32, 40,41,42,43, 46,47,48] and two studies [31, 48] described the frequency and intensity of EA ranging from 1 to 150 Hz and 0.2 mA to 1.5 mA, respectively. All studies described the acupoints, and a total of 19 acupoints were used. Acupoints used most frequently were GV20 (16 times), ST36 (13 times), BL23 (4 times), GV14 (4 times), and SP10 (4 times). GV20–ST36 was the acupoint combination used most often.

In the 22 included studies, seven oxidative stress indicators were reported, including ROS, MDA, NO, NOS, SOD, GSH-Px, and CAT. All studies used the MWM test to measure behavioural changes. For the control group, all studies used non-intervention, and 11 [24,25,26, 30, 33,34,35, 37,38,39, 44] used sham acupuncture in which a non-acupoint was stimulated. Four studies [41, 46,47,48] used nimodipine. The main features of the included studies are summarized in Table 1.

Among the 22 included studies, four [31, 32, 35, 36] reported the animals were randomized by using appropriate methods such as a random number table or computer-generated random numbers, whereas four studies [41, 46,47,48] reported an inappropriate approach for sequence generation, such as by sex or weight of animals. The remaining 14 studies [24,25,26, 30, 33,