Anorexia nervosa (AN) induces organ dysfunction caused by malnutrition, including liver damage leading to a rise in transaminases due to hepatocyte damage. The underlying pathophysiology of starvation-induced liver damage is poorly understood. We investigate the effect of a 25% body weight reduction on murine livers in a mouse model and examine possible underlying mechanisms of starvation-induced liver damage. Female mice received a restricted amount of food with access to running wheels until a 25% weight reduction was achieved. This weight reduction was maintained for two weeks to mimic chronic starvation. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured spectrophotometrically. Liver fat content was analyzed using an Oil Red O stain, and liver glycogen was determined using a Periodic acid–Schiff (PAS) stain. Immunohistochemical stains were used to investigate macrophages, proliferation, apoptosis, and autophagy. Starvation led to an elevation of AST and ALT values, a decreased amount of liver fat, and reduced glycogen deposits. The density of F4/80⁺ macrophage numbers as well as proliferating KI67⁺ cells were decreased by starvation, while apoptosis was not altered. This was paralleled by an increase in autophagy-related protein staining. Increased transaminase values suggest the presence of liver damage in the examined livers of starved mice. The observed starvation-induced liver damage may be attributed to increased autophagy. Whether other mechanisms play an additional role in starvation-induced liver damage remains to be investigated.

Anorexia nervosa (AN) is associated with hyperactivity, amenorrhea, and brain atrophy. The underlying pathophysiology is mostly unknown, and new targets for therapeutic interventions are needed. This study aimed to systematically establish a murine AN model with the parameter extent of starvation, animal age, and length of starvation for functional studies. The activity-based anorexia (ABA) model combines food restriction with running wheel access. Early adolescent and adolescent mice received 40% of their baseline food intake until a 20% or 25% weight reduction was reached (acute starvation). To mimic chronic starvation, body weight loss was maintained for another two weeks. Running activity was examined using wheel sensors, while amenorrhea was investigated by analysis of vaginal smears. Brain sections were used to analyze cerebral cortex volumes. Acute starvation did not lead to either AN-related symptoms, whereas chronic starvation led to hyperactivity and amenorrhea except in the adolescent cohort with 20% weight reduction. Only ABA mice with 25% weight reduction revealed a cortex volume reduction. The optimal parameters to mirror AN-related symptoms included a 25% weight reduction, early adolescent or adolescent mice, and chronic starvation. The ABA model enables functional analysis of the impact of chronic AN on the underlying hormonal, behavioral, and brain pathophysiology.

Objective: Anorexia nervosa (AN) is associated with hyperactivity, amenorrhea, and brain atrophy. Weight rehabilitation reversed these symptoms, although the underlying pathophysiological mechanisms are mostly unknown. Serum neurofilament light chain (NfL) levels are widely used as a biomarker of neurodegeneration. Based on neuroimaging studies and increased serum NfL levels, we assume that neurodegeneration is a core neuropathological feature in AN patients.Method: Female mice were given a limited amount of food once a day and had unlimited access to a running wheel until they reached a 25% weight reduction, which was maintained for 2 weeks to mimic chronic starvation. This was followed by 3 weeks of refeeding. Running activity was measured by wheel sensors, while amenorrhea was determined by analyzing vaginal smears. Brain sections were used to investigate brain volumes. NfL levels were determined using a NF‐light assay. Behavioral tests such as forced swim and elevated plus maze assessed behavioral changes. Immunohistochemistry was used to quantify the density of microglia, while their morphological analysis was performed using Neurolucida 360.Results: Chronic starvation led to AN‐related symptoms of hyperactivity and amenorrhea. The decreased cerebral cortex, hippocampal, and corpus callosum volumes were paralleled by increased NfL levels after chronic starvation. A behavioral association was reduced anxiety‐like behavior after chronic starvation. Starvation induced decreased microglial density, increased soma area, and prolonged microglial processes.Discussion: Chronic starvation led to an increase in NfL levels and changed microglial morphology in a mouse model of AN, suggesting that neuronal pathophysiology may contribute to the disease.

Objective: Anorexia nervosa (AN) is an eating disorder characterized by severe weight loss and associated with hyperactivity and circadian rhythm disruption. However, the cellular basis of circadian rhythm disruption is poorly understood. Glial cells in the suprachiasmatic nucleus (SCN), the principal circadian pacemaker, are involved in regulating circadian rhythms. We hypothesize that the circadian rhythm disruption in AN patients is associated with glial cell changes in the SCN.Method: In the starvation‐induced hyperactivity mouse model, mice had free access to a running wheel and received a restricted amount of food once a day, until a 25% body weight loss was reached and maintained their weight loss for two weeks. This was followed by a refeeding phase. Different daily periods of running wheel activity were defined, such as food anticipatory activity up to 4 h before feeding. Circadian rhythmicity was analyzed using the cosinor method. Gene expression was evaluated using real‐time polymerase chain reaction. Immunohistochemistry was used to quantify astrocytes, microglia, and oligodendrocytes.Results: Starvation induced changes in circadian rhythm, as indicated by changes in cosinor‐based characteristics. Refeeding reversed these effects. Additionally, there was an increase in cryptochrome circadian regulator 1 expression and a decrease in the density of astrocytes and oligodendrocytes in the SCN after chronic starvation.Discussion: Starvation‐induced alterations in circadian rhythms are associated with molecular, and cellular changes in the hypothalamus. Reduced astrocytes and oligodendrocytes in the SCN in a mouse model of AN suggest that glial pathophysiology may play a role in circadian rhythm disruption.

Reactive astrocytes are a hallmark of several neurological diseases in multiple sclerosis and experimental demyelination models. Their morphological alterations are commonly assessed by qualitative histopathology, yet quantitative tools are required to better capture astrocytic heterogeneity and to allow correlations with imaging-derived biomarkers. Here, we present a workflow for the quantitative analysis of Glial Fibrillary Acidic Protein (GFAP) network remodeling in astrocytes in the cuprizone model of demyelination. C57BL/6 mice were intoxicated with cuprizone for 3 or 5 weeks to induce progressive demyelination, microglial activation, and reactive astrogliosis. Brain sections were processed for anti-GFAP immunohistochemistry, and individual astrocytes from the stratum oriens of the hippocampus were digitally reconstructed. Diverse parameters of GFAP topology, including soma size, process length, branching order, convex hull area, and ramification index, were extracted using either the commercial Neurolucida^® 360 software or the open-source Simple Neurite Tracer (SNT) plugin in ImageJ. Principal component analysis revealed clear differences between control astrocytes and astrocytes in cuprizone-intoxicated animals, with reactive astrocytes displaying increased numbers of primary processes, enhanced bifurcation, and process complexity. Comparative evaluation of Neurolucida^® 360 and SNT demonstrated that both tools are suitable for astrocyte reconstruction, although Neurolucida^® 360 enabled faster and more detailed tracing. This protocol provides a reproducible pipeline for the quantitative assessment of astrocyte morphology under control and pathological conditions, thereby supporting future efforts to link cellular remodeling to functional outcomes in neuroinflammatory disease models.

Objective: Anorexia nervosa (AN) is a severe eating disorder associated with extreme weight loss, hyperactivity, and amenorrhea. Neuroimaging studies revealed brain atrophy and disruption of white matter integrity in the corpus callosum (CC) of patients with AN. However, the underlying pathophysiological mechanisms remain unclear. Emerging evidence indicates that starvation induces changes in mitochondrial metabolism and dynamics. We hypothesize that disturbances in white matter integrity arise from modifications in oligodendrocytes, associated with changes in the morphology of myelinated fibers and mitochondrial structure. Method: The starvation‐induced hyperactivity (SIH) model was used, in which mice received a restricted daily amount of food in combination with free access to a running wheel. A body weight loss of 25% was maintained over 2 weeks, followed by a 3‐week refeeding phase. Oligodendrocyte density and staining intensity of oligodendrocyte lineage transcription factor 2 (OLIG2) in the CC were analyzed using immunohistochemical staining. Morphometric investigation of myelinated fibers and mitochondria was conducted by transmission electron microscopy (TEM) analysis. Results: Starvation led to decreased oligodendrocyte density and reduced anti‐OLIG2 staining intensity in the CC, which was reversible following refeeding. Additionally, starvation induced a decrease in axonal caliber and an increase in mitochondrial density in the white matter, accompanied by a reduction of mitochondrial area. Discussion: The findings suggest that oligodendroglial and axonal alterations, alongside disrupted mitochondrial dynamics, impair structural integrity in the white matter and contribute to the pathophysiology of AN.