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The central nervous system produces many of the enzymes responsible for corticosteroid synthesis. A model system to study the regulation of this local system would be valuable. Previously, we have shown that primary cultures of hippocampal neurons isolated from the fetal rat can perform the biochemical reactions associated with the enzymes 11beta-hydroxylase and aldosterone synthase. Here, we demonstrate directly that these enzymes are present within primary cultures of fetal rat hippocampal neurons.

The terminal stages of cortisol and aldosterone production in the human adrenal gland are catalysed by the enzymes 11beta-hydroxylase and aldosterone synthase, which are encoded by the CYP11B1 and CYP11B2 genes respectively. Recent studies have suggested that aldosterone and cortisol are also made in other tissues such as the brain, heart and vascular system and may play a role in cardiovascular homeostasis. The aim of this study was to confirm the presence of these enzymes and localise them precisely in the rat brain. Reverse transcription-polymerase chain reaction (RT-PCR)/Southern blotting confirmed transcription of CYP11B1 and CYP11B2 in whole brain and hypothalamus minces from Wistar-Kyoto rats. 11beta-Hydroxylase and aldosterone synthase were immunolocalised in paraffin-embedded rat adrenal and brain sections using mouse monoclonal antibodies. Negative controls utilised a mouse monoclonal antibody raised against a non-mammalian epitope. In the brain, 11beta-hydroxylase and aldosterone synthase were detected in the cerebellum, especially the Purkinje cells, as well as the hippocampus. The specificities of the 11beta-hydroxylase and aldosterone synthase antibodies were confirmed by positive immunostaining of the relevant regions of the adrenal cortex. This is the first direct evidence that steroid hydroxylases involved in the final stages of corticosteroid biosynthesis are present in specific regions of the central nervous system.

This study has been performed to test the hypothesis that different oestrogen receptor beta (ERβ) splice variants may be important determinants of clinical parameters, including outcome, in post-menopausal women with breast cancer receiving adjuvant endocrine treatment but no chemotherapy. Splice variants ERβ1, ERβ2 and ERβ5 have been analysed by semi-quantitative RT-PCR in a cohort of 105 patients with primary breast cancer. Clinical correlates included age, grade, size, nodal status, ERα, progesterone receptor, Ki67, relapse-free survival (RFS) and overall survival (OS). Seventy per cent of cases were ERβ1 positive, 69% ERβ2 positive and 70% ERβ5 positive. Within the cohort, 47% were positive for all three variants while 10% were negative for all three. ERβ1 exhibited no discernible relationship with disease outcome. ERβ2 and ERβ5 expression was significantly associated with better RFS (P<0.005), and ERβ2 with better OS (P=0.0002). In multivariate analysis, ERβ2 (P=0.006), nodal status and the level of Ki67 expression were independent predictors for RFS while ERβ2 (P=0.0008) and Ki67 status were independent predictors for OS. In the ERα-positive cases, or in the subset of those receiving adjuvant tamoxifen, ERβ2 was significantly associated with good RFS (P<0.0005) and was the only independent marker of OS. We conclude that precise identification of splice variants of ERβ are more important assessors than is ERβ1 alone of the biological status of individual breast cancers, and hence in predicting their response to endocrine therapy.