RESUMEN
The γ-aminobutyric acid type A (GABAA) receptor is modulated by a number of neuroactive steroids. Sulfated steroids and 3ß-hydroxy steroids inhibit, while 3α-hydroxy steroids typically potentiate the receptor. Here, we have investigated inhibition of the α1ß3γ2L GABAA receptor by the endogenous neurosteroid 3α-hydroxy-5ß-pregnan-20-one (3α5ßP) and the synthetic neuroactive steroid 3α-hydroxy-5α-androstane-17ß-carbonitrile (ACN). The receptors were expressed in Xenopus oocytes. All experiments were done using two-electrode voltage-clamp electrophysiology. In the presence of low concentrations of GABA, 3α5ßP and ACN potentiate the GABAA receptor. To reveal inhibition, we conducted the experiments on receptors activated by the combination of a saturating concentration of GABA and propofol to fully activate the receptors and mask potentiation, or on mutant receptors in which potentiation is ablated. Under these conditions, both steroids inhibited the receptor with IC50s of â¼13 µM and maximal inhibitory effects of 70-90%. Receptor inhibition by 3α5ßP was sensitive to substitution of the α1 transmembrane domain (TM) 2-2' residue, previously shown to ablate inhibition by pregnenolone sulfate. However, results of coapplication studies and the apparent lack of state dependence suggest that pregnenolone sulfate and 3α5ßP inhibit the GABAA receptor independently and through distinct mechanisms. Mutations to the neurosteroid binding sites in the α1 and ß3 subunits statistically significantly, albeit weakly and incompletely, reduced inhibition by 3α5ßP and ACN. SIGNIFICANCE STATEMENT: The heteromeric GABAA receptor is inhibited by sulfated steroids and 3ß-hydroxy steroids, while 3α-hydroxy steroids are considered to potentiate the receptor. We show here that 3α-hydroxy steroids have inhibitory effects on the α1ß3γ2L receptor, which are observed in specific experimental settings and are expected to manifest under different physiological conditions.
Asunto(s)
Neuroesteroides , Receptores de GABA-A , Xenopus laevis , Receptores de GABA-A/metabolismo , Receptores de GABA-A/genética , Animales , Humanos , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Oocitos/metabolismo , Oocitos/efectos de los fármacos , Pregnanolona/farmacología , Ácido gamma-Aminobutírico/metabolismo , Ácido gamma-Aminobutírico/farmacología , Femenino , Pregnenolona/farmacologíaRESUMEN
Imbalances in dopamine activity significantly contribute to the pathophysiology of several neuropsychiatric disorders, including addiction, ADHD, schizophrenia, impulse control disorders, and Parkinson's Disease. Neuro(active)steroids, comprising endogenous steroids that finely modulate neuronal activity, are considered crucial regulators of brain function and behavior, with implications in various physiological processes and pathological conditions. Specifically, subclasses of Neuro(active)steroids belonging to the 5α reductase pathway are prominently involved in brain disorders characterized by dopaminergic signaling imbalances. This review highlights the neuromodulatory effects of Neuro(active)steroids on the dopamine system and related aberrant behavioral phenotypes. We critically appraise the role of pregnenolone, progesterone, and allopregnanolone on dopamine signaling. Additionally, we discuss the impact of pharmacological interventions targeting 5α reductase activity in neuropsychiatric conditions characterized by excessive activation of the dopaminergic system, ranging from psychotic (endo)phenotypes and motor complications to decision-making problems and addiction.
Asunto(s)
Dopamina , Humanos , Animales , Dopamina/metabolismo , Neuroesteroides/farmacología , Neuroesteroides/metabolismo , Fenotipo , Trastornos Mentales/tratamiento farmacológico , Trastornos Mentales/metabolismo , Trastornos Mentales/fisiopatología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/fisiopatologíaRESUMEN
GABAergic transmission is influenced by post-translational modifications, like phosphorylation, impacting channel conductance, allosteric modulator sensitivity, and membrane trafficking. O-GlcNAcylation is a post-translational modification involving the O-linked attachment of ß-N-acetylglucosamine on serine/threonine residues. Previously we reported an acute increase in O-GlcNAcylation elicits a long-term depression of evoked GABAAR inhibitory postsynaptic currents (eIPSCs) onto hippocampal principal cells. Importantly, O-GlcNAcylation and phosphorylation can co-occur or compete for the same residue; whether they interact in modulating GABAergic IPSCs is unknown. We tested this by recording IPSCs from hippocampal principal cells and pharmacologically increased O-GlcNAcylation, before or after increasing serine phosphorylation using the adenylate cyclase activator, forskolin. Although forskolin had no significant effect on baseline eIPSC amplitude, we found that a prior increase in O-GlcNAcylation unmasks a forskolin-dependent increase in eIPSC amplitude, reversing the O-GlcNAc-induced eIPSC depression. Inhibition of adenylate cyclase or protein kinase A did not prevent the potentiating effect of forskolin, indicating serine phosphorylation is not the mechanism. Surprisingly, increasing O-GlcNAcylation also unmasked a potentiating effect of the neurosteroids 5α-pregnane-3α,21-diol-20-one (THDOC) and progesterone on eIPSC amplitude in about half of the recorded cells, mimicking forskolin. Our findings show that under conditions of heightened O-GlcNAcylation, the neurosteroid site on synaptic GABAARs is possibly accessible to agonists, permitting strengthening of synaptic inhibition.
Asunto(s)
Colforsina , Hipocampo , Receptores de GABA-A , Sinapsis , Colforsina/farmacología , Animales , Hipocampo/metabolismo , Hipocampo/efectos de los fármacos , Receptores de GABA-A/metabolismo , Sinapsis/metabolismo , Sinapsis/efectos de los fármacos , Fosforilación/efectos de los fármacos , Potenciales Postsinápticos Inhibidores/efectos de los fármacos , Ratas , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Masculino , Transmisión Sináptica/efectos de los fármacos , Ratas Sprague-DawleyRESUMEN
Zuranolone (SAGE-217) is a neuroactive steroid (γ-aminobutyric acid)A (GABAA) receptor positive allosteric modulator (PAM) as the first oral drug approved by the FDA in 2023, which is used to treat patients with postpartum depression (PPD). SAGE-217 has a "black box" warning with impairing ability to drive or engage in other potentially hazardous activities. In addition, SAGE-217 can cause CNS depressant effects such as somnolence and confusion, suicidal thoughts and behavior and embryo-fetal toxicity. Based on the structure-activity relationship (SAR) of SAGE-217, a total of 28 neuroactive steroids with novel pharmacophore at C-21 modulated SAGE-217 derivatives were designed and synthesized. The biological activities were evaluated by both synaptic α1ß2γ2 GABAA receptor and extrasynaptic α4ß3δ GABAA receptor cell assays. The optimal compound S28 exhibited much more potent potency and similar efficacy at extrasynaptic GABAA receptor than SAGE-217. Different from above, compound S28 exhibited similar potency and lower efficacy at synaptic GABAA receptor than SAGE-217, which were consistent with the analysis of molecular docking and dynamics simulation results. The appropriate lower efficacy at synaptic GABAA receptor of compound S28 might contribute to reduce the side effects of excessive sedation. Furthermore, compound S28 was demonstrated to have excellent in vivo pharmacokinetic (PK) parameters, robust in vivo pharmacodynamic (PD) effects and good safety profiles. Therefore, compound S28 represents a potentially promising treatment of PPD candidate that warrants further investigation.
Asunto(s)
Receptores de GABA-A , Receptores de GABA-A/metabolismo , Relación Estructura-Actividad , Humanos , Animales , Estructura Molecular , Relación Dosis-Respuesta a Droga , Ratones , Neuroesteroides/farmacología , Neuroesteroides/metabolismo , Neuroesteroides/síntesis química , Neuroesteroides/química , Simulación del Acoplamiento Molecular , Regulación Alostérica/efectos de los fármacos , Masculino , Moduladores del GABA/farmacología , Moduladores del GABA/síntesis química , Moduladores del GABA/química , Farmacóforo , Pregnanolona , PirazolesRESUMEN
Trilostane is a 3ß-hydroxysteroid dehydrogenase/Δ5-4 isomerase inhibitor able to produce a manyfold increase in brain levels of various neurosteroids, including allopregnanolone. We previously found that treatment with trilostane can slow down epileptogenesis in the kainic acid (KA) model of temporal lobe epilepsy. It is unknown whether trilostane may have a similar effect on the progression of epilepsy severity, as observed in KA-treated rats. Consequently, we investigated the effects of trilostane (50 mg/kg/day, 1 week) in epileptic rats, given 64 days after KA administration. Seizures were monitored by video-electrocorticographic recordings before and during the treatment with trilostane or vehicle (sesame oil), and neurosteroid levels were measured in serum and cerebral tissue using liquid chromatography-electrospray tandem mass spectrometry after treatment. Pregnenolone sulfate, pregnenolone, progesterone, 5α-dihydroprogesterone, and allopregnanolone peripheral levels were massively increased by trilostane. With the only exception of hippocampal pregnenolone sulfate, the other neurosteroids augmented in both the neocortex and hippocampus. Only pregnanolone levels were not upregulated by trilostane. As expected, a significant increase in the seizure occurrence was observed in rats receiving the vehicle, but not in the trilostane group. This suggests that the increased availability of neurosteroids produced a disease-modifying effect in the brain of epileptic rats.
Asunto(s)
Epilepsia , Neuroesteroides , Ratas , Animales , Neuroesteroides/farmacología , Pregnanolona/farmacología , Epilepsia/inducido químicamente , Epilepsia/tratamiento farmacológico , Encéfalo , Convulsiones/inducido químicamente , Convulsiones/tratamiento farmacológicoRESUMEN
Type A γ-aminobutyric acid receptors (GABAARs) are the principal inhibitory receptors in the brain and the target of a wide range of clinical agents, including anaesthetics, sedatives, hypnotics and antidepressants1-3. However, our understanding of GABAAR pharmacology has been hindered by the vast number of pentameric assemblies that can be derived from 19 different subunits4 and the lack of structural knowledge of clinically relevant receptors. Here, we isolate native murine GABAAR assemblies containing the widely expressed α1 subunit and elucidate their structures in complex with drugs used to treat insomnia (zolpidem (ZOL) and flurazepam) and postpartum depression (the neurosteroid allopregnanolone (APG)). Using cryo-electron microscopy (cryo-EM) analysis and single-molecule photobleaching experiments, we uncover three major structural populations in the brain: the canonical α1ß2γ2 receptor containing two α1 subunits, and two assemblies containing one α1 and either an α2 or α3 subunit, in which the single α1-containing receptors feature a more compact arrangement between the transmembrane and extracellular domains. Interestingly, APG is bound at the transmembrane α/ß subunit interface, even when not added to the sample, revealing an important role for endogenous neurosteroids in modulating native GABAARs. Together with structurally engaged lipids, neurosteroids produce global conformational changes throughout the receptor that modify the ion channel pore and the binding sites for GABA and insomnia medications. Our data reveal the major α1-containing GABAAR assemblies, bound with endogenous neurosteroid, thus defining a structural landscape from which subtype-specific drugs can be developed.
Asunto(s)
Microscopía por Crioelectrón , Neuroesteroides , Receptores de GABA-A , Ácido gamma-Aminobutírico , Animales , Ratones , Sitios de Unión/efectos de los fármacos , Depresión Posparto/tratamiento farmacológico , Flurazepam/farmacología , Ácido gamma-Aminobutírico/metabolismo , Hipnóticos y Sedantes/farmacología , Activación del Canal Iónico/efectos de los fármacos , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Fotoblanqueo , Pregnanolona/farmacología , Conformación Proteica/efectos de los fármacos , Subunidades de Proteína/química , Subunidades de Proteína/efectos de los fármacos , Subunidades de Proteína/metabolismo , Receptores de GABA-A/química , Receptores de GABA-A/efectos de los fármacos , Receptores de GABA-A/metabolismo , Receptores de GABA-A/ultraestructura , Trastornos del Inicio y del Mantenimiento del Sueño/tratamiento farmacológico , Zolpidem/farmacologíaRESUMEN
Traumatic brain injury (TBI) triggers wide-ranging pathology that impacts multiple biochemical and physiological systems, both inside and outside the brain. Functional recovery in patients is impeded by early onset brain edema, acute and chronic inflammation, delayed cell death, and neurovascular disruption. Drug treatments that target these deficits are under active development, but it seems likely that fully effective therapy may require interruption of the multiplicity of TBI-induced pathological processes either by a cocktail of drug treatments or a single pleiotropic drug. The complex and highly interconnected biochemical network embodied by the neurosteroid system offers multiple options for the research and development of pleiotropic drug treatments that may provide benefit for those who have suffered a TBI. This narrative review examines the neurosteroids and their signaling systems and proposes directions for their utility in the next stage of TBI drug research and development.
Asunto(s)
Lesiones Traumáticas del Encéfalo , Lesiones Encefálicas , Neuroesteroides , Humanos , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Lesiones Traumáticas del Encéfalo/tratamiento farmacológico , Lesiones Traumáticas del Encéfalo/metabolismo , Encéfalo/metabolismo , Lesiones Encefálicas/patologíaRESUMEN
Affective disorders such as depression and anxiety are among the most prevalent psychiatric illnesses and causes of disability worldwide. The recent FDA-approval of a novel antidepressant treatment, ZULRESSO® (Brexanolone), a synthetic neurosteroid has fueled interest into the role of neurosteroids in the pathophysiology of depression as well as the mechanisms mediating the antidepressant effects of these compounds. The majority of studies examining the impact of neurosteroids on affective states have relied on the administration of exogenous neurosteroids; however, neurosteroids can also be synthesized endogenously from cholesterol or steroid hormone precursors. Despite the well-established influence of exogenous neurosteroids on affective states, we still lack an understanding of the role of endogenous neurosteroids in modulating affective tone. This review aims to summarize the current literature supporting the influence of neurosteroids on affective states in clinical and preclinical studies, as well as recent evidence suggesting that endogenous neurosteroids may set a baseline affective tone.
Asunto(s)
Neuroesteroides , Humanos , Neuroesteroides/farmacología , Neuroesteroides/uso terapéutico , Antidepresivos/uso terapéutico , Ansiedad , Trastornos del Humor/tratamiento farmacológicoRESUMEN
Preclinical studies have established that neonatal exposure to contemporary sedative/hypnotic drugs causes neurotoxicity in the developing rodent and primate brains. Our group recently reported that novel neuroactive steroid (3ß,5ß,17ß)-3-hydroxyandrostane-17-carbonitrile (3ß-OH) induced effective hypnosis in both neonatal and adult rodents but did not cause significant neurotoxicity in vulnerable brain regions such as subiculum, an output region of hippocampal formation particularly sensitive to commonly used sedatives/hypnotics. Despite significant emphasis on patho-morphological changes, little is known about long-term effects on subicular neurophysiology after neonatal exposure to neuroactive steroids. Hence, we explored the lasting effects of neonatal exposure to 3ß-OH on sleep macrostructure as well as subicular neuronal oscillations in vivo and synaptic plasticity ex vivo in adolescent rats. At postnatal day 7, we exposed rat pups to either 10 mg/kg of 3ß-OH over a period of 12 h or to volume-matched cyclodextrin vehicle. At weaning age, a cohort of rats was implanted with a cortical electroencephalogram (EEG) and subicular depth electrodes. At postnatal day 30-33, we performed in vivo assessment of sleep macrostructure (divided into wake, non-rapid eye movement, and rapid eye movement sleep) and power spectra in cortex and subiculum. In a second cohort of 3ß-OH exposed animals, we conducted ex vivo studies of long-term potentiation (LTP) in adolescent rats. Overall, we found that neonatal exposure to 3ß-OH decreased subicular delta and sigma oscillations during non-rapid eye movement sleep without altering sleep macrostructure. Furthermore, we observed no significant changes in subicular synaptic plasticity. Interestingly, our previous study found that neonatal exposure to ketamine increased subicular gamma oscillations during non-rapid eye movement sleep and profoundly suppressed subicular LTP in adolescent rats. Together these results suggest that exposure to different sedative/hypnotic agents during a critical period of brain development may induce distinct functional changes in subiculum circuitry that may persist into adolescent age.
Asunto(s)
Neuroesteroides , Ratas , Animales , Neuroesteroides/farmacología , Ratas Sprague-Dawley , Hipocampo , Plasticidad Neuronal , Hipnóticos y Sedantes/farmacologíaRESUMEN
Neurosteroids and benzodiazepines are modulators of the GABAA receptors, thereby causing anxiolysis. Furthermore, benzodiazepines such as midazolam are known to cause adverse side-effects on cognition upon administration. We previously found that midazolam at nanomolar concentrations (10 nM) blocked long-term potentiation (LTP). Here, we aim to study the effect of neurosteroids and their synthesis using XBD173, which is a synthetic compound that promotes neurosteroidogenesis by binding to the translocator protein 18 kDa (TSPO), since they might provide anxiolytic activity with a favourable side-effect profile. By means of electrophysiological measurements and the use of mice with targeted genetic mutations, we revealed that XBD173, a selective ligand of the translocator protein 18 kDa (TSPO), induced neurosteroidogenesis. In addition, the exogenous application of potentially synthesised neurosteroids (THDOC and allopregnanolone) did not depress hippocampal CA1-LTP, the cellular correlate of learning and memory. This phenomenon was observed at the same concentrations that neurosteroids conferred neuroprotection in a model of ischaemia-induced hippocampal excitotoxicity. In conclusion, our results indicate that TSPO ligands are promising candidates for post-ischaemic recovery exerting neuroprotection, in contrast to midazolam, without detrimental effects on synaptic plasticity.
Asunto(s)
Midazolam , Neuroesteroides , Ratones , Animales , Midazolam/farmacología , Neuroesteroides/farmacología , Neuroprotección , Hipoglucemiantes/farmacología , Receptores de GABA-A/metabolismo , Benzodiazepinas/farmacología , Proteínas Portadoras , Ligandos , Potenciación a Largo Plazo , Ácido gamma-Aminobutírico/farmacologíaRESUMEN
Neuroactive steroids can rapidly regulate multiple physiological functions in the central and peripheral nervous systems. The aims of the present study were to determine whether allopregnanolone (ALLO), administered in low nanomolar and high micromolar concentrations, can: (i) induce changes in the ovarian progesterone (P4) and estradiol (E2) release; (ii) modify the ovarian mRNA expression of Hsd3b1 (3ß-hydroxysteroid dehydrogenase, 3ß-HSD)3ß-, Akr1c3 (20α-hydroxysteroid dehydrogenase, 20α-HSD), and Akr1c14 (3α-hydroxy steroid oxidoreductase, 3α-HSOR)); and (iii) modulate the ovarian expression of progesterone receptors A and B, α and ß estrogenic receptors, luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR). To further characterize ALLO peripheral actions, the effects were evaluated using a superior mesenteric ganglion-ovarian nervous plexus-ovary (SMG-ONP-O) and a denervated ovary (DO) systems. ALLO SMG administration increased P4 concentration in the incubation liquid by decreasing ovarian 20α-HSD mRNA, and it also increased ovarian 3α-HSOR mRNA expression. In addition, ALLO neural peripheral modulation induced an increase in the expression of ovarian LHR, PRA, PRB, and ERα. Direct ALLO administration to the DO decreased E2 and increased P4 concentration in the incubation liquid. The mRNA expression of 3ß-HSD decreased and 20α-HSD increased. Further, ALLO in the OD significantly changed ovarian FSHR and PRA expression. This is the first evidence of ALLO's direct effect on ovarian steroidogenesis. Our results provide important insights about how this neuroactive steroid interacts both with the PNS and the ovary, and these findings might help devise some of the pleiotropic effects of neuroactive steroids on female reproduction. Moreover, ALLO modulation of ovarian physiology might help uncover novel treatment approaches for reproductive diseases.
Asunto(s)
Neuroesteroides , Pregnanolona , Femenino , Humanos , Pregnanolona/farmacología , Pregnanolona/metabolismo , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Ovario/metabolismo , Progesterona/farmacología , Progesterona/metabolismo , Hidroxiesteroide Deshidrogenasas/metabolismo , Hidroxiesteroide Deshidrogenasas/farmacología , ARN Mensajero/metabolismo , 3-Hidroxiesteroide Deshidrogenasas/genética , 3-Hidroxiesteroide Deshidrogenasas/metabolismo , 3-Hidroxiesteroide Deshidrogenasas/farmacologíaRESUMEN
Premenstrual dysphoric disorder (PMDD) is a debilitating disorder characterized by severe mood symptoms in the luteal phase of the menstrual cycle. PMDD symptoms are hypothesized to be linked to an altered sensitivity to normal luteal phase levels of allopregnanolone (ALLO), a GABAA-modulating progesterone metabolite. Moreover, the endogenous 3ß-epimer of ALLO, isoallopregnanolone (ISO), has been shown to alleviate PMDD symptoms through its selective and dose-dependent antagonism of the ALLO effect. There is preliminary evidence showing altered recruitment of brain regions during emotion processing in PMDD, but whether this is associated to serum levels of ALLO, ISO or their relative concentration is unknown. In the present study, subjects with PMDD and asymptomatic controls underwent functional magnetic resonance imaging (fMRI) in the mid-follicular and the late-luteal phase of the menstrual cycle. Brain responses to emotional stimuli were investigated and related to serum levels of ovarian steroids, the neurosteroids ALLO, ISO, and their ratio ISO/ALLO. Participants with PMDD exhibited greater activity in brain regions which are part of emotion-processing networks during the late-luteal phase of the menstrual cycle. Furthermore, activity in key regions of emotion processing networks - the parahippocampal gyrus and amygdala - was differentially associated to the ratio of ISO/ALLO levels in PMDD subjects and controls. Specifically, a positive relationship between ISO/ALLO levels and brain activity was found in PMDD subjects, while the opposite was observed in controls. In conclusion, individuals with PMDD show altered emotion-induced brain responses in the late-luteal phase of the menstrual cycle which may be related to an abnormal response to physiological levels of GABAA-active neurosteroids.
Asunto(s)
Neuroesteroides , Trastorno Disfórico Premenstrual , Femenino , Humanos , Trastorno Disfórico Premenstrual/metabolismo , Progesterona/farmacología , Neuroesteroides/farmacología , Ciclo Menstrual/fisiología , Emociones/fisiología , Encéfalo/metabolismo , Ácido gamma-AminobutíricoRESUMEN
Neurosteroids are important endogenous modulators of GABAA receptor-mediated neurotransmission within the CNS and play a vital role in maintaining normal healthy brain function. Research has mainly focussed on neurosteroids such as allopregnanolone and tetrahydro-deoxycorticosterone (THDOC) which are allosteric potentiators of GABAA receptors, whilst the sulphated steroids, including pregnenolone sulphate (PS), which inhibit GABAA receptor function, have been relatively neglected. Importantly, a full description of PS effects on inhibitory synaptic transmission, at concentrations that are expected to inhibit postsynaptic GABAA receptors, is lacking. Here, we address this deficit by recording inhibitory postsynaptic currents (IPSCs) from rat hippocampal neurons both in culture and in acute brain slices and explore the impact of PS at micromolar concentrations. We reveal that PS inhibits postsynaptic GABAA receptors, evident from reductions in IPSC amplitude and decay time. Concurrently, PS also causes an increase in synaptic GABA release which we discover is due to the activation of presynaptic TRPM3 receptors located close to presynaptic GABA release sites. Pharmacological blockade of TRPM3 receptors uncovers a PS-evoked reduction in IPSC frequency. This second presynaptic effect is caused by PS activation of inwardly-rectifying Kir2.3 channels on interneurons, which act to depress synaptic GABA release. Overall, we provide a comprehensive characterisation of pre- and postsynaptic modulation by PS of inhibitory synaptic transmission onto hippocampal neurons which elucidates the diverse mechanisms by which this understudied neurosteroid can modulate brain function.
Asunto(s)
Neuroesteroides , Canales Catiónicos TRPM , Ratas , Animales , Receptores de GABA-A/metabolismo , Neuroesteroides/farmacología , Transmisión Sináptica , Pregnenolona/farmacología , Hipocampo , Potenciales Postsinápticos Inhibidores , Ácido gamma-Aminobutírico/farmacologíaRESUMEN
Growing preclinical and clinical evidence highlights neurosteroid pathway imbalances in Parkinson's Disease (PD) and L-DOPA-induced dyskinesias (LIDs). We recently reported that 5α-reductase (5AR) inhibitors dampen dyskinesias in parkinsonian rats; however, unraveling which specific neurosteroid mediates this effect is critical to optimize a targeted therapy. Among the 5AR-related neurosteroids, striatal pregnenolone has been shown to be increased in response to 5AR blockade and decreased after 6-OHDA lesions in the rat PD model. Moreover, this neurosteroid rescued psychotic-like phenotypes by exerting marked antidopaminergic activity. In light of this evidence, we investigated whether pregnenolone might dampen the appearance of LIDs in parkinsonian drug-naïve rats. We tested 3 escalating doses of pregnenolone (6, 18, 36 mg/kg) in 6-OHDA-lesioned male rats and compared the behavioral, neurochemical, and molecular outcomes with those induced by the 5AR inhibitor dutasteride, as positive control. The results showed that pregnenolone dose-dependently countered LIDs without affecting L-DOPA-induced motor improvements. Post-mortem analyses revealed that pregnenolone significantly prevented the increase of validated striatal markers of dyskinesias, such as phospho-Thr-34 DARPP-32 and phospho-ERK1/2, as well as D1-D3 receptor co-immunoprecipitation in a fashion similar to dutasteride. Moreover, the antidyskinetic effect of pregnenolone was paralleled by reduced striatal levels of BDNF, a well-established factor associated with the development of LIDs. In support of a direct pregnenolone effect, LC/MS-MS analyses revealed that striatal pregnenolone levels strikingly increased after the exogenous administration, with no significant alterations in downstream metabolites. All these data suggest pregnenolone as a key player in the antidyskinetic properties of 5AR inhibitors and highlight this neurosteroid as an interesting novel tool to target LIDs in PD.
Asunto(s)
Discinesia Inducida por Medicamentos , Neuroesteroides , Enfermedad de Parkinson , Masculino , Ratas , Animales , Levodopa/efectos adversos , Enfermedad de Parkinson/patología , Dutasterida/metabolismo , Dutasterida/farmacología , Dutasterida/uso terapéutico , Oxidopamina/toxicidad , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Neuroesteroides/uso terapéutico , Ratas Sprague-Dawley , Discinesia Inducida por Medicamentos/metabolismo , Cuerpo Estriado/metabolismo , Antiparkinsonianos/efectos adversos , Modelos Animales de EnfermedadRESUMEN
Certain selective serotonin reuptake inhibitors (SSRIs) have anti-inflammatory effects in preclinical models, and recent clinical studies suggest that fluvoxamine can prevent deterioration in patients with COVID-19, possibly through activating sigma 1 receptors (S1Rs). Here we examined potential mechanisms contributing to these effects of fluvoxamine and other SSRIs using a well-characterized model of pro-inflammatory stress in rat hippocampal slices. When hippocampal slices are exposed acutely to lipopolysaccharide (LPS), a strong pro-inflammatory stimulus, basal synaptic transmission in the CA1 region remains intact, but induction of long-term potentiation (LTP), a form of synaptic plasticity thought to contribute to learning and memory, is completely disrupted. Administration of low micromolar concentrations of fluvoxamine and fluoxetine prior to and during LPS administration overcame this LTP inhibition. Effects of fluvoxamine required both activation of S1Rs and local synthesis of 5-alpha reduced neurosteroids. In contrast, the effects of fluoxetine did not involve S1Rs but required neurosteroid production. The ability of fluvoxamine to modulate LTP and neurosteroid production was mimicked by a selective S1R agonist. Additionally, fluvoxamine and fluoxetine prevented learning impairments induced by LPS in vivo. Sertraline differed from the other SSRIs in blocking LTP in control slices likely via S1R inverse agonism. These results provide strong support for the hypothesis that S1Rs and neurosteroids play key roles in the anti-inflammatory effects of certain SSRIs and that these SSRIs could be beneficial in disorders involving inflammatory stress including psychiatric and neurodegenerative illnesses.
Asunto(s)
COVID-19 , Neuroesteroides , Ratas , Animales , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Fluvoxamina/farmacología , Neuroesteroides/farmacología , Fluoxetina/farmacología , Agonismo Inverso de Drogas , Lipopolisacáridos/farmacología , Hipocampo , Antiinflamatorios/farmacologíaRESUMEN
N-methyl-D-aspartate receptors (NMDARs) play vital roles in normal brain functions (i.e., learning, memory, and neuronal development) and various neuropathological conditions, such as epilepsy, autism, Parkinson's disease, Alzheimer's disease, and traumatic brain injury. Endogenous neuroactive steroids such as 24(S)-hydroxycholesterol (24(S)-HC) have been shown to influence NMDAR activity, and positive allosteric modulators (PAMs) derived from 24(S)-hydroxycholesterol scaffold can also enhance NMDAR function. This study describes the structural determinants and mechanism of action for 24(S)-hydroxycholesterol and two novel synthetic analogs (SGE-550 and SGE-301) on NMDAR function. We also show that these agents can mitigate the altered function caused by a set of loss-of-function missense variants in NMDAR GluN subunit-encoding GRIN genes associated with neurological and neuropsychiatric disorders. We anticipate that the evaluation of novel neuroactive steroid NMDAR PAMs may catalyze the development of new treatment strategies for GRIN-related neuropsychiatric conditions.
Asunto(s)
Enfermedad de Alzheimer , Enfermedades del Sistema Nervioso , Neuroesteroides , Humanos , Receptores de N-Metil-D-Aspartato/metabolismo , Neuroesteroides/farmacología , Neuroesteroides/uso terapéutico , Hidroxicolesteroles/farmacología , Hidroxicolesteroles/uso terapéutico , Enfermedades del Sistema Nervioso/tratamiento farmacológico , Enfermedades del Sistema Nervioso/genética , Enfermedad de Alzheimer/tratamiento farmacológico , Esteroides/farmacología , Regulación Alostérica/fisiologíaRESUMEN
BACKGROUND: Alcohol affects multiple circuits in the brain, mainly disrupting the delicate balance between inhibitory γ-aminobutyric acid (GABA) transmission and excitatory glutamate signaling in brain areas involved in reward circuits. These include the amygdala, nucleus accumbens (Acb), and ventral tegmental area (VTA). This action impairs circuits that regulate behavioral control of craving and alcohol seeking and intake. Studies in both rodent models and postmortem human brain of patients with alcohol use disorder (AUD) have highlighted the association between the loss of GABAergic inhibition and the development of addiction. The neurosteroid (3α,5α)-3-hydroxypregnan-20-one (3α,5α-THP) is a potent positive modulator of GABAA receptors. Chronic alcohol consumption reduces 3α,5α-THP levels, resulting in decreased GABA inhibition. We previously demonstrated that enhancing neurosteroid biosynthesis by overexpression of the cholesterol side-chain cleavage enzyme P450scc decreased alcohol intake in male alcohol-preferring rats (P-rats). While most of the evidence of alcohol-induced alterations comes from studies in male subjects, some data show that females are more vulnerable to alcohol's effects than males. METHODS: In this study, we investigated the ability of 3α,5α-THP direct infusions in two brain regions that contribute to alcohol reinforcement, the VTA and Acb core (AcbC), to regulate alcohol self-administration in female P-rats. RESULTS: Administration of 3α,5α-THP into the AcbC increased 3α,5α-THP-positive cell expression in this area and reduced alcohol self-administration. By contrast, 3α,5α-THP infusion into the VTA did not significantly affect alcohol self-administration, though trends for a reduction were found. CONCLUSIONS: Our results show that local increases in 3α,5α-THP in the AcbC may alter mesolimbic activity that drives a reduction in alcohol self-administration.
Asunto(s)
Neuroesteroides , Núcleo Accumbens , Humanos , Ratas , Masculino , Femenino , Animales , Núcleo Accumbens/metabolismo , Neuroesteroides/metabolismo , Neuroesteroides/farmacología , Etanol , Encéfalo , Pregnanolona/metabolismo , Ácido gamma-Aminobutírico/metabolismoRESUMEN
There is need for novel fast acting treatment options in affective disorders. 3α-reduced neurosteroids such as allopregnanolone are powerful positive allosteric modulators of GABAA receptors and target also extrasynaptic receptors. Their synthesis is mediated by the translocator protein 18 kDa (TSPO). TSPO ligands not only promote endogenous neurosteroidogenesis, but also exert a broad spectrum of functions involving modulation of mitochondrial activity and acting as anti-inflammatory and neuroregenerative agents. Besides affective symptoms, in depression cognitive impairment can be frequently observed, which may be ameliorated through targeting of extrasynaptic GABAA receptors either via TSPO ligands or exogenously administered 3α-reduced neurosteroids. Interestingly, recent findings indicate an enhanced activation of the complement system, e.g., enhanced expression of C1q, both in depression and dementia. It is of note that benzodiazepines have been shown to reduce long-term potentiation and to cause cognitive decline. Intriguingly, TSPO may be crucial in mediating the effects of benzodiazepines on synaptic pruning. Here, we discuss how benzodiazepines and TSPO may interfere with synaptic pruning. Moreover, we highlight recent developments of TSPO ligands and 3α-reduced neurosteroids as therapeutic agents. Etifoxine is the only clinically available TSPO ligand so far and has been studied in anxiety disorders. Regarding 3α-reduced neurosteroids, brexanolone, an intravenous formulation of allopregnanolone, has been approved for the treatment of postpartum depression and zuranolone, an orally available 3α-reduced neurosteroid, is currently being studied in major depressive disorder and postpartum depression. As such, 3α-reduced neurosteroids and TSPO ligands may constitute promising treatment approaches for affective disorders.
Asunto(s)
Ansiolíticos , Depresión Posparto , Trastorno Depresivo Mayor , Neuroesteroides , Humanos , Femenino , Neuroesteroides/farmacología , Ansiolíticos/uso terapéutico , Pregnanolona/farmacología , Ligandos , Depresión , Depresión Posparto/tratamiento farmacológico , Trastorno Depresivo Mayor/tratamiento farmacológico , Neurotransmisores/farmacología , Neurotransmisores/metabolismo , Receptores de GABA-A , Benzodiazepinas , Proteínas Portadoras , Plasticidad Neuronal , Cognición , Ácido gamma-Aminobutírico , Receptores de GABA/metabolismoRESUMEN
RATIONALE: Chronic alcohol intake down-regulates GABAergic transmission and reduces levels of neuroactive steroids. These changes are associated with greater stress dysregulation and high alcohol craving which in turn increases relapse risk. OBJECTIVES: This study tested whether potentiation of the neurosteroid system with pregnenolone (PREG), a precursor to neuroactive steroids and known to increase GABAergic transmission, will normalize chronic alcohol-related stress adaptations in the hypothalamic-pituitary-adrenal (HPA) axis and autonomic responses and reduce alcohol craving to significantly impact relapse risk. METHODS: Forty-three treatment-seeking individuals with alcohol use disorder (AUD) were randomized to placebo (PBO) or supraphysiologic pregnenolone doses of 300 mg or 500 mg treatment using a parallel-between subject design as part of a larger 8-week pilot clinical trial. In week 2, they participated in a 3-day laboratory experiment where on each day they self-administered the assigned study drug in the laboratory and were then exposed to 5-min personalized guided imagery provocation of stress, alcohol, or neutral/relaxing cues, one condition per day on separate days, in a random, counterbalanced order. Repeated assessments of alcohol craving, anxiety, HPA axis, heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP) and serum pregnenolone levels were made on each day. RESULTS: Pregnenolone levels were significantly increased in the PREG groups versus PBO. PREG treatment decreased stress- and alcohol cue- induced craving and dose-specifically reduced stress-induced anxiety in the 300 mg/day group. Both PREG doses compared to PBO also normalized CORT/ACTH and increased stress-induced HR, stress- and cue-induced SBP, and in the 300 mg PREG group cue-induced DBP responses relative to neutral condition. CONCLUSIONS: Findings indicate that pregnenolone decreases stress- and alcohol cue-provoked craving and normalizes HPA axis and autonomic arousal in individuals with AUD, thereby supporting the need for further assessment of pregnenolone in the treatment of AUD.
Asunto(s)
Alcoholismo , Neuroesteroides , Humanos , Alcoholismo/tratamiento farmacológico , Ansia , Sistema Hipotálamo-Hipofisario , Pregnenolona/farmacología , Neuroesteroides/farmacología , Sistema Hipófiso-Suprarrenal , Ansiedad/tratamiento farmacológico , Consumo de Bebidas Alcohólicas , Etanol/farmacología , Nivel de Alerta , Recurrencia , Señales (Psicología)RESUMEN
Background and Aims: A third of patients with primary biliary cholangitis (PBC) experience poorly understood cognitive symptoms, with a significant impact on quality of life (QOL), and no effective medical treatment. Allopregnanolone, a neurosteroid, is a positive allosteric modulator of gamma-aminobutyricacid-A (GABA-A) receptors, associated with disordered mood, cognition, and memory. This study explored associations between allopregnanolone and a disease-specific QOL scoring system (PBC-40) in PBC patients. Method: Serum allopregnanolone levels were measured in 120 phenotyped PBC patients and 40 age and gender-matched healthy controls. PBC subjects completed the PBC-40 at recruitment. Serum allopregnanolone levels were compared across PBC-40 domains for those with none/mild symptoms versus severe symptoms. Results: There were no overall differences in allopregnanolone levels between healthy controls (median = 0.03 ng/ml (IQR = 0.025)) and PBC patients (0.031 (0.42), p = 0.42). Within the PBC cohort, higher allopregnanolone levels were observed in younger patients (r (120) = -0.53, p < 0.001) but not healthy controls (r (39) = -0.21, p = 0.21). Allopregnanolone levels were elevated in the PBC-40 domains, cognition (u = 1034, p = 0.02), emotional (u = 1374, p = 0.004), and itch (u = 795, p = 0.03). Severe cognitive symptoms associated with a younger age: severe (50 (12)) vs. none (60 (13); u = 423 p = 0.001). Conclusion: Elevated serum allopregnanolone is associated with severe cognitive, emotional, and itch symptoms in PBC, in keeping with its known action on GABA-A receptors. Existing novel compounds targeting allopregnanolone could offer new therapies in severely symptomatic PBC, satisfying a significant unmet need.