Pharmacokinetic study and neuropharmacological effects of atractylenolide Ⅲ to improve cognitive impairment via PI3K/AKT/GSK3β pathway in intracerebroventricular-streptozotocin rats.

Ethnopharmacological Relevance: The traditional Chinese herbal remedy Atractylodes macrocephala Koidz is renowned for its purported gastrointestinal regulatory properties and immune-enhancing capabilities. Atractylenolide III (ATL III), a prominent bioactive compound in Atractylodes macrocephala Koidz, has demonstrated significant pharmacological activities. However, its impact on neuroinflammation, oxidative stress, and therapeutic potential concerning Alzheimer's disease (AD) remain inadequately investigated.

Aim Of The Study: This study aims to assess the plasma pharmacokinetics of ATL III in Sprague-Dawley (SD) rats and elucidate its neuropharmacological effects on AD via the PI3K/AKT/GSK3β pathway. Through this research, we endeavor to furnish experimental substantiation for the advancement of novel therapeutics centered on ATL III.

Materials And Methods: The pharmacokinetic profile of ATL III in SD rat plasma was analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). AD models were induced in SD rats through bilateral intracerebroventricular (ICV) administration of streptozotocin (STZ). ATL III was administered at doses of 0.6 mg/kg, 1.2 mg/kg, and 2.4 mg/kg, while donepezil (1 mg/kg) served as control. Cognitive function assessments were conducted employing behavioral tests including the Morris Water Maze and Novel Object Recognition. Neuronal pathology and histological changes were evaluated through Nissl staining and Hematoxylin-Eosin (HE) staining, respectively. Oxidative stress levels were determined by quantifying malondialdehyde (MDA) content and total superoxide dismutase (T-SOD) activity. Molecular docking analysis was employed to explore the direct binding between ATL III and its relevant targets, followed by validation using Western blot (WB) experiments to assess the expression of p-Tau, PI3K, AKT, GSK3β, and their phosphorylated forms.

Results: Within the concentration range of 5-500 ng/mL, ATL III demonstrated exceptional linearity (R = 0.9991), with a quantification limit of 5 ng/mL. In male SD rats, ATL III exhibited a T of 45 min, a t1/2 of 172.1 min, a C of 1211 ng/L, and an AUC of 156031 ng/L*min. Treatment with ATL III significantly attenuated Tau hyperphosphorylation in intracerebroventricular-streptozotocin (ICV-STZ) rats. Furthermore, ATL III administration mitigated neuroinflammation and oxidative stress, as evidenced by reduced Nissl body loss, alleviated histological alterations, decreased MDA content, and enhanced T-SOD activity. Molecular docking analyses revealed strong binding affinity between ATL III and the target genes PI3K, AKT, and GSK3β. Experimental validation corroborated that ATL III stimulated the phosphorylation of PI3K and AKT while reducing the phosphorylation of GSK3β.

Conclusions: Our results indicate that ATL III can mitigate Tau protein phosphorylation through modulation of the PI3K/AKT/GSK3β pathway. This attenuation consequently ameliorates neuroinflammation and oxidative stress, leading to enhanced learning and memory abilities in ICV-STZ rats.