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Ovarian hormone effects on 5-hydroxytryptamine (2A) and 5-hydroxytryptamine (2C) receptor mRNA expression in the ventral hippocampus and frontal cortex of female rats.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
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2002 (English)In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 319, no 3, 157-161 p.Article in journal (Refereed) Published
Abstract [en]

Alterations in female gonadal hormones are associated with anxiety and mood changes. The aim of the present study was to determine influences of chronic gonadal hormone supplementation on 5-HT(2A) and 5-HT(2C) receptor mRNA levels in the ventral hippocampus and the frontal cerebral cortex. Ovariectomized adult female Sprague-Dawley rats (n=37) received implantation of subcutaneous pellets containing different dosages of 17beta-estradiol alone or in combination with progesterone, or placebo pellets, for 2 weeks. Serotonin receptor mRNA levels were analyzed by in situ hybridization in the ventral hippocampus and 5-HT(2A) receptor mRNA also in the frontal cortex. Estradiol treatment in combination with low-dose progesterone increased 5-HT(2A) receptor mRNA by 43% in the CA2 region of the ventral hippocampus, while estradiol combined with high-dose progesterone increased the expression of this gene by 84% in ventral CA1. 5-HT(2A) mRNA expression in the frontal cortex was not influenced by hormone manipulation. 5-HT(2C) receptor gene expression was in the ventral hippocampus decreased in the CA2, ventral CA1 and the subiculum subregions by high-dose estradiol treatment (8-20% decreases). Effects on mood by gonadal hormones can be mediated, at least partly, through influences on 5-HT(2A) and 5-HT(2C) receptor expression.

Place, publisher, year, edition, pages
2002. Vol. 319, no 3, 157-161 p.
Identifiers
URN: urn:nbn:se:umu:diva-4029DOI: 10.1016/S0304-3940(01)02570-8PubMedID: 11834317OAI: oai:DiVA.org:umu-4029DiVA: diva2:142977
Available from: 2004-08-11 Created: 2004-08-11 Last updated: 2011-04-12Bibliographically approved
In thesis
1. Neuroactive steroids and rat CNS
Open this publication in new window or tab >>Neuroactive steroids and rat CNS
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Several studies suggest profound effects on mood and cognition by neuroactive steroids. Estrogen alone or in combination with antidepressant drugs affecting the serotonin system has been used to treat mood disorders. On the other hand, progesterone is related to negative effects on mood and memory. A major part of the progesterone effects on the brain can be mediated by its metabolite allopregnanolone, which is also de novo synthesized in the brain, and affects the GABAA receptors. It would be of great importance to find a substance that antagonize allopregnanolone adverse effects.

To investigate how long term supplementation of estradiol and progesterone, resembling postmenopausal hormone replacement therapy, affects serotonin receptors in different brain areas important for mood and memory functions, we used ovariectomized female rats. After 2 weeks of supplementation with 17β-estradiol alone or in combination with progesterone, or placebo pellets, estradiol alone decreases but estradiol supplemented together with progesterone increases 5HT1A mRNA expression in the hippocampus. Estradiol decreases the 5HT2C receptor gene expression, while estradiol in combination with progesterone increases the 5HT2A mRNA expression in the ventral hippocampus. Thus, estradiol alone has opposite effects compared to the estradiol/progesterone combination. To detect if acute tolerance develops to allopregnanolone, an EEG method was used where male rats by continuous allopregnanolone infusion were kept on anesthesia level of the silent second (SS). After different time intervals (first SS, 30 min or 90 min of anesthesia) several GABAA receptor subunit mRNAs were measured for detecting if changed expression of any GABAA receptor subunits is involved in development of acute tolerance. There is development of acute tolerance to allopregnanolone and brain regions of importance are hippocampus, thalamus and hypothalamus. The GABAA receptor alpha4 subunit in thalamus and alpha2 subunit in the dorsal hippocampus are related to development of acute tolerance. For assessing allopregnanolone behavioral effects, we studied how this neurosteroid affects spatial learning in the Morris water maze task Allopregnanolone inhibits spatial learning short after the injection and shows a specific behavioral pattern with swimming close to the pool wall. The steroid UC1011 can inhibit the increase in chloride ion uptake induced by allopregnanolone. UC1011 decreases allopregnanoloneinduced impairment of spatial learning in the water maze, as well as the specific behavioral swim pattern.

In conclusion, the present work demonstrates that neuroactive steroids affect the 5HT and GABA systems in a brain region specific way. GABAA receptor subunit changes in hippocampus and thalamus are related to acute allopregnanolone tolerance. Allopregnanolone induces cognitive deficits, like spatial learning impairment and UC1011 can inhibit allopregnanolone-induced effects in vitro and in vivo.

Key words: Estradiol, progesterone, HRT, allopregnanolone, UC1011, serotonin receptor, GABAA receptor, mRNA, Morris water maze, silent second, tolerance.

Publisher
91 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 898
Keyword
Estradiol, progesterone, HRT, allopregnanolone, UC1011, serotonin receptor, GABAA receptor, mRNA, Morris water maze, silent second, tolerance
Research subject
Clinical Neurophysiology
Identifiers
urn:nbn:se:umu:diva-296 (URN)91-7305-668-5 (ISBN)
Public defence
2004-09-16, E04, 6E, 09:00 (English)
Opponent
Available from: 2004-08-11 Created: 2004-08-11 Last updated: 2009-12-18Bibliographically approved

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Johansson, I-MWang, MDBäckström, T

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