Regional stimulatory and inhibitory effects of guanine nucleotides on [125I]galanin binding in rat brain: Relationship with the rate of occupancy of galanin receptors by endogenous Galanin

Lagny-Pourmir, Isabelle; Epelbaum, Jacques

doi:10.1016/0306-4522(92)90360-e

Cited by 33 publications

(19 citation statements)

References 64 publications

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“…Taken together, the results are in favor of a local role of the GAL-R 1 receptor within these hypothalamic nuclei. On the other hand, GAL-binding sites have been found in high concentration in the ME [11][12][13] which did not express GAL-R1 mRNA. Since the ME is the projection site of neurosecretory axons from most hypophysiotropic nuclei, it appears that median eminence GAL-R 1 receptors are transported to have a local role at the nerve terminal.…”

Section: Discussionmentioning

confidence: 99%

“…The levels of expression might vary from one nucleus to another. On the one hand it was noteworthy that high levels of hypothalamic GAL-R 1 expression cor responded with the highest levels of 125I-GAL binding (ta ble 1) [3,[11][12][13]20] and more especially in the preoptic region, Pe, PVN and DM. Taken together, the results are in favor of a local role of the GAL-R 1 receptor within these hypothalamic nuclei.…”

Section: Discussionmentioning

confidence: 99%

“…Distribution of GAL-R 1 mRNA-expressing cells and comparison with GAL-binding sites, GAL-immunoreactive fibers (GAL-IR) and GAL mRNA-expressing neurons in the rat hypotha lamic nuclei and median eminence GAL-R 1 mRNA GAL binding [11] GAL-IR fibers [12] GAL mRNA [19] However, as we obtained a higher expression in certain arcuate cells than expression described by Chan et al [ 18], it is likely that GAL-R 1 expression concerns other cell types than GH-RH in this nucleus.…”

Section: Discussionmentioning

confidence: 99%

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Semiquantitative Distribution of Galanin-Receptor (GAL-R1) mRNA-Containing Cells in the Male Rat Hypothalamus

Mitchell

Habert-Ortoli²,

Epelbaum

et al. 1997

Neuroendocrinology

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The semiquantitative distribution of mRNA encoding for rat galanin receptor (GAL-R1) was examined by in situ hybridization in the rat hypothalamus using a ³⁵S-riboprobe. Most hypothalamic nuclei expressed GAL-R1 mRNA. In the anterior hypothalamus, high levels of expression were found in the medial preoptic area, paraventricular and supraoptic nuclei. Numerous cells also expressed the GAL-R1 mRNA with a moderate level of expression in the periventricular region. Very few GAL-R1-expressing cells were present in the suprachiasmatic nucleus. In the medial hypothalamus, numerous expressing cells were detected in the dorsomedial and ventromedial nuclei. The arcuate nucleus was moderately labeled throughout its rostrocaudal extent; labeled cell bodies were visible in the ventromedial and ventrolateral subdivisions as well. These results indicate that the GAL-R1 mRNA is not only expressed in anterior hypothalamic nuclei but also in the mediobasal hypothalamus and periventricular region. This hypothalamic distribution correlates well with that of ¹²⁵I-GAL-binding sites and GAL-immunoreactive fibers. This distribution represents the morphological substrate for GAL roles in the hypothalamic regulation of neuroendocrine, behavioral and autonomic functions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Semiquantitative Distribution of Galanin-Receptor (GAL-R1) mRNA-Containing Cells in the Male Rat Hypothalamus

Mitchell

Habert-Ortoli²,

Epelbaum

et al. 1997

Neuroendocrinology

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“…The arcuate nucleus (ARC) of the hypothalamus participates in the control of reproduction and feeding and might represent one of the targets for galanin in its control of these functions [4, 5]. In the rat, the ARC is abundantly innervated by galanin-containing nerve terminals [1, 6]and possesses binding sites for galanin [7, 8]. Galanin interacts with three distinct G-protein-coupled receptor subtypes [9].…”

Section: Introductionmentioning

confidence: 99%

Direct Inhibitory Action of Galanin on Hypothalamic Arcuate Nucleus Neurones Expressing Galanin Receptor Gal-R1 mRNA

Poulain¹,

Decrocq²,

Mitchell³

2003

Neuroendocrinology

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Galanin may act in the regulation of reproduction and feeding behaviour through a direct action on arcuate nucleus (ARC) neurones but evidence for a postsynaptic action is absent. The effects of rat galanin(1–29) on rat ARC neurones were examined during recordings with biocytin-filled sharp microelectrodes from brain slices. Neurones were subsequently visualised and hybridized for the mRNA of the galanin receptor Gal-R1. Current-clamp recordings revealed that ARC neurones displayed a functional heterogeneity in their firing properties. A great majority of neurones showed low-threshold spikes, instantaneous and time-dependent inward rectifications and an outward rectification. Two types of bursting behaviours were recorded, depending on the level of the membrane potential. Galanin (500 nM) elicited a reversible hyperpolarisation with a decrease in the resistance or a decrease in resistance only in 9 of 34 tested neurones, independent of the electrophysiological phenotype. The reversal potential for the galanin response was about –94 mV, near the equilibrium potential for K⁺. Galantide (10 nM) antagonised the effects which were not blocked by tetrodotoxin, indicating a postsynaptic action. In situ hybridisation revealed that Gal-R1 mRNA occurred in the neurones that responded to galanin, whereas the unresponsive neurones never exhibited the hybridisation signal. This suggests that the responsive neurones possess functional postsynaptic Gal-R1. The study demonstrates for the first time a direct inhibitory action of galanin on ARC neurones, probably mediated by activation of Gal-R1. This action may have important implications for the functioning of neurones involved in the regulation of reproduction and feeding behaviour, such as proopiomelanocortin neurones.

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“…The effects of galanin on the various functions are mediated by binding of the peptide to specific membrane recep-tors that have been localized within several regions of the hypothalamus (17)(18)(19). More recently, cloning of the galanin receptor Gal-R1 (20) allowed the localization of Gal-R1-expressing cells in the rat hypothalamus, including the POA (21).…”

mentioning

confidence: 99%

Effects of Estrous Cyclicity on the Expression of the Galanin Receptor Gal-R1 in the Rat Preoptic Area: A Comparison with the Male**This work was supported by the Direction de la Recherche et de la Technologie from the Conseil Régional of the Région Nord-Pas de Calais.

et al. 1998

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Variations in the number of galanin receptor (Gal-R1)-expressing cells and levels of Gal-R1 messenger RNA (mRNA) were determined in the preoptic area in intact female rats throughout the phases of the estrous cycle and compared with those in the male. Female and male Wistar rats were fixed by perfusion with 4% paraformaldehyde. Cryostat sections were hybridized with a 35S-labeled antisense Gal-R1 riboprobe. The number of Gal-R1 mRNA-expressing cells was lower in the rostral preoptic area than in the medial preoptic area. During the estrous cycle, the highest number of Gal-R1 mRNA-expressing cells in the rostral preoptic region was detected at 0800 h on proestrus, whereas in the medial preoptic area, the maximum number was observed at 1800 h on estrus. Gal-R1 mRNA levels in individual cells were low during diestrus and increased at estrus in both areas. In the male, the number of mRNA-expressing cells and the hybridization signal were significantly lower than those in females during estrus. The results demonstrate that Gal-R1 gene expression in the preoptic area varies during the estrous cycle and is low in males. Short term treatment of ovariectomized rats with estradiol plus progesterone caused significantly decreased preoptic Gal-R1 mRNA levels compared with those after treatment with estrogen only. These observations suggest that in the preoptic area, expression of Gal-R1 is influenced by progesterone. The variation in Gal-R1 expression is likely to influence the extent to which galanin can influence the preoptic cells implicated in the control of neighboring GnRH cells.

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Regional stimulatory and inhibitory effects of guanine nucleotides on [125I]galanin binding in rat brain: Relationship with the rate of occupancy of galanin receptors by endogenous Galanin

Cited by 33 publications

References 64 publications

Semiquantitative Distribution of Galanin-Receptor (GAL-R1) mRNA-Containing Cells in the Male Rat Hypothalamus

Semiquantitative Distribution of Galanin-Receptor (GAL-R1) mRNA-Containing Cells in the Male Rat Hypothalamus

Direct Inhibitory Action of Galanin on Hypothalamic Arcuate Nucleus Neurones Expressing Galanin Receptor Gal-R1 mRNA

Effects of Estrous Cyclicity on the Expression of the Galanin Receptor Gal-R1 in the Rat Preoptic Area: A Comparison with the Male**This work was supported by the Direction de la Recherche et de la Technologie from the Conseil Régional of the Région Nord-Pas de Calais.

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