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Title: Regulation by osmotic stimuli of galanin-R1 receptor expression in magnocellular neurones of the paraventricular and supraoptic nuclei of the rat.
Austin Authors: Burazin, T C;Larm, J A;Gundlach, Andrew L
Affiliation: The University of Melbourne, Department of Medicine, Austin and Repatriation Medical Centre, Heidelberg, Victoria 3010, Australia
Issue Date: 1-Apr-2001
Publication information: Journal of Neuroendocrinology; 13(4): 358-70
Abstract: Neurones of the supraoptic nucleus (SON) and the magnocellular and parvocellular divisions of the paraventricular nucleus (PVN) express galanin and [125I]galanin binding sites. Although the precise role(s) of galanin in these different cell populations is still unknown, it has been shown to regulate the electrophysiological, neurochemical and secretory activity of magnocellular neurones. In light of the well-described effects of hyperosmotic stimuli, such as salt-loading on magnocellular neurone activity and galanin synthesis and release, and the recent identification of multiple galanin receptors in brain, this study assessed the possible regulation of galanin receptor subtype expression in the PVN/SON of salt-loaded, dehydrated and food-deprived rats. Gal-R1 mRNA was abundant in the SON (and magnocellular PVN) of control rats and levels were increased in these same cells after 4 days of salt-loading (2% NaCl solution as drinking water) or water deprivation. The density of specific [125I]galanin(1-29) binding and the intensity of Gal-R1-like immunostaining were also increased in the characteristically enlarged, magnocellular neurones of the PVN and SON after these treatments. Gal-R2 mRNA was detected in the parvocellular PVN, but levels were not altered by the hyperosmotic stimuli. In contrast, food deprivation (4 days), which has been shown to reduce levels of several neurochemical markers in magnocellular neurones, produced a significant reduction in Gal-R1 (and galanin) mRNA levels in the SON, but no consistent change in neurone size, [125I]galanin binding levels, or Gal-R1 immunostaining. Along with previous findings from this and other laboratories, these data suggest that the expression of galanin and Gal-R1 receptors is regulated in parallel with functional and morphological changes in hypothalamic magnocellular neurones. Furthermore, Gal-R1 immunoreactivity was primarily detected in somatodendritic areas and thus galanin may influence the activity of these cells, particularly vasopressin synthesis/release, via autocrine or paracrine activation of Gal-R1 receptors, especially during long-lasting stimulation.
Gov't Doc #: 11264724
Type: Journal Article
Subjects: Animals
Binding, Competitive.drug effects
Food Deprivation
In Situ Hybridization
Iodine Radioisotopes
Neurons.cytology.drug effects.metabolism
Organ Specificity
Osmolar Concentration
Paraventricular Hypothalamic Nucleus.cytology.drug effects.metabolism
RNA, Messenger.metabolism
Rats, Sprague-Dawley
Receptors, Galanin
Receptors, Neuropeptide.genetics.metabolism
Sodium Chloride.pharmacology
Supraoptic Nucleus.cytology.drug effects.metabolism
Water Deprivation
Appears in Collections:Journal articles

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