[Steroid receptors in the central nervous system. Implications in neurology]

This review deals with steroid hormones and receptors in relation to the physiology and the pathology of the central nervous system (CNS) and meninges. In recent years experiments performed in animals showed that: 1) endogenous steroid hormones cross the blood brain barrier: 2) radiolabelled steroid hormones bind in specific areas of the CNS; 3) all five classes of steroid receptors, i.e. oestrogen, progesterone, androgen, glucocorticoid and mineralocorticoid receptors (OR, PR, AR, GR, MR), are present in brain tissues, especially in the hypothalamus and the limbic system; 4) the interaction of steroid hormones and specific receptors induces the synthesis of proteins in the CNS; 5) finally, in situ metabolism of steroid hormones has been evidenced by the presence of specific enzymes. A few studies in human brain tissues have shown the presence of GR and OR as well as enzymes involved in the metabolism of sex steroid hormones. In neurology, some epidemiological and clinical data suggest the implication of steroid hormones and receptors in human CNS: 1) the influence of oestrogens in tardive dyskinesia; 2) the relevance of hormonal changes in benign intracranial hypertension; 3) the usefulness of glucocorticoid therapy in many patients with intracranial tumors and/or edema. Due to feasibility, most researches have concerned tumors: meningioma, neurinoma and glioma. Firstly, a reappraisal of biochemical and histochemical technics used to detect and characterize the receptors in tumors is presented. Then results from the recent literature are reviewed. In meningioma, PR was found in 89 p. 100 (152/177) of the cases, usually at moderate to high levels (up to 33 000 fmol/gT). In addition, PR has been fully characterized from a biochemical point of view. Furthermore, it has been hypothesized that PR may be a marker of leptomeningeal cells since it was detected at high levels in well differentiated tumors provided they had no or few psammoma. This was further supported by the discovery of PR in normal leptomeninges in human adults. OR was detected in 48 p. 100 (87/177) of the meningioma, at low levels. This is in contrast with PR but the percentage of cases with OR raises to 70 p. 100 (42/60) if one considers only tumors assayed for both cytosolic and nuclear receptors. Therefore it has been suggested that OR had translocated into the nucleus, at least in some cases, and subsequently the hypothesis of functional OR in meningioma was raised. AR was also detected in meningioma. Furthermore AR levels were found to correlate well with PR levels.(ABSTRACT TRUNCATED AT 400 WORDS)