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Inhibition by Lipopolysaccharide of Naloxone‐Induced Luteinising Hormone Secretion Is Accompanied by Increases in Corticotropin‐Releasing Factor Immunoreactivity in Hypothalamic Paraventricular Neurones in Female Rats

Inhibition by Lipopolysaccharide of Naloxone‐Induced Luteinising Hormone Secretion Is Accompanied... We have recently reported that lipopolysaccharide (LPS), a bacterial endotoxin, inhibits steroid‐induced as well as naloxone‐induced luteinising hormone (LH) secretion in ovariectomised oestrogen‐primed rats. In the present study, we examined whether corticotropin‐releasing factor (CRF) may be involved in the LPS‐induced inhibition of LH secretion. Unanaesthetised rats were treated with an intravenous (i.v.) injection of LPS (10 µg) or saline, followed by an i.v. injection of naloxone (20 mg/kg). After sequential blood samples were collected for determination of serum LH concentrations, the brains were fixed and CRF‐immunoreactivity was examined histochemically. In control rats receiving saline injections, only a small number of CRF‐immunoreactive (ir) cells were found in the parvocellular portion of the hypothalamic paraventricular nucleus (PVN), and naloxone significantly increased serum LH concentrations within 10 min. By contrast, in LPS‐treated rats, the number of CRF‐ir cells was significantly greater than that in control rats, and the effect of naloxone was completely abolished. In a separate experiment, an intracerebroventricular injection of 5 µg CRF inhibited naloxone‐induced LH release, mimicking the effect of LPS. These results suggest that LPS stimulates production of CRF in PVN neurones, which in turn inhibits LH secretion without opioidergic mediation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Neuroendocrinology Wiley

Inhibition by Lipopolysaccharide of Naloxone‐Induced Luteinising Hormone Secretion Is Accompanied by Increases in Corticotropin‐Releasing Factor Immunoreactivity in Hypothalamic Paraventricular Neurones in Female Rats

Journal of Neuroendocrinology , Volume 17 (2) – Feb 1, 2005

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References (41)

Publisher
Wiley
Copyright
Copyright © 2005 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0953-8194
eISSN
1365-2826
DOI
10.1111/j.1365-2826.2005.01275.x
pmid
15796756
Publisher site
See Article on Publisher Site

Abstract

We have recently reported that lipopolysaccharide (LPS), a bacterial endotoxin, inhibits steroid‐induced as well as naloxone‐induced luteinising hormone (LH) secretion in ovariectomised oestrogen‐primed rats. In the present study, we examined whether corticotropin‐releasing factor (CRF) may be involved in the LPS‐induced inhibition of LH secretion. Unanaesthetised rats were treated with an intravenous (i.v.) injection of LPS (10 µg) or saline, followed by an i.v. injection of naloxone (20 mg/kg). After sequential blood samples were collected for determination of serum LH concentrations, the brains were fixed and CRF‐immunoreactivity was examined histochemically. In control rats receiving saline injections, only a small number of CRF‐immunoreactive (ir) cells were found in the parvocellular portion of the hypothalamic paraventricular nucleus (PVN), and naloxone significantly increased serum LH concentrations within 10 min. By contrast, in LPS‐treated rats, the number of CRF‐ir cells was significantly greater than that in control rats, and the effect of naloxone was completely abolished. In a separate experiment, an intracerebroventricular injection of 5 µg CRF inhibited naloxone‐induced LH release, mimicking the effect of LPS. These results suggest that LPS stimulates production of CRF in PVN neurones, which in turn inhibits LH secretion without opioidergic mediation.

Journal

Journal of NeuroendocrinologyWiley

Published: Feb 1, 2005

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