&lt;i&gt;In vitro&lt;/i&gt; Regulation of ACTH Release from Neurointermediate Lobe of Rat Hypophysis

Briaud, B.; Koch, B; Lutz-Bucher, B.; Mialhe, C

doi:10.1159/000122886

Cited by 36 publications

(17 citation statements)

References 8 publications

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“…Both DA and apomorphine (10-12, lO'13 M) were found to stimulate the release of bioac tive ACTH from perfused rat NILs [4] in a manner similar to the DA-induced stimulation of prolactin (PRL) release from rat anterior pituitary cells by low concentrations of DA [ 12]. Both effects were blocked by haloperidol which led to the proposal [12] that the dopaminergic control of PRL release involves both a stimulatory and an inhibitory DA receptor.…”

Section: Discussionmentioning

confidence: 93%

“…Despite the generally accepted inhibitory effect of DA on the PI, recent studies have indicated a stimulatory role for this catecholamine [4]. Both DA and apomorphine (10-12, lO'13 M) were found to stimulate the release of bioac tive ACTH from perfused rat NILs [4] in a manner similar to the DA-induced stimulation of prolactin (PRL) release from rat anterior pituitary cells by low concentrations of DA [ 12].…”

Section: Discussionmentioning

confidence: 96%

“…Unlike the PD, the PI is poorly vascularised but richly innervated by catecholaminergic nerve fibres which originate from the arcuate nucleus of the hypothalamus [2] and have been shown to be respon sible for the inhibitory dopaminergic control of the melano tropes [58]. Besides DA, other neurotransmitter substances and hypothalamic peptides have been shown to influence the release of PI peptides [3,4,6,27, 35,57,59,60,63] and evidence that the intermediate lobe is controlled by a stimu latory, p-adrenergic input in addition to the inhibitory do paminergic influence has emerged. Therefore, the effects of DA, AD, NA, 5-HT, isoprenaline and MIF, as well as the…”

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confidence: 99%

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Secretion of Pro-Opiocortin Peptides from Isolated Perfused Rat Pars intermedia Cells

Jackson¹,

Lowry²

1983

Neuroendocrinology

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The perfused, isolated, pituitary cell column was used to measure the release of α-melanotropin (α-MSH)-like immunoreactivity (LI), carboxyl terminal corticotropin (C-ACTH)-LI, γ-lipotropin (γ-LPH)-LI, α-endorphin-LI, β-endorphin-LI and amino-terminal pro-opiocortin (N-POC)-LI from rat pars intermedia (PI) cells. Concomitant secretion of all PI peptides was observed during basal release and in response to all applied stimuli. Dopamine (DA) caused a dose-dependent (10^–9–10^–5 M) simultaneous inhibition of peptide release which was antagonised by haloperidol. Isoprenaline stimulated the release of PI peptides in a parallel, dose-related (10^–10–10^–6 M) manner and was blocked by propranolol. Stimulation of peptide secretion caused by low concentrations (10^–8M), of adrenaline (AD) and noradrenaline (NA) changed to inhibition at high concentrations (10^–5 M) whereas intermediate concentrations (10^–6, 10^–7 M) possessed both inhibitory and excitatory effects. A 45 mM solution of K⁺ ions stimulated the release of PI peptides and both the K⁺-stimulated secretion and basal secretion were Ca⁺⁺-dependent. MSH-release-inhibiting factor (MIF) and 5-hydroxytryptamine (5-HT) failed to alter peptide secretion from the perfused PI cells. We conclude that pro-opiocortin (POC) peptides are released concomitantly from rat PI cells and that biogenic amines are involved in their release.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 99%

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Secretion of Pro-Opiocortin Peptides from Isolated Perfused Rat Pars intermedia Cells

Jackson¹,

Lowry²

1983

Neuroendocrinology

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“…In rats, such a dichotomy in the control of the release of a pep tide present in both AP and N-IL has been previously docu mented for adrenocorticotropin (ACTH) and a-melanocyte stimulating hormone (aMSH) [15,46], which are both de rived from the same common precursor as p-EP [30, 32, 38]. Recent evidence suggests that, when animals are acutely stressed, changes in AP ACTH levels involve the hypothalamo-pituitary-adrenal axis [24, 26, 40]; in contrast, changes in N-IL aMSH levels (and those of N-IL ACTH, where de termined) appear under the control of an aminergic system, presumably related to that present in the median eminence [6,17, 37], However, in rats, it has not been determined whether PEP and/or PLPH present in AP, N-IL and hypo thalamus (HT) behave in a parallel manner to that of ACTH and aMSH under similar conditions. …”

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confidence: 99%

Stress-Induced Changes in Plasma, Pituitary and Hypothalamic Immunoreactive β-Endorphin: Effects of Diurnal Variation, Adrenalectomy, Corticosteroids, and Opiate Agonists and Antagonists

Lim

Funder²

1983

Neuroendocrinology

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Immunoreactive β-endorphin (ir-βEP) levels were determined in plasma, anterior pituitary (AP), neuro-intermediate lobe (N-IL) and hypothalamus (HT) of intact rats and adrenalectomized rats subjected to swimming stress. In intact rats, plasma ir-βEP was elevated fourfold, and ir-βEP levels in AP and N-IL significantly reduced after 30 min swimming; in contrast, HT ir-βEP in these animals was not affected. In adrenalectomized animals, similar but even more marked changes were found in plasma and tissue ir-βEP following stress. The effect of diurnal variation, morphine and naloxone on stress-induced changes in tissue ir-βEP was also examined; in addition, the influence of acute and chronic treatment of adrenalectomized animals with dexamethasone or deoxycorticosterone was explored. Plasma ir-βEP of rats swum in the afternoon was significantly higher than of those swum in the morning; no differences were detected in AP, N-IL or HT ir-βEP. Acute morphine administration (10 mg/kg) did not affect levels of ir-βEP in any tissue, baseline or post-stress; however, naloxone (10 mg/kg) consistently and significantly prevented the reduction in N-IL ir-βEP otherwise found following prolonged stress. Both acute and chronic dexamethasone (2 and 20 µg) attenuated the stress-induced changes found in AP and plasma ir-βEP in a dose-related manner; equivalent effects, however, were not seen in deoxycorticosterone (20, 200 µg) treated animals. In contrast, the stress-induced reduction found in N-IL ir-βEP was influenced neither by acute nor chronic treatment with dexamethasone or deoxycorticosterone. These results suggest that changes found in AP and plasma ir-βEP after swimming stress are glucocorticoid-sensitive, but do not involve pathways including opiate receptors; in contrast, though baseline levels of N-IL ir-βEP are mineralocorticoid-sensitive, the changes after swimming stress are steroid-independent and involve the action of endogenous opioids.

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“…At present, there is no clear evidence that 5-HT stimulates follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH) release. In contrast, the in vitro studies have failed to show a direct action of 5-HT on anterior pituitary (AP) cells [8, 9], although there are controversial data on ACTH release by AP cells [10, 11, 12]. The effect of 5-HT on α-melanocyte-stimulating hormone (αMSH) release by rat intermediate lobe (IL) is also controversial in vitro [13, 14], while in vivo clearly stimulates αMSH release, this action being probably mediated through inhibition of tuberohypophyseal dopaminergic neurons [15, 16].…”

Section: Introductionmentioning

confidence: 99%

Direct Action of Serotonin on Prolactin, Growth Hormone, Corticotropin and Luteinizing Hormone Release in Cocultures of Anterior and Posterior Pituitary Lobes: Autocrine and/or Paracrine Action of Vasoactive Intestinal Peptide

et al. 1998

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There is extensive evidence that serotonin (5-HT) is implicated in the neuroendocrine control regulating the secretion of several anterior pituitary hormones. It has also been reported that the posterior pituitary is necessary for prolactin (PRL) response to 5-HT as well as to suckling, in which 5-HT implication has been demonstrated. As we have previously shown that vasoactive intestinal peptide (VIP) mediates through an autocrine or paracrine action the PRL release induced by insulin-like growth factor I, thyrotropin-releasing hormone (TRH) and dopamine withdrawal, the aim of the present work was to determine whether 5-HT has a direct action on pituitary secretion and to study the possible role of pituitary VIP in this situation. Cells from the anterior pituitary lobe (AP) were cultured either alone or together with cells from the posterior pituitary lobe (PP). As melanotropes from PP express glucocorticoid receptors in vitro, both AP cultures and cocultures of AP/PP cells were incubated in the presence or absence of corticosterone (0.1 µg/ml), thus designing four experimental conditions. Then both AP and mixed cultures were incubated with 5-HT (100 nM) for 20, 45 and 180. The release of PRL, growth hormone (GH), corticotropin (ACTH) and luteinizing hormone (LH) was stimulated by 5-HT, but only in cocultures of AP/PP cells preincubated with corticosterone, whereas follicle-stimulating hormone and thyroid-stimulating hormone release was not modified. As AP cultures did not show any response to 5-HT, both in the presence or absence of corticosterone, and as melanotropes are the main cellular type present in the PP cultures, we studied the response of α-melanocyte-stimulating hormone (αMSH) to 5-HT in PP cells cultured with or without corticosterone. Serotonin did not modify αMSH release either in the absence or the presence of corticosterone. VIP release was also stimulated by 5-HT in the cocultures, and the time response profile was only similar to that of PRL. In order to study whether pituitary VIP is implicated in 5-HT action, cocultures preincubated with corticosterone were incubated in the presence of 5-HT, a VIP-receptor antagonist (VIP-At) or simultaneously with 5-HT plus VIP-At. PRL response to 5-HT was abolished by the simultaneous presence of VIP-At, whereas GH, ACTH and LH response remained unchanged. These data demostrate that: (1) 5-HT stimulates the secretion of PRL, GH, ACTH, LH and VIP acting directly at pituitary level on PP, probably by releasing an unidentified mediator from melanotropes; (2) glucocorticoids make the response of AP cells to 5-HT possible due to the presence of PP cells in the coculture; (3) PRL response to 5-HT is mediated through an autocrine and/or paracrine action of VIP.

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<i>In vitro</i> Regulation of ACTH Release from Neurointermediate Lobe of Rat Hypophysis

Cited by 36 publications

References 8 publications

Secretion of Pro-Opiocortin Peptides from Isolated Perfused Rat Pars intermedia Cells

Secretion of Pro-Opiocortin Peptides from Isolated Perfused Rat Pars intermedia Cells

Stress-Induced Changes in Plasma, Pituitary and Hypothalamic Immunoreactive β-Endorphin: Effects of Diurnal Variation, Adrenalectomy, Corticosteroids, and Opiate Agonists and Antagonists

Direct Action of Serotonin on Prolactin, Growth Hormone, Corticotropin and Luteinizing Hormone Release in Cocultures of Anterior and Posterior Pituitary Lobes: Autocrine and/or Paracrine Action of Vasoactive Intestinal Peptide

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