We provided evidence that Licl provides significant protection from DM-induced apoptosis in neuronal cells. GSK-3 activity. Results We found that cytochrome C, Caspase-3, and Caspase-9 were overproduced in the hippocampus. Furthermore, the cytochrome C, Caspase-3, and Caspase-9 levels were restored after GSK-3 inhibitors Licl treatment. Conclusions Our results show that GSK-3 regulates the production of cytochrome C, Caspase-3, and Caspase-9 in STZ-induced rat brain and MK-5046 may therefore contribute to DM-caused cognitive dysfunction via inhibition of neural cell apoptosis. strong class=”kwd-title” MeSH Keywords: Enzyme Inhibitors, Glycogen Synthase Kinase 3, Mild Cognitive Impairment, Neural Cell Adhesion Molecules Background Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance and hyperglycemia [1]. It is reported that T2DM is strongly associated with dementia, with a 50 % increase in the risk for dementia [2]. Strong evidence showed that T2DM could lead to impaired attention, executive functioning and verbal memory [3]. Many findings showed hypoglycemia, the components of metabolic syndrome, could lead to neuronal cell death and learning and memory damage, eventually cause dementia, such as Alzheimers disease (AD) [4]. GSK-3 includes 2 forms: GSK-3 and GSK-3. GSK-3 has a mass of 51 kDa, while GSK-3 encodes a protein of 47 kDa [5]. They are both active in many physiological processes, controlled by phosphorylation at 2 levels: (i) inhibitory phosphorylation of serine residues S21/S9 in GSK3/ and (ii) tyrosine phosphorylation at Y279/Y216 in GSK3/ [6,7]. GSK3 has a role as tau-kinase I in AD and contributes to phosphorylation of Tau protein [8]. The positive and negative regulators of GSK-3 are Tyr2l6, Ser9, and phosphorylated Tyr2l6, whose phenyl ring is twisted outward to allow the substrate to enter the active pocket, while phosphorylated Ser9/Ser 2l is incorporated as a pre-phosphorylated pseudo-substrate [5]. A T-loop block prevents entry of substrate proteins. GSK-3, a multifunctional serine-threonine kinase, plays an important role in glycogen metabolism and has an important role in many cellular physiological events by phosphorylation of multifold substrate proteins, including Wnt and Hedgehog signal transduction pathways. Small molecular inhibitors of GSK-3 are new drugs for the treatment of chronic neurodegenerative disease [9], cancer [10], and type II diabetes [11], although the potential regulatory mechanisms of GSK-3 in T2DM and AD are still unclear. In the present study, we examined whether activation of the PI3K/AKT/GSK pathway leads to phosphorylation of GSK3 (ser9), thus inhibiting apoptosis and reducing cognitive dysfunction in a rat model of diabetes. Material and Methods All procedures were performed in accordance with current guidelines for Animal Experimentation at the Institutional Animal Care and Use Committee of MK-5046 Taizhou University (approval 15th of March 2018). Adult male Sprague-Dawley rats (200C250 g) were housed in groups of 3 at 252C, relative humidity of 50C60% and a natural 12/12-hour light/dark cycle. Forty Sprague-Dawley male rat were used in the experiments. The rats were randomly divided into 3 groups: control group (n=10), DM group (n=10), and DM plus Licl group (n=10). Experimental rats received intraperitoneal injection with 60 mg/kg STZ. The DM rats were determined by fasting blood glucose 16.7 mmol/L 72 h after STZ injection. Body weight was measured weekly. The 24-h food and water intake were assessed at week 6. Water Morris maze The apparatus [12,13] was 150 cm wide, 50 cm high, and Ccna2 40 cm deep, and water was maintained at 221C. The hidden platform (10 cm in diameter) was submerged 1 cm below the water surface and was placed in the middle of the same quadrant during the whole training stage. For the next 4 days (days 1C4), the rats (n=10 in each group) were tested MK-5046 3 times a day for a continuous interval of 5 min. In each experiment, a rat was placed in water facing the wall of the pool and allowed to search for the platform for 120 s. If the rat did not locate the platform within 120 s, it.