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

• Published in: Journal of neuroendocrinology Vol. 26; no. 5; pp. 310 - 320
• Main Authors: Pietranera, L, Brocca, ME, Roig, P, Lima, A, Garcia-Segura, L M, De Nicola, AF
• Format: Journal Article
• Language: English
• Published: 01.05.2014
• ISSN: 0953-8194; 1365-2826
• DOI: 10.1111/jne.12151

17 beta -oestradiol is a powerful neuroprotective factor for the brain abnormalities of spontaneously hypertensive rats (SHR). 17 alpha -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 17 alpha -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 mu g pellet of 17 alpha -oestradiol dissolved in cholesterol or vehicle only for 2 weeks Normotensive Wistar-Kyoto (WKY) rats were used as controls. 17 alpha -Oestradiol did not modify blood pressure, serum prolactin, 17 beta -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 17 alpha -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 17 alpha -oestradiol. These data indicate a role for 17 alpha -oestradiol as a protective factor for the treatment of hypertensive encephalopathy. Furthermore, 17 alpha -oestradiol is weakly oestrogenic in the periphery and can be used in males.