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PubMed1991

Immunohistochemical distribution of simple-epithelial-type keratins and other intermediate filament proteins in the developing human pituitary gland.

An immunohistochemical study of the production of the intermediate filaments [vimentin, cytokeratin, and glial filament acidic protein (GFAP)] during development of the pituitary gland was made by use of fetal and adult human pituitary tissue. Among these intermediate filament proteins in the anterior and intermediate lobes of the pituitary, cytokeratin is the first to appear, followed by GFAP and vimentin. However, only cytokeratin is seen during the period of morphogenesis of the pituitary gland, with the type-II subfamily cytokeratin 8 being the earliest to appear. Among the simple-epithelial-type cytokeratins, cytokeratins 8 and 19 were observed within the pituitary primordium during morphogenesis. Cells immunoreactive for cytokeratins 8 and 19 showed a heterogeneous three-dimensional distribution pattern in Rathke's pouch. Both cytokeratins 8 and 19 tended to be strongly positive at sites in the pituitary primordium where cells had become more loosely arranged (i.e., areas far from the diencephalon) but were only weakly positive in areas in which the epithelial cells were densely packed (i.e., areas closely associated with the diencephalon). It is concluded that, during the period of morphogenesis, Rathke's pouch has the intermediate filaments characteristic of simple epithelium and shows different immunoreactivity for simple-epithelial-type cytokeratins from place to place according to the extent of cellular differentiation.

Cell Differentiation↗
PubMed1989

Potentiation of antibody responsiveness after the transplantation of a syngeneic pituitary gland.

Transplantation of a pituitary graft under the kidney capsule and the resulting elevation of serum prolactin enhances the primary humoral antibody response to sheep red blood cells. Enhancement of the response is not due to marked changes in the percentage of T-cells and their subsets, B-cells, or the number of nucleated spleen cells. Quantitation of serum prolactin levels correlates well with the proportion of enhancement as mice with two grafts and higher levels of prolactin have increased responsiveness compared to mice with one graft. Systemic administration of mouse prolactin at the time of immunization also enhances the humoral immune response; however, if prolactin treatment is delayed and given 24 h after immunization, no potentiation of the response occurs. Thus, prolactin is enhancing the immune response by affecting an early afferent event in the induction of the immune response.

Animals↗
PubMed1977

Inhibition of thyrotrophin-releasing hormone responsiveness by physiological concentrations of thyroid hormones in the cultured rat pituitary gland.

Diced quarter anterior pituitaries from mature females Wistar rats were cultured in synthetic medium with or without added serum. Using each culture as its own control, the thyrotrophin-releasing hormone (TRH) dose-thyrotrophin (TSH) response characteristics of both media were similar; significant TSH secretion being stimulated at TRH doses around 1-5 X 10(-9) mol/l. During days 1-3 of culture, basal TSH secretion fell significantly but TRH responsiveness was unchanged. Neither tri-iodothyronine (T3) nor thyroxine (T4) influenced basal TSH secretion. In both culture media inhibition of TRH responsiveness was demonstrated with concentrations of T3 and T4 within the ranges 1-5 X 10(-12) to 1-5 X 10(-9) mol/l for T3 and 6-5 X 10(-10) to 6-5 X 10(-7) mol/l for T4. Equivalent inhibition was accompanied by similar T3 concentrations whether T3 or T4 supplements were used, suggesting that T4 itself has no feedback action. The similar concentrations of T3 required to inhibit TRH responsiveness in media either with or without serum suggest that the pituitary is responsive not only to free but also to total thyroid hormone concentrations, since serum-free medium contains no thyroid hormone-binding protein.

Animals↗
PubMed1989

[Functional and morphological identification of FSH- and LH-producing cells in the pituitary gland].

The identification of pituitary FSH and LH cells in states of pharmacological treatment influencing the pituitary FSH and LH production was performed by histological staining at the isoelectric points of these hormones in the cat. The intensity of the stained material in the hormone-producing cells was determined by a microphotometric technique. As a physiological control, the FSH and LH levels in blood were measured by a radioimmunoassay.

Animals↗
PubMed1985

Changes in the spontaneous action potentials from the whole, isolated, intact bovine pituitary gland following an injection of various bovine pituitary intraglandular colloid fractions.

Bovine pituitary intraglandular colloid (IGC) of intermediate lobe (IL) origin with accessions from the anterior lobe (AL), can modify the spontaneous action potentials (SAP) from AL, IL and posterior lobe (PL) cells. It was discovered that intraglandular colloid contains peptides ACTH, alpha-MSH, and beta-LPH when subjected to a series of radioimmunoassays. These peptides are thought, in part, to be responsible for altering the SAP.

Action Potentials↗
PubMed1988

The development and morphogenesis of the human pituitary gland.

In order to clarify the environmental factors which are involved in the development of the primordium of the pituitary gland such as cell-cell interactions, a three-dimensional reconstruction of this organ and its surrounding tissues was carried out. Pituitary material was obtained from human fetuses mainly during the period of organogenesis. Rathke's diverticulum was found to stretch rostrally from the stomodeal epithelium to the middle of the mesoderm, and already by the 5th week of fetal growth, it was clearly seen to be involved with the diencephalon. The area of contact between Rathke's pouch and the diencephalon gradually moved from the rostral to caudal regions and, after 13 weeks of development, had a position similar to that found in the newborn infant. Among the cells forming Rathke's pouch, it was found that the closer their relationship was to the diencephalon, the greater were their epithelial characteristics. When the relationship of such cells to the diencephalon was weaker, their differentiation to endocrine cells occurred earlier. Immunohistochemically, that portion of the pituitary primordium which has a close relationship with the diencephalon, later to become the pars intermedia, showed an adrenocorticotropic hormone (ACTH) immunoreactivity later than that of the pars anterior. On the other hand, in the 21st fetal week, nearly all of the cells of the pars intermedia were found to be ACTH-positive. This finding is thought to indicate a close connection between the physical contact between the brain (diencephalon) and the pituitary primordium and the development of the pars intermedia; the differentiation of ACTH cells. The surface of the epithelium of Rathke's cavity continues to increase at least until the 21st fetal week, so the growth of the epithelium of Rathke's pouch is thought to be heavily involved in the growth of the primordium of the pituitary gland in the early stages of development.

Cell Communication↗
PubMedDate not supplied

Interaction of putative vasopressin receptors in rat brain and bovine pituitary gland with a vasopressin anti-idiotype antibody as revealed by immunoblotting.

Vasopressin (AVP)-binding proteins were obtained from rat brain and the anterior and posterior lobes of bovine pituitary glands by (a) preparation of crude membranes, (b) solubilization of membrane proteins, (c) passage through an affinity column containing immobilized AVP, and (d) elution from the column with excess AVP. Gel electrophoresis revealed protein bands of 55 and 62 kilodaltons in rat brain, bovine posterior lobe and, to a far lesser extent, in the anterior lobe, which were similar to those previously identified in rat brain to be associated with AVP binding. Immunoblotting demonstrated that the 55 kilodalton bands of rat brain and bovine pituitary gland were selectively immunoreactive with an AVP anti-idiotype antibody. In addition, immunoreactivity occurred with a 62 kilodalton component of rat brain.

Animals↗
PubMed2000

Dendritic cells in the rat pituitary gland evaluated by the use of monoclonal antibodies and electron microscopy.

A detailed analysis of the difference in the localization and the immunoreactivity for various surface markers among folliculo-stellate cells, macrophages, and dendritic cells was performed using immunohistochemistry and electron microscopy of the rat pituitary gland. The folliculo-stellate cells were selectively labeled by an antiserum against S100 protein. The majority of dendritic cells were immunoreactive for the MHC class II (Ia) antigen (OX6) and/or the dendritic cell antibodies (OX62). The main population of macrophages was positive for the macrophage antibodies (ED1, ED2, and/or OX42). The cellular density of adenohypophyseal macrophages was significantly lower than that of folliculo-stellate cells and of dendritic cells. All the neurohypophyseal microglial cells were labeled with OX42, while the mAb OX6 labeled a small population of cells different from the cells identified by OX42 in the neurohypophysis. Double-immunoperoxidase staining for ED1 and OX6 revealed that positively stained cells could be classified into ED1+OX6-, ED1+OX6+, and ED1-OX6+ cells. Double staining with OX62 and OX6 mAbs showed that about 60% of the OX6+ cells were also immunolabeled with OX62 in the anterior lobe: OX62 detects a subpopulation of dendritic cells but does not recognize macrophage populations. Furthermore, double staining for S100 and OX6 resulted in no S100+ OX6+ cells. At the electron-microscopic level, reaction products for OX6 were confirmed in the cell membrane and labeled cells were distinguished from macrophages and folliculo-stellate cells by distinctive short, broad cytoplasmic processes and the rare presence of cytoplasmic organelles. Such cytological characteristics of the OX6-positive cells in the pituitary gland are similar to dendritic cells. Our results suggest that resident dendritic cells and folliculo-stellate cells are two different main components of interstitial cells in the pituitary gland.

Animals↗
PubMed1999

Immunocytochemical study on the localization and distribution of the somatolactin cells in the pituitary gland and the brain of Oreochromis niloticus (Teleostei, cichlidae).

Using specific antibody for chum salmon somatolactin (SL), immunocytochemical studies were employed to determine the distribution of this hormone in the pituitary gland and the brain of Orechromis niloticus. The results indicated that the SL-immunoreactive (ir) cells are found in the pars intermedia (PI) of the pituitary gland. The SL-ir cells showed strong and specific immunoreactivity to anti-chum salmon SL. Moreover, SL-ir cells were found to be widely distributed in most brain regions. Most of the SL-ir cell bodies were scattered along a nearly continuous line extending posteriorly from the olfactory bulb to the medulla oblongata through the nucleus preopticus periventricularis, habenula, and midbrain tegmentum and ventral to the nucleus lateralis tuberis pars posterior through the nucleus preopticus basalis lateralis and organum vasculosum luminae terminalis. Also SL-ir cells were observed in the cerebellum. The synthetic and secretory activity of the SL-ir cells, in the pituitary and the brain, showed an increase during sexual maturation and spawning. The highly organized SL-containing system and the gradual stimulation of SL synthesis and release during sexual maturation and spawning of O. nilotcus suggest that SL may be involved in the control of some steps of reproductive processes.

Animals↗
PubMed1983

Uptake and retention of sex steroids by the baboon pituitary gland--evidence of sexual dimorphism with respect to dihydrotestosterone.

The localization and identification of the target cells for estradiol (E2) and dihydrotestosterone (DHT) were studied in the pituitary gland of male and female baboons (Papio cynocephalus) using autoradiography and autoradiography combined with immunocytochemistry. The largest number of cells which sequestered 3H-E2 were located in the pars distalis of both the males and females. Immunocytochemistry revealed that these target cells were predominantly gonadotrophs and mammotrophs, albeit a few somatotrophs and thyrotrophs were also labeled. A distinct sexual dimorphism was not observed with respect to the uptake and retention of the tritiated estrogen but was clearly evident in those animals given 3H-DHT. Significantly more cells in all three lobes of the male baboon, the partes distalis, intermedia and nervosa, concentrated the radiolabeled androgen as compared to that found in the females. Regardless of sex, however, the gonadotrophs were the major cell type in the pars distalis which was labeled. A small population of mammotrophs, somatotrophs and thyrotrophs also retained 3H-DHT. In both males and females, the pars nervosa was the portion of the hypophysis most sensitive to 3H-DHT. These findings indicate that all three lobes of the hypophysis of the male and female baboon contain target cells for E2 and DHT and that the propensity for DHT uptake is greater in males than in females.

Animals↗
PubMed1997

Effects of bromocriptine and terguride on cell proliferation and apoptosis in the estrogen-stimulated anterior pituitary gland of the rat.

The effects of bromocriptine and terguride on the estrogen-stimulated anterior pituitary gland of the female Wistar rat were investigated. Pituitary weight and serum prolactin (PRL) levels were reduced by treatment with bromocriptine or terguride. Immunohistological staining for proliferating cell nuclear antigen (PCNA) revealed that the PCNA labeling index of PRL-producing cells was significantly decreased by treatment with bromocriptine or terguride compared with untreated cells. The number of apoptotic cells analyzed by the terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate-biotin nick end labeling method was significantly increased in rats treated with bromocriptine or terguride. Suppression of cell proliferation and induction of apoptosis are important effects of bromocriptine and terguride in the treatment of prolactinomas and other hyperprolactinemias.

Animals↗
PubMed1977

Dynamics and mechanics of corticosteroid feedback at the hypothalamus and anterior pituitary gland.

Corticosteroid feedback mechanisms were investigated at the hypothalamic level using the rat hypothalamus in vitro and the pituitary level using basal hypthalamic-lesioned rats. Both fast and delayed corticosteroid feedback effects were demonstrated at the level of the hypothalamus and pituitary gland with doses of corticosteroids within or near the physiological range. These two phases of feedback were separated temporally by a 'silent period' during which no feedback was apparent. Studies on the mechanism of action of corticosteroids at the hypothalamic level showed that the fast feedback mechanism acts by inhibition of release whilst the delayed feedback mechanism acts by inhibition of both synthesis and release. The fast feedback action of corticosterone does not appear to act by excitation of neuroinhibitory pathways since neither picrotoxin nor phentolamine prevented the feedback action of corticosteroids in vitro. Corticosterone inhibition of corticotrophin releasing factor release was overcome by depolarization of the membrane with K+ suggesting that the mechanism of action of the fast feedback of corticosteroids is by membrane stabilization.

Acetylcholine↗
PubMed1993

[Morphological changes in the pituitary gland and ovary in testosterone-induced anovulatory rat treated with Chinese medicinal herbs].

Injection of testosterone propionate 1.25 mg were given to SD rats on 9 days of age, and fed with replenishing Kidney herbal decoction as well as with distilled water as control from 80 to 94 days of age. On 100 days of age, all the rats were sacrificed and the pituitary glands and ovaries were excised for examination. In the ovaries, increase in interstitial glands' count and lowering of lipid drop's quantity in cytoplasm of interstitial glandular cells were observed after the treatment, and intracellular "crinophagy" and "autophagy" disappeared in the pituitary gland. After treatment with replenishing Kidney drugs, ovarian estrogen receptors increased whereas the ovarian progesterone receptors raised even higher. It suggests that both ovaries and pituitary gland in testosterone induced anovulatory rats were affected by herbs of replenishing Kidney.

Animals↗
PubMed2002

Human lipocalin-1, a physiological scavenger of lipophilic compounds, is produced by corticotrophs of the pituitary gland.

Lipocalin-1 (Lcn-1), a member of the lipocalin superfamily that binds a broad array of different chemical classes of lipophilic ligands, is believed to act as a physiological scavenger of potentially harmful lipophilic molecules. Thus far, it was thought to be produced exclusively by a number of exocrine glands and tissues, including lachrymal and lingual glands, prostate, secretory glands of the tracheobronchial tract, and sweat glands. Using Northern blotting analysis, we were able to demonstrate Lcn-1 expression by the human pituitary gland. Moreover, double immunolabeling with antibodies against Lcn-1 and pituitary gland hormones and detection with fluorophore-conjugated secondary antibodies revealed that Lcn-1 is specifically produced by corticotrophs, clearly indicating that its distribution is not restricted to exocrine tissues.

Acute-Phase Proteins↗
PubMed1977

In-vitro studies of the effects of oestrogen pretreatment on the sensitivity of the immature female rat pituitary gland to stimulation with gonadotrophin releasing hormone.

The effects of oestrogen priming on the sensitivity of the anterior pituitary gland to stimulation with gonadotrophin releasing hormone (GnRH) was investigated in immature female rats using a new organ culture technique. Hemipituitary glands obtained from animals primed with a single dose of oestradiol benzoate (OB; 20 microgram/100 g body weight) released significantly more LH when pulsed with GnRH (4 nmol/1) than did control hemipituitary glands. This potentiating effect was detectable as early as 5 days after birth. After a second stimulation, LH secretion remained high. These results were compared with those obtained from animals treated to induce increased levels of endogenous oestrogen on day 26 of life. Thus, hemipituitary glands were obtained from animals given two injections of OB, an injection of pregnant mare serum gonadotrophin (PMSG) or a unilateral brain lesion placed in the basal hypothalamus. Pituitary tissue was stimulated as before with a pulse of GnRH. Two injections of OB enhanced the sensitivity to stimulation. Conversely, both PMSG and lesion treatment severely reduced the sensitivity to GnRH, although PMSG-treated and lesioned animals have been used as models for the study of ovulation.

Animals↗