Interaction of α-Melanocyte-Stimulating Hormone withβ-Endorphin to Influence Anterior Pituitary Hormone Secretion in the Female Rat*

Endocrinology ◽  
1986 ◽  
Vol 119 (3) ◽  
pp. 1071-1075 ◽  
Author(s):  
OMID KHORRAM ◽  
SAMUEL M. McCANN
1993 ◽  
Vol 129 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Andreas Kjær

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.


1994 ◽  
Vol 42 (8) ◽  
pp. 1117-1125 ◽  
Author(s):  
M A Japón ◽  
M Rubinstein ◽  
M J Low

We used 35S-labeled oligonucleotides and cRNAs (riboprobes) to detect the temporal order and spatial pattern of anterior pituitary hormone gene expression in (B6CBF1 x B6CBF1)F2 fetal mice from embryonic Day 9.5 (E9.5) to postnatal Day 1 (P1). Pro-opiomelanocortin (POMC) mRNA was expressed in the basal diencephalon on Day E10.5, in the ventromedial zone of the pars distalis on Day E12.5, and in the pars intermedia on Day E14.5. The common alpha-glycoprotein subunit (alpha-GSU) mRNA first appeared in the anterior wall of Rathke's pouch on Day E11.5 and extended to the pars tuberalis and ventromedial zone of the pars distalis on Day E12.5. Thyroid-stimulating hormone-beta (TSH beta) subunit mRNA was expressed initially in both the pas tuberalis and ventromedial pars distalis on Day E14.5, with an identical spatial distribution to alpha-GSU at the time. In contrast, luteinizing hormone-beta (LH beta) subunit and follicle-stimulating hormone beta (FSH beta) subunit mRNAs were detected initially only in the ventromedial pars distalis on Days E16.5 and E17.5, respectively, in an identical distribution to each other. POMC-, alpha-GSU-, TSH beta, LH beta-, and FSH beta-positive cells within the pars distalis all increased in number and autoradiographic signal with differing degrees of spatial expansion posteriorly, laterally, and dorsally up to Day P1. POMC expression was typically the most intense and extended circumferentially to include the entire lateral and dorsal surfaces of the pars distalis. The expression of both growth hormone (GH) and prolactin (PRL) started coincidentally on Day E15.5. However PRL cells localized in the ventromedial area similarly to POMC and the glycoprotein hormone subunits, whereas GH cells were found initially in a more lateral and central distribution within the lobes of the pars distalis. Somatotrophs increased dramatically in number and autoradiographic signal, extending throughout the pars distalis except for the most peripheral layer of cells on Day E17.5. Mammotrophs also increased in number but less abundantly than somatotrophs, and PRL expression remained more confined to central-medial and ventrolateral areas of the pars distalis up to Day P1. These data demonstrate distinctive patterns of expression for each of the major anterior pituitary hormone genes during development of the mouse pituitary gland and suggest that different groups of committed cells are the immediate precursors to the terminally differentiated hormone-secreting cell types.


1991 ◽  
Vol 34 (4) ◽  
pp. 299-304 ◽  
Author(s):  
P. J. Trainer ◽  
J. M. W. Kirk ◽  
L. McLoughlln ◽  
R. J. Touzel ◽  
L. Perry ◽  
...  

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