Fig. 1

Illustration of the injection protocols and study design. Dual-hit stereology cohort. (a). Subjects (n = 29) received two consecutive intraperitoneal injections of DSP4 (50 mg/kg; administered 2 months apart) to induce a stable noradrenergic lesion (as described in af Bjerkén et al.²), followed by a single dose of LPS (2.5 mg/kg body weight) one week after the final DSP4 injection. At 6-months, the animals were euthanized, brains dissected, and the tissue processed for immunohistochemistry and cell quantification using unbiased stereology. Neuroinflammatory response cohort. 3-months group (b), 6-months group, (c). Subjects (n = 64) were divided into two groups and administered intraperitoneal injections of either N-ethyl-2-bromobenzylamine (DSP4; 50 mg/kg) or saline. One week later, to induce a neuroinflammatory response, half of the subjects received intraperitoneal injections of LPS (2.5 mg/kg body weight), while the remaining half were given saline. Three months later, a subset of the rats (n = 32, designated as 6-months point subjects, (c) received booster DSP4 injections. At the conclusion of each experimental period, the animals were euthanized, and their brains were rapidly dissected on ice for subsequent biochemical analyses, including cytokine array and ELISA. Behavioral testing was performed on a sub-set of animals at 3 and 6 months (c). (Adapted and retrieved from https://app.biorender.com/biorender-templates.).