The mechanism of the negative impact of corticosteroids on the induction and progress of mental illness remains unclear. In this work, we studied the effects of corticosteroids on the activity of neuronal glycine receptors (GlyR) and GABA-A receptors (GABAAR) by measuring the chloride current induced by the application of GABA (2 or 5 μM) to isolated cerebellar Purkinje cells (IGABA) and by the application of glycine (100 μM) to pyramidal neurons of the rat hippocampus (IGly). It was found that corticosterone, 5α-dihydrodeoxycorticosterone, allotetrahydrocorticosterone, cortisol, and 17α,21-dihydroxypregnenolone were able to accelerate the desensitization of the IGly at physiological concentrations (IC50 values varying from 0.39 to 0.72 μM). Next, cortisone, 11-deoxycortisol, 11-deoxycorticosterone, 5β-dihydrodeoxycorticosterone, and tetrahydrocorticosterone accelerated the desensitization of IGly with IC50 values varying from 10.3 to 15.2 μM. Allotetrahydrocorticosterone and tetrahydrocorticosterone potentiated the IGABA albeit with high EC50 values (18-23 μM). The rest of the steroids had no effect on IGABA in the range of concentrations of 1-100 μM. Finally, our study has suggested a structural relationship of the 3β-hydroxyl group/3-oxo group with the selective modulatory activity on GlyRs in contrast to the 3α-hydroxyl group that is pivotal for GABAARs. In summary, our results suggest that increased GlyR desensitization by corticosteroids may contribute to brain dysfunction under chronic stress and identify corticosteroids for further development as selective modulators of GlyRs.

• Klíčová slova
• GABAA receptor, corticosteroids, glycine receptor, structure−activity relationship study,
• MeSH
• GABA farmakologie   MeSH
• glycin * farmakologie   MeSH
• hormony kůry nadledvin farmakologie   MeSH
• krysa rodu Rattus MeSH
• neurony MeSH
• receptory GABA-A MeSH
• receptory glycinu * fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• GABA MeSH
• glycin * MeSH
• hormony kůry nadledvin MeSH
• receptory GABA-A MeSH
• receptory glycinu * MeSH

BACKGROUND: Neurosteroids are investigated as effective antidotes for the poisoning induced by tetramethylenedisulfotetramine (TMDT) as well as treatments for epileptic spasms during infancy. Both these conditions are quite resistant to pharmacotherapy; thus, a search for new treatments is warranted. METHODS: In this study, we determined the efficacy of two novel neurosteroids, pregnanolone glutamate (PAG) and pregnanolone pyroglutamate (PPG), and tested these drugs in doses of 1-10 mg/kg (ip) against the TMDT syndrome and in our rodent model of infantile spasms. RESULTS: Only PPG in doses 5 and 10 mg/kg suppressed the severity of the TMDT syndrome and TMDT-induced lethality, while the 1 mg/kg dose was without an effect. Interestingly, the 1 mg/kg dose of PPG in combination with 1 mg/kg of diazepam was also effective against TMDT poisoning. Neither PAG nor PPG were effective against experimental spasms in the N-methyl-D-aspartate (NMDA)-triggered model of infantile spasms. CONCLUSIONS: While evidence suggests that PAG can act through multiple actions which include allosteric inhibition of NMDA-induced and glycine receptor-evoked currents as well as augmentation of ɣ-aminobutyric acid subtype A (GABAA) receptor-induced currents, the agent appears to neither have the appropriate mechanistic signature for activity in the infantile spasm model, nor the adequate potency, relative to PPG, for ameliorating the TMDT syndrome. The full mechanisms of action of PPG, which may become a potent TMDT antidote either alone or in combination with diazepam are yet unknown and thus require further investigation.

• Klíčová slova
• Antidote, Neurosteroids, Neurotoxicity, Severe seizures, Tetramethylenedisulfotetramine,
• MeSH
• diazepam farmakologie   MeSH
• hlodavci MeSH
• křeče u dětí * chemicky indukované   farmakoterapie   MeSH
• kyselina glutamová MeSH
• kyselina pyrrolidonkarboxylová MeSH
• N-methylaspartát toxicita   terapeutické užití   MeSH
• neurosteroidy * MeSH
• neurotoxické syndromy * MeSH
• pregnanolon škodlivé účinky   MeSH
• spasmus MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• diazepam MeSH
• kyselina glutamová MeSH
• kyselina pyrrolidonkarboxylová MeSH
• N-methylaspartát MeSH
• neurosteroidy * MeSH
• pregnanolon MeSH
• tetramethylenedisulfotetramine MeSH Prohlížeč

Pregnanolone glutamate (PA-G) is a neuroactive steroid that has been previously demonstrated to be a potent neuroprotective compound in several biological models in vivo. Our in vitro experiments identified PA-G as an inhibitor of N-methyl-D-aspartate receptors and a potentiator of γ-aminobutyric acid receptors (GABAARs). In this study, we addressed the hypothesis that combined GABAAR potentiation and NMDAR antagonism could afford a potent anticonvulsant effect. Our results demonstrated the strong age-related anticonvulsive effect of PA-G in a model of pentylenetetrazol-induced seizures. PA-G significantly decreased seizure severity in 12-day-old animals, but only after the highest dose in 25-day-old animals. Interestingly, the anticonvulsant effect of PA-G differed both qualitatively and quantitatively from that of zuranolone, an investigational neurosteroid acting as a potent positive allosteric modulator of GABAARs. Next, we identified 17-hydroxy-pregnanolone (17-OH-PA) as a major metabolite of PA-G in 12-day-old animals. Finally, the administration of PA-G demonstrated direct modulation of unexpected neurosteroid levels, namely pregnenolone and dehydroepiandrosterone sulfate. These results suggest that compound PA-G might be a pro-drug of 17-OH-PA, a neurosteroid with a promising neuroprotective effect with an unknown mechanism of action that may represent an attractive target for studying perinatal neural diseases.

• Klíčová slova
• GABA, NMDA, anticonvulsant, metabolomics, neurosteroids, zuranolone,
• Publikační typ
• časopisecké články MeSH

Evidence from clinical and preclinical studies implicates dysfunction of N-methyl-D-aspartate receptors (NMDARs) in schizophrenia progression and symptoms. We investigated the antipsychotic effect of two neuroactive steroids in an animal model of schizophrenia induced by systemic application of MK-801. The neuroactive steroids differ in their mechanism of action at NMDARs. MS-249 is positive, while PA-Glu is a negative allosteric NMDAR modulator. We hypothesized that the positive NMDA receptor modulator would attenuate deficits caused by MK-801 co-application more effectively than PA-Glu. The rats were tested in a battery of tests assessing spontaneous locomotion, anxiety and cognition. Contrary to our expectations, PA-Glu exhibited a superior antipsychotic effect to MS-249. The performance of MS-249-treated rats in cognitive tests differed depending on the level of stress the rats were exposed to during test sessions. In particular, with the increasing severity of stress exposure, the performance of animals worsened. Our results demonstrate that enhancement of NMDAR function may result in unspecific behavioral responses. Positive NMDAR modulation can influence other neurobiological processes besides memory formation, such as anxiety and response to stress.

• Klíčová slova
• MK-801, anxiety, cognition, neurosteroids, schizophrenia, stress,
• MeSH
• antipsychotika farmakologie   MeSH
• bicyklické sloučeniny heterocyklické metabolismus   MeSH
• chování zvířat účinky léků   MeSH
• dizocilpinmaleát farmakologie   MeSH
• HEK293 buňky MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• potkani Long-Evans MeSH
• potkani Wistar MeSH
• pregnenolon metabolismus   farmakologie   MeSH
• receptory N-methyl-D-aspartátu antagonisté a inhibitory   metabolismus   MeSH
• schizofrenie farmakoterapie   metabolismus   MeSH
• steroidy farmakologie   MeSH
• test vyvýšeného křížového bludiště MeSH
• úleková reakce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antipsychotika MeSH
• bicyklické sloučeniny heterocyklické MeSH
• dizocilpinmaleát MeSH
• pregnenolon MeSH
• pregnenolone sulfate MeSH Prohlížeč
• receptory N-methyl-D-aspartátu MeSH
• steroidy MeSH
• tert-butylbicyclophosphorothionate MeSH Prohlížeč

Epipregnanolone (3β-hydroxy-5β-pregnan-20-one, Epi) is an endogenous steroid with important physiological effects and high affinity for GABAA receptors. The effect of Epi on GABA-induced chloride current (IGABA) in native neurons has hardly been studied. In this work, we studied the influence of Epi on the IGABA in the Purkinje cells of rat cerebellum and pyramidal neurons of rat hippocampus with the patch clamp technique. We showed that Epi is a positive modulator of the IGABA with EC50 of 5.7 µM in Purkinje cells and 9.3 µM in hippocampal neurons. Epi-induced potentiation of the IGABA was more potent at low vs. high GABA concentrations. Isopregnanolone (3β-hydroxy-5α-pregnan-20-one, Iso) counteracted Epi, reducing its potentiating effect by 2-2.3 times. Flumazenil, a nonsteroidal GABAA receptor antagonist, does not affect the Epi-induced potentiation. Comparison of the potentiating effects of Epi and allopregnanolone (3α-hydroxy-5α-pregnan-20-one, ALLO) showed that ALLO is, at least, a four times more potent positive modulator than Epi. The combined application of ALLO and Epi showed that the effects of these two steroids are not additive. We conclude that Epi has a dual effect on the IGABA increasing the current in the control solution and decreasing the stimulatory effect of ALLO.

• Klíčová slova
• GABA receptor, allopregnanolone, epipregnanolone, flumazenil patch clamp, isopregnanolone,
• MeSH
• agonisté receptorů GABA-A farmakologie   MeSH
• hipokampus metabolismus   MeSH
• krysa rodu Rattus MeSH
• mozeček metabolismus   MeSH
• potkani Wistar MeSH
• pregnanolon farmakologie   MeSH
• pyramidové buňky metabolismus   MeSH
• receptory GABA-A metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• agonisté receptorů GABA-A MeSH
• pregnanolon MeSH
• receptory GABA-A MeSH

The ability of androstane and androstene neurosteroids with modifications at C-17, C-5, and C-3 (compounds 1-9) to influence the functional activity of inhibitory glycine and γ-aminobutyric acid (GABA) receptors was estimated. The glycine- and GABA-induced chloride current (I Gly and I GABA) were measured in isolated pyramidal neurons of the rat hippocampus and isolated rat cerebellar Purkinje cells, correspondingly, using the patch-clamp technique. Our results demonstrate that all the nine neurosteroids display similar biological activity, namely, they strongly inhibited I Gly and weakly inhibited I GABA. The threshold concentration of neurosteroids inducing effects on I Gly was 0.1 μM, and for effects on I GABA was 10-50 μM. Moreover, our compounds accelerated desensitization of the I Gly with the IC50 values varying from 0.12 to 0.49 μM and decreased the peak amplitude with IC50 values varying from 16 to 22 μM. Interestingly, our study revealed that only compounds 4 (epiandrosterone) and 8 (dehydroepiandrosterone) were able to cause a significant change in I GABA in 10 μM concentration. Moreover, compounds 3 (testosterone), 5 (epitestosterone), 6 (dihydroandrostenedione), and 9 (etiocholanedione) did not modulate I GABA up to the concentration of 50 μM. Thus, we conclude that compounds 3, 5, 6, and 9 may be identified as selective modulators of I Gly. Our results offer new avenues of investigation in the field of drug-like selective modulators of I Gly.

• Klíčová slova
• GABA receptor, androstane, androstene, glycine receptor, neurosteroid, structure-activity relationship,
• Publikační typ
• časopisecké články MeSH