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Pharmacology, Biochemistry, and Behavior Sep 2011Neuroactive steroids produce effects similar to other GABA(A) modulators (e.g., benzodiazepines and barbiturates) and have a large therapeutic potential; however, a... (Comparative Study)
Comparative Study
Neuroactive steroids produce effects similar to other GABA(A) modulators (e.g., benzodiazepines and barbiturates) and have a large therapeutic potential; however, a greater understanding of the effects of these substances on learning and memory is needed. To specifically assess the effects of a neurosteroid on memory, pregnanolone (1-18 mg/kg) was administered to male Long-Evans rats responding under a repeated acquisition and delayed-performance procedure in which different 4-response sequences were acquired and then retested after varying delays. Responding was maintained under a second-order fixed-ratio (FR) 2 schedule of food reinforcement, and incorrect responses (errors) produced a 5-sec timeout. For comparison purposes, both a high (flunitrazepam) and low efficacy agonist/antagonist (flumazenil) of the GABA(A) receptor complex were also administered both alone and in combination. Retention of each sequence was quantified as percent savings in errors-to-criterion and this dependent measure was shown to be sensitive to increases in delay. When administered 15 min prior to the end of either a 30- or 180-minute delay, pregnanolone produced both dose- and delay-dependent decreases in percent savings, response rate and accuracy; this effect was selective in that decreases in retention occurred at doses lower than those that disrupted response rate or accuracy. Flunitrazepam (0.056-1mg/kg) produced similar disruptions in retention and these disruptions were antagonized by 5.6 mg/kg of flumazenil. Both an ineffective (0.056 mg/kg) and an effective (0.18 mg/kg) dose of flunitrazepam also potentiated the dose- and delay-dependent disruptions in retention produced by pregnanolone. These data indicate that the neurosteroid pregnanolone disrupts retention in a manner similar to the benzodiazepine flunitrazepam, and suggests that the interaction of flunitrazepam and pregnanolone on retention may be mediated by the GABA(A) receptor complex.
Topics: Animals; Drug Combinations; Flunitrazepam; Male; Pregnanolone; Psychomotor Performance; Rats; Rats, Long-Evans; Reaction Time; Retention, Psychology
PubMed: 21640749
DOI: 10.1016/j.pbb.2011.05.023 -
Psychopharmacology Nov 2013Neurosteroids are steroids synthesized within the brain with rapid effects on neuronal excitability. Allopregnanolone, allotetrahydrodeoxycorticosterone, and... (Review)
Review
Neurosteroid interactions with synaptic and extrasynaptic GABA(A) receptors: regulation of subunit plasticity, phasic and tonic inhibition, and neuronal network excitability.
RATIONALE
Neurosteroids are steroids synthesized within the brain with rapid effects on neuronal excitability. Allopregnanolone, allotetrahydrodeoxycorticosterone, and androstanediol are three widely explored prototype endogenous neurosteroids. They have very different targets and functions compared to conventional steroid hormones. Neuronal γ-aminobutyric acid (GABA) type A (GABA(A)) receptors are one of the prime molecular targets of neurosteroids.
OBJECTIVE
This review provides a critical appraisal of recent advances in the pharmacology of endogenous neurosteroids that interact with GABA(A) receptors in the brain. Neurosteroids possess distinct, characteristic effects on the membrane potential and current conductance of the neuron, mainly via potentiation of GABA(A) receptors at low concentrations and direct activation of receptor chloride channel at higher concentrations. The GABA(A) receptor mediates two types of inhibition, now characterized as synaptic (phasic) and extrasynaptic (tonic) inhibition. Synaptic release of GABA results in the activation of low-affinity γ2-containing synaptic receptors, while high-affinity δ-containing extrasynaptic receptors are persistently activated by the ambient GABA present in the extracellular fluid. Neurosteroids are potent positive allosteric modulators of synaptic and extrasynaptic GABA(A) receptors and therefore enhance both phasic and tonic inhibition. Tonic inhibition is specifically more sensitive to neurosteroids. The resulting tonic conductance generates a form of shunting inhibition that controls neuronal network excitability, seizure susceptibility, and behavior.
CONCLUSION
The growing understanding of the mechanisms of neurosteroid regulation of the structure and function of the synaptic and extrasynaptic GABA(A) receptors provides many opportunities to create improved therapies for sleep, anxiety, stress, epilepsy, and other neuropsychiatric conditions.
Topics: Allosteric Regulation; Androstane-3,17-diol; Animals; Brain; Desoxycorticosterone; Humans; Nerve Net; Neural Inhibition; Neuronal Plasticity; Neurotransmitter Agents; Pregnanolone; Receptors, GABA-A
PubMed: 24071826
DOI: 10.1007/s00213-013-3276-5 -
Progress in Neuro-psychopharmacology &... Jun 2024Postpartum depression (PPD) poses a major threat to maternal mental health and wellbeing while also adversely affecting the mother's relationship with her baby, leading... (Review)
Review
Postpartum depression (PPD) poses a major threat to maternal mental health and wellbeing while also adversely affecting the mother's relationship with her baby, leading to significant repercussions that may hinder the growth and cognitive development of the child. For decades, antidepressants have been the mainstay of treating PPD; however, recent evidence suggests that antidepressants are not as effective as they are believed to be and there is a dire need to explore new treatment options. In 2023, a breakthrough in treating PPD emerged with the recent FDA approval of zuranolone, a gamma-aminobutyric acid (GABA) receptor selective positive allosteric modulator. The implementation of zuranolone in treating PPD can prove to be revolutionary, considering it is the first oral medication available for PPD. Our review aims to discuss the various clinical trials that have been conducted to validate the efficacy of zuranolone in mitigating the symptoms of PPD, hence, leading to better outcomes for mothers.
Topics: Humans; Female; Child; Depression, Postpartum; Pregnanolone; Pyrazoles; Antidepressive Agents
PubMed: 38412941
DOI: 10.1016/j.pnpbp.2024.110983 -
British Journal of Pharmacology Dec 20011. An anaesthesia threshold was used to investigate the pharmacodynamic and pharmacokinetic interactions between ethanol and pregnanolone in male rats. 2. The criterion...
1. An anaesthesia threshold was used to investigate the pharmacodynamic and pharmacokinetic interactions between ethanol and pregnanolone in male rats. 2. The criterion to determine threshold doses of pregnanolone was the first burst suppression of 1 s in the EEG. 3. Ethanol (0.5, 1.0, 1.5 and 2.0 g kg(-1)) was injected i.p. 15 min before pregnanolone infusion. Trunk blood, serum, cortex, cerebellum, hippocampus, striatum, brain stem, fat and muscle tissues obtained at criterion were used to determine ethanol (blood) and pregnanolone. Ethanol reduced threshold doses in a dose dependent linear manner. A similar reduction of pregnanolone tissue concentrations was only found in brain stem and striatum. Deviations consisted of larger decreases in serum, cerebellum and hippocampus after 0.5 g kg(-1) ethanol and in cerebellum, cortex and hippocampus after 2.0 g kg(-1) of ethanol. Positive correlations between dose and concentration of pregnanolone was recorded in brain stem, hippocampus, cerebellum and cortex. A kinetic component influenced the concentration in cortex. There was a correlation between dose and serum concentration of pregnanolone only after ethanol. In the muscle 0.5 g kg(-1) ethanol had no influence on pregnanolone concentration. 4. The linear, additive pharmacodynamic interaction could involve the GABA ionophore. A pharmacokinetic interaction was found in cortex. The retained high uptake of pregnanolone in muscle (after 0.5 g kg(-1)) corresponded to losses in other tissues (including serum). The reduced uptake of pregnanolone in cerebellum, cortex and hippocampus (after 2.0 g kg(-1)) was not due to a corresponding change in serum concentration. It was probably due to a reduced blood flow.
Topics: Anesthesia; Anesthetics; Animals; Brain Stem; Cerebellum; Cerebral Cortex; Corpus Striatum; Dose-Response Relationship, Drug; Drug Interactions; Electroencephalography; Ethanol; Hippocampus; Male; Pregnanolone; Rats; Rats, Sprague-Dawley
PubMed: 11724744
DOI: 10.1038/sj.bjp.0704385 -
Anesthesiology Sep 2014The neurosteroids allopregnanolone and pregnanolone are potent positive modulators of γ-aminobutyric acid type A receptors. Antinociceptive effects of allopregnanolone...
Neurosteroids allopregnanolone sulfate and pregnanolone sulfate have diverse effect on the α subunit of the neuronal voltage-gated sodium channels Nav1.2, Nav1.6, Nav1.7, and Nav1.8 expressed in xenopus oocytes.
BACKGROUND
The neurosteroids allopregnanolone and pregnanolone are potent positive modulators of γ-aminobutyric acid type A receptors. Antinociceptive effects of allopregnanolone have attracted much attention because recent reports have indicated the potential of allopregnanolone as a therapeutic agent for refractory pain. However, the analgesic mechanisms of allopregnanolone are still unclear. Voltage-gated sodium channels (Nav) are thought to play important roles in inflammatory and neuropathic pain, but there have been few investigations on the effects of allopregnanolone on sodium channels.
METHODS
Using voltage-clamp techniques, the effects of allopregnanolone sulfate (APAS) and pregnanolone sulfate (PAS) on sodium current were examined in Xenopus oocytes expressing Nav1.2, Nav1.6, Nav1.7, and Nav1.8 α subunits.
RESULTS
APAS suppressed sodium currents of Nav1.2, Nav1.6, and Nav1.7 at a holding potential causing half-maximal current in a concentration-dependent manner, whereas it markedly enhanced sodium current of Nav1.8 at a holding potential causing maximal current. Half-maximal inhibitory concentration values for Nav1.2, Nav1.6, and Nav1.7 were 12 ± 4 (n = 6), 41 ± 2 (n = 7), and 131 ± 15 (n = 5) μmol/l (mean ± SEM), respectively. The effects of PAS were lower than those of APAS. From gating analysis, two compounds increased inactivation of all α subunits, while they showed different actions on activation of each α subunit. Moreover, two compounds showed a use-dependent block on Nav1.2, Nav1.6, and Nav1.7.
CONCLUSION
APAS and PAS have diverse effects on sodium currents in oocytes expressing four α subunits. APAS inhibited the sodium currents of Nav1.2 most strongly.
Topics: Animals; Female; NAV1.2 Voltage-Gated Sodium Channel; NAV1.6 Voltage-Gated Sodium Channel; NAV1.7 Voltage-Gated Sodium Channel; NAV1.8 Voltage-Gated Sodium Channel; Pregnanolone; Receptors, GABA-A; Voltage-Gated Sodium Channels; Xenopus laevis
PubMed: 24809977
DOI: 10.1097/ALN.0000000000000296 -
Epilepsia Sep 2013Benzodiazepines are the current first-line standard-of-care treatment for status epilepticus but fail to terminate seizures in about one third of cases. Synaptic GABAA... (Review)
Review
Benzodiazepines are the current first-line standard-of-care treatment for status epilepticus but fail to terminate seizures in about one third of cases. Synaptic GABAA receptors, which mediate phasic inhibition in central circuits, are the molecular target of benzodiazepines. As status epilepticus progresses, these receptors are internalized and become functionally inactivated, conferring benzodiazepine resistance, which is believed to be a major cause of treatment failure. GABAA receptor positive allosteric modulator neuroactive steroids, such as allopregnanolone, also potentiate synaptic GABAA receptors, but in addition they enhance extrasynaptic GABAA receptors that mediate tonic inhibition. Extrasynaptic GABAA receptors are not internalized, and desensitization of these receptors does not occur during continuous seizures in status epilepticus models. Here we review the broad-spectrum antiseizure activity of allopregnanolone in animal seizure models and the evidence for its activity in models of status epilepticus. We also demonstrate that allopregnanolone inhibits ongoing behavioral and electrographic seizures in a model of status epilepticus, even when there is benzodiazepine resistance. Parenteral allopregnanolone may provide an improved treatment for refractory status epilepticus.
Topics: Anesthetics; Animals; Benzodiazepines; Diazepam; Humans; Neurotransmitter Agents; Pregnanolone; Status Epilepticus
PubMed: 24001085
DOI: 10.1111/epi.12289 -
Epilepsia Oct 2018Allopregnanolone (5α-pregnan-3α-ol-20-one) and its synthetic 3β-methyl analog, ganaxolone, are positive allosteric modulators of synaptic and extrasynaptic...
Allopregnanolone (5α-pregnan-3α-ol-20-one) and its synthetic 3β-methyl analog, ganaxolone, are positive allosteric modulators of synaptic and extrasynaptic γ-aminobutyric acid (GABA) receptors that exhibit antiseizure activity in diverse animal seizure models, including models of status epilepticus (SE). The 2 neuroactive steroids are being investigated as treatments for SE, including as a treatment for SE induced by chemical threat agents. Intramuscular injection is the preferred route of administration in the prehospital treatment of SE. The objective of this study was to assess the efficacy of intramuscular allopregnanolone and ganaxolone in the treatment of SE induced by the chemical threat agent tetramethylenedisulfotetramine (TETS). The test agents were administered 40 minutes after the onset of SE when mice are refractory to treatment. Allopregnanolone and ganaxolone (each at 3 mg/kg) terminated SE in, respectively, 92% and 75% of animals, and prevented mortality in 85% and 50% of animals; the mean times to termination of behavioral seizures were, respectively, 172 ± 16 and 447 ± 52 seconds. In a separate series of experiments, mice were dosed with the neuroactive steroids by intramuscular injection, and plasma and brain levels were sampled at various time points following injection to estimate pharmacokinetic parameters. Plasma C (maximum concentration) values for allopregnanolone and ganaxolone were 645 and 550 ng/mL, respectively. Brain exposure of both steroids was approximately 3-fold the plasma exposure. Two-compartment pharmacokinetic analysis revealed that the central compartment V (volume of distribution), CL (clearance), t (terminal half-life), and F (intramuscular bioavailability) values for allopregnanolone and ganaxolone were, respectively, 4.95 L/kg 12.88 L/kg/h,16 minutes, 97%, and 5.07 L/kg, 8.35 L/kg/h, 25 minutes, 95%. Allopregnanolone and ganaxolone are effective in the treatment of TETS-induced SE when administered by the intramuscular route. Allopregnanolone is more rapidly acting and modestly more effective, possibly because it has greater potency on GABA receptors.
Topics: Animals; Anticonvulsants; Brain; Bridged-Ring Compounds; Convulsants; Disease Models, Animal; Dose-Response Relationship, Drug; Injections, Intramuscular; Longitudinal Studies; Male; Mice; Pregnanolone; Status Epilepticus; Time Factors
PubMed: 29453777
DOI: 10.1111/epi.13999 -
Seizure Dec 2018The anti-seizure effects of progesterone family compounds have long been known. Over the years, however, most studies have focused on progesterone and on its secondary... (Review)
Review
The anti-seizure effects of progesterone family compounds have long been known. Over the years, however, most studies have focused on progesterone and on its secondary metabolite allopregnanolone (ALLO), with less attention being paid to its primary metabolite 5a-dihydroprogesterone (DHP). Here we review animal and clinical studies related to the anti-seizure effects of progesterone and its 5a neuroactive metabolites, including DHP and ALLO. Progesterone and its reduced metabolites all have demonstrated seizure-suppression effects in animal models - except in models of absence seizures - with the common side effects of sedation and ataxia. Progesterone and ALLO have also shown anti-seizure effects in clinical trials. A large Phase III trial has revealed that female patients with premenstrual exacerbations of seizures benefit most from progesterone therapy. A liquid suspension of ALLO has also been tested in patients with supra-refractory status epilepticus with some success in a small phase II trial. ALLO's C3 methyl analog ganaxolone is under development as an anti-seizure drug. Progesterone's anti-seizure effects are mostly independent of its genomic receptors and are, in large part, due to its active metabolites. ALLO is a potent allosteric modulator of GABA receptors. Other membrane receptors are thought to be involved in the DHP's anti-seizure actions, but their exact nature is not yet known. Potential drawbacks to the development of progesterone family compounds as anti-seizure drug are their endocrine effects. These compounds might form a basis for the future development of novel anti-seizure drugs, however, with hormonal side effects being mitigated through rational drug design.
Topics: 20-alpha-Dihydroprogesterone; Animals; Anticonvulsants; Humans; Pregnanolone; Progesterone; Seizures
PubMed: 30391663
DOI: 10.1016/j.seizure.2018.10.012 -
International Journal of Molecular... May 2021Under stressful conditions, the hypothalamic-pituitary-adrenal (HPA) axis acts to promote transitory physiological adaptations that are often resolved after the... (Review)
Review
Under stressful conditions, the hypothalamic-pituitary-adrenal (HPA) axis acts to promote transitory physiological adaptations that are often resolved after the stressful stimulus is no longer present. In addition to corticosteroids (e.g., cortisol), the neurosteroid allopregnanolone (3α,5α-tetrahydroprogesterone, 3α-hydroxy-5α-pregnan-20-one) participates in negative feedback mechanisms that restore homeostasis. Chronic, repeated exposure to stress impairs the responsivity of the HPA axis and dampens allopregnanolone levels, participating in the etiopathology of psychiatric disorders, such as major depressive disorder (MDD) and post-traumatic stress disorder (PTSD). MDD and PTSD patients present abnormalities in the HPA axis regulation, such as altered cortisol levels or failure to suppress cortisol release in the dexamethasone suppression test. Herein, we review the neurophysiological role of allopregnanolone both as a potent and positive GABAergic neuromodulator but also in its capacity of inhibiting the HPA axis. The allopregnanolone function in the mechanisms that recapitulate stress-induced pathophysiology, including MDD and PTSD, and its potential as both a treatment target and as a biomarker for these disorders is discussed.
Topics: Adaptation, Physiological; Animals; Antidepressive Agents; Chronic Disease; Corticosterone; Depressive Disorder, Major; Feedback, Physiological; Female; GABA-A Receptor Agonists; Humans; Hypothalamo-Hypophyseal System; Male; Models, Biological; Pituitary-Adrenal System; Pregnanolone; Receptors, GABA-A; Sex Characteristics; Stress Disorders, Post-Traumatic; Stress, Physiological; Stress, Psychological; gamma-Aminobutyric Acid
PubMed: 34071053
DOI: 10.3390/ijms22115495 -
Acta Obstetricia Et Gynecologica... Dec 2012To measure serum concentrations of progesterone, estradiol and 5α- and 5β-reduced progesterone metabolites in the follicular and luteal phases of the menstrual cycle...
OBJECTIVE
To measure serum concentrations of progesterone, estradiol and 5α- and 5β-reduced progesterone metabolites in the follicular and luteal phases of the menstrual cycle in women with latent acute intermittent porphyria and manifest acute intermittent porphyria in comparison with healthy control women.
DESIGN
A descriptive study with repeated measurements during a complete, ovulatory menstrual cycle.
SETTING
University hospital out-patient clinic.
POPULATION
Thirty-two women with DNA-diagnosed acute intermittent porphyria and 20 healthy control women.
METHODS
Blood samples for serum progesterone, estradiol, allopregnanolone and pregnanolone were drawn on predefined menstrual cycle days, twice in the follicular phase and three times in the luteal phase. Serum levels of estradiol and progesterone were analysed with commercial kits. Allopregnanolone and pregnanolone levels were analysed with radioimmunoassay following diethylether extraction and celite column chromatography.
MAIN OUTCOME MEASURES
Changes in serum levels of progesterone, estradiol, allopregnanolone and pregnanolone throughout the menstrual cycle.
RESULTS
Women with acute intermittent porphyria displayed lower serum concentrations of allopregnanolone in comparison with healthy control women, the difference being most prominent in the luteal phase (p < 0.001). Levels of pregnanolone did not differ significantly between groups. No significant difference was found between women with latent acute intermittent porphyria and manifest acute intermittent porphyria.
CONCLUSIONS
Decreased levels of the 5α-reduced progesterone metabolite allopregnanolone were found in the menstrual cycle of women with acute intermittent porphyria. This has not been reported previously and could indicate a reduced 5α-reductase type 1 capacity in the ovary and liver among these women.
Topics: 3-Oxo-5-alpha-Steroid 4-Dehydrogenase; Adult; Case-Control Studies; Estradiol; Female; Humans; Menstrual Cycle; Middle Aged; Porphyria, Acute Intermittent; Pregnanolone; Progesterone; Statistics, Nonparametric; Sweden
PubMed: 22924787
DOI: 10.1111/j.1600-0412.2012.01536.x