Spirulina, a dietary supplement, attenuates streptozotocin-induced diabetes by improving cognitive function through anti-inflammatory and antioxidant effects in rats

BACKGROUND AND AIM: Prolonged diabetes mellitus leads to cognitive impairments and attentional dysfunctions. Spirulina, a blue-green microalga, has been reported to have antidiabetic properties and various protective effects. This research aimed to examine the impact of Spirulina on improving learning and memory decline in a rat model of type 1 diabetes induced by streptozotocin (STZ). Additionally, the study explored the mechanisms behind its effects, particularly its role in oxidative stress and inflammation. METHODS: Rats were divided into four experimental groups: control, control with Spirulina treatment, diabetic, and diabetic with Spirulina treatment. Spirulina was administered daily via oral route (200 mg/kg) for a duration of 4 weeks. RESULTS: The administration of Spirulina to the diabetic group improved functional performance in various behavioral tests, including the open field test, novel object discrimination tasks (recognition), and the Morris water maze. Additionally, Spirulina treatment reduced hippocampal acetyl cholinesterase activity and lowered levels of malondialdehyde, while enhancing antioxidants such as superoxide dismutase. Furthermore, the levels of inflammatory indicators in the hippocampus, specifically interleukin-6 and tumor necrosis factor α, were lower after Spirulina administration. Conversely, the number of intact neurons in the CA1 region of the hippocampus, particularly the pyramidal neurons, decreased in the diabetic group, but this reduction was alleviated following Spirulina treatment. CONCLUSION: In summary, Spirulina can improve cognitive deficits in STZ-diabetic animals. This is partly due to its ability to reduce oxidative stress and inflammation, as well as potentially enhance cholinergic function and provide neuroprotective benefits.