Page 96 - GTM-4-2

Global Translational Medicine Thyroid status in obesity

2.2. Morphological analysis 3. Results

At necropsy, the thyroid gland was extracted from the 3.1. Mass-metric parameters
animals for morphologic examination. Thyroid tissue
fragments were subjected to rapid freezing in an HM At the start of the experiment, male and female rats
(2 months old) weighed approximately 220 – 230 g. After
525 cryostat (MICROM International GmbH, Germany). 16 weeks, the mean body weight of males in the control
Cryostat sections (7 μm) were stained with hematoxylin-
eosin for structural analysis. Microstructure examination, group was 433.46 ± 48.38 g, while those in the HCD
morphometry, and microphotography were performed group reached 471.14 ± 94.11 g. The mean body weight of
using a light microscope (Altami LUM-1, Altami LLC, females in the control group was 310.93 ± 25.43 g, while
that of the HCD group was 316.31 ± 72.07 g. No significant
Russia) equipped with a digital camera (1300D EOS Body,
Canon, Japan). differences in final body weight were observed between the
control and HCD groups of the same sex.
Images were analyzed using ImageJ software (National
Institutes of Health, USA). For thyroid follicles counted Male rats in the control group had visceral adipose tissue
in ten fields of view at ×400 magnification, we measured that weighed 7.99 ± 2.64 g and had an MC of 1.82 ± 0.49%.
follicle area (in μm ), inner follicle diameter (in μm), In the HCD group, these values increased significantly to
2
and follicular epithelium height (in μm). The colloid 22.99 g ± 11.97 g (p<0.001) and 4.64 ± 1.67% (p<0.0001),
accumulation index (CAI) was calculated as the ratio of respectively (Figure 1A and B). In female rats, visceral fat
the inner follicle diameter to twice the follicular epithelium mass was 8.86 ± 4.86 g in the control group (MC: 2.78 ±
height. 1.31%) and significantly higher than in the HCD group
(17.22 ± 9.07 g, p=0.006; MC: 5.15 ± 2.11%; p=0.002)
2.3. Biochemical and hormonal parameters (Figure 1A and B). These data indicate the development
of visceral obesity in rats of both sexes following HCD
Biochemical parameters in blood serum and thyroid administration.
homogenates (diluted 1:80 in 0.05 M PBS) were
determined using a BS-200 biochemical automatic 3.2. Morphological analysis of the thyroid gland
analyzer (Shenzhen Mindray Bio-Medical Electronics,
China) and commercial kits (Production Unitary The examination of thyroid gland preparations from control
Enterprise “Diasens,” Belarus). Quality control was male and female rats revealed a well-developed follicular
performed using control sera (Randox Laboratories, UK). structure with thin connective tissue septa separating
Malonic dialdehyde (MDA) levels in thyroid homogenates gland lobules (Figure 2A and C). The follicles were round
were determined using the spectrophotometric method or angular, lined with single-layer cuboidal epithelium,
by reaction with thiobarbituric acid. Thyroid peroxidase and larger at the gland periphery compared to the
10
(TPO) activity was estimated based on iodide oxidation center. The follicular cavities contained colloid, including
reaction in the presence of hydrogen peroxide, producing thyroglobulin. Thyrocytes had a cubic shape, with nuclei
11
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molecular iodine and I (periodide ion). The periodide located in the basal part of the cell (Figure 2B and D).
3
concentration, determined spectrophotometrically at Their cytoplasm appeared oxyphilic, and the cells were
353 nm, was used to estimate TPO activity in thyroid tightly adherent. Interfollicular islets, consisting of poorly
tissue. The triiodothyronine (T3) and thyroxine differentiated thyrocytes, were observed between follicles.
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(T4) levels in blood serum were determined by These features indicate that the thyroid glands of rats
enzyme immunoassay using commercial kits (Xema Co., maintained on a balanced diet were within physiological
Russia). norms.
In the HCD group, male rats maintained the thyroid
2.4. Statistical analysis gland’s lobular structure (Figure 3A), but follicles
Statistical analysis was performed using Statistica 10.0 enlarged with colloid accumulation (Figure 3A).
(Tibco, USA). Normality was assessed with the Shapiro– The walls of follicles were thinned (Figure 3B) and
Wilk test. Parametric variables were expressed as mean ± thyrocytes appeared flattened, revealing pyknotic nuclei
standard deviation and analyzed with Student’s t-test. Non- surrounded by a thin rim of cytoplasm. The number
parametric variables were expressed as 25 percentiles, of interfollicular islets was insignificant, and moderate
th
median, and 75 percentiles and analyzed using the Mann– diffuse leukocytic infiltration was observed. Large lipid
th
Whitney U-test. Correlation analysis was performed inclusions were frequently visualized near blood vessels
using the Pearson correlation coefficient. A p<0.05 was (Figure 3A and B). Morphometric analysis relative to the
considered statistically significant for all tests. control males showed a statistically significant increase

Volume 4 Issue 2 (2025) 88 doi: 10.36922/GTM025080020