The Pars tuberalis-A Pituitary Target for Melatonin

1997 ◽  
pp. 3-13 ◽  
Author(s):  
D.G. Hazlerigg ◽  
P.J. Morgan
Keyword(s):  
Pars Tuberalis

Sensitization: A Mechanism for Melatonin Action in the Pars Tuberalis

2003 ◽  
Vol 15 (4) ◽  
pp. 415-421 ◽  
Author(s):  
P. Barrett ◽  
C. Schuster ◽  
J. Mercer ◽  
P. J. Morgan
Keyword(s):  
Pars Tuberalis

scholarly journals Comentários neurocirúrgicos e fisiológicos sobre a secção da haste pituitária em seres humanos (miscotomia)

1967 ◽  
Vol 25 (4) ◽  
pp. 239-254 ◽  
Author(s):  
J. Le Beau ◽  
J. F. Foncin ◽  
S. Nicolaidis
Keyword(s):  
Pars Tuberalis

Nossa primeira hipofisectomia para tratamento de carcinoma metastático do seio foi feita em novembro de 1951 e a secção da haste pituitária (miscotomia) para o mesmo fim foi iniciada em novembro de 1956. Quando se consegue impedir a regeneração vascular hipotálamo-hipofisária os resultados gerais da miscotomia são pouco diferentes daqueles obtidos com a hipofisectomia. Empregamos a miscotomia sempre que, por condições locais ou gerais, a remoção total da hipófise parece constituir grande risco cirúrgico. Temos publicado estudos anatomo-fisiológicos desde 1958 mostrando: (a) as variações da necrose do lobo anterior da hipófise que não são totais nem definitivas (regeneração pituitária) e a importância das artérias trabeculares a este respeito; b) a grande capacidade de regeneração vascular a partir do hipctálamo e dirigindo-se para a parte restante do lobo anterior da hipófise, o que constitui um novo sistema anatomo-funcional portal; c) após isolamento permanente da pituitária ocorre proliferação das células de prolactina (células orangeófilas) e hipertrofia compensadora da pars tuberalis. A remoção cirúrgica de tecido hipofisário normal nos permitiu descrever, pela primeira vez no ser humano, as células ACTH (1964) e as células FSH (1966).

Rhythms in clock proteins in the mouse pars tuberalis depend on MT1 melatonin receptor signalling

2005 ◽  
Vol 22 (11) ◽  
pp. 2845-2854 ◽  
Author(s):  
Antje Jilg ◽  
Juliane Moek ◽  
David R. Weaver ◽  
Horst-Werner Korf ◽  
Jörg H. Stehle ◽  
...  
Keyword(s):  
Pars Tuberalis ◽  
Melatonin Receptor ◽  
Receptor Signalling ◽  
Clock Proteins ◽  
Mt1 Melatonin Receptor

scholarly journals Clock genes in calendar cells as the basis of annual timekeeping in mammals--a unifying hypothesis

2003 ◽  
Vol 179 (1) ◽  
pp. 1-13 ◽  
Author(s):  
GA Lincoln ◽  
H Andersson ◽  
A Loudon
Keyword(s):  
Gene Expression ◽  
Molecular Mechanism ◽  
Clock Genes ◽  
Prolactin Secretion ◽  
Secretory Cells ◽  
Dark Phase ◽  
Pars Tuberalis ◽  
Cry Protein ◽  
Wide Range

Melatonin-based photoperiod time-measurement and circannual rhythm generation are long-term time-keeping systems used to regulate seasonal cycles in physiology and behaviour in a wide range of mammals including man. We summarise recent evidence that temporal, melatonin-controlled expression of clock genes in specific calendar cells may provide a molecular mechanism for long-term timing. The agranular secretory cells of the pars tuberalis (PT) of the pituitary gland provide a model cell-type because they express a high density of melatonin (mt1) receptors and are implicated in photoperiod/circannual regulation of prolactin secretion and the associated seasonal biological responses. Studies of seasonal breeding hamsters and sheep indicate that circadian clock gene expression in the PT is modulated by photoperiod via the melatonin signal. In the Syrian and Siberian hamster PT, the high amplitude Per1 rhythm associated with dawn is suppressed under short photoperiods, an effect that is mimicked by melatonin treatment. More extensive studies in sheep show that many clock genes (e.g. Bmal1, Clock, Per1, Per2, Cry1 and Cry2) are expressed in the PT, and their expression oscillates through the 24-h light/darkness cycle in a temporal sequence distinct from that in the hypothalamic suprachiasmatic nucleus (central circadian pacemaker). Activation of Per1 occurs in the early light phase (dawn), while activation of Cry1 occurs in the dark phase (dusk), thus photoperiod-induced changes in the relative phase of Per and Cry gene expression acting through PER/CRY protein/protein interaction provide a potential mechanism for decoding the melatonin signal and generating a long-term photoperiodic response. The current challenge is to identify other calendar cells in the central nervous system regulating long-term cycles in reproduction, body weight and other seasonal characteristics and to establish whether clock genes provide a conserved molecular mechanism for long-term timekeeping.

Histopathology of pituitary tumours

2011 ◽  
pp. 121-127
Author(s):  
Eva Horvath ◽  
Kalman Kovacs
Keyword(s):  
Mammalian Species ◽  
Cell Types ◽  
Pars Intermedia ◽  
Pars Tuberalis ◽  
Posterior Lobe ◽  
Human Pituitary ◽  
Human Pituitary Gland ◽  
Fibre Network ◽  
Pars Anterior ◽  
A Minor

The human pituitary gland consists of two major components: the adenohypophysis comprising the hormone producing cells of the pars anterior, pars intermedia, and pars tuberalis, and the neurohypophysis, also called pars nervosa or posterior lobe (1). In contrast to most mammalian species, the human gland has no anatomically distinct pars intermedia (2). The exclusively proopiomelanocortin (POMC)-producing cells of the pars intermedia are sandwiched between the anterior and posterior lobes in the majority of mammals, whereas in the human they are incorporated within the pars anterior, thereby constituting the pars distalis (3). The pars tuberalis is a minor upward extension of the adenohypophysis attached to the exterior of the lower pituitary stalk. In this chapter we deal only with adenohypophyseal tumours. Histologically, the adenohypophysis consists of a central median (or mucoid) wedge flanked by the two lateral wings. The hormone-producing cell types are distributed in an uneven, but characteristic manner. The cells are arranged within evenly sized acini surrounded by a delicate but well-defined reticulin fibre network giving the pituitary its distinct architecture (4). In the center of the acini is the long-neglected pituitary follicle composed of the agranular nonendocrine folliculo-stellate cells (5).

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