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PubMed1983

Effect of inhibin-like activity on LH-RH-stimulated release of FSH by pituitary glands from female rats in vitro.

During long-term incubation of pituitary glands from intact female rats in the presence of inhibin-like activity, LH-RH-stimulated release of FSH becomes inhibited after 4 h of incubation. However, at the same time inhibition of basal FSH release is included. Therefore, glands were at first incubated for 4 h in the presence of inhibin-like activity to block basal release completely and thereafter LH-RH was added to the medium. It was found that LH-RH still could stimulate FSH release, despite the continuous presence of inhibin-like activity. This means that LH-RH-stimulated release of FSH could be investigated separately from basal release. Using this way of incubation, it was found that part of the action of LH-RH on FSH release was independent of protein synthesis. Also part of LH-RH-stimulated FSH release was independent of the presence of extracellular Ca2+. Furthermore it was found that LH-RH, when added after 4 h of incubation did stimulate FSH synthesis, in the presence as well as absence of inhibin-like activity. The present results indicate that LH-RH-stimulated release of FSH is not affected by inhibin-like activity. Complete inhibition of basal release and synthesis of FSH does not prevent LH-RH from stimulating FSH release and synthesis. It is suggested that two separate releasing mechanisms for FSH could exist in the pituitary gland.

Animals↗
PubMed2003

Immunohistochemical proliferation markers may overestimate the growth potential after ionizing radiation: in vivo study in the rat anterior pituitary gland.

The effect of ionizing radiation on the expression of immunohistochemical proliferation markers was examined in the rat pituitary gland. Rats were irradiated in the pituitary region with a dose of 40 Gy, or were sham-irradiated as controls. Bromodeoxyuridine (BrdU) was given to the rats after one week, either one hour (Br-1 group) or 17 hours (Br-17 group) before perfusion fixation. Immunohistochemical staining for BrdU, topoisomerase II-alpha (TopoII), Ki-67 (MIB-5), p21WAF1/Cip1 (p21), and p27Kip1 (p27) was performed. Apoptotic cells were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling method. The mean BrdU labeling index (LI) and MIB-5 LI were significantly higher in the irradiated rats than in the sham rats in the Br-1 group. TopoII LI was higher in the irradiated rats than in the sham rats, although not significantly. p27-positive cells decreased in irradiated rats, but p21-positive cells increased more than in the sham rats. The number of apoptotic cells increased significantly after radiation. BrdU LIs were lower in the irradiated rats than in the sham rats in the Br-17 group. A few small BrdU-positive fragments with apoptotic features were phagocytosed in the anterior lobe cells. These results indicate that some "immunohistochemically proliferating cells" subsequently undergo apoptosis in the irradiated pituitary gland. The values of proliferative indices should be cautiously interpreted after irradiation of tissue.

Animals↗
PubMed1987

Laminin in the anterior pituitary gland of the rat. Laminin in the gonadotrophic cells correlates with their functional state.

The distribution pattern of laminin in the rat anterior pituitary gland under physiological and hormonally altered conditions was studied immunohistochemically. Intense immunoreactivity of the capillaries and of the basement membranes surrounding parenchymal cells was found. Five to 10% of the parenchymal cells of normal adult rat pituitary gland exhibited also intense positive cytoplasmic staining. These were identified as gonadotrophic cells on the basis of their topographic distribution and typical 700-nm light bodies. By immunoelectron microscopy it was shown that the light bodies contain laminin and tubulin. After treatment with estrogen, which is known to suppress the function of the gonadotrophic cells, virtually no cytoplasmic laminin was found. Ultrastructurally, the number of light bodies in the gonadotrophic cells diminished significantly, from approximately 3 to 8 per cell to 0 to 1 per cell in a given section. In contrast, after castration, the number of laminin positive cells increased to a number above that found in the normal adult male rat, and the number of light bodies increased two to four times. Based on these results, it appears that the presence of cytoplasmic laminin and the number of light bodies reflects the hormonal activity of the gonadotrophic cells of the rat pituitary gland.

Animals↗
PubMed1981

A comparative histochemical study on alkaline phosphatase of the anterior pituitary gland in various mammals.

Alkaline phosphatase was histochemically studied in the anterior pituitary gland of mammals. By the azo dye method, the enzymatic activity was observed on the cell membrane, and in the cytoplasm and Golgi apparatus of the glandular cells in the swine, dog and guinea pig, while it was found on the cell membrane and in the cytoplasm of the glandular cells in the cattle, sheep and rabbit but only in the cytoplasm of the glandular cells in the hamster, rat and mouse. By the lead citrate method, the enzymatic activity in the glandular cells decreased in all the mammals examined, and was hardly found in the hamster, rat and mouse. It was shown that the localization of alkaline phosphatase activity by the lead citrate method is finer than that by the azo dye method in the anterior pituitary gland. In the swine and dog, the cells with the enzymatic activity were found throughout the gland though they mainly concentrated in the zona tuberalis. In the castrated males, the enzymatic activity was stronger than that in the males and females, and the cells with the activity increased in number. From these results, these cells in the two species studied were regarded as gonadotrophs. Furthermore, it was suggested that the alkaline phosphatase in the glandular cells of the gland displays a high activity in active stage of the synthesis and/or release of gonadotrophic hormone, and have some connection with the regulatory mechanism of membrane permeability.

Alkaline Phosphatase↗
PubMed2005

Localization of interleukin-18 and its receptor in somatotrophs of the bovine anterior pituitary gland.

A pro-inflammatory cytokine, interleukin 18 (IL-18), induces intracellular expression of IL-1 and the release of IL-6. IL-1 and IL-6 has been detected in anterior pituitary cells, suggesting that IL-18 is produced in anterior pituitary cells and may serve to aid immuno-endocrine regulation. In the present study, we addressed this hypothesis by investigating the intracellular localization of IL-18 and its receptor in bovine anterior pituitary gland. IL-18 mRNA and its protein were detected in the anterior pituitary gland by RT-PCR and Western blotting. In situ hybridization showed that IL-18 mRNA was expressed in the anterior pituitary cells. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs. Furthermore, the expression of GH mRNA in IL-18 immunoreactive cells was confirmed by immuno-laser microdissection. These results first demonstrated that somatotrophs produced IL-18. Subsequently, the distribution of the IL-18 receptor alpha (IL-18Ralpha) was investigated in order to understand IL-18 signaling among the anterior pituitary cells. Bovine IL-18Ralpha cDNA was partially sequenced and detected in the anterior pituitary gland by RT-PCR. Immunohistochemistry of IL-18Ralpha, IL-18 and GH showed that IL-18Ralpha was co-localized in IL-18 immunoreactive cells or somatotrophs. These data suggest that IL-18 acts on somatotrophs as an immuno-endocrine mediator through the autocrine pathway.

Amino Acid Sequence↗
PubMed1984

Dopamine receptor of the porcine anterior pituitary gland. Solubilization and characterization.

In the anterior pituitary gland, dopamine controls the release of prolactin from the mammotrophs. The dopamine receptors in the porcine gland have been shown to exist in two different affinity states of equal proportion, one bearing high affinity for agonists and labeled by 3H-agonist-ligands and the other displaying low affinity for agonists. Both forms of the receptor can be labeled by 3H-antagonist-ligands. Dopamine receptors from porcine anterior pituitary membranes can be solubilized with retention of their ability to interact with specific dopaminergic ligands. Treatment of membrane preparations with 1% digitonin resulted in the solubilization of 20-25% of the specific binding sites labeled by [3H] spiroperidol with a specific activity of about 100 fmoles/mg. The receptor was a glycoprotein as assessed by the interaction of these binding sites with agarose-immobilized lectin. [3H]Spiroperidol binding in solubilized preparations was saturable, of high affinity (KD = 570 pM), and to a single class of stereoselective binding sites. Agonist competition for [3H]spiroperidol binding indicated that, whereas the solubilized receptor retained its dopaminergic specificity, the high-affinity interactions of the receptor with agonists present in membranes and sensitive to guanine nucleotides were lost in solubilized preparations. Thus, the KD values calculated from the agonist competition curves for [3H]spiroperidol corresponded to the agonist affinities for the low-affinity state of the receptor documented in membranes. However, high-affinity agonist binding and its sensitivity to guanine nucleotides were preserved when the membrane-bound receptor was prelabeled with the agonist [3H]N-n-propylnorapomorphine prior to solubilization. These results suggest that a component that confers agonist high-affinity binding and guanine nucleotide responsiveness to the receptor is lost during solubilization unless a stable complex is formed with the agonist prelabeled receptor prior to solubilization.

Animals↗
PubMedDate not supplied

Localization and pharmacology of some dopamine receptor complexes in the striatum and the pituitary gland: synaptic and son-synaptic communication.

The striatum receives massive dopaminergic projections from neurons in the ventral tegmental area, the substantia nigra and the retro-rubral cell group. Dopaminergic neurons in the arcuate nucleus and periventricular hypothalamic nuclei project to the median eminence and the neuro-intermediate lobe of the pituitary gland. The anterior lobe of the pituitary gland is not innervated by dopaminergic neurons, but receives dopamine via a vascular route from the median eminence. Two categories of dopamine receptors (D-1 and D-2) can be identified on the basis of the ability of various drugs to discriminate between these two entities. Dopamine stimulates both D-1 and D-2 receptors. The affinity of dopamine for the D-2 receptor is approximately 1000 times higher than for the D-1 receptor. Dopamine is involved in synaptic as well as non-synaptic communication. Examples of non-synaptic communication via D-2 receptors are the dopamine induced inhibition of prolactin release from the anterior pituitary gland and most likely the D-2 receptor mediated inhibition of the release of acetylcholine in the striatum. Examples of synaptic communication have been found in the striatum where (with ultrastructural techniques) synaptic contacts between dopaminergic nerve terminals and elements from cells containing GABA, substance P or enkephalin have been demonstrated. It is tempting to speculate that synaptic and non-synaptic communication occurs via D-1 and D-2 receptors respectively.

Acetylcholine↗
PubMed2003

Influence of estradiol, progesterone, and nutrition on concentrations of gonadotropins and GnRH receptors, and abundance of mRNA for GnRH receptors and gonadotropin subunits in pituitary glands of beef cows.

Nutritionally induced anovulatory cows (n = 28) were used to determine the effect of steroids on regulation of synthesis and secretion of gonadotropins. Anovulatory cows were ovariectomized and received intravaginal inserts containing estradiol (E2), progesterone (P4), E2 and P4 (E2P4), or a sham intravaginal insert (C) for 7 d. Concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were quantified in serum and E2 and P4 were quantified in plasma. Cows were exsanguinated within 1 to 2 h after removal of intravaginal inserts and pituitary glands were collected and stored at -80 degrees C until messenger ribonucleic acid (mRNA) for gonadotropin-releasing hormone receptor (GnRH-R) and gonadotropin subunits, pituitary content of GnRH-R, and LH and FSH were quantified. Pituitary glands from five proestrous cows were harvested to compare gonadotropin characteristics between ovariectomized, anovulatory cows and intact cows. Plasma concentrations of E2 were greater (P < 0.05) in E2-treated cows than in sham-treated cows. Concentrations of P4 were greater (P < 0.05) in cows treated with P4 than in sham-treated cows. Mean serum concentrations of LH and FSH were not significantly influenced by steroid treatments. However, frequency of LH pulses of ovariectomized, nutritionally induced anovulatory cows was increased (P < 0.05) by treatment with E2 and amplitude of LH pulses was greater (P < 0.05) in cows treated with E2 or P4 than in cows treated with E2P4 or sham-treated. Quantity of mRNA for LHbeta in the pituitary gland was greater when cows were treated with P4. Concentrations of LH in the pituitary gland were not affected by steroid treatments; however, pituitary concentrations of FSH were less (P < 0.1) in E2 cows than in sham-treated cows. The number of GnRH-R was increased (P < 0.05) in cows treated with E2, but P4 treatment did not influence the number of GnRH-R. Abundance of mRNA for GnRH-R, common alpha-subunit, and FSHbeta were not affected by treatments. Pituitary concentrations of LH were greater (P < 0.05) and concentrations of FSH were less (P < 0.05) in proestrous cows than in ovariectomized, anovulatory cows treated with or without steroids. Abundance of mRNA for GnRH-R, common alpha-subunit, LHbeta and FSHbeta were similar for proestrous and anovulatory cows. We conclude that treatment of nutritionally induced anovulatory cows with progesterone and estradiol may cause pulsatile secretion of LH.

Animal Nutritional Physiological Phenomena↗
PubMed1975

Microtubules in thyroidectomy cells of the rat anterior pituitary gland.

Microtubules were successfully illustrated in thyrotrophs and thyroidectomy cells of rat pituitary glands. In contrast, microfilaments were mostly seen in the nonglandular follicular cells. Numerous microtubules were observed in the early stages of development of the thyroidectomy cells. In thyroidectomy cells microtubules were located in close proximity to mitochondria, endoplasmic reticula, secretory granules, and membranes of Golgi complexes. Consequently, it is suggested that microtubules may play a role in degranulation or other processes associated with the hypersecretory state.

Animals↗
PubMed1986

Human pharyngeal and sellar pituitary glands: differences and similarities revealed by an immunocytochemical study.

Fifteen pharyngeal and sellar pituitary glands, obtained at autopsy from unselected adult patients, were compared in an attempt to elucidate the functional significance of the pharyngeal pituitary. The study was carried out using light microscopy and an indirect peroxidase technique to detect the presence of prolactin, GH, ACTH, LH, FSH, TSH and lipotrophin (LPH) immunoreactive cells. A quantitative analysis of these cell types in each gland was performed. Neither the pharyngeal nor the sellar pituitaries were abnormal in six cases. In this group the average percentage of immunoreactive cells in the sellar vs the pharyngeal pituitary was 11.3 vs 7.4 for FSH cells, 13.3 vs 4.4 for LH cells, 6.4 vs 5.2 for TSH cells, 14 vs 1.5 for ACTH cells, 13.1 vs 6 for LPH cells, 29.4 vs 5.2 for GH cells and 21.2 vs 8.5 for prolactin cells. A comparative statistical evaluation of the seven hormone-producing cell types indicated that, in most cases, the percentage of immunoreactive cells was significantly higher in the sellar pituitary. Examination of serial sections revealed hyperplasia, with or without microadenomas, in nine sellar pituitaries. In these abnormal cases most of the pharyngeal pituitary glands showed hyperplasia of the same cell type as was found hyperplastic in the sellar adenohypophysis. However, hyperplasia restricted to the sellar pituitary was also seen. There were two cases in which the pharyngeal pituitary was almost lacking in immunoreactive cells; in one of them the sellar pituitary had GH and prolactin cell hyperplasia. The results obtained confirm that under normal conditions the pharyngeal pituitary is not an important source of adenohypophyseal hormones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Hormone levels of anterior pituitary gland and serum in Nagase analbuminemia rats.

The hormone levels in the anterior pituitary gland and serum in Nagase analbuminemia rats (NAR), a mutant strain established from Sprague-Dawley rats with hyperlipidemia, were examined. For the anterior pituitary gland, the prolactin, TSH, GH, LH and FSH contents in male NAR were significantly lower than those of normal rats. In female NAR, prolactin, TSH and LH levels were also lower than those in normal rats, whereas FSH and GH were normal. For the serum, the concentrations of TSH, total T3, total and free T4, estradiol-17 beta and testosterone were examined. The serum testosterone concentration in NAR was lower than that of normal rats. Histochemical examination of the hydroxysteroid dehydrogenase (HSD) activity of testes was made in relation to the serum testosterone level. NAR testes, which are rather small compared with those of normal rats, have lower HSD activity. A higher level of serum TSH was seen in NAR. Total and free T4 concentrations were low in the male NAR only. Estradiol-17 beta and T3 concentrations in NAR were unchanged. Changes in serum LH and FSH levels during the estrous cycle in NAR were also studied. Their patterns of change are normal.

Age Factors↗
PubMed2001

Proliferation and differentiation of thyrotrophs in the pars distalis of the rat pituitary gland during the fetal and postnatal period.

Pituitary glands from rat fetuses (gestational age 17.5-21.5 days) and rat pups (3, 7, 10, 14, 28 days old) were labeled with bromodeoxyuridine (BrdU) 2 h prior to sacrifice and embedded in paraffin. Sections were consecutively immunostained with anti-BrdU and anti-rat TSH. The number of cells stained with anti-BrdU, anti-rTSH, or both of them were counted. The area of the section and the volume of the pituitary were measured and the number of immunostained cells per mm3 or per pituitary was calculated. Thyrotrophs were few in 17.5 day-fetuses but increased thereafter, with a rapid increase during the 2nd week after birth. The number of cells labeled with both BrdU and TSH peaked at 7 days after birth. It was estimated that about 1/5 of the thyrotrophs increased during this period was derived from the mitosis of existing thyrotrophs.

Aging↗
PubMed1998

Cobalt 60 irradiation of pituitary gland tumors in three cats with acromegaly.

Acromegaly was diagnosed in 3 cats with insulin-resistant diabetes mellitus (DM) on the basis of history and physical examination findings, which ruled out other causes of insulin-resistant DM, and by documenting high plasma concentrations of growth hormone. Computed tomography revealed a mass in the area of the pituitary gland in each cat. Pituitary gland tumors were irradiated with cobalt 60, and none of the cats developed complications to radiotherapy. Each cat received a total dose of 48 Gy of cobalt 60 during 12 treatments. After completion of radiotherapy, insulin requirements were less for all cats, although in 1 cat, this improvement was transient. Diabetes mellitus resolved in 2 of 3 cats. After treatment, decreases in insulin requirements correlated with decreases in plasma growth hormone concentrations in 2 of 3 cats in which DM resolved. On the basis of these findings, irradiation of pituitary gland tumors appears to be a treatment option for cats with acromegaly.

Acromegaly↗
PubMed1968

Adenosine triphosphate and adenosine triphosphatase in hormone-containing granules of posterior pituitary gland.

Neurosecretory granules prepared from bovine posterior pituitary glands by cell fractionation methods contain adenosine triphosphate and adenosine triphosphatase activity. Addition of adenosine triphosphate to suspensions of granules stimulates release of vasopressin. It is suggested that adenosine triphosphate and adenosine triphosphatase participate in the storage and release of vasopressin.

Adenosine Triphosphatases↗
PubMed2003

Temporal parenteral nutrition in children causing t1 shortening in the anterior pituitary gland and globus pallidus.

Patients receiving long-term parenteral nutrition (PN) with trace elements (TE) may exhibit T (1) shortening in the anterior pituitary gland and basal ganglia. The purposes of this study were to clarify at what time or from what site the signal change begins in children. Retrospective analysis of magnetic resonance imaging results was performed for 10 pediatric patients aged from 1 to 16 years receiving temporal PN, eight of which received PN with TE for less than two months, and 13 patients with headache or seizures as age-matched controls. Axial and sagittal T (1)-weighted images were obtained to analyze the T (1) shortening in the anterior pituitary gland and globus pallidus. All eight patients receiving PN with TE exhibited T (1) shortening in the anterior pituitary gland (six patients) and/or globus pallidus (five patients). No T (1) shortening was observed in the other two patients without TE, or the 13 age-matched controls. Therefore, the signal change may be associated with TE administration, and begins markedly earlier than previously reported. We discussed the possibility that manganese (Mn) caused the signal change, and proposed that the administration of a lower dose of Mn is recommended, even in the case of temporal PN, to prevent possible Mn toxicity toward both the brain and liver.

Adolescent↗
PubMed1975

Gonadotrophs following removal of the ovaries: a fine structural study of human pituitary glands.

The fine structure of gonadotrophs has been investigated in surgically removed pituitary glands of 12 women who because of disseminated breast cancer, underwent bilateral ovariectomy at various periods before hypophysectomy. Compared with the adenohypophyses of 3 non-ovariectomized female subjects with diabetes mellitus, electron microscopy revealed that two cell types were affected by gonadectomy. These cell types corresponded to those which were regarded as FSH gonadotrophs and LH gonadotrophs in previous studies. In addition in the adenohypophyses stimulated by removal of the ovaries, intermediary cell types began to appear suggesting a transformation of LH gonadotrophs to FSH gonadotrophs. The most conspicuous change following gonadectomy was the formation of castration cells. These cells arose from FSH gonadotrophs and exhibited ultrastructural features interpreted as representing the morphologic manifestations of sustained hypersecretion of gonadotrophins. It seemed that castration cells have a limited life span and in their advanced stages of development they show ultrastructural signs indicative of irreversible involution.

Adult↗
PubMed1985

Cleaved prolactin: evidence for its occurrence in human pituitary gland and plasma.

A form of PRL that is cleaved in its large disulfide loop has been reported in rat and mouse pituitary glands, but it is not known whether it exists in the human pituitary gland and whether it circulates in blood. Recently, we developed an immunoelectrophoretic technique which is capable of measuring immunoreactive variants of PRL and other hormones in plasma. We describe here detection of cleaved PRL in normal and tumor pituitary tissue from a prolactinoma patient and in the plasma of pregnant women.

Autoradiography↗
PubMed2005

Inflammatory and infectious processes involving the pituitary gland.

Inflammatory and infectious diseases of the pituitary gland are rare, and imaging diagnosis may be difficult. They encompass a wide spectrum of pathology including autoimmune (lymphocytic) hypophysitis, granulomatous hypophysitis, local manifestations of systemic disease, and a multitude of infectious processes. Based on extensive review of the literature, this article will present a classification scheme, description of pathology, and imaging findings of the various inflammatory and infectious entities, along with selected images from our case material.

Granulomatosis with Polyangiitis↗