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

Duvilanski, Beatriz H.; Perez, Rogelio; Seilicovich, Adriana; Lasaga, Mercedes; Díaz, María Dolores Díaz; Debéljuk, Luciano

doi:10.1054/tice.2000.0116

Cited by 7 publications

(7 citation statements)

References 33 publications

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“…Concentrations of GABA in portal blood are higher than in peripheral blood, and electrical stimulation of median eminence induces an ∼8‐fold increase in the rate of GABA release (Mitchell et al 1983). In addition, GABA is synthesized and released in the pituitary (Duvilanski et al 2000; Mayerhofer et al 2001; Alvarez et al 2005), and substance P modifies hypothalamic GABA release and anterior pituitary GABA concentration (Afione et al 1990). Finally, injection of oestradiol leads to a 7‐fold increase in anterior pituitary GABA concentration (Nicoletti et al 1985).…”

Section: Discussionmentioning

confidence: 99%

Molecular, pharmacological and functional properties of GABA_A receptors in anterior pituitary cells

Bjelobaba¹,

Tomić²,

Zemková³

et al. 2008

The Journal of Physiology

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Section: Discussionmentioning

confidence: 99%

Molecular, pharmacological and functional properties of GABA_A receptors in anterior pituitary cells

Bjelobaba¹,

Tomić²,

Zemková³

et al. 2008

The Journal of Physiology

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“…Corroborating the hypophysial actions of GABA, GABA A receptors have been identified on anterior pituitary cells (Berman et al ., 1994). In addition, somatotrophs and lactotrophs, but no other types of adenohypophysial cells, are capable of internalizing [ 3 H]GABA through mechanisms that are currently unknown (Duvilanski et al ., 2000). Somewhat contradicting the idea that the secreted GABA regulates the anterior pituitary is the finding that GABA levels are not higher in the hypophysial portal vs. the peripheral blood (Mulchahey & Neill, 1982).…”

Section: Discussionmentioning

confidence: 99%

Presence of vesicular glutamate transporter‐2 in hypophysiotropic somatostatin but not growth hormone‐releasing hormone neurons of the male rat

Hrabovszky

Túri

Liposits

2005

Eur J of Neuroscience

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Recent evidence indicates that hypophysiotropic gonadotropin-releasing hormone (GnRH), corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH) neurons of the adult male rat express mRNA and immunoreactivity for type-2 vesicular glutamate transporter (VGLUT2), a marker for glutamatergic neuronal phenotype. In the present study, we investigated the issue of whether these glutamatergic features are shared by growth hormone-releasing hormone (GHRH) neurons of the hypothalamic arcuate nucleus (ARH) and somatostatin (SS) neurons of the anterior periventricular nucleus (PVa), the two parvicellular neurosecretory systems that regulate anterior pituitary somatotrophs. Dual-label in situ hybridization studies revealed relatively few cells that expressed VGLUT2 mRNA in the ARH; the GHRH neurons were devoid of VGLUT2 hybridization signal. In contrast, VGLUT2 mRNA was expressed abundantly in the PVa; virtually all (97.5 +/- 0.4%) SS neurons showed labelling for VGLUT2 mRNA. In accordance with these hybridization results, dual-label immunofluorescent studies followed by confocal laser microscopic analysis of the median eminence established the absence of VGLUT2 immunoreactivity in GHRH terminals and its presence in many neurosecretory SS terminals. The GHRH terminals, in turn, were immunoreactive for the vesicular gamma-aminobutyric acid (GABA) transporter, used in these studies as a marker for GABA-ergic neuronal phenotype. Together, these results suggest the paradoxic cosecretion of the excitatory amino acid neurotransmitter glutamate with the inhibitory peptide SS and the cosecretion of the inhibitory amino acid neurotransmitter GABA with the stimulatory peptide GHRH. The mechanisms of action of intrinsic amino acids in hypophysiotropic neurosecretory systems require clarification.

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“…Subsequent studies showed that GABA is released from tuberoinfundibular and other hypothalamic regions, that concentrations of GABA in portal blood are higher than in peripheral blood, and that electrical stimulation of the median eminence induces a several-fold increase in the rate of GABA release (435), which could indicate that GABA acts in the pituitary as a hypothalamic neurohormone. However, it has also been reported that GABA is synthesized and released from intermediate and anterior pituitary lobes (435)(436)(437)(438), which could suggest that GABA acts as a paracrine factor. At the present time, little information exists about the mechanism of GABA release in the portal blood and pituitary.…”

Section: Gaba Receptor Channelsmentioning

confidence: 99%

Ion Channels and Signaling in the Pituitary Gland

2010

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Endocrine pituitary cells are neuronlike; they express numerous voltage-gated sodium, calcium, potassium, and chloride channels and fire action potentials spontaneously, accompanied by a rise in intracellular calcium. In some cells, spontaneous electrical activity is sufficient to drive the intracellular calcium concentration above the threshold for stimulus-secretion and stimulus-transcription coupling. In others, the function of these action potentials is to maintain the cells in a responsive state with cytosolic calcium near, but below, the threshold level. Some pituitary cells also express gap junction channels, which could be used for intercellular Ca(2+) signaling in these cells. Endocrine cells also express extracellular ligand-gated ion channels, and their activation by hypothalamic and intrapituitary hormones leads to amplification of the pacemaking activity and facilitation of calcium influx and hormone release. These cells also express numerous G protein-coupled receptors, which can stimulate or silence electrical activity and action potential-dependent calcium influx and hormone release. Other members of this receptor family can activate calcium channels in the endoplasmic reticulum, leading to a cell type-specific modulation of electrical activity. This review summarizes recent findings in this field and our current understanding of the complex relationship between voltage-gated ion channels, ligand-gated ion channels, gap junction channels, and G protein-coupled receptors in pituitary cells.

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

Cited by 7 publications

References 33 publications

Molecular, pharmacological and functional properties of GABA_A receptors in anterior pituitary cells

Molecular, pharmacological and functional properties of GABA_A receptors in anterior pituitary cells

Presence of vesicular glutamate transporter‐2 in hypophysiotropic somatostatin but not growth hormone‐releasing hormone neurons of the male rat

Ion Channels and Signaling in the Pituitary Gland

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

Cited by 7 publications

References 33 publications

Molecular, pharmacological and functional properties of GABAA receptors in anterior pituitary cells

Molecular, pharmacological and functional properties of GABAA receptors in anterior pituitary cells

Presence of vesicular glutamate transporter‐2 in hypophysiotropic somatostatin but not growth hormone‐releasing hormone neurons of the male rat

Ion Channels and Signaling in the Pituitary Gland

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Product

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Molecular, pharmacological and functional properties of GABA_A receptors in anterior pituitary cells

Molecular, pharmacological and functional properties of GABA_A receptors in anterior pituitary cells