Differential Regulation of Angiotensinogen and Natriuretic Peptide mRNAs in Rat Brain by Osmotic Stimulation: Focus on Anterior Hypothalamus and Supraoptic Nucleus

doi:10.1016/S0196-9781(97)00192-7

Peptides

Volume 18, Issue 9, 1997, Pages 1365-1375

https://doi.org/10.1016/S0196-9781(97)00192-7 Get rights and content

Abstract

Ryan, M. C. and A. L. Gundlach.

Differential regulation of angiotensinogen and natriuretic peptide mRNAs in rat brain by osmotic stimulation: Focus on anterior hypothalamus and supraoptic nucleus.

Peptides 18(9) 1365–1375, 1997.—Central angiotensin II and natriuretic peptide systems have been shown to be involved in the central regulation of blood fluid homeostasis with alterations in central peptide and/or receptor levels observed following changes in osmotic status. The present study investigated the effects of sodium loading on mRNA encoding the angiotensin II precursor, angiotensinogen (AOGEN), and the natriuretic peptides, atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) in rat brain using quantitative in situ hybridization histochemistry of [³⁵S]- and [³³P]-labeled oligonucleotide probes. Following 7 and 14 days of 2% sodium chloride in drinking water a significant increase was detected in preproAOGEN (ppAOGEN) mRNA in presumed astrocytes in regions of the anterior hypothalamus, including the periventricular nucleus, the medial preoptic area and medial preoptic nucleus, while a decrease was observed in astrocytes in the supraoptic nucleus. Other forebrain regions examined including the subfornical organ, bed nucleus of the stria terminalis and the arcuate nucleus showed no significant alteration in the level of ppAOGEN mRNA. Sodium loading did not appreciably alter ppANP or ppCNP mRNA levels in neurons of the anteromedial preoptic or arcuate nuclei or hippocampus at the times studied. PpANP mRNA levels were also unaltered in Barrington’s nucleus following sodium loading, while preprocorticotropin-releasing hormone mRNA was significantly decreased. These results indicate that AOGEN mRNA transcription/stability in vivo is modulated by alterations in osmotic balance, consistent with previous reports of a central role for AII in cardiovascular and body fluid homeostasis. In contrast, despite reports of modulation of hypothalamic ANP-immunoreactivity following changes in osmotic status, it would appear that osmotic stimulation over periods of 7–14 days does not markedly alter the transcription or stability of hypothalamic natriuretic peptide mRNAs in vivo.

Section snippets

Animals

Adult male Sprague–Dawley rats (n = 15; 200–250 g; Biological Research Laboratories, Austin and Repatriation Medical Centre) were maintained on a 12 h light:dark cycle with access to food and either tap water (controls) or a 2% saline solution ad lib for 7 or 14 days [31].

Tissue Processing

Rats were killed by decapitation, brains removed, dissected, frozen over liquid nitrogen and stored at −70°C. Coronal sections (14 μM) were cut on a cryostat at −16°C and mounted on poly-l-lysine coated slides. Sections were

Effect of Sodium Loading on ppANP and ppCNP mRNA Levels in Rat Basal Forebrain

PpANP and ppCNP mRNAs were successfully detected in various regions of the hypothalamus and other brain areas as previously described 26, 45, 46. Sodium loading did not alter levels of ppANP or ppCNP mRNAs in the anteromedial preoptic nucleus (Fig. 1). PpCNP mRNA was not altered in the arcuate nucleus, however a slight, but statistically significant (ANOVA), decrease in ppANP mRNA was observed in the arcuate nucleus following 14 days of 2% NaCl in drinking water (92 ± 2% of control, p < 0.05;

Discussion

Using [³⁵S]-labeled oligonucleotide probes, we have shown the modulation of ppAOGEN mRNA in presumed astrocytes in the rat periventricular nucleus, medial preoptic area, ventral region of the medial preoptic area, medial preoptic nucleus and supraoptic nucleus by hyperosmotic stimulation. PpANP or ppCNP mRNA levels were not appreciably altered in basal forebrain regions following either 7 or 14 days of 2% sodium chloride replacement of drinking water, although following 14 days of sodium

Acknowledgements

This work was supported by a fellowship grant to A.L.G. from the National Health and Medical Research Council (NH&MRC) of Australia. M.C.R. was the recipient of an NH&MRC of Australia Dora Lush (Biomedical) Postgraduate Research Scholarship.

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ArticleDifferential Regulation of Angiotensinogen and Natriuretic Peptide mRNAs in Rat Brain by Osmotic Stimulation: Focus on Anterior Hypothalamus and Supraoptic Nucleus

Abstract

Section snippets

Animals

Tissue Processing

Effect of Sodium Loading on ppANP and ppCNP mRNA Levels in Rat Basal Forebrain

Discussion

Acknowledgements

Brain Res.

Reg. Peptides

J. Chem. Neuroanat.

Neurosci.

Neurosci.

Neurosci.

Eur. J. Pharmacol.

Neurosci.

FEBS Lett.

Peptides

Neurosci. Lett.

Brain Res.

Peptides

Brain Res.

Neurosci. Lett.

Neurosci.

Brain Res.

Biochem. Biophys. Res. Commun.

Neurosci.

Neurosci.

Brain Res. Rev.

Atrial natriuretic factor inhibits dehydration- and angiotensin II-induced water intake in the conscious, unrestrained rat

Proc. Natl. Acad. Sci. USA

Radial glia-like cells in the supraoptic nucleus of the adult rat

J. Neuroendocrinol.

Isolation of cDNA clones encoding rat glial fibrillary acidic proteinExpression in astrocytes and in Schwann cells

J. Neurosci. Res.

Origin of the angiotensin II secreted by cells

Proc. Soc. Exp. Biol. Med.

Effects of aldosterone and dexamethasone on atrial natriuretic peptide levels in preoptic and hypothalamic nuclei of adrenalectomized and intact rats

Neuroendocrinol.

Distribution of preproatrial natriuretic peptide mRNA in rat brain detected by in situ hybridization of DNA oligonucleotidesEnrichment in hypothalamic and limbic regions

J. Neurochem.

Localization of natriuretic peptide-activated guanylate cyclase mRNAs in the rat brain

J. Comp. Neurol.

Localization of C-type natriuretic peptide mRNA in rat hypothalamus

Endocrinol.

Regulation of corticotropin-releasing factor mRNA in neuroendocrine and autonomic neurons by osmotic stimulation and volume loading

Neuroendocrinol.

The natriuretic peptide system in the brainImplications in the central control of cardiovascular and neuroendocrine functions

Front. Neuroendocrinol.

Diuretic and natriuretic actions of rat atrial natriuretic peptide (6–33) administered intracerebroventricularly in rats

Brain Res. Bull.

Article
Differential Regulation of Angiotensinogen and Natriuretic Peptide mRNAs in Rat Brain by Osmotic Stimulation: Focus on Anterior Hypothalamus and Supraoptic Nucleus