l-carnosine improves shortterm spatial recognition memory and passive avoidance learning and memory in streptozotocin-diabetic rats

Background and objective: diabetes mellitus (dm) affects synaptic plasticity in the hippocampus, leading to impairments in learning and memory. l-carnosine, an endogenous dipeptide, is reported to exhibit anti-diabetic and antioxidant effects. therefore, this study was designed to evaluate its effect on learning and memory in diabetic rats. materials and methods: in the present study, male wistar rats (n=32) were randomly divided into four groups: control, control treated with carnosine (100 mg/kg), diabetic, and diabetic treated with carnosine (100 mg/kg). diabetes was induced by streptozotocin (stz) at a dose of 60 mg/kg. l-carnosine was injected i.p. at a dose of 100 mg/kg one week after stz injection for 8 weeks. blood sample was taken from retro-orbital plexus before stz injection and 4 and 8 weeks after stz injection to measure blood glucose level. passive avoidance and y maze tests were done to assess learning and memory deficits. results: after 8 weeks, diabetic rats showed a significant cognitive dysfunction in passive avoidance and y maze tests that was significantly attenuated following carnosine treatment. in addition, carnosine showed a hypoglycemic effect. conclusion: this study demonstrated that treatment with carnosine for 8 weeks could improve cognitive functions in diabetic condition and part of its beneficial effect is due to its reduction of blood glucose.