GABA Transport and Subcellular Distribution in the Rat Anterior Pituitary Gland

Duvilanski, Beatriz H.; Seilicovich, Adriana; Debéljuk, Luciano; Lasaga, Mercedes; Díaz, María Dolores Díaz; Pisera, Daniel

doi:10.1159/000126657

Cited by 4 publications

(7 citation statements)

References 16 publications

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“…Considering that these are pharmacological properties of most CNS GABAa receptors, we conclude that the anterior pituitary gland possesses the neuronal type of GABAa receptors. Pentobarbital, which has been shown in many studies to directly activate neuronal GABAa receptors in the ab sence of GABA [24,32] [4] and which is controlled by a high-affinity uptake system (Km 4.1 pM) in anterior pituitary cells [40]. The presence of GABAa receptors with lower sensi tivity is apparently advantageous for the GABA-ergic con trol of anterior pituitary cell functions by the potentially high concentrations of GABA in hypophysial blood.…”

Section: Atmentioning

confidence: 99%

Electrophysiological Characterization of GABA<sub>A</sub> Receptors in Anterior Pituitary Cells of Newborn Rats

Zemková¹,

Vanĕcek²,

Krůšek³

1995

Neuroendocrinology

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The γ-aminobutric acid (GABA)-ergic communication between the CNS and the anterior pituitary gland has been documented in numerous histochemical and biochemical studies but electrophysiological studies characterizing the GABA_A receptor in the anterior pituitary are still lacking. In the present report we studied the GABA-induced current responses in cultured cells from the anterior pituitary gland of 6- to 10-day-old rats using the patch-clamp technique in the whole cell configuration. Fast application of GABA (100 µM) induced membrane currents in 90% of cells in 2-day-old cultures. The EC₅₀ for GABA was 22.9 µM and the Hill coefficient was 1.8. The responses to GABA (10 µM) were inhibited by bicuculline (2 µM) to 14%, by picrotoxin (5 µM) to 21% and by zinc (10 µM) to 33%. Inhibition to 56% was observed with 6 µM strychnine. The GABA responses were sensitive to diazepam and pentobarbital. Half-maximal potentiation of responses to GABA (10 µM) was found with 1.0 µM diazepam and with 14.4 µM pentobarbital. The maximal potentiation of GABA responses was 222% for diazepam and 195% for pentobarbital. Pentobarbital (100 µM) did not induce any response in anterior pituitary cells in the absence of GABA. The application of GABA at concentrations 10 µM or higher, induced membrane currents that desensitized. Desensitization proceeded as a biexponential process with estimated fast and slow time constants which decreased with concentration. The responses to GABA (300 µM) desensitized to 93% with time constants of 1.4 and 5.3 s. Half-maximal desensitization was found with 13.4 µM GABA. The recovery of GABA responses from desensitization proceeded as a single-exponential process. Responses induced by 300 µM GABA, resensitized with a time constant of 20.8 s. We conclude that anterior pituitary cells possess GABA_A receptors which exhibit the same pharmacological characteristics and desensitization kinetics but lower sensitivity to GABA as compared to those present in CNS neurones.

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Section: Atmentioning

confidence: 99%

Electrophysiological Characterization of GABA<sub>A</sub> Receptors in Anterior Pituitary Cells of Newborn Rats

Zemková¹,

Vanĕcek²,

Krůšek³

1995

Neuroendocrinology

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“…GABA transporters have been identified in several neural tissues (Radian et al, 1986, Borden, 1996. Since the anterior pituitary gland can specifically take up and concentrate [ 3 H] GABA by a process independent of receptors (Duvilanski et al, 1994) we can suggest the existence of a GABA transport system in the anterior pituitary cells. It is also possible that GABA could enter the lactotrophs by a receptor mechanism such as endocytosis, which has been observed for haloperidol, a dopamine agonist (Goldsmith et al, 1979).…”

Section: Discussionmentioning

confidence: 89%

“…3d). Neither lactotrophs nor somatotrophs showed silver grains when cells were incubated with [ 3 H] GABA and non-labeled 10 -3 M GABA (data not shown), ensuring the specificity of the GABA internalization mechanism in anterior pituitary cells [Duvilanski et al 1994].…”

Section: Intracellular Distribution Of [ 3 H] Gaba In Dispersed Anter...mentioning

confidence: 88%

“…No reports have been published on the localization of these GABA receptors on a specific type of pituitary cells. Previously we demonstrated that the anterior pituitary gland is able to transport and incorporate GABA, which interacts with intracellular particles (Duvilanski et al, 1994). In the present investigation we studied the internalization and intracellular localization of [ 3 H] GABA in rat anterior pituitary and human prolactin-secreting pituitary adenomas by electron microscopic autoradiography.…”

Section: Introductionmentioning

confidence: 84%

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Intracellular distribution of GABA in the rat anterior pituitary. An electron microscopic autoradiographic study

et al. 2000

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“…GABA has been detected in the hypophyseal portal blood (Mitchell et al, 1983) and the anterior pituitary gland (Racagni et al, 1979), where it is synthesized and secreted (Duvilanski et al, 1994, Mayerhofer et al, 2001, Alvarez et al, 2005, Powers, 2012). GABA is also released from pituitary lobe axons (Mayerhofer et al, 2001).…”

Section: Neurotransmitter Receptors and Their Ligands In The Antermentioning

confidence: 99%

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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GABA Transport and Subcellular Distribution in the Rat Anterior Pituitary Gland

Cited by 4 publications

References 16 publications

Electrophysiological Characterization of GABA<sub>A</sub> Receptors in Anterior Pituitary Cells of Newborn Rats

Electrophysiological Characterization of GABA<sub>A</sub> Receptors in Anterior Pituitary Cells of Newborn Rats

Intracellular distribution of GABA in the rat anterior pituitary. An electron microscopic autoradiographic study

Neurotransmitter receptors as signaling platforms in anterior pituitary cells

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