Biology subjects

Macheda, T.

Publications and source records attributed to Macheda, T..

4 recordsLinked to original sources

bioRxiv2026

Closed-head injury produces a delayed, region-specific defect in glucose-carbon routing at the pyruvate branchpoint in APP/PS1 KI mice

Traumatic brain injury (TBI) is a risk factor for Alzheimer's disease (AD), and both conditions are associated with impaired glucose metabolism and mitochondrial dysfunction. We previously reported time-dependent mitochondrial dysfunction following closed-head injury (CHI) in amyloid precursor protein/presenilin 1 (APP/PS1) knock-in (KI) mice, but whether glucose-derived carbon labeling showed a corresponding temporal pattern remained unknown. We hypothesized that early deficits would involve tricarboxylic acid (TCA)-cycle metabolites, whereas chronic changes persisted upstream at the pyruvate-lactate branchpoint. Here, oral uniformly 13C-labeled glucose ([U-13C]-glucose) tracing and gas chromatography-mass spectrometry (GC-MS)-based isotopologue analysis were used to quantify first-turn glucose-derived carbon fate in cortex and hippocampus. To distinguish the effects of age at injury from those of post-injury interval, mice were analyzed 1 month after injury either at 7 or 12 months of age or 8 months after injury at 12 months of age. The most pronounced alterations occurred 8 months after CHI, when KI mice exhibited increased pyruvate and lactate labeling in the cortex and broader increases in glycolytic labeling in the hippocampus. These findings suggest that in APP/PS1 KI mice, chronic closed-head injury produced a delayed shift in glucose-derived carbon labeling centered on glycolytic and pyruvate/lactate nodes, with loss of hippocampal precursor-product coupling but without broad reduction of first-turn TCA-linked labeling.

neuroscience↗

bioRxiv2025

Dim light at night impacts circadian rhythms and Alzheimer's disease-like neuroinflammation and neuropathology in humanized APP SAA knock-in mice

Artificial light at night (light pollution) is widespread but understudied in the context of Alzheimers disease (AD). Sleep and circadian disruption have been linked to amyloid-{beta} (A{beta}) accumulation and neuroinflammation, but whether dim light at night (dLAN) modifies these processes remains unclear. We tested whether chronic dLAN exposure (8 lux during the dark phase, 8 weeks) alters circadian rhythms, amyloid pathology, and neuroinflammation in 12-13 month-old humanized APP knock-in (KI) mice. hAPPSAA KI mice, which develop plaques, were compared with hAPPWT KI controls carrying only a humanized APP sequence. dLAN reduced circadian rhythm amplitude and stability while increasing fragmentation in both genotypes within two weeks. In hAPPSAA KI mice, dLAN modestly increased hippocampal plaque burden and soluble neocortical A{beta}. Astrocyte reactivity was elevated by genotype but not altered by nighttime light exposure. In contrast, microglial markers (CD45, MHCII) were increased with dLAN with CD45+ area elevated in hippocampus, and MHCII+ cell counts greater in the cortex and hippocampus of hAPPSAA KI mice. There were also distinct spatial responses between the microglia markers suggesting that dLAN primes microglia toward an antigen-presenting phenotype (MHCII) in the presence of A{beta}. Yet, the microglia/macrophage priming was not associated with amplified cytokine or chemokine levels at the 8-week dLAN exposure timepoint in the brain. These findings add to growing evidence that nighttime light exposure can disrupt circadian and immune regulation, and suggest that environmental light pollution should be further explored as a modifiable factor contributing to Alzheimers disease progression. Statement of SignificanceLight at night is a common feature of modern life, yet its influence on Alzheimers disease remains poorly understood. We show that dim light at night disrupts circadian rhythms, modestly increases amyloid pathology, and shifts microglia toward an antigen-presenting state in an amyloid-prone model. These findings identify light at night as a modifiable factor that may worsen risk or progression of neurodegenerative disease. A critical gap is whether circadian and immune changes resolve after darkness at night is restored. If they persist, early exposure could leave lasting imprints on brain aging. Addressing this question is essential for guiding strategies to mitigate the impact of light pollution.

neuroscience↗

bioRxiv2025

Traumatic brain injury exacerbates mitochondrial dysfunction in APP/PS1 knock-in mice through time-dependent pathways

Cerebral hypometabolism occurs in both traumatic brain injury (TBI) and Alzheimers disease (AD), but whether these conditions act through distinct or overlapping mechanisms is unclear. TBI disrupts cerebral metabolism via blood-brain barrier damage, altered glucose transporter expression, calcium buffering abnormalities, and oxidative damage to metabolic enzymes. AD-related hypometabolism is linked to amyloid-{beta} (A{beta}) effects on mitochondria, including impaired respiration, oxidative stress, and altered mitophagy, fusion, and fission. We tested whether TBI-induced mitochondrial dysfunction exacerbates A{beta}-mediated impairment using a closed-head injury (CHI) model in APP/PS1 knock-in (KI) mice. Injuries were delivered at 4-5 months of age, before plaque formation and mitochondrial deficits in KI mice. Bioenergetics were measured at 1, 4, and 8 months post-injury in hippocampus and cortex using Seahorse assays on isolated mitochondria. At 1 month, genotype-by-injury interactions revealed greater dysfunction in KI mice than either condition alone, with males more vulnerable than females. At 4-8 months, amyloid-mediated effects predominated, while TBI-specific changes were no longer apparent, suggesting recovery or convergence onto shared mechanisms. These results indicate that TBI can temporarily worsen mitochondrial dysfunction in the context of early amyloidosis, with sex influencing vulnerability. Findings provide insight into the temporal relationship between TBI and amyloid-induced mitochondrial deficits and support the importance of sex as a biological variable in neurodegenerative disease progression. HighlightsTBI and APP/PS1 genotype interact to worsen early mitochondrial dysfunction. Hippocampus exhibits greater susceptibility to combined TBI and amyloid pathology. Sex-specific effects and temporal patterns underscore TBIs role in AD risk. Male mice show heightened vulnerability to TBI-induced mitochondrial dysfunction. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=71 SRC="FIGDIR/small/679790v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@198e17org.highwire.dtl.DTLVardef@1bfa6d4org.highwire.dtl.DTLVardef@161c1d0org.highwire.dtl.DTLVardef@fb4dc1_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2020

Validation and standardization of a new radial-arm water maze protocol using a murine model of mild closed head traumatic brain injury

Cognitive impairments can be a significant problem after a traumatic brain injury (TBI), which affects millions worldwide each year. There is a need for establish reproducible cognitive assays in rodents to better understand disease mechanisms and to develop therapeutic interventions towards treating TBI-induced impairments. Our goal was to validate and standardize the radial arm water maze (RAWM) test as an assay to screen for cognitive impairments caused by TBI. RAWM is a visuo-spatial learning test, originally designed for use with rats, and later adapted for mice. The present study investigates whether test procedures, such us the presence of extra-maze cues influences learning and memory performance. C57BL/6 mice were tested in an 8-arm RAWM using a four-day protocol. We demonstrated that two days of training, exposing the mice to extra-maze cues and a visible platform, influenced learning and memory performance. Mice that did not receive training performed poorer compared to mice trained. To further validate our RAWM protocol, we used scopolamine. We, also, demonstrated that a single mild closed head injury (CHI) caused deficits in this task at two weeks post-CHI. Our data supported the use of 7 trials per day and a spaced training protocol as key factor to unmask memory impairment following CHI. Here, we provide a detailed standard operating procedure for RAWM test, which can be applied to a variety of mouse models including neurodegenerative diseases and pathology, as well as when pharmacological approaches are used.

neuroscience↗