Potential clinical uses of neuroactive steroids

Neuroactive steroids rapidly modulate gamma-aminobutyric acid (GABA) and glutamate receptors. GABA-enhancing steroids have potential clinical utility as anesthetics, hypnotics, anticonvulsants and anxiolytics. Furthermore, GABAergic neurosteroids may participate in regulating mood and the effects of alcohol on the nervous system, suggesting a potential role in major psychiatric disorders. Neuroactive steroids that alter the function of glutamate receptors could be useful for treating neurodegenerative disorders, and as cognitive enhancers. Recent progress in developing water-soluble steroids and steroids with enhanced oral efficacy foster optimism that certain neuroactive steroids will be developed for clinical use.     

Social isolation stress and neuroactive steroids.

Social isolation of rats immediately after weaning is associated to a reduction in the cerebrocortical and plasma concentrations of progesterone and its metabolites 3alpha,5alpha-TH PROG and 3alpha,5alpha-THDOC. Although we found that the basal plasma concentration of adrenocorticotropic hormone in isolated rats was slightly decreased compared with that in group-housed animals no other significant changes were found in the steroidogenic machinery (peripheral benzodiazepine receptors, steroidogenic regulatory protein (StAR)). However, the functional response of the hypothalamic-pituitary-adrenal axis HPA axis to an acute stressful stimulus (foot shock), or to an acute injection of ethanol or isoniazid is markedly increased in isolated rats. Behavioral studies have also indicated that the ability of ethanol to inhibit isoniazid-induced convulsions is greater in isolated rats than in group-housed animals and this effect of isolation is prevented by treatment with the 5alpha-reductase inhibitor finasteride. Social isolation modified the effects of ethanol on the amounts of StAR mRNA and protein in the brain suggesting an alteration in the mechanism of cholesterol transport in mitochondria. Moreover, the amounts of the alpha4 and delta subunits of the GABA(A) receptor in the hippocampus were increased in isolated rats, and these effects were accompanied by an increase in GABA(A) receptor-mediated tonic inhibitory currents in granule cells of the dentate gyrus. Ethanol also increased the amplitude of GABA(A) receptor-mediated miniature inhibitory postsynaptic currents (mIPSC) recorded from CA1 pyramidal neurons with a greater potency in hippocampal slices prepared from socially isolated rats than in those from group-housed, an effect inhibited by finasteride.     

Potential clinical uses of neuroactive steroids

Neuroactive steroids rapidly modulate gamma-aminobutyric acid (GABA) and glutamate receptors. GABA-enhancing steroids have potential clinical utility as anesthetics, hypnotics, anticonvulsants and anxiolytics. Furthermore, GABAergic neurosteroids may participate in regulating mood and the effects of alcohol on the nervous system, suggesting a potential role in major psychiatric disorders. Neuroactive steroids that alter the function of glutamate receptors could be useful for treating neurodegenerative disorders, and as cognitive enhancers. Recent progress in developing water-soluble steroids and steroids with enhanced oral efficacy foster optimism that certain neuroactive steroids will be developed for clinical use.     

Oral contraceptives and mood

The past 40 years of research on the mood and behavioural effects of combined oral contraceptives (OCs) have yielded inconclusive results due to dramatic changes in the compounds and to methodological flaws inherent in studies undertaken to assess the effects of OCs. Since the late 1960s, the dosages of oestrogen and progestin in marketed OCs significantly declined and novel progestins were developed to deliver higher levels of progestogenic activity with a lower risk of adverse oestrogenic and androgenic effects. This review evaluates controlled, comparative studies that have focused on the efficaciousness of OCs as treatment for premenstrual syndrome (PMS) and those examining whether OCs may cause negative mood. It is suggested that the mood and behavioural effects of OCs might be attributed to different progestin compounds and possibly, their oestrogen ratios. There is a great need for more longitudinal, randomised, placebo-controlled studies to further clarify the mood and behavioural effects of OCs.     

Oral contraceptives and mood

The past 40 years of research on the mood and behavioural effects of combined oral contraceptives (OCs) have yielded inconclusive results due to dramatic changes in the compounds and to methodological flaws inherent in studies undertaken to assess the effects of OCs. Since the late 1960s, the dosages of oestrogen and progestin in marketed OCs significantly declined and novel progestins were developed to deliver higher levels of progestogenic activity with a lower risk of adverse oestrogenic and androgenic effects. This review evaluates controlled, comparative studies that have focused on the efficaciousness of OCs as treatment for premenstrual syndrome (PMS) and those examining whether OCs may cause negative mood. It is suggested that the mood and behavioural effects of OCs might be attributed to different progestin compounds and possibly, their oestrogen ratios. There is a great need for more longitudinal, randomised, placebo-controlled studies to further clarify the mood and behavioural effects of OCs.     

口服避孕药与静脉血栓栓塞

目前常用的避孕药为复方口服避孕药（COC）,由雌激素和孕激素配伍而成,仅供女性应用。COC可致一些严重不良反应,其中之一为静脉血栓栓塞（venous thromboembolism,VTE）。VTE一般发生在COC开始使用1~2年内,但不受使用持续时间的影响,停药后VTE消失。服用COC者发生VTE的风险约为未服用者的4倍。VTE的发生与COC中雌激素含量和孕激素类型有关。COC制剂中雌激素含量〈50μg时VTE发生率明显降低;第3代COC致VTE风险通常高于第2代COC。COC引致VTE的机制可能是与其所含雌激素促进纤维蛋白原活化、增高凝血因子水平、降低抗凝血酶原水平和增强凝血功能有关。COC致VTE的危险因素有心血管疾病、高龄、嗜烟、有VTE病史和（或）家族史及长期卧床。育龄期女性在服用COC前应进行危险因素筛查,以降低发生VTE的风险。     

Neuropsychopharmacological properties of neuroactive steroids in depression and anxiety disorders

Neuroactive steroids modulate neurotransmission through modulation of specific neurotransmitter receptors such as γ-aminobutyric acid type A (GABA_A) receptors. Preclinical studies suggested that neuroactive steroids may modulate anxiety- and depression-related behaviour and may contribute to the therapeutical effects of antidepressant drugs. Attenuations of 3α-reduced neuroactive steroids have been observed during major depression. This disequilibrium can be corrected by successful treatment with antidepressant drugs. However, non-pharmacological antidepressant treatment strategies did not affect neuroactive steroid composition independently from the clinical response. Further research is needed to clarify whether enhancement of neuroactive steroid levels might represent a new therapeutical approach in the treatment of affective disorders. Nevertheless, the first studies investigating the therapeutical effects of exogenously administered dehydroepiandosterone revealed promising results in the treatment of major depression. In addition, in various anxiety disorders alterations of neuroactive steroid levels have been observed. In panic disorder, in the absence of panic attacks, neuroactive steroid composition is opposite to that seen in depression, which may represent counter-regulatory mechanisms against the occurrence of spontaneous panic attacks. However, during experimentally induced panic attacks, there was a pronounced decline in GABAergic neuroactive steroids, which might contribute to the pathophysiology of panic attacks. In conclusion, neuroactive steroids contribute to the pathophysiology of affective disorders and the mechanisms of action of antidepressants. They are important endogenous modulators of depression and anxiety and may provide a basis for the development of novel therapeutic agents in the treatment of affective disorders.     

Neurosteroids, neuroactive steroids, and symptoms of affective disorders

Neurosteroids (NS) are steroids synthesized by the brain. Neuroactive steroids (NAS) refers to steroids that, independent of their origin, are capable of modifying neural activities. NAS bind and modulate different types of membrane receptors. The gamma amino butyric acid (GABA) and sigma receptor complexes have been the most extensively studied. Oxidized ring A reduced pregnanes, tetrahydroprogesterone (THP), and tetrahydrodeoxycorticosterone (THDOC) bind to the progesterone intracellular receptor (PR), and in this way can also regulate gene expression. Animal experimentation showed that salient symptoms of depression, viz., anxiety, sleep disturbances, and memory and sexual dysfunctions, are modulated by NAS. In turn, psychotropic drugs modulate NS and NAS levels. NS levels as well as NAS plasma concentrations change in patients with depression syndromes, the levels return to normal baseline with recovery, but normalization is not necessary for successful therapy. Results from current studies on the evolution of nervous systems, including evolutionary developmental biology as well as anatomical and physiological findings, almost preclude a categorical classification of the psychiatric ailments the human brain succumbs to. The persistence in maintaining such essentialist classifications may help to explain why up to now the search for biological markers in psychiatry has been an unrewarding effort. It is proposed that it would be more fruitful to focus on relationships between NAS and symptoms of psychiatric disorders, rather than with typologically defined disorders.     

Oral contraceptives and cardiovascular risk

In 1992, we advised that "the oral contraceptive of choice for a healthy young woman probably remains a combined preparation containing 30 or 35 micrograms oestrogen and one of the newer progestogens" (i.e. desogestrel, gestodene, norgestimate). In 1995, evidence emerged suggesting that combined oral contraceptives containing desogestrel or gestodene were associated with a risk of venous thromboembolism about twice that of pills containing other progestogens, and the Committee on Safety of Medicines (CSM) advised that desogestrel- and gestodene-containing pills should be used only by women who were intolerant of other combined oral contraceptives and prepared to accept an increased risk of venous thromboembolism. Following an appeal by the drug manufacturers to the UK Medicines Commission, this advice has been modified to state that, provided women are fully informed of the increased risks, "it should be a matter of clinical judgement and personal choice which type of oral contraceptive should be prescribed". Here, we discuss the evidence and events leading to the latest advice, reconsider our previous recommendations, and discuss other cardiovascular problems that may be associated with oral contraceptive pills.     

Insight into the mechanism of action of neuroactive steroids

Rho(1) receptor-channels (rho(1)Rs) are GABA-gated chloride channels that exhibit slow kinetics, little desensitization, and inert pharmacology to most anesthetics, except for neuroactive steroids (NSs). NSs differentially modulate rho(1)Rs dependent on the steric arrangement of the hydrogen atom at the fifth carbon position. In particular, the NS allotetrahydrodeoxycorticosterone (5alpha-THDOC) potentiates, whereas 5beta-pregnane-3alpha-ol-20-one (pregnanolone) and 5beta-dihydroprogesterone (5beta-DHP) inhibit rho(1) GABA currents. Here, we used Xenopus laevis oocytes expressing rho(1)Rs as a model system to study the mechanism of NS modulation. The second transmembrane residue, Ile307, was mutated to 16 amino acids. Subsequent testing of these mutants with 5alpha- and 5beta-NSs, at equivalent GABA activity, showed the following paradigm. For 5beta-DHP, Ile307 mutation either altered the degree of inhibition or entirely reversed the direction of modulation, rendering 5beta-DHP a potentiator. Dependent on the mutation, pregnanolone remained an inhibitor, transformed into a potentiator, or converted to inhibitor and potentiator based on concentration. The extent of mode reversal for both 5beta compounds showed a correlation with the side-chain hydrophilicity of the 307 residue. In contrast, Ile307 substitutions did not alter the direction of modulation for 5alpha-THDOC but caused a significant increase in the level of potentiation. Paradoxical to their impact on the mode and/or the degree of modulation, none of the mutations altered the concentration range producing the response significantly for any of the above NSs. Moreover, preincubation of Ile307 mutants with 5alpha or 5beta alone produced an equivalent effect on the activation time course. Based on the above data, a universal model is presented wherein anesthetic compounds like NSs can potentiate or inhibit the activity of ligand-gated ion channels distinct from interaction with alternative binding sites.