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Effects of chronic estradiol treatment on the thyroid gland structure and function of ovariectomized rats.

Abdel-Dayem MM, Elgendy MS - BMC Res Notes (2009)

Bottom Line: The results of this study revealed that serum levels of T3 and T4 decreased in ovariectomized animals and significantly increased after estradiol treatment, while TSH increased in ovariectomized animals and decreased with estradiol treatment.After estradiol treatment the follicles became smaller in size, having small amount of colloid with increased epithelial height in addition to decreased connective tissue content.Ultrastructural study supported these results in addition to the presence of large amount of intracytoplasmic colloid vesicles after estradiol treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Histology Department, Faculty of Medicine, Fayoum University, Fayoum, Egypt. dmenna@msn.com

ABSTRACT

Background: Estrogen therapy is widely used nowadays in women to treat many postmenopausal symptoms but it may have some undesirable effects due to multiple organs affection. So, the aim of this study was to determine the effects of chronic estradiol treatment on the structure and function of the thyroid gland in ovarictomized rats as a model simulating menopause.

Findings: Thirty adult female Wistar rats divided into three groups were used in this study; the first group was sham-operated, while the second and third groups were ovariectomized. The first and second groups were injected with olive oil while the third group was injected with estradiol dipropionate daily for three months, after that; hormonal assay for T3, T4, TSH and specimens of the thyroid were taken and processed to be examined by light and electron microscopy. The results of this study revealed that serum levels of T3 and T4 decreased in ovariectomized animals and significantly increased after estradiol treatment, while TSH increased in ovariectomized animals and decreased with estradiol treatment. Histological and morphometric study in ovariectomized group revealed marked accumulation of colloid in follicular lumens with decreased epithelial height in addition to increased connective tissue amount. After estradiol treatment the follicles became smaller in size, having small amount of colloid with increased epithelial height in addition to decreased connective tissue content. Ultrastructural study supported these results in addition to the presence of large amount of intracytoplasmic colloid vesicles after estradiol treatment.

Conclusion: Low estrogen level may lead to mild thyroidal hypofunction while estradiol treatment may lead to hyperactivity so it should be used very cautiously in the treatment of postmenopausal symptoms to avoid its undesirable stimulatory effect on the thyroid.

No MeSH data available.


Related in: MedlinePlus

light microscopic pictures of thyroid gland of group II (ovarictomized rat). (a) large peripheral thyroid follicles (thick arrows) beneath the capsule (caps). The central ones are variable in size with cuboidal and flattened epithelial lining (thin arrows) (Hx&E × 200). (b) higher magnification of the central zone from the previous section showing enlarged follicles (thick arrows) with flat epithelial lining and flattened nuclei of many cells (thin arrows). The colloid demonstrates minimal vacuolization (arrow heads) (Hx&E × 400). (c) follicles distended with large amount of colloid (C) (PAS × 400). (d) increased connective tissue in between the thyroid follicles (thin arrows) (Masson trichrome × 400).
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Figure 2: light microscopic pictures of thyroid gland of group II (ovarictomized rat). (a) large peripheral thyroid follicles (thick arrows) beneath the capsule (caps). The central ones are variable in size with cuboidal and flattened epithelial lining (thin arrows) (Hx&E × 200). (b) higher magnification of the central zone from the previous section showing enlarged follicles (thick arrows) with flat epithelial lining and flattened nuclei of many cells (thin arrows). The colloid demonstrates minimal vacuolization (arrow heads) (Hx&E × 400). (c) follicles distended with large amount of colloid (C) (PAS × 400). (d) increased connective tissue in between the thyroid follicles (thin arrows) (Masson trichrome × 400).

Mentions: In the ovariectomized rats, preserved secretory activity of the thyroid gland was noticed, it was mainly characterized by central follicles of a flattened, cuboidal or low prismatic epithelium surrounding the colloid. Occasionally, enlarged distended follicles with very flat epithelium were noticed. The peripheral follicles were large and lined with flattened epithelium. The colloid appeared filling up the entire lumen in most of the follicles with no or little peripheral vacuolization. The connective tissue around the follicles was more prominent than in sham-operated group (fig. 2a-d).


Effects of chronic estradiol treatment on the thyroid gland structure and function of ovariectomized rats.

Abdel-Dayem MM, Elgendy MS - BMC Res Notes (2009)

light microscopic pictures of thyroid gland of group II (ovarictomized rat). (a) large peripheral thyroid follicles (thick arrows) beneath the capsule (caps). The central ones are variable in size with cuboidal and flattened epithelial lining (thin arrows) (Hx&E × 200). (b) higher magnification of the central zone from the previous section showing enlarged follicles (thick arrows) with flat epithelial lining and flattened nuclei of many cells (thin arrows). The colloid demonstrates minimal vacuolization (arrow heads) (Hx&E × 400). (c) follicles distended with large amount of colloid (C) (PAS × 400). (d) increased connective tissue in between the thyroid follicles (thin arrows) (Masson trichrome × 400).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2743701&req=5

Figure 2: light microscopic pictures of thyroid gland of group II (ovarictomized rat). (a) large peripheral thyroid follicles (thick arrows) beneath the capsule (caps). The central ones are variable in size with cuboidal and flattened epithelial lining (thin arrows) (Hx&E × 200). (b) higher magnification of the central zone from the previous section showing enlarged follicles (thick arrows) with flat epithelial lining and flattened nuclei of many cells (thin arrows). The colloid demonstrates minimal vacuolization (arrow heads) (Hx&E × 400). (c) follicles distended with large amount of colloid (C) (PAS × 400). (d) increased connective tissue in between the thyroid follicles (thin arrows) (Masson trichrome × 400).
Mentions: In the ovariectomized rats, preserved secretory activity of the thyroid gland was noticed, it was mainly characterized by central follicles of a flattened, cuboidal or low prismatic epithelium surrounding the colloid. Occasionally, enlarged distended follicles with very flat epithelium were noticed. The peripheral follicles were large and lined with flattened epithelium. The colloid appeared filling up the entire lumen in most of the follicles with no or little peripheral vacuolization. The connective tissue around the follicles was more prominent than in sham-operated group (fig. 2a-d).

Bottom Line: The results of this study revealed that serum levels of T3 and T4 decreased in ovariectomized animals and significantly increased after estradiol treatment, while TSH increased in ovariectomized animals and decreased with estradiol treatment.After estradiol treatment the follicles became smaller in size, having small amount of colloid with increased epithelial height in addition to decreased connective tissue content.Ultrastructural study supported these results in addition to the presence of large amount of intracytoplasmic colloid vesicles after estradiol treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Histology Department, Faculty of Medicine, Fayoum University, Fayoum, Egypt. dmenna@msn.com

ABSTRACT

Background: Estrogen therapy is widely used nowadays in women to treat many postmenopausal symptoms but it may have some undesirable effects due to multiple organs affection. So, the aim of this study was to determine the effects of chronic estradiol treatment on the structure and function of the thyroid gland in ovarictomized rats as a model simulating menopause.

Findings: Thirty adult female Wistar rats divided into three groups were used in this study; the first group was sham-operated, while the second and third groups were ovariectomized. The first and second groups were injected with olive oil while the third group was injected with estradiol dipropionate daily for three months, after that; hormonal assay for T3, T4, TSH and specimens of the thyroid were taken and processed to be examined by light and electron microscopy. The results of this study revealed that serum levels of T3 and T4 decreased in ovariectomized animals and significantly increased after estradiol treatment, while TSH increased in ovariectomized animals and decreased with estradiol treatment. Histological and morphometric study in ovariectomized group revealed marked accumulation of colloid in follicular lumens with decreased epithelial height in addition to increased connective tissue amount. After estradiol treatment the follicles became smaller in size, having small amount of colloid with increased epithelial height in addition to decreased connective tissue content. Ultrastructural study supported these results in addition to the presence of large amount of intracytoplasmic colloid vesicles after estradiol treatment.

Conclusion: Low estrogen level may lead to mild thyroidal hypofunction while estradiol treatment may lead to hyperactivity so it should be used very cautiously in the treatment of postmenopausal symptoms to avoid its undesirable stimulatory effect on the thyroid.

No MeSH data available.


Related in: MedlinePlus