Calcium‐dependent stimulation of prolactin release in rat anterior pituitary<i>in vitro</i> by n<sup>6</sup>‐monobutyryl adenosine 3′,5′‐monophosphate

Lemay, André; Labrie, Fernand

doi:10.1016/0014-5793(72)80003-6

Cited by 46 publications

(8 citation statements)

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confidence: 60%

“…These data pertain to our studies on the plasma membrane receptor for thyrotropin-releasing hormone [1,2] and the observed stimulation of adenohypophyseal adenylate cyclase activity by synthetic thyrotropin (P. Borgeat, P. Garneau, and F. Labrie, unpublished data) and luteinizing hormone-releasing hormones [3] and by purified growth hormone-releasing hormone [4]. It is well known that cyclic AMP, or its derivatives, stimulate the release of adenohypophyseal hormones [5].Although the short-term stimulatory effect of cyclic AMP on total adenohypophyseal protein [6], growth hormone and prolactin [4] synthesis seems to be exerted at a translational level, it is likely that the long-term effects of the cyclic nucleotide, in the anterior pituitary gland, will include an action at a transcriptional level.Much evidence has accumulated to support the hypothesis that in many systems, cyclic-AMP-dependent protein kinase mediates the various intracellular effects of the cyclic nucleotide [7]. Many studies indicate that the phosphorylation of histones [8,9] and non-histone [lo--121 nuclear proteins can be correlated with the rate of RNA synthesis.…”

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Phosphorylation of Nuclear Proteins from Bovine Anterior Pituitary Gland Induced by Adenosine 3′:5′‐monophosphate

Jolicoeur

Labrie

1974

European Journal of Biochemistry

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In the presence of exogenous protein kinase dependent on adenosine 3' : 5'-monophosphate (cyclic AMP), cyclic AMP leads to an important stimulation of 32P incorporation into chromatin purified from bovine anterior pituitary tissue. Over 80% of 32P incorporated into isolated adenohypophyseal histones is associated with Fzb histone while small uptake is measured in F1 and F3 (and its dimer form) histones. Cyclic AMP leads to a 3 to 4-fold stimulation of incorporation of radioactivity into histone Fzb. The radioactivity associated with F2b histone is almost exclusively recovered into two phosphopeptides. Eigthteen bands can be resolved after separation of adenohypophyseal acidic nuclear proteins on 5 % sodium dodecylsulfate polyacrylamide gels and their apparent molecular weights range from 12000 to 300000. Protein kinase catalyses the cyclic-AMP-dependent phosphorylation of a large number of acidic proteins although preferential labeling occurs in five bands. The present data suggest a possible role of cyclic AMP on the transcriptional activity of the anterior pituitary gland through phosphorylation of histones and non-histone acidic nuclear proteins.We have recently obtained direct evidence for a role of the adenylate cyclase system as mediator of the action of at least three hypothalamic releasing hormones in the anterior pituitary gland. These data pertain to our studies on the plasma membrane receptor for thyrotropin-releasing hormone [1,2] and the observed stimulation of adenohypophyseal adenylate cyclase activity by synthetic thyrotropin (P. Borgeat, P. Garneau, and F. Labrie, unpublished data) and luteinizing hormone-releasing hormones [3] and by purified growth hormone-releasing hormone [4]. It is well known that cyclic AMP, or its derivatives, stimulate the release of adenohypophyseal hormones [5].Although the short-term stimulatory effect of cyclic AMP on total adenohypophyseal protein [6], growth hormone and prolactin [4] synthesis seems to be exerted at a translational level, it is likely that the long-term effects of the cyclic nucleotide, in the anterior pituitary gland, will include an action at a transcriptional level.Much evidence has accumulated to support the hypothesis that in many systems, cyclic-AMP-dependent protein kinase mediates the various intracellular effects of the cyclic nucleotide [7]. Many studies indicate that the phosphorylation of histones [8,9] and non-histone [lo--121 nuclear proteins can be correlated with the rate of RNA synthesis. Moreover, glucagon enhances the phosphorylation, at specific sites, of rat liver F1 histone [8] while insulin and prolactin increase the phosphorylation of nuclear proteins (both histones and non-histones) in mouse mammary epithelial cells in organ culture [13]. Chorionic gonadotropin has also been reported to enhance the phosphorylation of both histone and non-histone proteins in rat ovarian tissue [14].In bovine anterior pituitary gland, we have already found a high level of endogenous phosphorylation in the nuclear fraction [15]. It thus seeme...

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confidence: 62%

Phosphorylation of Nuclear Proteins from Bovine Anterior Pituitary Gland Induced by Adenosine 3′:5′‐monophosphate

Jolicoeur

Labrie

1974

European Journal of Biochemistry

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“…Porcine adrenocorticotropic hormone (Mann-Schwartz) was used as standard. Growth hormone was also measured by densitometry of the proteins of the incubation medium separated by polyacrylamide gel electrophoresis (22,34,35). Thyrotropin was measured by bioassay (36).…”

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confidence: 99%

Stimulation of Adenosine 3′:5′-Cyclic Monophosphate Accumulation in Anterior Pituitary Gland In Vitro by Synthetic Luteinizing Hormone-Releasing Hormone

Borgeat

Chavancy

Dupont

et al. 1972

Proc. Natl. Acad. Sci. U.S.A.

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183

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A near-maximal dose (20 ng/ml) of synthetic luteinizing hormone(LH)-releasing hormone/follicle-stimulating hormone(FSH)-releasing hormone added to incubated anterior pituitary tissue of male rats leads to concomitant increases of intracellular concentrations of adenosine 3': 5'-monophosphate and of release of both LH and FSH. The stimulatory effect of LH-releasing hormone/ FSH-releasing hormone is observed after a lag period of about 90 min and is progressive at later time intervals; a 3-fold stimulation of cAMP accumulation over control is seen after 210 min of incubation. Half-maximal stimulation of cAMP accumulation is observed between 0.1 and 1.0 ng/ml (0.1-1 nM) of LH-releasing hormone/FSH-releasing hormone. In the presence of 10 mM theophylline, the stimulatory effect of LH-releasing hormone/FSH-releasing hormone on cAMP accumulation is similar to that observed in the absence of the inhibitor of cyclic nucleotide phosphodiesterase, indicating that the releasing hormone exerts its effect by specific activation of adenylate cyclase in LH-and FSH-secreting cells rather than by inhibition of cyclic nucleotide phosphodiesterase. Since the release of growth hormone, thyrotropin, prolactin, and adrenocorticotropic hormone is not affected by LH-releasing hormone/FSH-releasing hormone, and since cAMP stimulates the release of all six adenohypophyseal hormones. the observed changes of cAMP concentrations indicate specific stimulation of adenylate cyclase activity in LHand FSH-secreting cells of the adenohypophysis.Secretion of luteinizing hormone (LH) and of follicle-stimulating hormone (FSH) by the anterior pituitary gland is controlled by a neurohormone released from the hypothalamic area and carried to its specific adenohypophyseal site of action by a portal blood system (1-4). Recently, after more than 10 years of research in many laboratories, this neurohormone was isolated from porcine (5-7) and ovine (8) hypothalami and characterized as a decapeptide having the following structure: (pyro)Glu-His-Try-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 (9-11). Since this peptide stimulates the release of both LH and FSH under various experimental conditions (4-8, 10-13), it has been called the LH-releasing hormone/FSH-releasing hormone (4, 5, 7) or the gonadotropin-releasing factor (12). The availability of synthetic LH-releasing hormone/FSHreleasing hormone (14-16) and of its analogs is of obvious importance for studies of the mechanism of action of this neurohormone in the adenohypophysis.There was suggestive evidence for a role of adenosine 3': 5'-cyclic monophosphate (cAMP) as a mediator of the action of LH-releasing hormone/FSH-releasing hormone. These studies pertained to reported stimulatory effects of N6,2'.-Odibutyryl cAMP and theophylline (17) (20, 21). However, definitive proof of the role of the adenylate cyclase system as mediator of the action of LH-releasing hormone/FSH-releasing hormone could be obtained only by measurements of adenohypophyseal adenylate cyclase activity or cAMP concentrations under the inf...

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“…Several workers found that in vitro PRL secretion is stimulated by the phosphodiesterase inhibitors theophylline (13,14,16,35) and IBMX (7,17,36) and by cAMP analogs (7,12,16,(36)(37)(38)(39)(40)(41), although others found no effect with theophylline (12) or IBMX (16). In agreement with some investigators (40), we found that IBMX and dibutyryl cAMP partially reversed the dopaminergic inhibition of PRL release, but other researchers found no effect with IBMX (16) or 8-bromo-cAMP (36).…”

Section: Swennen and Denefmentioning

confidence: 99%

Physiological Concentrations of Dopamine Decrease Adenosine 3′,5′-Monophosphate Levels in Cultured Rat Anterior Pituitary Cells and Enriched Populations of Lactotrophs: Evidence for a Causal Relationship to Inhibition of Prolactin Release*

1982

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The possible involvement of cAMP in mediating the dopaminergic inhibition of PRL release was studied in primary cultures of anterior pituitary cells from female rats and in lactotroph-enriched subpopulations. In the presence of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX), dopamine (DA) depressed cAMP accumulation in a concentrationdependent fashion between 1-100 nM. The effect was significant within less than 1 min and maximal after about 10 min. Inhibition of PRL release by DA occurred at similar concentrations and paralleled the time course of inhibition of cAMP levels. The DA agonist apomorphine also inhibited cAMP levels and PRL release at nanomolar concentrations and acted as a full agonist, whereas the a-adrenoceptor agonist phenylephrine had no effect at 1 /iM. The DA receptor blockers spiperone, domperidone, pimozide, Z-sulpiride, and flupentixol reversed the DA-induced inhibition of cAMP accumulation with a rank order of potency comparable to that of reversing DA-induced inhibition of PRL release. The high potency of these substances suggests that the DA receptor involved is a D-2 receptor. In subpopulations of pituitary cells, separated by gradient sedimentation at unit gravity, DA failed to depress cAMP accumulation in fractions virtually devoid of PRL secretory activity but had a profound inhibitory effect in lactotroph-rich populations. In the absence of IBMX, DA decreased cAMP levels in the lactotroph-rich populations but not in the total pituitary cell population. DAinduced inhibition of PRL release was significantly antagonized by increasing the intracellular levels of cAMP with 1 mM IBMX or 3 mM dibutyryl cAMP.These data show that DA at physiological concentrations causes a prompt inhibition of cAMP accumulation in cultured anterior pituitary cells. This effect most likely occurs in the lactotrophs and may be part of the mechanisms underlying the dopaminergic inhibition of PRL release. (Endocrinology 111: 398, 1982) T HERE is substantial evidence that dopamine (DA) is a physiological regulator of PRL release (1, 2). It inhibits PRL secretion through stereospecific DA receptors (3-5) located on the lactotrophs (6). Although there is evidence for a role for cAMP in mediating the response to substances stimulating PRL release (7, 8), conflicting data have been reported as to the possible participation of cAMP in the dopaminergic inhibition of PRL release. Whereas a DA-stimulated adenylate cyclase has been described in the brain (9), several investigators failed to find an effect of DA on intracellular cAMP levels or on adenylate cyclase activity in the intact anterior pituitary gland (10-12), isolated cells (12), or homogenates (12,13).

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Calcium‐dependent stimulation of prolactin release in rat anterior pituitaryin vitro by n⁶‐monobutyryl adenosine 3′,5′‐monophosphate

Cited by 46 publications

References 23 publications

Phosphorylation of Nuclear Proteins from Bovine Anterior Pituitary Gland Induced by Adenosine 3′:5′‐monophosphate

Phosphorylation of Nuclear Proteins from Bovine Anterior Pituitary Gland Induced by Adenosine 3′:5′‐monophosphate

Stimulation of Adenosine 3′:5′-Cyclic Monophosphate Accumulation in Anterior Pituitary Gland In Vitro by Synthetic Luteinizing Hormone-Releasing Hormone

Physiological Concentrations of Dopamine Decrease Adenosine 3′,5′-Monophosphate Levels in Cultured Rat Anterior Pituitary Cells and Enriched Populations of Lactotrophs: Evidence for a Causal Relationship to Inhibition of Prolactin Release*

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Calcium‐dependent stimulation of prolactin release in rat anterior pituitaryin vitro by n6‐monobutyryl adenosine 3′,5′‐monophosphate

Cited by 46 publications

References 23 publications

Phosphorylation of Nuclear Proteins from Bovine Anterior Pituitary Gland Induced by Adenosine 3′:5′‐monophosphate

Phosphorylation of Nuclear Proteins from Bovine Anterior Pituitary Gland Induced by Adenosine 3′:5′‐monophosphate

Stimulation of Adenosine 3′:5′-Cyclic Monophosphate Accumulation in Anterior Pituitary Gland In Vitro by Synthetic Luteinizing Hormone-Releasing Hormone

Physiological Concentrations of Dopamine Decrease Adenosine 3′,5′-Monophosphate Levels in Cultured Rat Anterior Pituitary Cells and Enriched Populations of Lactotrophs: Evidence for a Causal Relationship to Inhibition of Prolactin Release*

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Calcium‐dependent stimulation of prolactin release in rat anterior pituitaryin vitro by n⁶‐monobutyryl adenosine 3′,5′‐monophosphate