Analysis of the Pituitary‐Thyroid Axis in Bilaterally Adrenalectomized or Adrenal Transplanted Rats

Sarrı́a, R.; Losada, Joaquín; Oliver, F. Donate

doi:10.1111/j.1439-0264.1994.tb00474.x

Cited by 2 publications

(3 citation statements)

References 35 publications

(32 reference statements)

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“…The average nuclear size in pituitary cells (which reflects their functional state) is known to be changed due to perturbations in hormonal status [40-42]. Although the average nuclear size from pituitaries of DES-treated or phytoestrogen-treated animals showed no difference compared to cholesterol-treated control animals, the observed changes in nuclear size heterogeneity with DES (and especially with DES in combination with all phytoestrogens), suggested that the functions of pituitary cells had been altered.…”

Section: Discussionmentioning

confidence: 99%

Subchronic exposure to phytoestrogens alone and in combination with diethylstilbestrol - pituitary tumor induction in Fischer 344 rats

et al. 2010

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Background: Subchronic administration of the potent pharmaceutical estrogen diethylstilbestrol (DES) to female Fischer 344 (F344) rats induces growth of large, hemorrhagic pituitaries that progress to tumors. Phytoestrogens (dietary plant estrogens) are hypothesized to be potential tumor inhibitors in tissues prone to estrogen-induced cancers, and have been suggested as "safer" estrogen replacements. However, it is unknown if they might themselves establish or exacerbate the growth of estrogen-responsive cancers, such as in pituitary. Methods:We implanted rats with silastic capsules containing 5 mg of four different phytoestrogens -either coumestrol, daidzein, genistein, or trans-resveratrol, in the presence or absence of DES. We examined pituitary and other organ weights, blood levels of prolactin (PRL) and growth hormone (GH), body weights, and pituitary tissue histology.Results: Blood level measurements of the administered phytoestrogens confirmed successful exposure of the animals to high levels of these compounds. By themselves, no phytoestrogen increased pituitary weights or serum PRL levels after 10 weeks of treatment. DES, genistein, and resveratrol increased GH levels during this time. Phytoestrogens neither changed any wet organ weight (uterus, ovary, cervix, liver, and kidney) after 10 weeks of treatment, nor reversed the adverse effects of DES on pituitaries, GH and PRL levels, or body weight gain after 8 weeks of co-treatment. However, they did reverse the DES-induced weight increase on the ovary and cervix. Morphometric examination of pituitaries revealed that treatment with DES, either alone or in combination with phytoestrogens, caused gross structural changes that included decreases in tissue cell density, increases in vascularity, and multiple hemorrhagic areas. DES, especially in combination with phytoestrogens, caused the development of larger and more heterogeneous nuclear sizes in pituitary.Conclusions: High levels of phytoestrogens by themselves did not cause pituitary precancerous growth or change weights of other estrogen-sensitive organs, though when combined with DES, they counteracted the growth effects of DES on reproductive organs. In the pituitary, phytoestrogens did not reverse the effects of DES, but they did increase the sizes and size heterogeneity of nuclei. Therefore, phytoestrogens may oppose some but not all estrogenresponsive tissue abnormalities caused by DES overstimulation, and appear to exacerbate DES-induced nuclear changes. BackgroundSteroid hormones such as the dominant physiologic estrogen, estradiol (E 2 ) have many effects on pituitary function, including regulation of most pituitary hormones and proliferation of several pituitary cell types

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Section: Discussionmentioning

confidence: 99%

Subchronic exposure to phytoestrogens alone and in combination with diethylstilbestrol - pituitary tumor induction in Fischer 344 rats

et al. 2010

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“…(1972) reported that TSH cells in the rat are more prominent in the ventral and middle part of the lateral section of pars distalis and rare in its dorsal. Sarria et al. (1994) reported that these cells are found single or in small groups widely along the pars distalis.…”

Section: Discussionmentioning

confidence: 98%

“…Different ideas on localization of TSH cells are propound. While Sarria et al (1994) reported that these cells are found as single or in small groups distributed widely along the pars distalis, Baker et al. (1972) observed them generally in the ventral and middle part of the lateral section of the pars distalis and in lesser extent in its dorsal regions.…”

Section: Introductionmentioning

confidence: 98%

A Histochemical Investigation of Different Distribution of TSH Cells in Adenohypophsis of Female and Male Rats

Kum¹,

Eren²,

Sandıkçı³

et al. 2006

Anat Histol Embryol

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The aim of the present study was to investigate histochemically the localization of thyroid-stimulating hormone (TSH) cells and the number of TSH cells in adenohypophysis of ovariectomized adult females, intact females at estrous and diestrous phase of sexual cycles and castrated and non-castrated adult male rats. TSH cells, distributed throughout the pars distalis in all groups, were observed more frequent in areas near to the pars intermedia than other regions. The cells were round, ovoid, stellar-shaped and had contacts with sinusoids. Their nuclei were large and round-shaped. The cells were found mostly single or occasionally in groups of double and triple. The number of TSH cells was higher in estrous than diestrous phase in intact rats. In adenohypophysis of ovariectomized rats, their numbers were less than that of intacts in estrous, but higher than that of found in diestrous phases. Furthermore, the numbers of TSH cells in intact females during estrous phase was higher than those found in intact and castrated male rats. On the other hand, castration reduced the number of TSH cells while ovariectomy had no effect in this respect.

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Analysis of the Pituitary‐Thyroid Axis in Bilaterally Adrenalectomized or Adrenal Transplanted Rats

Cited by 2 publications

References 35 publications

Subchronic exposure to phytoestrogens alone and in combination with diethylstilbestrol - pituitary tumor induction in Fischer 344 rats

Subchronic exposure to phytoestrogens alone and in combination with diethylstilbestrol - pituitary tumor induction in Fischer 344 rats

A Histochemical Investigation of Different Distribution of TSH Cells in Adenohypophsis of Female and Male Rats

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