Flavia di Michele

Concentrations of 3α-reduced neuroactive steroids and their precursors in plasma of patients with major depression and after clinical recovery

BACKGROUND There is preclinical and clinical evidence that plasma concentrations of 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-tetrahydroprogesterone; 3 alpha,5 alpha-THP), a neuroactive steroid that is a positive allosteric modulator of the GABAA receptor, are altered in depression and normalize as a result of antidepressant treatment. However, no data are available on the concentrations of 3 alpha,21-dihydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-tetrahydrodeoxycorticosterone; 3 alpha,5 alpha-THDOC), another GABA ergic neuroactive steroid, in depression. METHODS We studied nine depressed patients before and after treatment with various antidepressants and compared them to healthy matched control subjects. Blood samples were quantified by means of a highly sensitive combined gas chromatography/mass spectrometry analysis. RESULTS Compared to control subjects, plasma concentrations of 3 alpha,5 alpha-THDOC and its precursor 5 alpha-dihydrodeoxycorticosterone (5 alpha-DHDOC) were increased in depressed patients and were not significantly influenced by antidepressant treatment. However, 3 alpha,5 alpha-THP plasma concentrations were decreased in depression and clinically effective antidepressant treatment was accompanied by an increase of 3 alpha,5 alpha-THP concentrations in these patients. CONCLUSIONS Our results provide the first evidence for a differential alteration in the plasma concentrations of the 3 alpha-reduced neuroactive steroids 3 alpha,5 alpha-THDOC and 3 alpha,5 alpha-THP in major depression, which is only partially reversed by successful antidepressant treatment.

Plasma Concentrations of Neuroactive Steroids before and after Repetitive Transcranial Magnetic Stimulation (rTMS) in Major Depression

There is evidence for altered levels of neuroactive steroids in major depression that normalize after successful antidepressant pharmacotherapy. Currently it is not known whether this is a general principle of clinically effective antidepressant therapy or a pharmacological effect of antidepressants. Here, we investigated whether repetitive transcranial magnetic stimulation (rTMS) may affect plasma concentrations of neuroactive steroids in a similar way as antidepressant pharmacotherapy. Progesterone, 3α,5α-tetrahydroprogesterone (3α,5α-THP), 3α,5β- tetrahydroprogesterone (3α,5β–THP), 3β,5α-tetrahydroprogesterone (3β, 5α-THP) and dehydroepiandrosterone (DHEA) were quantified in 37 medication-free patients suffering from a major depressive episode before and after 10 sessions of left prefrontal rTMS. Plasma samples were analyzed by means of a highly sensitive and specific combined gas chromatography/mass spectrometry analysis. There was a significant reduction of depressive symptoms after rTMS. However, plasma concentrations of neuroactive steroids were not affected by rTMS and not related to clinical response. Clinical improvement after extended daily treatment with rTMS is not accompanied by changes in neuroactive steroid levels. Changes in neuroactive steroid levels after antidepressant pharmacotherapy more likely reflect specific pharmacological effects of antidepressant drugs and are not necessary for the amelioration of depressive symptoms.

Panic Induction with Cholecystokinin-Tetrapeptide (CCK-4) Increases Plasma Concentrations of the Neuroactive Steroid 3|[alpha]|, 5|[alpha]| Tetrahydrodeoxycorticosterone (3|[alpha]|, 5|[alpha]|-THDOC) in Healthy Volunteers

3α-reduced neuroactive steroids such as 3α, 5α-tetrahydroprogesterone (3α, 5α-THP) and 3α, 5α-tetrahydrodeoxycorticosterone (3α, 5α-THDOC) are potent positive allosteric modulators of γ-aminobutyric acid type A (GABAA) receptors and display pronounced anxiolytic activity in animal models. Experimental panic induction with cholecystokinin-tetrapeptide (CCK-4) and sodium lactate is accompanied by a decrease in 3α, 5α-THP concentrations in patients with panic disorder, but not in healthy controls. However, no data are available on 3α, 5α-THDOC concentrations during experimental panic induction. Therefore, we quantified 3α, 5α-THDOC concentrations in 10 healthy volunteers (nine men, one woman) before and after panic induction with CCK-4 by means of a highly sensitive and specific gas chromatography/mass spectrometry analysis. CCK-4 elicited a strong panic response as assessed by the Acute Panic Inventory. This was accompanied by an increase in 3α, 5α-THDOC, ACTH and cortisol concentrations. This increase in 3α, 5α-THDOC might be a consequence of hypothalamic–pituitary–adrenal (HPA) axis activation following CCK-4-induced panic, and might contribute to the termination of the anxiety/stress response following challenge with CCK-4 through enhancement of GABAA receptor function.

Neuroactive steroid concentrations following metyrapone administration in depressed patients and healthy volunteers.

BACKGROUND There is evidence that treatment with the 11 beta-hydroxylase inhibitor metyrapone may represent an alternative treatment strategy in major depression. As a consequence of inhibition of cortisol synthesis the overdrive of corticotropin leads to an accumulation of precursor steroids. However, the effects of metyrapone on the concentrations of endogenous neuroactive steroids that modulate ion channels, e.g., the GABAA receptor, have not yet been studied systematically. METHODS Therefore, we quantified the concentrations of an array of neuroactive steroids following administration of 1.5 g metyrapone before and after pretreatment with 1 mg dexamethasone in 19 patients suffering from severe depression in comparison to 13 healthy controls by means of a highly sensitive gas chromatography/mass spectrometry analysis. RESULTS The administration of metyrapone induced a pronounced increase in all neuroactive steroids studied both in patients and controls that was prevented by dexamethasone pretreatment. CONCLUSIONS Thus, the psychotropic properties of endogenous neuroactive steroids may contribute to the antidepressant properties of metyrapone in the treatment of major depression.

Plasma concentrations of neuroactive steroids before and after electroconvulsive therapy in major depression

There is evidence that both cerebrospinal fluid (CSF) and plasma concentrations of 3α-reduced neuroactive steroids are decreased in major depressive disorder. Successful antidepressant pharmacotherapy, for example, with selective serotonin reuptake inhibitors (SSRIs), over several weeks is accompanied by an increase in CSF and plasma concentrations of these neuroactive steroids. However, no such increase has been observed during nonpharmacological treatments such as partial sleep deprivation or repetitive transcranial magnetic stimulation. In order to investigate whether concentration changes in neuroactive steroids are an important component of clinically effective antidepressant treatment, we examined plasma concentrations of the neuroactive steroids 3α,5α-tetrahydroprogesterone, 3α,5β-tetrahydroprogesterone, 3β,5α-tetrahydroprogesterone, and their precursors progesterone, 5α-dihydroprogesterone, and 5β-dihydroprogesterone in 31 pharmacotherapy-resistant depressed in-patients before and after unilateral electroconvulsive therapy (ECT) as a monotherapy over 4 weeks. Samples were quantified for neuroactive steroids by means of a highly sensitive and specific combined gas chromatography/mass spectrometry analysis. In all, 51.6% of the patients were treatment responders. There was no influence of ECT on the plasma concentrations of any neuroactive steroid studied. Moreover, neuroactive steroid levels did not differ between treatment responders and nonresponders. Our study shows that changes in neuroactive steroid plasma levels are not a mandatory factor for successful antidepressant treatment by ECT. Thus, the previously observed changes in plasma concentrations of neuroactive steroids following treatment with antidepressants such as SSRIs more likely reflect distinct pharmacological properties of these compounds rather than clinical improvement.

Effects of fluoxetine, indomethacine and placebo on 3 alpha, 5 alpha tetrahydroprogesterone (THP) plasma levels in uncomplicated alcohol withdrawal.

Summary Objective: The purpose of this study was to investigate the effects of fluoxetine (F) and indomethacine (I), two drugs that regulate the synthesis of the GABAergic neurosteroid 3α, 5α tetrahydroprogesterone (allopregnanolone, THP) on THP plasma levels and on symptoms of anxiety and depression in alcoholics during ethanol withdrawal. Method: Patients who met DSM-IV criteria for alcohol abuse were randomly assigned to treatment with F (40 mg/day) plus misoprostol (M) (500 mg/day) or I (100 mg/day) plus M or placebo (PL) plus M. Patients were rated with the Hamilton Anxiety (14-HAS) and Depression (17-HDS) scales on days 1, 5, 7, 15 and 28 of ethanol withdrawal and with a Visual Analogue Scale for Depression (VASD) and a Visual Analogue Scale for Anxiety (VASA) on days 1, 2, 4, 5, 7, 15 and 28 of withdrawal. On the same days a plasma sample was collected to measure the concentrations of THP by means of a very sensitive gas chromatographic mass spectrometric method. Results: During withdrawal at days 1, 2, 4 and 5, THP plasma values were lower and symptoms of anxiety and depression were significantly higher compared to the late withdrawal phase at days 15 and 28. In the F or I treatment, the depression and anxiety score, measured by VASD and VASA, decreased significantly at day 5-7 whereas THP plasma levels significantly increased compared to PL condition. Conclusions: Treatment of alcohol withdrawal either with F or I reduced the extent of anxiety and depression and normalised THP plasma levels that were decreased during withdrawal.

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 (GABAA) 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.

Neurosteroid and neurotransmitter alterations in Parkinson's disease

Parkinsons disease (PD) is associated with a massive loss of dopaminergic cells in the substantia nigra leading to dopamine hypofunction and alteration of the basal ganglia circuitry. These neurons, are under the control, among others, of the excitatory glutamatergic and inhibitory γ-aminobutyric acid (GABA) systems. An imbalance between these systems may contribute to excitotoxicity and dopaminergic cell death. Neurosteroids, a group of steroid hormones synthesized in the brain, modulate the function of several neurotransmitter systems. The substantia nigra of the human brain expresses high concentrations of allopregnanolone (3α, 5αtetrahydroprogesterone), a neurosteroid that positively modulates the action of GABA at GABAA receptors and of 5α-dihydroprogesterone, a neurosteroid acting at the genomic level. This article reviews the roles of NS acting as neuroprotectants and as GABAA receptor agonists in the physiology and pathophysiology of the basal ganglia, their impact on dopaminergic cell activity and survival, and potential therapeutic application in PD.

Neurosteroids as Neuromodulators in the Treatment of Anxiety Disorders

Anxiety disorders are the most common psychiatric disorders. They are frequently treated with benzodiazepines, which are fast acting highly effective anxiolytic agents. However, their long-term use is impaired by tolerance development and abuse liability. In contrast, antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are considered as first-line treatment but have a slow onset of action. Neurosteroids are powerful allosteric modulators of GABAA and glutamate receptors. However, they also modulate sigma receptors and they are modulated themselves by SSRIs. Both pre-clinical and clinical studies have shown that neurosteroid homeostasis is altered in depression and anxiety disorders and antidepressants may act in part through restoring neurosteroid disbalance. Moreover, novel drugs interfering with neurosteroidogenesis such as ligands of the translocator protein (18 kDa) may represent an attractive pharmacological option for novel anxiolytics which lack the unwarranted side effects of benzodiazepines. Thus, neurosteroids are important endogenous neuromodulators for the physiology and pathophysiology of anxiety and they may constitute a novel therapeutic approach in the treatment of these disorders.

Increased behavioral neurosteroid sensitivity in a rat line selectively bred for high alcohol sensitivity

Acute administration of a neurosteroid 5beta-pregnan-3alpha-ol-20-one induced a greater impairment in motor performance of the selectively bred alcohol-sensitive (ANT) than alcohol-insensitive (AT) rats. This difference was not associated with the sensitivity of gamma-aminobutyrate type A (GABA(A)) receptors, as 5alpha-pregnan-3alpha-ol-20-one (allopregnanolone) decreased the autoradiographic signals of t-butylbicyclophosphoro[35S]thionate binding to GABA(A) receptor-associated ionophores more in the brain sections of AT than ANT rats. Nor was the difference associated with baseline levels of neuroactive progesterone metabolites, as 5alpha-pregnan-3,20-dione (5alpha-DHP) and 5alpha-pregnan-3alpha-ol-20-one were lower in the ANT rats. After ethanol (2 g/kg, i.p.) administration and the subsequent motor performance test, the increased brain concentrations of these metabolites were still lower in the ANT than AT rats, although especially in the cerebellum the relative increases were greater in the ANT than AT rats. The present data suggest that the mechanisms mediating neurosteroid-induced motor impairment are susceptible to genetic variation in rat lines selected for differences in ethanol intoxication.