scholarly journals Gonadotrope Plasticity at Cellular and Population Levels

Endocrinology ◽  
2012 ◽  
Vol 153 (10) ◽  
pp. 4729-4739 ◽  
Author(s):  
Zahara Alim ◽  
Cheryl Hartshorn ◽  
Oliver Mai ◽  
Iain Stitt ◽  
Colin Clay ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Ex Vivo ◽  
Single Cells ◽  
Anterior Pituitary Gland ◽  
Female Mice ◽  
Model Animal ◽  
Pituitary Glands ◽  
Acute Changes

Abstract Hormone-secreting cells within the anterior pituitary gland may form organized and interdigitated networks that adapt to changing endocrine conditions in different physiological contexts. For gonadotropes, this might reflect a strategy to cope with acute changes throughout different female reproductive stages. The current study examined gonadotropes in female mice at characteristically different hormonal stages: prepubertal, postpubertal, and lactating. Gonadotrope plasticity was examined at the level of the whole population and single cells at different stages by imaging both fixed and live pituitary slices. The use of a model animal providing for the identification of selectively fluorescent gonadotropes allowed the particular advantage of defining cellular plasticity specifically for gonadotropes. In vivo analyses of gonadotropes relative to vasculature showed significantly different gonadotrope distributions across physiological states. Video microscopy studies using live slices ex vivo demonstrated pituitary cell plasticity in the form of movements and protrusions in response to GnRH. As positive feedback from rising estradiol levels is important for priming the anterior pituitary gland for the LH surge, experiments provide evidence of estradiol effects on GnRH signaling in gonadotropes. The experiments presented herein provide new insight into potential plasticity of gonadotropes within the anterior pituitary glands of female mice.

Posttranscriptional regulation of rat growth hormone gene expression: increased message stability and nuclear polyadenylation accompany thyroid hormone depletion

1992 ◽  
Vol 12 (6) ◽  
pp. 2624-2632
Author(s):  
D Murphy ◽  
K Pardy ◽  
V Seah ◽  
D Carter
Keyword(s):  
Growth Hormone ◽  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Posttranscriptional Regulation ◽  
Anterior Pituitary Gland ◽  
Growth Hormone Gene ◽  
Gh Gene ◽  
Rat Growth ◽  
Pituitary Glands

In thyroid hormone-depleted rats, the rate of transcription of the growth hormone (GH) gene in the anterior pituitary gland is lower than the rate in euthyroid controls, and there is a corresponding reduction in the abundance of the GH mRNA. Concomitantly, the poly(A) tail of the GH mRNA increases in length. Examination of nuclear RNA from anterior pituitary glands of control and thyroid hormone-depleted rats revealed no difference in the length of pre-mRNAs containing the first and last introns of the GH gene. However, mature nuclear GH RNA is differentially polyadenylated in euthyroid and hypothyroid animals. We suggest that the extent of polyadenylation of the GH transcript is regulated in the cell nucleus concomitant with or subsequent to the splicing of the pre-mRNA. Experiments with anterior pituitary gland explant cultures demonstrated that the GH mRNA from thyroid hormone-depleted rats is more stable than its euthyroid counterpart and that the poly(A) tail may contribute to the differential stability of free GH ribonucleoproteins.

scholarly journals Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study

1975 ◽  
Vol 67 (2) ◽  
pp. 469-476 ◽  
Author(s):  
WH Fletcher ◽  
NC Anderson ◽  
JW Everett
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
In Vitro Study ◽  
Anterior Pituitary Gland ◽  
Stimulus Secretion Coupling ◽  
Unpublished Observation ◽  
Cellular Ca

The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions.

scholarly journals In Vivo and In Vitro Arsenic Exposition Induces Oxidative Stress in Anterior Pituitary Gland

2016 ◽  
Vol 35 (4) ◽  
pp. 463-475 ◽  
Author(s):  
Sonia A. Ronchetti ◽  
María S. Bianchi ◽  
Beatriz H. Duvilanski ◽  
Jimena P. Cabilla
Keyword(s):  
Oxidative Stress ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Inorganic Arsenic ◽  
Anterior Pituitary Gland ◽  
Pituitary Cells ◽  
Prolactin Release ◽  
Stress Responsive Genes

Inorganic arsenic (iAs) is at the top of toxic metalloids. Inorganic arsenic-contaminated water consumption is one of the greatest environmental health threats worldwide. Human iAs exposure has been associated with cancers of several organs, neurological disorders, and reproductive problems. Nevertheless, there are no reports describing how iAs affects the anterior pituitary gland. The aim of this study was to investigate the mechanisms involved in iAs-mediated anterior pituitary toxicity both in vivo and in vitro. We showed that iAs administration (from 5 to 100 ppm) to male rats through drinking water increased messenger RNA expression of several oxidative stress-responsive genes in the anterior pituitary gland. Serum prolactin levels diminished, whereas luteinizing hormone (LH) levels were only affected at the higher dose tested. In anterior pituitary cells in culture, 25 µmol/L iAs significantly decreased prolactin release in a time-dependent fashion, whereas LH levels remained unaltered. Cell viability was significantly reduced mainly by apoptosis evidenced by morphological and phosphatidylserine externalization studies. This process is characterized by early depolarization of mitochondrial membrane potential and increased levels of reactive oxygen species. Expression of some key oxidative stress-responsive genes, such as heme oxygenase-1 and metallothionein-1, was also stimulated by iAs exposure. The antioxidant N-acetyl cysteine prevented iAs-induced effects on the expression of oxidative stress markers, prolactin release, and apoptosis. In summary, the present work demonstrates for the first time that iAs reduces prolactin release both in vivo and in vitro and induces apoptosis in anterior pituitary cells, possibly resulting from imbalanced cellular redox status.

scholarly journals Diabetes and Hypercholesterolemia Impair the Cytological Structure of the Anterior Pituitary Gland

2019 ◽  
Vol 16 (3) ◽  
pp. 649-658
Author(s):  
Ahmed MR Abdo ◽  
Mohamed E El-Beeh ◽  
Sameer H. Qari ◽  
Dina A El-badry ◽  
Hassan IH El-Sayyad
Keyword(s):  
Body Weight ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Secretory Granules ◽  
Reproductive Function ◽  
Anterior Lobe ◽  
Anterior Pituitary Gland ◽  
Albino Rats ◽  
Pituitary Glands ◽  
Cytological Picture

Increase consumption of high fat diet was found to alter blood sugar level similar to diabetes and contributed to the development of obesity and affected the reproductive function of both sexes. The study aimed to clarify the influence of diabetes and or hypercholesterolemia on the cytological picture of cells of the anterior lobe of pituitary gland of male albino rats. Eighteen male albino rats weighing approximately 120 gram body weight were divided into three main groups; control, diabetes, hypercholesterolemia, diabetes (single i.p. 40 mg streptozotocin/kg B.wt plus 100mg. nicotinamide /kg body weight) and hypercholesterolemia (diet containing 3% cholesterol). Dietary feeding on cholesterol and diabetes were carried out for 12 weeks. At the end of treatment, animals were sacrificed, and pituitary glands were separated and their anterior lobe was processed for cytological investigations by transmission electron microscopy. The present study revealed that the rats subjected to experimental diabetes and/ or hypercholesterolemia exhibited a decrease of the secretory granules within the gonadotroph cells somatotroph and corticotrophin cells. There was a detected intracellular accumulation of fat globules in both the gonado- and sommatotroph cells. The authors reported that the altered cytological structures of the secretory function of the anterior pituitary gland led to marked impairment of the male hormonal level and causing infertility.

Multiple species of follicle-stimulating hormone exist within the anterior pituitary gland of male golden hamsters

1982 ◽  
Vol 95 (2) ◽  
pp. 257-266 ◽  
Author(s):  
Alfredo Ulloa-Aguirre ◽  
S. C. Chappel
Keyword(s):  
Pituitary Gland ◽  
Isoelectric Point ◽  
Receptor Binding ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Anterior Pituitary Gland ◽  
Con A ◽  
Pituitary Glands ◽  
Multiple Species ◽  
Gel Isoelectric Focusing

Anterior pituitary glands were collected from immature and mature (intact and castrated) male hamsters. The various species of FSH present within these glands were separated by Concanavalin A (Con A) chromatography and polyacrylamide gel isoelectric focusing (PAG-IEF) and measured by a specific FSH radioimmunoassay (RIA) as well as a radioreceptor assay (RRA). Two distinct forms of FSH (Con A unbound and bound) were separated by Con A chromatography and detected by both RIA and RRA. These two populations of FSH were present within anterior pituitary glands of all three animal models tested. Castration before collection of anterior pituitary glands reduced the ratio of Con A unbound: bound immunoreactive FSH. When measured by RRA this reduction was not observed. When homogenates of anterior pituitary glands obtained from mature animals were separated by PAG-IEF, six distinct species of FSH were observed by RIA with isoelectric points (pI) of 6·0, 5·7, 5·3, 5·0, 4·7 and 4·2–3·8. Homogenates of anterior pituitary glands obtained from immature male hamsters did not contain one of these species of FSH (pI value, 4·7). The relative contribution of some of the species of FSH to the total amount of detectable FSH differed depending upon the endocrine status of the animal. The species with pI value of 4·2–3·8 did not show any receptor-binding activity in any of the three models studied. The overall ratio of the activity of FSH measured by RRA compared with RIA was highest in anterior pituitary glands from intact mature and immature hamsters and lowest in anterior pituitary glands obtained from castrated animals. The RRA: RIA ratio for each species of FSH in all models tested declined as the isoelectric point of that species decreased. Thus, these results demonstrated the presence of multiple species of FSH within the anterior pituitary glands of immature and mature male hamsters. The relative proportions and receptor-binding activities of these species differed according to the isoelectric point and the pattern of hormone secretion at the time of collection of pituitary glands. Gonadal and other endocrine factors may influence not only the relative amount of each species of FSH but also the receptor-binding capacity of the FSH species synthesized by the anterior pituitary gland.

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