scholarly journals Effects of Melatonin on Anterior Pituitary Plasticity: A Comparison Between Mammals and Teleosts

2021 ◽  
Vol 11 ◽  
Author(s):  
Elia Ciani ◽  
Trude M. Haug ◽  
Gersende Maugars ◽  
Finn-Arne Weltzien ◽  
Jack Falcón ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Future Research ◽  
Pituitary Hormone ◽  
Hormone Production ◽  
Physiological Processes ◽  
Important Target ◽  
Specific Receptors ◽  
Positive And Negative Feedback

Melatonin is a key hormone involved in the photoperiodic signaling pathway. In both teleosts and mammals, melatonin produced in the pineal gland at night is released into the blood and cerebrospinal fluid, providing rhythmic information to the whole organism. Melatonin acts via specific receptors, allowing the synchronization of daily and annual physiological rhythms to environmental conditions. The pituitary gland, which produces several hormones involved in a variety of physiological processes such as growth, metabolism, stress and reproduction, is an important target of melatonin. Melatonin modulates pituitary cellular activities, adjusting the synthesis and release of the different pituitary hormones to the functional demands, which changes during the day, seasons and life stages. It is, however, not always clear whether melatonin acts directly or indirectly on the pituitary. Indeed, melatonin also acts both upstream, on brain centers that control the pituitary hormone production and release, as well as downstream, on the tissues targeted by the pituitary hormones, which provide positive and negative feedback to the pituitary gland. In this review, we describe the known pathways through which melatonin modulates anterior pituitary hormonal production, distinguishing indirect effects mediated by brain centers from direct effects on the anterior pituitary. We also highlight similarities and differences between teleosts and mammals, drawing attention to knowledge gaps, and suggesting aims for future research.

scholarly journals Estrogen mediates sex differences in preoptic neuropeptide and pituitary hormone production in medaka

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Junpei Yamashita ◽  
Yuji Nishiike ◽  
Thomas Fleming ◽  
Daichi Kayo ◽  
Kataaki Okubo
Keyword(s):  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Pituitary Hormone ◽  
Sexually Dimorphic ◽  
Hormone Production ◽  
Anterior Pituitary Hormones ◽  
Vertebrate Brain ◽  
Pituitary Adenylate Cyclase ◽  
Evolutionarily Conserved ◽  
Sexually Dimorphic Expression

AbstractThe preoptic area (POA) is one of the most evolutionarily conserved regions of the vertebrate brain and contains subsets of neuropeptide-expressing neurons. Here we found in the teleost medaka that two neuropeptides belonging to the secretin family, pituitary adenylate cyclase-activating polypeptide (Pacap) and vasoactive intestinal peptide (Vip), exhibit opposite patterns of sexually dimorphic expression in the same population of POA neurons that project to the anterior pituitary: Pacap is male-biased, whereas Vip is female-biased. Estrogen secreted by the ovary in adulthood was found to attenuate Pacap expression and, conversely, stimulate Vip expression in the female POA, thereby establishing and maintaining their opposite sexual dimorphism. Pituitary organ culture experiments demonstrated that both Pacap and Vip can markedly alter the expression of various anterior pituitary hormones. Collectively, these findings show that males and females use alternative preoptic neuropeptides to regulate anterior pituitary hormones as a result of their different estrogen milieu.

scholarly journals Expression and regulation of glucocorticoid-induced leucine zipper in the developing anterior pituitary gland

2008 ◽  
Vol 42 (2) ◽  
pp. 171-183 ◽  
Author(s):  
Laura E Ellestad ◽  
Stefanie A Malkiewicz ◽  
H David Guthrie ◽  
Glenn R Welch ◽  
Tom E Porter
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Leucine Zipper ◽  
Pituitary Hormones ◽  
Neuroendocrine System ◽  
Pituitary Hormone ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Anterior Pituitary Hormone

The expression profile of glucocorticoid-induced leucine zipper (GILZ) in the anterior pituitary during the second half of embryonic development in the chick is consistent with in vivo regulation by circulating corticosteroids. However, nothing else has been reported about the presence of GILZ in the neuroendocrine system. We sought to characterize expression and regulation of GILZ in the chicken embryonic pituitary gland and determine the effect of GILZ overexpression on anterior pituitary hormone levels. Pituitary GILZ mRNA levels increased during embryogenesis to a maximum on the day of hatch, and decreased through the first week after hatch. GILZ expression was rapidly upregulated by corticosterone in embryonic pituitary cells. To determine whether GILZ regulates hormone gene expression in the developing anterior pituitary, we overexpressed GILZ in embryonic pituitary cells and measured mRNA for the major pituitary hormones. Exogenous GILZ increased prolactin mRNA above basal levels, but not as high as that in corticosterone-treated cells, indicating that GILZ may play a small role in lactotroph differentiation. The largest effect we observed was a twofold increase in FSH β subunit in cells transfected with GILZ but not treated with corticosterone, suggesting that GILZ may positively regulate gonadotroph development in a manner not involving glucocorticoids. In conclusion, this is the first report to characterize avian GILZ and examine its regulation in the developing neuroendocrine system. We have shown that GILZ is upregulated by glucocorticoids in the embryonic pituitary gland and may regulate expression of several pituitary hormones.

The Pituitary Gland: Embryology, Physiology, and Pathophysiology

2000 ◽  
Vol 19 (2) ◽  
pp. 9-17 ◽  
Author(s):  
Angela Dorton
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Thyroid Stimulating Hormone ◽  
The Body ◽  
Pars Intermedia ◽  
Pituitary Hormone ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Stimulating Hormone

The pituitary gland, the “master gland” of the body, is composed of endocrine cells, which secrete hormones essential for homeostasis. The gland consists of the adenohypophysis (anterior pituitary) and the neurohypophysis (posterior pituitary), two unique structures that differ anatomically and functionally.The neurohypophysis is innervated by nerve cells in the hypothalamus and forms the connection between it and the pituitary gland. The hypothalamus stimulates release and inhibition of pituitary hormones. The neurohypophysis secretes oxytocin and antidiuretic hormone.The adenohypophysis is composed of three structures: the pars distalis, the pars intermedia, and the pars tuberalis. The anterior pituitary (pars distalis) is responsible for the release of hormones that include growth hormone, prolactin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, and melanocyte-stimulating hormone.Disorders of the pituitary are predominately those of insufficient hormone release and may have profound effects on the neonate. The potential causes of and clinical symptomatology that may accompany pituitary hormone insufficiency in the neonatal period are explored.

Vasopressin as a neuroendocrine regulator of anterior pituitary hormone secretion

1993 ◽  
Vol 129 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Andreas Kjær
Keyword(s):  
Arginine Vasopressin ◽  
Mode Of Action ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Pituitary Hormones ◽  
Pituitary Hormone ◽  
Anterior Pituitary Hormones ◽  
Anterior Pituitary Hormone

Secretion of the anterior pituitary hormones adrenocorticotropin (ACTH), β-endorphin and prolactin (PRL) is complex and involves a variety of factors. This review focuses on the involvement of arginine-vasopressin (AVP) in neuroendocrine regulation of these anterior pituitary hormones with special reference to receptor involvement, mode of action and origin of AVP. Arginine-vasopressin may act via at least two types of receptors: V1− and V2−receptors, where the pituitary V1−receptor is designated V1b. The mode of action of AVP may be mediating, i.e. anterior pituitary hormone secretion is transmitted via release of AVP, or the mode of action may be permissive, i.e. the presence of AVP at a low and constant level is required for anterior pituitary hormones to be stimulated. Under in vivo conditions, the AVP-induced release of ACTH and β-endorphin is mainly mediated via activation of hypothalamic V1− receptors, which subsequently leads to the release of corticotropin-releasing hormone. Under in vitro conditions, the AVP-stimulated release of ACTH and β-endorphin is mediated via pituitary V1b− receptors. The mode of action of AVP in the ACTH and β-endorphin response to stress and to histamine, which is involved in stress-induced secretion of anterior pituitary hormones, is mediating (utilizing V1− receptors) as well as permissive (utilizing mainly V1− but also V2−receptors). The AVP-induced release of PRL under in vivo conditions is conveyed mainly via activation of V1−receptors but V2−receptors and probably additional receptor(s) may also play a role. In stress- and histamine induced PRL secretion the role of AVP is both mediating (utilizing V1 −receptors) and permissive (utilizing both V1− and V2− receptors). Arginine-vasopressin may be a candidate for the PRL-releasing factor recently identified in the posterior pituitary gland. Arginine-vasopressin of both magno- and parvocellular origin may be involved in the regulation of anterior pituitary hormone secretion and may reach the corticotrophs and the lactotrophs via three main routes: the peripheral circulation, the long pituitary portal vessels or the short pituitary portal vessels.

Prolactin release, oestrogens and proliferation of prolactin-secreting cells in the anterior pituitary gland of adult male rats

1986 ◽  
Vol 108 (3) ◽  
pp. 399-403 ◽  
Author(s):  
R. L. Pérez ◽  
G. A. Machiavelli ◽  
M. I. Romano ◽  
J. A. Burdman
Keyword(s):  
Cell Proliferation ◽  
Pituitary Gland ◽  
Adult Male ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Serum Prolactin ◽  
Prolactin Release ◽  
Experimental Conditions

ABSTRACT Relationships among the release of prolactin, the effect of oestrogens and the proliferation of prolactin-secreting cells were studied under several experimental conditions. Administration of sulpiride or oestradiol released prolactin and stimulated cell proliferation in the anterior pituitary gland of adult male rats. Clomiphene completely abolished the rise in cell proliferation, but did not interfere with the sulpiride-induced release of prolactin. Treatment with oestradiol plus sulpiride significantly increased serum prolactin concentrations and the mitotic index compared with the sum of the stimulation produced by both drugs separately. Bromocriptine abolished the stimulatory effect of oestradiol on the serum prolactin concentration and on cell proliferation. In oestradiol- and/or sulpiride-treated rats, 80% of the cells in mitoses were lactotrophs. The remaining 20% did not stain with antisera against any of the pituitary hormones. The number of prolactin-secreting cells in the anterior pituitary gland significantly increased after the administration of oestradiol or sulpiride. The results demonstrate that treatment with sulpiride and/or oestradiol increases the proliferation and the number of lactotrophs in the anterior pituitary gland of the rat. J. Endocr. (1986) 108, 399–403

scholarly journals Evaluation of pituitary imaging in patients with PROP-1 gene mutation

Medicina ◽  
2009 ◽  
Vol 45 (9) ◽  
pp. 693 ◽  
Author(s):  
Natalija Tkačenko ◽  
Danutė Lašienė ◽  
Silvija Jakštienė ◽  
Algidas Basevičius ◽  
Rasa Verkauskienė
Keyword(s):  
Transcription Factor ◽  
Pituitary Gland ◽  
Gene Mutation ◽  
Anterior Pituitary ◽  
Hormone Deficiency ◽  
Pituitary Hormone ◽  
Imaging Studies ◽  
Pituitary Hyperplasia ◽  
Pituitary Hypoplasia ◽  
Genetically Determined

The most common genetically determined cause of multiple pituitary hormone deficiency is PROP-1 gene mutation. PROP-1 is a transcription factor involved in the development of pituitary gland and affects hormonal synthesis of anterior pituitary. The aim of our study was to evaluate radiological aspects of the pituitary region in patients with PROP-1 gene mutation. Pituitary imaging studies were performed in 12 patients with a confirmed PROP-1 gene mutation. Pituitary hyperplasia was found in 5 (42%) and pituitary hypoplasia in 4 (33%) patients. Changes in pituitary size were not associated with the type of PROP-1 gene mutation.

Characteristics of Action of Prostaglandins on Cyclic AMP Accumulation in Rat Anterior Pituitary Gland

1975 ◽  
Vol 53 (4) ◽  
pp. 455-460 ◽  
Author(s):  
Pierre Borgeat ◽  
Fernand Labrie ◽  
Pierre Garneau
Keyword(s):  
Cyclic Amp ◽  
Pituitary Gland ◽  
Incubation Medium ◽  
Anterior Pituitary ◽  
Complete Removal ◽  
Anterior Pituitary Gland ◽  
Pituitary Hormone ◽  
Maximal Effect ◽  
Cyclic Amp Accumulation

Prostaglandins (PGs) were found to lead to a marked stimulation of cyclic AMP accumulation in rat anterior pituitary gland in vitro in the following decreasing order of potency: [Formula: see text]. The effect of PGs is potentiated by theophylline. The stimulatory effect of PGs on cyclic AMP accumulation is already detected 2 min after the addition of 1 × 10−7 to 1 × 10−6 M PG E2 and its maximal effect is reached after approximately 30 min of incubation, with a progressive decrease toward basal cyclic AMP levels at later time intervals. Increased intracellular cyclic AMP concentrations are accompanied by an increased release of the nucleotide into the incubation medium. Complete removal of Ca2+ from the incubation medium by addition of EGTA was found to increase the stimulatory effect of PG E2 on cyclic AMP accumulation. The action of PGs on hormonal release and cyclic AMP accumulation support the hypothesis of a role of PGs in the mechanism of anterior pituitary hormone (particularly growth hormone) release.

Multiple pituitary hormone gradients from inferior petrosal sinus sampling in Cushing's disease

1988 ◽  
Vol 119 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Patricia A. Crock ◽  
Richard G. Pestell ◽  
Anthony J. Calenti ◽  
Eric J. Gilford ◽  
J. Keith Henderson ◽  
...  
Keyword(s):  
Cushing’S Disease ◽  
Anterior Pituitary ◽  
Close Association ◽  
Pituitary Hormones ◽  
Cushing's Disease ◽  
Pituitary Hormone ◽  
Inferior Petrosal Sinus ◽  
The Novel ◽  
Inferior Petrosal Sinus Sampling ◽  
Left And Right

Abstract. Pre-operative bilateral simultaneous inferior petrosal sinus sampling with assessment of ACTH levels in the left and right sinuses and the periphery was performed in 9 patients with pituitary dependent Cushing's disease who were subsequently found at surgery to have basophil microadenomata. The novel observation of this study was the pattern of secretion of other pituitary hormones so that significant inter-sinus gradients ≥ 1.4:1 were seen for β-endorphin (2.8 ± 1.3, mean ± sem), PRL (4.2 ± 1.3) and GH (6.9 ± 2.4) as well as for ACTH (5.1 ± 1.1). There was no inter-sinus gradient for LH, FSH and TSH. In these 9 patients with adenomata, the correlations between the inter-sinus gradients for ACTH and β-endorphin were r = 0.95 (P <0.01), ACTH and PRL r = 0.90 (P < 0.01) and for ACTH and GH r = 0.89 (P <0.05). This close association between the gradients for ACTH and other anterior pituitary hormones could be due either to cosecretion of β-endorphin, PRL and GH by the ACTH-producing pituitary adenomata or to a paracrine effect of β-endorphin from the tumours on adjacent pituitary tissue. By reflecting the central pituitary hormone milieu, petrosal sinus sampling can give information about pituitary function unobtainable from peripheral hormone levels.

Comparison of anterior pituitary hormone levels in the inferior petrosal sinuses and peripheral blood in various pituitary disorders during perihypophysial phlebography

1991 ◽  
Vol 124 (3) ◽  
pp. 258-266 ◽  
Author(s):  
Gaetano Lombardi ◽  
Bartolomeo Merola ◽  
Annamaria Colao ◽  
Paolo Miletto ◽  
Giovanni De Chiara ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Pituitary Hormone ◽  
Inferior Petrosal Sinus ◽  
Hormone Levels ◽  
Anterior Pituitary Hormone ◽  
Two Factors ◽  
The Right ◽  
Concentration Ratios

Abstract. The present study aimed at evaluating the anterior pituitary hormone levels in the inferior petrosal sinuses and in the peripheral blood of 55 patients affected by various pituitary disorders and undergoing perihypophysial phlebography on neurosurgical indication or for diagnostic purposes. The results indicated that in 6 patients with Cushing's disease and in 4 with hyperprolactinemia the secreting adenoma could be localized by inferior petrosal sinus sampling. Furthermore, the concentrations of all the pituitary hormones were found to be higher in the right and/or in the left inferior petrosal sinus than in peripheral blood, showing a clear gradient between central and peripheral samples. Moreover, the evaluation of hormone central/peripheral concentration ratios revealed noteworthy differences, namely, that central/peripheral concentration ratios of GH, ACTH, and PRL were significantly higher than those of TSH, FSH, and LH (p<0.01). On the contrary, no significant differences were found when the concentration ratios of GH, ACTH and PRL or TSH, FSH and LH were compared among themselves. This finding may be attributed to at least two factors: the increased pulsatility and the relatively short biological halftime of polypeptic hormones (GH, ACTH, and PRL) compared with glycoprotein hormones (TSH, FSH, and LH).

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