IntroductionIn the present study, we assessed the effects of the hyper‐harmonized‐hydroxylated fullerene–water complex (3HFWC) on Alzheimer's disease (AD) neuropathological hallmarks in 5XFAD mice, an AD animal model.MethodsThe 3‐week‐old 5XFAD mice were exposed to 3HFWC water solution ad libitum for 3 months in the presymptomatic phase of pathology. The functional effects of the treatment were confirmed through near‐infrared spectroscopy (NIRS) analysis through machine learning (ML) using artificial neural networks (ANNs) to classify the control and 3HFWC‐treated brain tissue samples. The effects of 3HFWC treatment on amyloid‐β (Aβ) accumulation, plaque formation, gliosis, and synaptic plasticity in cortical and hippocampal tissue were assessed.ResultsThe 3HFWC treatment significantly decreased the amyloid‐β plaque load in specific parts of the cerebral cortex. At the same time, 3HFWC treatment did not induce the activation of glia (astrocytes and microglia) nor did it negatively affect synaptic protein markers (GAP‐43, synaptophysin, and PSD‐95).ConclusionThe obtained results point to the potential of 3HFWC, when applied in the presymptomatic phase of AD, to interfere with amyloid plaque formation without inducing AD‐related pathological processes such as neuroinflammation, gliosis, and synaptic vulnerability.

Changes in housing density, including individual housing, are commonly necessary in animal research. Obtaining reproducibility and translational validity in biomedical research requires an understanding of how animals adapt to changes in housing density. Existing literature mainly addresses acclimatization after transportation. We used a within-subject design to examine changes in behavior and weight gain of 4-mo-old male Wistar Han rats after reduction of their social group (RSG; due to removal of one rat from a cage containing 3 rats) and social isolation (SI; the removed rat) for the subsequent 2 wk. Changes in weight gain and in exploratory and center-avoidance behavior in an inescapable open arena (OA) were measured before (D0) and on days 7 and 14 (D7 and D14, respectively) after social change. The motor response to d-amphetamine (1.5 mg/kg), which stimulates behavioral arousal in response to novelty, was assessed at D14. Within-subject design revealed that RSG rats in OA had less locomotion at D7 but not more center-avoidance behavior and had returned to the D0 activity level at D14; SI rats in OA had consistently less locomotion and more center-avoidance behavior. Rearing behavior during OA exposure did not change in either group. However, SI rats showed more center-avoidance behavior in OA, greater weight gain, and less amphetamine-induced rearing at D14 as compared with RSG rats. These data indicate that after RSG, mature adult male rats require 2 wk to return to their baseline level of OA-related behavior, while after SI they gain weight and acquire maladaptive exploratory and center-avoidance behavior. The finding that SI produces maladaptive behavioral and physiologic alterations in adult male rats deserves attention because these changes could have confounding effects on research findings.