histological and immunohistochemical study of the effects of leptin on the pars distalis of the pituitary gland in female albino rats

Leptin is an adipocyte-derived hormone. The plasma level of leptin is elevated in obesity and decreased in emaciation. It is involved in the neuroendocrine regulation of pituitary gland function. The present work was carried out to study the histological changes in the pars distalis of the pituitary gland after an injection of leptin in female albino rats. Thirty just-weaned immature female albino rats [22 days] were divided into two groups: group I included 10 animals and served as a control group and group II included 20 animals that received a daily subcutaneous injection of 5 micro g leptin up to the end of the experiment. The females were subjected daily to vaginal smear. After the maturation was established, rats from each group were again subdivided into groups a and b, which were sacrificed 4 and 20 days after puberty, respectively. The pituitary glands were dissected and specimens were prepared for electron microscopic and immunohistochemical assessment. Leptin injection induced various changes in the pars distalis of the pituitary gland. Some cells had deeply stained nuclei and vacuolated cytoplasm. There was a statistically significant increase in the number of positive p53 antibody immunostained cells in the leptin-treated group, especially after 4 days of leptin injection. The most affected cells were somatotrophs, thyrotrophs, and gonadotrophs. They showed features of hyperactivity, with the appearance of some apoptotic cells. Later, necrotic changes such as pyknotic nuclei, ballooned mitochondria with destroyed cristae, and dilated rough endoplasmic reticulum were observed. Prepubertal increase in leptin led to histological changes in some cells of the pars distalis. It is recommended to avoid increase in body weight, especially at a young age

Effect of malathion on pars distalis of the pituitary gland and the possible protective role of vitamin C in adult female albino rats: a histological, immunohistochemical, and ultrastructural study

Malathion is one of the organophosphorus insecticides that are widely used in agriculture and have been reported to cause multiple organ damage. Vitamin C has been proposed as an antioxidant because it reduces oxidative stress. This work aimed to study the possible histological, immunohistochemical, and ultrastructural changes of gonadotrophs and somatotrophs of the pars distalis of the anterior pituitary gland associated with chronic sublethal malathion administration and assess the possible beneficial role of vitamin C in ameliorating these possible changes. Forty adult female albino rats were divided into four groups. Group I served as the control group. Group II received vitamin C at a dose of 20 mg/100 g/day. Group III animals were treated with malathion at a dose of 100 mg/kg/day. Groups IV animals received vitamin C and then malathion after 2 h at the previous doses. The treatments were given orally to the rats for 2 months. The rats were then sacrificed and specimens from the anterior pituitary gland were taken for light and electron microscopic examination. Light microscopic examination of rats treated with malathion revealed that gonadotrophs exhibited vacuolated degranulated cytoplasm and pyknotic nuclei, whereas somatotrophs appeared shrunken with dense nuclei. Immunohistochemically, there was a decrease in the immunoreactivity of follicle stimulating hormone, luteinizing hormone, and growth hormone-secreting cells. Ultrastructurally, gonadotrophs and somatotrophs showed disintegration of cellular organelles and apoptosis of the nuclei. Coadministration of malathion with vitamin C showed a slight improvement in some gonadotrophs and somatotrophs that looked normal in both light microscopic and electron microscopic examination; however, still others were markedly affected, showing signs of degeneration and apoptosis. The results showed that malathion in chronic doses induces histological, immunohistochemical, and ultrastructural changes in gonadotrophs and somatotrophs because of oxidative stress, and the use of vitamin C partially improves the malathion-induced toxicity

Ultrastructural characterization of the pars distalis of the Indian female Sheath-tailed bat, Taphozous longimanus (Hardwicke) / Caracterización ultraestructural de la pars distalis del murciélago cola de vaina hembra indio, Taphozous longimanus (Hardwicke)

The present ultrastructural observations demonstrate the presence of six cell types in the pars distalis of non-pregnant and pregnant bats of Taphozous longimanus. In the pars distalis of T. longimanus, STH cells are round to oval with eccentrically placed nucleus, numerous secretory granules and well developed Golgi indicate a cell under vigorous synthetic activity while those filled with secretory granules with reduced Golgi complex suggest reserve or storage state of cells. LTH cell is characterized by the large secretory granules, dilated endoplasmic reticulum and numerous mitochondria in the cytoplasm which indicate that these cells are hypertrophied and synthetically very active during pregnancy. ACTH cells are found either singly or in groups and are elongated or angular with long cytoplasmic processes. The size and peripheral arrangement of secretory granules are characteristic of ACTH cell. TSH cells are distributed mostly towards the periphery of the pars distalis of T. longimanus. They are elongated, polygonal or triangular in shape. The secretory granules are small, electron dense, 150-200 nm in diameter. The rough endoplasmic reticulum is very well developed. In FSH, the secretory granules are small (200 to 400 nm) and less in number and are distributed towards the periphery of the cell. FSH cells show well developed mitochondria, Golgi and rough endoplasmic reticulum indicating active state of FSH during estrus and pregnancy. The hypertrophy of FSH and LH cells during pregnancy is associated with filigreed cytoplasmic pattern giving a bizarre appearance. At late pregnancy, FSH and LH cells are highly active and synthesize large quantities of hormone as indicated by the development of cell organelles.

Las observaciones ultraestructurales actuales demuestran la presencia de seis tipos de células en la pars distalis de murciélagos Taphozous longimanus preñadas y no preñadas. En la pars distalis del T. longimanus, las células STH son redondas u ovaladas con un núcleo excéntrico, numerosos gránulos de secreción y un Golgi bien desarrollado que indican una célula en actividad de síntesis vigorosa, mientras que las llenas de gránulos de secreción con un complejo de Golgi reducido sugieren un estado celular de reserva o almacenamiento. Las células LTH se caracterizan por grandes gránulos de secreción, el retículo endoplásmico dilatado y numerosas mitocondrias en el citoplasma, indicando que estas células están hipertrofiadas y con una actividad sintética muy activa durante el embarazo. Células de ACTH se encuentran de forma individual o en grupos, son alargadas o angulares, con largos procesos citoplásmicos. El tamaño y la disposición periférica de los gránulos de secreción de ACTH son característicos de la célula. Células de TSH se distribuyen principalmente hacia la periferia de la pars distalis del T. longimanus. Ellos son alargadas, poligonales o de forma triangular. Los gránulos de secreción son pequeños, electrodensos, de 150-200 nm de diámetro. El retículo endoplasmático rugoso está muy bien desarrollado. En células FSH, los gránulos de secreción son pequeños (200 a 400 nm), menores en número y se distribuyen hacia la periferia de la célula. Células FSH muestran mitocondrias bien desarrolladas, Golgi y retículo endoplasmático rugoso que indica el estado activo de la FSH durante el estro y la preñez. La hipertrofia de las células de FSH y LH durante la preñez se asocia con un patrón citoplasmático filigrana dando una extraña apariencia. Al final de la preñez, las células de FSH y LH son muy activas y sintetizan grandes cantidades de hormonas, como producto del desarrollo de las organelos celulares.

Immunohistochemical and ultrastructural age-related changes in rat lactotroph cells

Ageing produces alterations in some functions of the hypothalamo-pituitary axis leading to sexually dimorphic changes in the prolactin (PRL)-secreting cells. Since quantitative morphological data of these age-associated alterations are scarce, we carried out a morphometric immunohistochemical assessment as well as an ultrastructural study of the PRL cell population in male and female rats of different ages. Young (3-month-old), old (20-month-old), and senescent (31-month-old) Sprague-Dawley rats of both sexes were sacrificed by rapid decapitation, their pituitaries immediately dissected out and processed for both immunohistochemistry and electron microscopy. Analysis of different morphometric parameters revealed that the cell density (CD) and volume density (VD) significantly decreased with age in male rats. In females, while CD showed a significant age-related diminution when young rats were compared to old ones, this parameter increased in senescent animals. The VD presented higher values in senescent rats. When the data were compared between sexes, VD was found to be higher in females if old and senescent rats were considered. Finally, CD increased significantly in females when compared to males. The ultrastructure of the PRL cells from old and senescent animals of both sexes exhibited changes suggestive of an hyperstimulation state, with some prolactotrophs having the appearance of cells undergoing an involutive process. We conclude that ageing has a differential impact on the PRL cells of male and female rats with respect to the immunohistochemical and ultrastructural features of that cell population

Chronic alcoholism and morphological changes in hypophyseal gonadotropic cells of rat [stereological and ultrastructural study]

Adenohypophysis of male albino rats received 15% solution of ethyl alcohol for five months was examined by light and electron microscopy for the detection of morphological changes in hypophyseal gonadotropic cells as compared with the control group. Light microscopy revealed hyperplasia and hypertrophy of gonadotropic cells with the presence of vacuoles of varying size in large gonadotrophs. The increase of the volume and the numerical density of the gonadotropic cells of alcoholized rats in comparison with the control ones was proved by recent stereological methods. Ultrastructural results showed an increase in the number and size of gonadotrophs with the presence of large vacuole, which was formed by fusion of dilated cisternae of the endoplasmic reticulum. The results offered a morphological basis to the adoption of a biphasic effect of alcohol on gonadotropic secretion

Ultraestructura de las células adenohipofisiarias de la rata blanca sometida al efecto de una benzodiazepina en forma crónica / Ultrastructure of adenohypophyseal cells of white rats subjected to the effect of a benzodiazepine in chronic form

Se estudia la estructura de las células adenohipofisarias de la rata blanca (Rattus norvegicus) sometida al efecto de una benzodiazepina, aplicada crónicamente. Se observa que en relación con los controles, las células manotropas, somatotropas, tirotropas, gonadotropas, corticotropas, no muestran alteraciones ultra-estructurales. Se concluye que en la rata, el tratamiento crónico con diazepam, no produce alteraciones ultraestructurales visibles en las células secretoras de las hormonas adenohipofisiarias, debido probablemente al efecto de corta duración que tienen los metabolitos del diazepam en esta especie

Novel interpretación de los mecanismos que regulan la actividad de las células lactotropas / New interpretation of the mechanisms that regulate the activity of lactotropic cells

La correlación de microscopía, morfometría y RIA de prolactina en la hipófisis de la rata fue utilizada en el estudio bajo condiciones extremas de actividad secretoria. Durante la lactancia se observó una hipertrofia e hiperplasia de las células lactotropas, situación que es revertida con la interrupción de la lactancia. La generación masiva de células lactotropas en ratas ablactadas indican la presencia de células excedentes que son eliminadas cuando los requerimientos establecidos por una situación de excepción es suprimida. Un nuevo modelo de regulación de la actividad secretoria de las células de prolactina es propuesto

Estudio inmunocitoquimico de las hormonas de la adenohipofisis humana: hormona del crecimiento / Immunocytochemical study of the human adenohypophysis hormones: growth hormone

Con el objeto de verificar el concepto de que la hormona del crecimiento esta contenida en poblaciones de celulas acidofilas, se realizo la deteccion inmunocitoquimica de la hormona en cortes histologicos de adenohipofisis humana fijados en formalina. Se utilizo la reaccion inmunocitoquimica de peroxidasa antiperoxidasa (PAP). se encontro que las celulas detectadas inmunocitoquimicamente como productoras de la hormona del crecimiento (GH), corresponden a las celulas acidofilas naranjas en la reaccion de tincion naranja G. delineadas clara y especificamente por el metodo PAP, estas celulas fueron observadas formando filas a lo largo de sinusoides. Se presenta la ultraestructura de estas celulas y se compara con las observaciones hechas por otros autores. Se describe ademas la utilidad del metodo para detectar la hormona de crecimiento en adenomas de la pituitaria y sus metastasis. Finalmente se discute el papel de la hormona en el crecimiento y se analizan las perspectivas de investigacion y la utilizacion practica de ella en el tratamiento de algunas entidades clinicas y en el incremento del crecimiento