Long-Term Creatine Supplementation Improves Cognitive and Hippocampal Structural Plasticity Impairments in a D-Gal-Induced Aging Model via Increasing CK-BB Activity in the Brain.

Creatine (Cr) is recognized for its role in enhancing cognitive functions through the phosphocreatine (pCr)-creatine kinase system involved in brain energy homeostasis. It is reversibly converted into pCr by creatine kinase (CK). A brain-specific isoform of CK, known as CK-BB, is implicated in the brain's energy metabolism. The objective of this research is to ascertain the impact of Cr supplementation on learning and memory skills as well as on structural synaptic plasticity, by modulating CK-BB. First, we utilized various concentrations of D-galactose (D-gal) to create an aging mouse model. Our findings indicated that D-gal injections at 100 and 1000 mg/kg could lead to cognitive decline, oxidative stress, and damage to structural synaptic plasticity. CK-BB expression and its activity were reduced at least by approximately 20% in mice injected with 100 and 1000 mg/kg D-gal compared with control group. Next, an adeno-associated virus directed against CKB was employed to reduce CK-BB levels by 34% in the brain. The reduction of CK-BB in the brain resulted in deficits in learning and memory, oxidative stress, and morphological harm to the hippocampal spines of mice. Finally, the diet of the D-gal-induced aging model was enriched with 3% Cr. Mice that received 3% Cr supplementation exhibited a 36% increase in CK-BB activity and a 14.3% increase in CK-BB expression following prolonged D-gal administration. In addition, Cr supplementation mitigated the cognitive impairment, oxidative stress, and hippocampal structural plasticity damage caused by chronic D-gal injections. Overall, our study revealed that CK-BB has a critical role in mediating structural plasticity in D-gal-induced cognitive impairment. Moreover, it showed that supplementary Cr could serve as a potent neuroprotective substance, preventing or delaying the course of age-related cognitive deficits.