Cristiana Moreira da Silva

Foliculogênese e esteroidogênese ovarianas em ratas adultas hipertireóideas

Ovarian folliculogenesis and steroidogenesis were studied in hyperthyroid adult rats. Hyperthyroidism was induced in 27 five month-old Wistar rats by daily administration of 50µg L-thyroxin. Other 27 rats were maintained in euthyroid state as controls. At 30, 60 and 90 days after the beginning of the treatment, nine rats from each group were sacrificed. The ovaries were weighed, inspected and processed for histomorphometric evaluation. Plasmatic levels of free T4, estradiol and progesterone were determined. The levels of T4 were significantly higher in the hyperthyroid rats at 30, 60 and 90 days, but significant differences on the ovarian weight were detected only at 90 days. The number of secondary and tertiary follicles and of corpus luteum was greater at 60 or 90 days, but the rate of follicular atresia was different only at 90 days. No significant differences were observed on the number of primary and pre-ovulatory follicles and on the concentrations of estradiol and progesterone. Our data suggest that hyperthyroidism stimulates ovarian folliculogenesis in sexually mature rats. Furthermore, there is a reduction on the rate of follicular atresia.

Relação tireóide-gônadas e níveis plasmáticos de fósforo, cálcio e fosfatase alcalina em ratas

The interrelation between thyroid, gonads and osseous metabolism was studied in either intact or castrated adult female rats kept under hyperthyroidism or euthyroidism for 30, 60, or 90 days. Plasmatic levels of phosphorus, calcium, and alkaline phosphatase were measured to assess the osseous metabolism. These characteristics were correlated to the levels of estrogen, progesterone, and free T4. Either hypogonadism or hyperthyroidism interfered with the plasmatic characteristics of osseous metabolism. Hyperphosphatemia and hypocalcemia were induced by hyperthyroidism, whereas the hypogonadism had little effect on the levels of phosphorus, but it had a potencialization effect on the hyperphosphatemia and hypocalcemia induced by hyperthyroidism. The effect of hypogonadism on the alkaline phosphatase activity was reduced by the hyperthyroidism.

Histomorfometria e histoquímica dos ovários, tubas e útero de ratas hipotireóideas em metaestro-diestro

Ovarian folicullogenesis was studied in adult Wistar rats. The animals were hypothyroid in the metaestrus/diestrus phase of the estrous cycle. Hypothyroidism was induced by oral treatment with 1mg/animal of propylthiouracil. Euthyroid rats were kept under the same experimental conditions receiving placebo. After 120 days under treatment, all animals were killed and plasma was taken to assessing free thyroxine, progesterone, and estradiol. The ovaries, tubes and uterus were sampled for histomorphometric and histochemistry evaluation. Hypothyroidism significantly reduced the weight of the ovaries and the number of secondary and tertiary follicles, and corpora luteum. The number of atretic follicles as well as primary and pre-ovulatory follicles was not affected. Granulosa cells in the secondary follicles of treated rats had small nuclei with a reduced number of AgNORs. Significant reduction of the endometrium thickness, number of endometrial glands and the infundibulum epithelium height was observed.

Hipogonadismo e função tireoidiana em ratas hipertireóideas e eutireóideas

The effects of hypogonadism on thyroid function of hyper and euthyroid rats were measured based on plasmatic profile of thyroid hormones, ovarian steroids, TSH and thyroid histomorphometry. A group of five-month-old ovariectomized Wistar rats were maintained at hyper or euthyroid state for 30, 60 and 90 days. A group of non castrated was used as control. The hyperthyroidism was induced by gastric infusion of L-tiroxin 50µg daily. At the end of each period nine rats of each group were sacrificed, the blood plasma collected and the thyroid inspected, measured and processed for histomorphometric analyses. In blood plasma the concentrations of estradiol, progesterone, total and free tiroxin, total and free T3 and TSH were determined. The hypogonadism did not alter the values of free T3 and TSH but was able to rise free tiroxin in both hyper and euthyroid states. Total tiroxin levels were affected by castration, but only in the hyperthyroid state. Folicular epithelium height presented variations along the experiment in euthyroid individuals although these did not influence thyroid weight. No correlations between estrogen and any other variables were observed, but the progesterone levels were conversely proportional to the total and free tiroxin levels. It was concluded that hypogonadism alter the histomorphometric patterns of thyroid gland in euthyroid individuals, rise the plasmatic levels of free tiroxin regardless the functional state of thyroid gland and powered the total tyroxin rise in hyperthyroidism, probably due to the influence of hypoprogesteronism but not to the hypoestrogenism.

A osteoporose e os distúrbios endócrinos da tireóide e das gônadas

Despite the incessant dedication of the researchers to the study of osteoporosis, a lot still needs to be elucidated. The deficiency of sexual steroids, mainly of estrogen, is considered the main cause of osteoporosis, although a number of other factors are involved. Hyperthyroidism, for instance, is considered a risk factor for induction or aggravation of osteoporosis and has risen the interest in the study of the effects of T3 and T4 on osseous metabolism. Although hypothyroidism and gonadic dysfunction are frequently associated in women, thyroid hypofunction is not considered as a risk factor for postmenopausal osteoporosis. Thus, the study of the inter-relationship between endocrine disturbances, so common in advanced age, and osteoporosis is fundamental. Adequate means of control and treatment may result from this knowledge, as well as a definition of the real nature of the bone disturbance. The aim of this review is to present and discuss some aspects of osteoporosis and its inter-relation with the endocrine dysfunctions of the thyroid and the gonads.

Morfologia e histoquímica da pele de ratas hipotireóideas castradas e não castradas

The cutaneous alterations of castrated and intact female Wistar rats kept under a hypothyroidism state for 120 days were studied. Two euthyroid groups, one castrated and other intact, served as controls. Ventral abdominal and dorsal thoracic skin sections were stained by HE, PAS, alcian blue, picro-sirius red-polarized light and Verhoeff. Epidermis and sebaceous glands atrophy, partial or total reduction of elastic fibrils and type III dermal collagen were observed in both hypothyroidism and castration. Delay in hair follicle growth and hyperkeratosis were only observed when deficiency of thyroid hormones was present, independent of gonadal function. The association of hypothyroidism and castration was characterized by ventral abdominal epidermis atrophy, thickening and hyperplasia of dorsal thoracic epidermis, dermis atrophy with loss of elastic fibrils and type III collagen. In conclusion, ovarian steroids or thyroid hormones deficiency modifies all the components of the skin and that the injuries are aggravated in the association hypothyroidism-castration.

Quantificação das regiões organizadoras de nucléolo (NORs) como parâmetro para avaliar a proliferação das células da granulosa

The goal of this study was to determine whether the quantification of the nucleolar organizer regions (AgNORs) is a useful parameter for evaluation of the proliferative potential of non-neoplastic granulosa cells in ovarian follicles at different stages of development. Seven ovaries from six-month-old rats, all of which in metestrus-diestrus, were studied. The number of AgNORs from 60 granulosa cell nuclei was quantified in secondary follicles with two to three layers of cells and in follicles with more than five layers of granulosa cells. Follicles with two to three layers had larger AgNORs in lower numbers, whereas more developed secondary follicles the AgNORs were predominantly smaller, scattered throughout the nucleus, and in significantly higher numbers. In conclusion, quantification of the nucleolar organizer regions is an appropriate parameter for differentiation of the proliferative potential of non-neoplastic granulosa cells.

Testicular tumors in dogs: frequency and age distribution

Estudaram-se a ocorrencia e a predisposicao etaria de neoplasias testiculares em caes. Em 497 caes necropsiados, 47 apresentaram tumores testiculares, correspondendo a frequencia de 9,45% (47/497). Houve aumento significativo na frequencia de tumores testiculares em animais velhos.

Perfil hematológico de ratas adultas hipotireóideas castradas e não castradas

The relationship between thyroid-gonads on the blood profile was investigated in adult Wistar female rats. These animals were either castrated or intact and were kept under hypothyroidism, induced by daily administration of propylthiouracil (PTU) during 120 days. Two groups (castrated and intact) were kept in an euthyroid condition and used as controls. It was collected plasma for free T4 dosage and blood for hematological analysis. The significant low values of free T4 in the treated rats confirmed their hypothyroid state. The hypothyroidism caused anemia in the rats with functional gonads. The castration reverted the effects of thyroxine deficit in the erythrogram. Both the hypothyroidism and the hypogonadism showed just a discret effect on the leucogram.

Influência do hipogonadismo na histomorfometria e função tireoidiana de ratas hipotireóideas

The morphology and function of the thyroids of female adult Wistar rats were investigated. The animals were either castrated or intact and kept in a hypothyroid condition by a treatment with propylthiouracil for 120 days. Castrated and intact euthyroid rats were used as controls. The thyroids were collected at the end of the experiment, weighted, histologically processed, and morphometrically evaluated. Proportions of each glandular component, namely, follicular epithelium, colloid, and stroma, were determined. Serum concentrations of total T3, free T4, and TSH were assessed at the end of the experimental period. The weight and the morphometric parameters were not influenced by castration, whereas an increase in the epithelial component associated with a decreased amount of colloid were observed only in hypothyroid animals. Under an euthyroid state, the deficiency of sexual hormones induced an increase in the levels of free T4 and total T3. In hypothyroid animals, withdrawal of sexual hormones caused an exacerbation of the decrease in total T3, but not in free T4. TSH levels were not affected by the thyroid or the functional condition of gonads. In conclusion, hypogonadism did not influence the glandular hyperplasia and decrease in plasmatic levels of free thyroxin induced by propylthiouracil, but markedly changed the profile of total T3 according to the functional condition of the thyroid, in the absence of changes in the plasmatic levels of TSH.