Hypercholesterolemia Duration and Brain Area Determine Inflammatory Response Intensity and Apoptotic Mediator Activation in Apo E−/−/LDLR−/− Double-Knockout Mice

Hypercholesterolemia (Hch) is a risk factor for cerebrovascular and neurodegenerative diseases, manifesting with symptoms that vary depending on damage to specific brain regions. Hch triggers inflammatory responses and cell death. However, the progression of these processes in relation to the duration of Hch and the location of pathology in the central nervous system remains unclear. Therefore, we aimed to investigate (1) the impact of age and duration of Hch on neuroinflammatory responses and programmed cell death in the brain and (2) the intensity of these processes in various brain areas during Hch. In this study, we used 3-, 6-, and 12-month-old male Apo E^-/-/LDLR^-/- double-knockout mice and age-matched wild-type C57BL/6 mice (control group). Concentrations of cytokines IL-1β, IL-4, and IL-6, as well as apoptotic mediators AIF and Cas-3, were measured using enzyme-linked immunosorbent assay in the whole brain and separately in the prefrontal cortex (PFCx), hippocampus (HIP), and striatum (STR). The results showed that the Hch-induced release of cytokines IL-1β and IL-6, decreased expression of IL-4, and elevated level of apoptotic markers AIF and Cas-3 correlated with Hch duration. The inflammatory response and expression of apoptotic markers were more pronounced in the HIP and STR compared to the PFCx. Our results indicate a correlation between the neurodegenerative effects of Hch and its duration and highlight the varying susceptibility of different brain areas to Hch-induced damage.