CNR2 and Abnormal renal physiology: Seven studies [22, 26, 29, 36, 45, 52] reported Scr found that the knockout or blockade of CB2 group had no effect on Scr in renal dysfunction animals compared with the control group (Fig. 7B, 7 items, n = 102; SMD, 0.18; 95% CI − 0.85 to 1.20; P = 0.73; I2 = 77%).