Effect of the GABA&lt;sub&gt;A&lt;/sub&gt; Agonist Muscimol on Prolactin Secretion from Human Prolactin-Secreting Adenomas and GH&lt;sub&gt;3&lt;/sub&gt; Rat Pituitary Tumour Cells

Jones, T. Hugh; Brown, Barry L.; Cullen, D. R.; Dobson, Pauline R.M.

doi:10.1159/000182293

Cited by 4 publications

(6 citation statements)

References 18 publications

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“…Moreover, the amplitude of the GABA-induced current recorded from GH 3 cells is several orders of magnitude lower than the current measured in pituitary lactotrophs, indicating that GABA A subunit expression is reduced in these cells. This difference is consistent with the lack of an effect of muscimol on PRL release in GH 3 cells (Jones et al, 1992).…”

Section: Functional Roles Of Neurotransmitter Receptors In Anteriosupporting

confidence: 88%

“…Muscimol has been shown to exert a biphasic effect on PRL secretion in perfusion studies using the normal rat anterior pituitary gland, as a transient stimulation lasting for 5–10 min was followed by a more prolonged inhibitory phase. However, muscimol has no effect on basal or TRH-stimulated PRL secretion from GH 3 cells (Jones et al, 1992).…”

Section: Functional Roles Of Neurotransmitter Receptors In Anteriomentioning

confidence: 99%

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Neurotransmitter receptors as signaling platforms in anterior pituitary cells

Zemková

Stojilković

2018

Molecular and Cellular Endocrinology

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The functions of anterior pituitary cells are controlled by two major groups of hypothalamic and intrapituitary ligands: one exclusively acts on G protein-coupled receptors and the other activates both G protein-coupled receptors and ligand-gated receptor channels. The second group of ligands operates as neurotransmitters in neuronal cells and their receptors are termed as neurotransmitter receptors. Most information about pituitary neurotransmitter receptors was obtained from secretory studies, RT-PCR analyses of mRNA expression and immunohistochemical and biochemical analyses, all of which were performed using a mixed population of pituitary cells. However, recent electrophysiological and imaging experiments have characterized γ-aminobutyric acid-, acetylcholine-, and ATP-activated receptors and channels in single pituitary cell types, expanding this picture and revealing surprising differences in their expression between subtypes of secretory cells and between native and immortalized pituitary cells. The main focus of this review is on the electrophysiological and pharmacological properties of these receptors and their roles in calcium signaling and calcium-controlled hormone secretion.

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Section: Functional Roles Of Neurotransmitter Receptors In Anteriosupporting

confidence: 88%

Section: Functional Roles Of Neurotransmitter Receptors In Anteriomentioning

confidence: 99%

Neurotransmitter receptors as signaling platforms in anterior pituitary cells

Zemková

Stojilković

2018

Molecular and Cellular Endocrinology

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“…We also investigated seven cell lines derived from the periphery. The pituitary contains functional GABA, receptors, which appear to be involved in the regulation of hormone secretion (Jones et al, 1992;Valerio et al, 1992;Vincens et al, 1992). We therefore investigated the AtT-20 cell line, which secrets ACTH, and was derived from a mouse pituitary tumor (Buonassisi et al, 1962).…”

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confidence: 99%

Distinctive patterns of GABAA receptor subunit mRNAs in 13 cell lines

et al. 1994

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We have investigated the GABAA receptor mRNA composition in 13 cell lines, using 13 subunit-specific oligo-primers (alpha 1-6, beta 1-3, gamma 1-3, and delta) and reverse transcriptase PCR amplification. Cell lines (B35, B65, B103, B104, RINm5F, Rat1, PC12, C6, C17, C27, beta TC3, NB41A3, AtT-20), derived from diverse tissue origins, were investigated in order to identify homogeneous cellular sources with distinctive GABAA receptor subunits. Fifteen GABAA receptor subunits have been cloned from mammalian tissue (those listed above plus the retinal subunits rho 1 and rho 2). This multiplicity of GABAA receptor subunits underlies the diverse pharmacology of the GABAA receptor. Attempts to understand the regulation and pharmacology of individual subunits and of the heterooligomeric receptor combinations have been impeded by a lack of pure populations of cells expressing GABAA receptor subunits. Permanent cell lines provide such a resource. Each GABAA receptor subunit mRNA, alpha 1-5, beta 1-3, gamma 1-3, and delta, was detected in at least one cell line. All cell lines examined contained detectable levels of at least one GABAA receptor subunit mRNA. Each cell line contained distinctive combinations of subunit mRNAs. None of the cell lines examined contained detectable amounts of alpha 6 mRNA. These cell lines, which transcribe GABAA receptor subunit mRNAs, provide useful cellular sources for transcriptional and pharmacological studies. Our data also suggest that endogenous GABAA receptor subunit mRNAs may be present in cells that are routinely used for transfection studies, and that this expression might confound interpretation of the studies. In the following companion article, we have looked for functional GABAA receptor Cl- ion channels in these cell lines, using the patch-clamp technique (Hales and Tyndale, 1994).

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“…One effect was stimulatory and exerted through inhibition of tuberoinfundibular dopaminergic neurons [9][10][11]; the other was inhibitory and mediated by GABA receptors present on the membrane of the lactotroph cells [12][13][14], This latter inhibitory regulation of hormonal secretion of PRL cells was accompanied by an inhibition of PRL bio synthesis [15]. However, more recent studies using fast perifusion techniques have not only shown an inhibitory but a biphasic effect of GABA on rat PRL secretion in vitro [16,17], GABA first induces a short-lived stimula tion of PRL basal secretion, which is followed by sus tained inhibition. In this case, the two components of GABAergic control are fully mimicked by muscimol, sug gesting involvement of GABAa receptors alone.…”

mentioning

confidence: 99%

“…Whether GABAergic stimulation is a property specific to the normal pituitary cell remains to be clarified, since it was observed neither in the tumoral cell line GHj-B^ [47] nor in PRL-secreting adenomas [17] in vitro.…”

mentioning

confidence: 99%

Short Applications of Gamma-Aminobutyric Acid Increase Intracellular Calcium Concentrations in Single Identified Rat Lactotrophs

Lorsignol

Taupignon²,

Dufy³

1994

Neuroendocrinology

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We have investigated the direct effect of GABA receptor agonists on the cytosolic free calcium concentration ([Ca²⁺]_i) and the membrane potential of rat lactotrophs in primary culture. [Ca²⁺]_i was recorded in single identified lactotrophs by dual emission microspectrofluorimetry using indo-1 as intracellular fluorescent calcium probe. Whole cell and perforated patch-clamp were performed. A short application of GABA (10^–5M, 10 s) induced a marked transient [Ca²⁺]_i increase in 66% of lactotrophs, which could be readily mimicked by muscimol (10^–5M). By contrast, neither L-homocarnosine (10^–3M) nor baclofen (10^–5M), a GABAB agonist, had any effect on [Ca²⁺]_i. The GABA-induced [Ca²⁺]_i increase was antagonized by picrotoxin (10^–5M), bicuculline methio-dide (10^–5M) and strychnine (10^–4M), demonstrating GABA_A receptor specificity. Furthermore, clonazepan (1.5 × 10^–4M) could potentiate the GABA effect on [Ca²⁺]_i. The [Ca²⁺]_i increase disappeared in the absence of Ca²⁺ in the extracellular medium or in the presence of Ca²⁺ channel blockers (cadmium, PN 200-110). GABA and muscimol depolarized the membrane potential with a concomitant fall in cell input resistance, thus suggesting, as in other cell types, the opening of receptor-operated chloride channels. When Ca²⁺ entry was prevented by the use of cadmium (500 × 10^–6M), GABA still elicited membrane depolarization but did not raise [Ca²⁺]_i. Our results suggest that a short application of GABA leads to Ca²⁺ entry through voltage-gated Ca²⁺ channels in single lactotrophs. This Ca²⁺ influx is due to depolarization of the prolactin cell.

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Effect of the GABA<sub>A</sub> Agonist Muscimol on Prolactin Secretion from Human Prolactin-Secreting Adenomas and GH<sub>3</sub> Rat Pituitary Tumour Cells

Cited by 4 publications

References 18 publications

Neurotransmitter receptors as signaling platforms in anterior pituitary cells

Neurotransmitter receptors as signaling platforms in anterior pituitary cells

Distinctive patterns of GABAA receptor subunit mRNAs in 13 cell lines

Short Applications of Gamma-Aminobutyric Acid Increase Intracellular Calcium Concentrations in Single Identified Rat Lactotrophs

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