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Global Translational Medicine Brain morphology in obesity

The problem of obesity is now being considered not only Changes in the cerebral cortex, which is responsible for
in terms of its damage to somatic health but also its negative the cognitive control of food intake, may either contribute
effects on psycho-emotional status, cognitive abilities, to or result from obesity, further supporting the notion of
and behavior. Experiments in rats have shown that long- impaired regulation of eating behavior.
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term diet-induced obesity, initiated in prepubertal age, The study aimed to investigate the histological
leads to depression and neuroinflammation. A review of characteristics of the PFC and hippocampus in male and
the current literature generally confirms the link between female rats subjected to diet-induced visceral obesity.
obesity and depression in humans, although there are
conflicting findings in some studies. 5 2. Materials and methods
Experimental studies in rats also show that high-fat 2.1. Animals and diets
or combined high-fat and sucrose diets cause cognitive
impairments, particularly in reduced short-term and The study was conducted on 2-month-old sexually mature
visuospatial memories. Early obesity, before the onset male and female Wistar rats. These rats were bred in-house
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of diabetes or metabolic syndrome, leads to cognitive in a certified vivarium at the Institute of Physiology of the
impairment. This is due to changes in the PFC, including National Academy of Sciences of Belarus. They were kept
synapse loss, a reduction in dendritic spine density, altered under a 12/12 h light/dark cycle at a temperature of 22
expression of synaptic proteins, and structural changes in ± 2°C and humidity of 60 – 65%. The male (n = 27) and
microglia. The results strongly suggest that obesity can be female (n = 27) Wistar rats were randomly divided into
considered a contributing factor to dysfunction of the PFC. 7 two experimental groups: control and HCD. The control
group, consisting of 13 male and 14 female rats, received
There is emerging evidence of a link between obesity the standard diet (StD), while the HCD group, comprising
and brain development during ontogenesis. For example, 14 male and 13 female rats, was given an HCD for 16 weeks.
Laurent et al. examined the relationship between body
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mass index (BMI), cortical thickness, and executive The HCD consisted of StD supplemented with animal
function in children. Among the 3190 children studied fats (lard) (45% of daily caloric content) and a 10% fructose
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(mean age 10.0 years; 51.0% boys), those with a higher- solution (replacing water) ad libitum. The caloric content
than-normal BMI showed reduced cortical thickness. of StD for each rat was 150 kcal/day (i.e., the normal diet at
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Hall et al. suggested that the thickness of the inferior the vivarium of the Institute of Physiology of the National
frontal gyrus and lateral orbitofrontal cortex may serve Academy of Sciences of Belarus). In contrast, the caloric
as predictors of body composition. The study concluded content of HCD for each rat was 228 kcal/day.
that PFC morphology is a reliable predictor of body This study was approved by the Bioethics Committee
composition in early adolescence and is associated with of the Institute of Physiology of the National Academy of
certain cognitive functions, while also being partially Sciences of Belarus (protocols No:1 on January 22, 2021,
influenced by environmental factors. and No:2 on February 2, 2022) and was conducted in
Pathological changes in the state of the hippocampus accordance with the guidelines set forth by the European
in obesity in humans have been less studied, although Convention for the Protection of Vertebrate Animals (ETS
associations have been made between the state of the No. 123).
hippocampus and several neuropathological processes. The rats were euthanized by decapitation under
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However, there is evidence that a high-calorie diet (HCD) anesthesia induced with sodium thiopental. Female rats
and physical inactivity, which promote obesity and diabetes, were euthanized during the diestrus phase of the estrous
are risk factors for hippocampal neurodegeneration and cycle, determined by the type of cells present in vaginal
cognitive impairment. It has been suggested that diet- swabs. 12
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induced obesity may lead to impaired neuronal plasticity The body weight of the rats was measured using
in the hippocampus, which in turn may contribute to
cognitive decline, emotional disturbance, and hyperphagia. a weighing scale (Saturn ST-KS7230, China). After
Adipose tissue regulates hippocampal function through euthanasia, the visceral fat was collected and weighed on a
the release of adipokines, which may directly or indirectly laboratory weighing scale (Scout Pro, China). For male rats,
modulate both neural plasticity and neuroinflammation. the visceral fat mass included paranephral and epididymal
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However, the potential mechanisms by which adipose fat deposits, while for female rats, it included paranephral
tissue inflammation in obesity leads to neurodegeneration and periovarian fat deposits. The mass coefficient (MC) of
and neuroinflammation in the PFC and hippocampus the visceral fat was calculated using the following formula:
remain poorly understood. MC = (Visceral fat mass/Body weight) ×100% (I)

Volume 4 Issue 1 (2025) 81 doi: 10.36922/gtm.5000