17α-Oestradiol-Induced Neuroprotection in the Brain of Spontaneously Hypertensive Rats

Authors

  • L. Pietranera,

    1. Laboratory of Neuroendocrine Biochemistry, Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina
    2. Department of Human Biochemistry, Faculty of Medicine, University of Buenos Aires, Buenos Aires, Argentina
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  • M. E. Brocca,

    1. Laboratory of Neuroendocrine Biochemistry, Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina
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  • P. Roig,

    1. Laboratory of Neuroendocrine Biochemistry, Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina
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  • A. Lima,

    1. Laboratory of Neuroendocrine Biochemistry, Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina
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  • L. M. Garcia-Segura,

    1. Instituto Cajal, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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  • A. F. De Nicola

    Corresponding author
    1. Laboratory of Neuroendocrine Biochemistry, Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina
    2. Department of Human Biochemistry, Faculty of Medicine, University of Buenos Aires, Buenos Aires, Argentina
    • Correspondence to:

      Dr. Alejandro F. De Nicola, Laboratory of Neuroendocrine Biochemistry, Instituto de Biologia y Medicina Experimental, Obligado 2490, 1428 Buenos Aires, Argentina (e-mail: alejandrodenicola@gmail.com).

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Abstract

17β-oestradiol is a powerful neuroprotective factor for the brain abnormalities of spontaneously hypertensive rats (SHR). 17α-Oestradiol, a nonfeminising isomer showing low affinity for oestrogen receptors, is also endowed with neuroprotective effects in vivo and in vitro. We therefore investigated whether treatment with 17α-oestradiol prevented pathological changes of the hippocampus and hypothalamus of SHR. We used 20-week-old male SHR with a blood pressure of approximately 170 mmHg receiving s.c. a single 800 μg pellet of 17α-oestradiol dissolved in cholesterol or vehicle only for 2 weeks Normotensive Wistar–Kyoto (WKY) rats were used as controls. 17α-Oestradiol did not modify blood pressure, serum prolactin, 17β-oestradiol levels or the weight of the testis and pituitary of SHR. In the brain, we analysed steroid effects on hippocampus Ki67+ proliferating cells, doublecortin (DCX) positive neuroblasts, glial fibrillary acidic protein (GFAP)+ astrocyte density, aromatase immunostaining and brain-derived neurotrophic factor (BDNF) mRNA. In the hypothalamus, we determined arginine vasopressin (AVP) mRNA. Treatment of SHR with 17α-oestradiol enhanced the number of Ki67+ in the subgranular zone and DCX+ cells in the inner granule cell layer of the dentate gyrus, increased BDNF mRNA in the CA1 region and gyrus dentatus, decreased GFAP+ astrogliosis in the CA1 subfield, and decreased hypothalamic AVP mRNA. Aromatase expression was unmodified. By contrast to SHR, normotensive WKY rats were unresponsive to 17α-oestradiol. These data indicate a role for 17α-oestradiol as a protective factor for the treatment of hypertensive encephalopathy. Furthermore, 17α-oestradiol is weakly oestrogenic in the periphery and can be used in males.

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