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Global Translational Medicine Brain morphology in obesity

2.2. The Porsolt test 3. Results

The Porsolt test (assessment of depression) was carried 3.1. Mass-metric parameters
out at the final stage of the experiment (between 9:00 and
12:00, with the rats in a fasting state) and in females during As shown in Figure 1A and B, the body weight of rats in
the diestrus phase. Each rat was placed for 6 min in a vessel each experimental group increased progressively as the
filled with water up to a 30 cm mark and maintained at they matured from 2 to 6 months of age. By the end of
a temperature of 24 – 25°C. The duration of the first act the experiment, the body weight of rats of the same sex
was comparable in all groups. However, in both sexes of
of active swimming, as well as the number and duration rats receiving the HCD, there was a statistically significant
of “freezes” (absence of swimming movements), was increase in the mass (Figure 2A) and MC (Figure 2B) of
recorded. A refusal to actively swim characterizes a state of visceral adipose tissue, indicating the development of diet-
“despair”, which is considered a sign of depression. 13
induced visceral obesity.
2.3. Morphological analysis
3.2. Morphological analysis of the PFC
After the animals were sacrificed, the rat brain was In male rats on a StD, the histoarchitecture of the PFC was
isolated and placed on a cryostat block after deep freezing intact (Figure 3A). All six layers of neurons were visible.
to eliminate artifacts. Unfixed brains were sectioned into Most neurons were normochromic, with a centrally
frontal slices of 7 μm thickness using an HM525 Cryostat located nucleus and a distinct nucleolus. Mild changes
(MICROM International GmbH, Germany). The slice were observed in a few individual neurons, mainly with
level was determined according to the stereotaxic atlas disturbances in tinctorial properties. Blood vessels were
14
of the rat brain. For light microscopy, the slices were unchanged. The GI, representing the ratio of the number
stained with toluidine blue using the Nissl method. of glial cells to the number of neurons, was 0.46 in the
Micrographs and photomicrographs were captured male control group (Figure 4D). Similarly, in female rats
using an Altami LUM-1 light microscope equipped with on StD, the histoarchitecture of the PFC remained intact
a digital camera (Altami LLC, Russia). Morphometric (Figure 5A). All layers of neurons were identified. There
analysis of the digitized images was performed were individual neurons with slight changes, mainly with
automatically using ImageJ software (National Institutes disturbances of the tinctorial properties. Blood vessels
of Health, USA), utilizing tools from the “Analyze’ menu, were unchanged and the GI was 0.44 (Figure 4D).
including the “Analyze Particles” and “Multi-Point Tool”
options. Calibration of slice images in micrometers The overall structure of PFC in the male rats remained
was performed using the built-in “Set Scale” function. intact after 16 weeks of being on a HCD (Figure 3B). All
Morphometric analysis of histological preparations was layers of neurons were identified. However, there was a
performed at ×400 magnification in 10 fields of view. In tendency toward a reduction in neuron size and an increase
PFC preparations stained with the Nissl method, data in the number of neurons with moderate degenerative-
were collected on the number of neurons per field of dystrophic changes (Figure 4A-C). Hypochromic neurons
view, the mean neuron size (in μm ), and the number and cells with disturbed tinctorial properties were found in
2
of neurons with signs of destruction (ND). The total the population of neurons. Individual destroyed neurons
number of neurons and the number of neurons with were identified, with glial elements accumulating around
signs of destruction per 1 mm were determined in them in some areas, indicating neuronophagia (Figure 3B).
2
hippocampal preparations. The glial index (GI) was The GI was statistically significantly increased, exceeding
calculated as the ratio of the number of glial cells to the the control value by approximately 1.3 times (P = 0.007)
total number of neurons. (Figure 4D). In addition, perivascular edema was observed
around the vessels of the microcirculatory channel.
2.4. Statistical analysis
In female rats on a HCD, the overall structure of the
Statistical analysis was performed using Statistica 10.0 PFC remained undisturbed (Figure 5B). All neuronal
(Tibco, USA). Normality was assessed with the Shapiro– layers were identified. Morphometric analysis revealed a
Wilk test. Parametric variables were expressed as mean significant increase in neuron size. However, the proportion
± standard deviation and analyzed with Student’s t-test. (%) of neurons with degenerative-dystrophic changes was
The non-parametric variables were expressed as median significantly higher compared to the control group (1.5-
and the 25 and 75 percentiles, and the variables were fold, P = 0.018) (Figure 4A-C). Hypochromic neurons and
th
th
analyzed using the Mann–Whitney U-test. A P < 0.05 was cells with disturbed tinctorial properties were found in the
considered statistically significant for all tests. population of neurons, along with a few destroyed neurons

Volume 4 Issue 1 (2025) 82 doi: 10.36922/gtm.5000