Chronic somatostatin treatment affects pituitary gonadotrophs, ovaries and onset of puberty in rats.

The effects of chronic somatostatin (SRIH-14) treatment on the pituitary gonadotrophs (FSH and LH cells) and ovaries of female Wistar rats were examined. Females were given 20 microg/100 g b.w. twice per day from the immature (23rd day) till the adult period of life (71st day). The onset of puberty was determined by daily examination for vaginal opening. The peroxidase-antiperoxidase immunocytochemical procedure was used to study the gonadotrophs. Changes in the number per unit area (mm2), cell volume and volume densities of LH- and FSH-immunoreactive cells were evaluated by morphometry and stereology. Ovaries were analysed by simple point counting of follicles and corpora lutea (CL). Follicles were divided by size according to the classification of Gaytán and Osman. The mitotic indexes of granulosa and theca cells in the follicles were estimated at all stages of folliculogenesis. The number, volume and the volume density of FSH- and LH-immunoreactive cells decreased after chronic SRIH-14 treatment, particularly the latter. In the ovary, SRIH-14 treatment decreased the number of healthy follicles at all phases of folliculogenesis, lowered the mitotic indexes of granulosa and theca cells but increased the number of atretic follicles. Healthy CL were fewer in number, while regressive CL were increased. Vaginal opening occurred at a later age in treated females. It can be concluded that chronic SRIH-14 treatment markedly inhibited LH cells and to a lesser extent FSH cells. In the ovary SRIH-14 inhibited folliculogenesis, enhanced atretic processes and lowered proliferative activity of granulosa and theca cells. It also delayed puberty onset.

Effects of multiple somatostatin treatment on rat gonadotrophic cells and ovaries.

The effect of multiple somatostatin (SRIH-14) treatment on the pituitary gonadotrophs, follicle stimulating harmone (FSH) and luteinizing harmone (LH), and ovaries of adult female Wistar rats was examined. Females received two 20 microg/100 g body wt. doses daily subcutaneously, for five consecutive days. FSH and LH cells were studied using a peroxidase-antiperoxidase immunocytochemical procedure. Morphometry and stereology were used to evaluate changes in the number per unit area (mm2), cell volume and volume densities of LH- and FSH-immunoreactive cells. Ovaries were analysed by simple point counting of follicles and corpora lutea. Follicles were divided by size according to the classification of Gaytán and Osman. Morphometric and stereological analysis of the pituitary showed that the number, volume and the volume density of FSH- and LH-immunoreactive cells were decreased after multiple SRIH-14 treatment, particularly in the latter. In the ovary, SRIH-14 induced decreases in the number of healthy follicles in all phases of folliculogenesis and corpora lutea, but the large antral follicle stage was most affected. The number of atretic follicles was increased. It can be concluded that multiple SRIH-14 treatment markedly inhibited LH cells, but affected FSH cells as well. In the ovary, SRIH- 14 acted by inhibiting folliculogenesis and enhancing atretic processes.

Effect of centrally administered somatostatin on pituitary thyrotropes in male rats.

The effects of intracerebroventricularly administered somatostatin (SRIH-14 or -28) on growth and function of pituitary thyrotropes (TSH-cells) were examined in adult male Wistar rats. The animals were implanted with an intracerebroventricular cannula and after a recovery period, administered three 1 microg doses of SRIH-14 or -28 dissolved in 5 microl saline every second day. Controls were treated in the same way with the same volume of saline only. TSH-producing cells were studied using the peroxidase-antiperoxidase immunohistochemical procedure. Blood samples were collected for hormone (TSH) analyses 5 days after the last injection. Both SRIH-treatments significantly decreased (p < 0.05) all morphometric parameters obtained for TSH-cells in comparison with controls. The volume of TSH-cells decreased by 27%, nuclei by 44% and volume density by 33% in animals treated with SRIH-14. In animals treated with SRIH-28, these parameters were also significantly decreased (p < 0.05) (22%, 31%, and 25% respectively) compared to control rats. Serum concentrations of TSH were significantly decreased (p < 0.05) by 15% in SRIH-14- and by 12% in SRIH-28-treated animals in comparison with the controls. These observations suggest that centrally administered SRIH- 14 or -28 is specifically involved in the control of growth and secretory activity of TSH cells.

Effects of estradiol and calcium on gonadotrophic cells in middle-aged female rats.

The effects of multiple treatment with estradiol dipropionate (EDP) or calcium glucoheptonate (Ca) or a combination of the two on gonadotrophic cells in the pituitary pars distalis of middle-aged female rats were examined. The animals were treated daily for two weeks with EDP (0.625 mg i.p./kg body weight) or Ca (11.4 mg/kg body weight) or EDP + Ca. Luteinising (LH) and follicle stimulating hormone (FSH)-producing cells were examined by immunohistochemistry using antisera to the specific (beta) beta-subunits of LH and FSH and a peroxidase-anti-peroxidase immunohistochemical procedure. Plasma levels of FSH and LH were measured by radio-immune assay. A stereological method for determining morphometric parameters in immunopositive FSH and LH cells was used. The number of gonadotrophs per unit area (mm2), their cellular volume and relative volume densities, as well as plasma levels of FSH and LH, were decreased in all treated females in comparison with the controls. The most significant decrease of these parameters was observed in EDP-treated animals. Such changes were also expressed in Ca-treated animals, but the alterations were less distinct. These results demonstrate that multiple EDP or Ca application to middle-aged female rats is able to inhibit, directly or indirectly, the morphofunctional state of gonadotrophic cells in the pituitary pars distalis.

Effects of somatostatins on gonadotrophic cells in female rats.

The effects of intracerebroventricular application of SRIF-14 and SRIF-28 on pituitary gonadotrophic cells (FSH and LH) were examined using immunocytochemical and morphometrical methods in adult female Wistar rats. FSH- and LH-producing cells were studied using the peroxidase-antiperoxidase (PAP) immunohistochemical procedure. Morphometry and stereology were used to evaluate changes in the number, volume densities and relative volume densities of LH- and FSH-immunopositive cells. In females treated with SRIF-14 or SRIF-28, the gonadotrophs were smaller, often pycnotic and more intensely stained. The number of LH-positive cells per unit area (mm2) was significantly decreased in both somatostatin-treated groups, while the number of FSH-positive cells was similar to that in the controls. Volume densities of perykarya of LH- and FSH-positive cells were decreased in all treated females, but extremely different in LH-positive cells after SRIF-14 administration. The relative volume density of LH cells was significantly decreased in both somatostatin-treated groups, while immunopositive FSH cells were not significantly decreased compared with the controls. It can be concluded that centrally applied somatostatins lead to changes in the immunocytochemical and morphometric properties of LH cells, while there is no significant effect on FSH cells.

Morphometric and functional changes of rat pituitary somatotropes and lactotropes after central administration of somatostatin.

This study examined effects of intracerebroventricularly (i.c.v.) administered somatostatin (SRIH-14 and SRIH-28) on growth and function of pituitary somatotropes (GH cells) and lactotropes (PRL cells). Male rats received three i.c.v. injections (1 microgram/5 microliters) of SRIH-14 or SRIH-28 every second day. Blood samples were collected for hormone assays and pituitaries were removed for histological and morphometric evaluation 5 days after the last i.c.v. treatment. Compared to control animals, SRIH treatment decreased (p < 0.05) pituitary weight and all morphometric measurements obtained in GH and PRL cells. Concentrations of serum growth hormone (GH) and prolactin (PRL) in both SRIH-treated groups were also lower (p < 0.05) than in control rats. These findings suggest that centrally administered somatostatin is specifically involved in the control of growth and secretory activity of GH and PRL cells. Thus, pharmacological manipulation of SRIH receptors reached from cerebrospinal fluid may alter systemic effects of GH and PRL.

Immunoreactive TSH cells in the pituitary of female middle-aged rats after treatment with estradiol or calcium.

The pituitary TSH cell structure of middle-aged (14-month-old) female Wistar rats chronically treated with estradiol dipropionate (EDP), calcium glucoheptonate (Ca) or with the combination of both was studied. TSH-producing cells were examined in the pituitary pars distalis using rabbit anti-rat beta-thyrotropin (TSH) serum and peroxidase-antiperoxidase immunohistochemistry. A stereological method for the determination of morphometric changes of the volume of TSH cells and nuclei as well as of their number and relative volume densities was used. All examined morphometric parameters in treated animals showed a significant decrease in comparison with immunoreactive TSH cells of the controls; the most significant decrease was observed in EDP-treated rats. These results together with structural features of immunoreactive TSH cells in the pituitary of middle-aged rats after chronic application of EDP or Ca indicate that both compounds inhibit these cells.

Thyroid C cells of middle-aged rats treated with estradiol or calcium.

The structure and function of C cells of middle-aged female rats (14-months old) treated with estradiol dipropionate (EDP), calcium (Ca) or a combination of EDP+Ca were studied. A stereological method was used to determine the volume of calcitonin (CT)-immunoreactive C cells and their nuclei, and the relative volume density and mean number of the C cells per section were calculated. Serum levels of CT, osteocalcin, parathyroid hormone (PTH), and beta-estradiol were also measured. A significant decrease in body weight of the rats treated with EDP or EDP+Ca was observed. These treatments led to a significant decrease in cellular and nuclear volumes, relative volume density, and mean number of C cells per section, in comparison with the corresponding controls. A reduction of the serum level of CT, PTH, and osteocalcin was also recorded in EDP- and EDP+Ca-treated animals. No statistically significant differences between Ca- and vehicle-injected rats, with regard to all morphometric C cell parameters and biochemical values determined, were seen. However, a conspicuous degranulation of the C cells and decreased immunoreactivity for CT in the Ca-receiving group, which could be interpreted as the signs of increased activity of these cells, were noticed. This effect of Ca was also observed in rats injected with EDP and Ca in combination, when the inhibitory effect of EDP on C cell function was less noticeable than in the group treated with EDP alone.

Inhibitory effects of centrally administered somatostatin on the adrenal zona glomerulosa in male rats.

This study examined the effects of intracerebroventricularly administered somatostatin (SRIF-28 and SRIF-14) on growth and steroidogenic capacity of the rat adrenal zona glomerulosa. Male adult Wistar rats were subjected to intracerebroventricular administration of three 1 microgram doses of SRIF-28 or SRIF-14 every other day. Five days after the last dose, the rats were sacrificed by decapitation. Blood samples were collected for hormonal analyses, and left adrenal glands were taken for histological and morphometric evaluation. In comparison with control animals, the SRIF-treated rats had decreased (p < 0.05) adrenal gland weight and volume. Stereological and morphometric analyses showed decreased (p < 0.05) absolute and relative volumes of the cells and nuclei only in the zona glomerulosa. The plasma levels of aldosterone, growth hormone, and prolactin in both SRIF-treated groups were lower (p < 0.05) than in the control group. The levels of adrenocorticotropic hormone after SRIF treatment did not differ significantly from those in control rats. These findings suggest that centrally administered somatostatin is specifically involved in the control of zona glomerulosa growth and secretion; this effect is probably mediated by inhibiting the secretion of the corresponding pituitary hormones.

Estradiol-induced changes in TSH-like immunoreactivity of pituitary cells in female rats.

Beta-thyrotropin (TSH)-producing cells in the pituitary pars distalis of female rats were studied using rabbit anti-rat beta-thyrotropin (TSH) serum and a peroxidase-antiperoxidase (PAP) immunohistochemical procedure. Animals were neonatally treated with 1 mg estradiol-dipropionate (EDP) and sacrificed at different stages of development up to adulthood. Intact females of the corresponding age served as the controls. Morphometry and stereology were used to evaluate the changes in TSH-cell number and volume densities of the cells and nuclei. All morphometric parameters examined in estradiol-treated animals showed a significant decrease in comparison with immunoreactive TSH cells of age-matched controls. The most prominent EDP-induced changes were evident in peripubertal 38-day-old rats, the number and volumetric densities of both TSH cells and their nuclei being reduced by about 90% compared to intact pituitary. This decrease in the number and volume densities of TSH cells in EDP-treated rats explicitly demonstrated that this hormone, applied neonatally, has an inhibitory effect on TSH-immunoreactive cells up to adulthood, in accordance with our earlier data obtained by light and electron microscopy.

Alterations of thyroid parafollicular cell organization in aged rats neonatally treated with estradiol.

Cellular and subcellular organization of parafollicular cells of aged male Wistar rats (180- and 365-day-old), neonatally (3rd day) treated with a single dose (1 mg) of oestradiol-dipropionate (OeDP), were studied. Based on argyrophil properties of parafollicular cells in control and treated group, two morphometrically distinct cell types were observed (under and over 50 microns 2 of cell area), reflecting distinct functional status of the same cell type. The first signs of hyperplastic changes in parafollicular cells were observed in 180-day-old rats and they were more severe in 365-day-old animals. Morphometric averages for the area of parafollicular cells and nuclei, as well as for the cell number in estradiol-treated animals were higher than in the controls, but these differences were statistically insignificant. However, subcellular organization of parafollicular cells showed that besides the cells with clearly visible characteristics such as control hyperplastic cells, there were parafollicular cells with progressively more abnormalities expressed as myelin-like figures, cytoplasmic cribriform structures and dilated endoplasmic reticulum (ER), demonstrating long-lasting effects of neonatally applied estradiol.

[The effect of vincristine on dental pulp of experimental animals]. / Delovanje vincristina na pulpu molara wistar pacova.

Chemotherapy is applied in the treatment of malignant disease to decrease the number of malignant cells, and to avoid damage of the living tissue and growing cells which must be reduced to the lowest level. In the combination of cytostatics Vincristine, a Vinca-alkaloid, is widely used. The purpose of this study was to analyse the pulp and dentine in experimental animals after the administration of Vincristine. Wistar rats of both sexes were used. Vincristine (Onkovin, Lilly) was injected in the neck skin fold on the 7th and the 8th postnatal day in a single dose of 0.1 mg/kg b.w. At the 24th postnatal day experimental and control animals were sacrificed. Both jaws with teeth were prepared for routine histologic examination. The results showed that Vincristine effect was different in different regions of the tooth. The number and disposition of odontoblasts was reduced in all areas of tooth sections, especially in the pulp horn. In the central part of coronal and radicular pulp tissue blood vessels were dilated and filled with blood cells. A histologic appearance of newly formed dentine was irregular.

Changes in parafollicular cells of rats neonatally treated with estradiol.

The parafollicular cells of male and female rats neonatally (3rd day) treated with a single dose (1 mg) of estradiol dipropionate, and sacrificed in peripubertal (38th day) or adult (80th day) period of life, were investigated. These studies included examinations of silver-stained properties of parafollicular cells, morphometric analyses of both the cells and nuclear area and ultrastructural characteristics. Estradiol treatment led to a significant increase of the cellular and nuclear area (micron 2) in both females and males. Different from intact animals remarkable degranulation and hyperplasia of parafollicular cells were evident in estradiol-treated rats. It may be concluded that this sexual hormone applied in neonatal period has an effect on parafollicular cells expressed up to adult period of life.