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Klára Šíchová

National Institute of Mental Health, Klecany, Czechia.

14 papers in the library · 47 citations · publishing 2021-2026

Papers

2C-B-Fly-NBOMe Metabolites in Rat Urine, Human Liver Microsomes and C. elegans: Confirmation with Synthesized Analytical Standards.

Metabolites November 12, 2021 Jitka Nykodemová, Anna Šuláková, Petr Palivec et al. 14 citations

The metabolism of the psychoactive compound 2C-B-Fly-NBOMe was investigated using three systems: human liver microsomes, the fungus Cunninghamella elegans, and live rats. Thirty-five phase I and nine phase II metabolites were identified. Major metabolic pathways include hydroxylation, O-demethylation, oxidative debromination, and N-demethoxybenzylation, followed by glucuronidation or N-acetylation. Human liver microsomes produced the most metabolites at highest concentrations. Two poly-hydroxylated metabolites appeared only in rat urine, while the fungus generated dehydrogenated, N-oxygenated, and dibrominated metabolites. These findings clarify how the body processes this substance, aiding understanding of its effects and potential toxicity.

Pharmacokinetic, pharmacodynamic, and behavioural studies of deschloroketamine in Wistar rats.

British journal of pharmacology January 1, 2022 Kristýna Štefková-mazochová, Hynek Danda, Wim Dehaen et al. 13 citations

Deschloroketamine (DCK), a structural analogue of ketamine sold as a recreational drug, was tested in Wistar rats to examine its pharmacokinetics, acute effects, and addictive potential. DCK rapidly entered the brain, with peak levels at 30 minutes and sustained high levels for 2 hours. It blocks NMDA receptors similarly to ketamine, with the S-enantiomer more potent. DCK stimulated locomotion, induced place preference (a sign of reward), and strongly disrupted prepulse inhibition (PPI). Locomotor stimulation faded faster than PPI disruption. S-DCK had stronger stimulatory effects than R-DCK, but both equally disrupted PPI. DCK's behavioral and addictive profiles resemble ketamine's, with a slightly slower clearance, matching its reported longer duration. These findings clarify risks of illicit DCK use.

Mescaline-induced behavioral alterations are mediated by 5-HT2A and 5-HT2C receptors in rats.

Pharmacology, biochemistry, and behavior December 1, 2024 Lucie Olejníková-Ladislavová, Michaela Fujáková-Lipski, Klára Šíchová et al. 5 citations

Mescaline, a classical psychedelic, primarily acts on serotonin 5-HT2A/C receptors but also binds to 5-HT1A and 5-HT2B receptors. In adult male rats, the highest dose (100 mg/kg) caused hyperlocomotion, which was reversed by almost all antagonists tested. Sensorimotor gating deficits, measured as prepulse inhibition of acoustic startle, were selectively normalized by a 5-HT2A antagonist, while a 5-HT2C antagonist partially reversed deficits from lower doses. These findings indicate that mescaline's behavioral effects are mainly mediated by the 5-HT2A receptor subtype, with a lesser role for 5-HT2C receptors, and limited involvement of other subtypes.

Cross-Species Evidence for Psilocin-Induced Visual Distortions: Apparent Motion Is Perceived by Both Humans and Rats.

Biological psychiatry global open science September 1, 2025 Čestmír Vejmola, Klára Šíchová, Kateřina Syrová et al. 4 citations

Psilocin, the active compound in psychedelic mushrooms, impairs the ability to distinguish between static and moving images in both humans and rats. In a visual discrimination task, human participants and male rats were asked to judge whether an image was static or moving. Under psilocin, both species showed significant difficulty in this task. In humans, the impairment tracked psilocin plasma levels and self-reported hallucination intensity. In rats, psilocin selectively disrupted performance in a motion-based task but not a luminance-based task, suggesting a specific effect on motion perception. Decision time was also linked to discrimination impairment. This is the first evidence that rats experience visual distortions similar to those reported by humans, offering a model for studying altered visual perception in drug-induced and psychiatric conditions.

Acute pharmacological profile of 2C-B-Fly-NBOMe in male Wistar rats-pharmacokinetics, effects on behaviour and thermoregulation.

Frontiers in pharmacology January 1, 2023 Kateřina Syrová, Klára Šíchová, Hynek Danda et al. 4 citations

2C-B-Fly-NBOMe, a new psychoactive substance related to the psychedelic entactogen 2C-B, was studied in adult male Wistar rats. After injection, peak drug levels in blood serum occurred at 30 minutes (28 ng/ml) and in brain tissue at 60 minutes (171 ng/g), with the compound still detectable in the brain after 8 hours. The drug dose-dependently reduced locomotor activity and strongly disrupted the acoustic startle response, with a weaker effect on prepulse inhibition. It did not cause significant changes in body temperature. The overall profile resembles that of 2C-B and other NBOMe substances, suggesting slow brain penetration and inhibitory effects on motor performance and sensorimotor gating.

The acute effects of methoxphenidine on behaviour and pharmacokinetics profile in animal model.

Progress in neuro-psychopharmacology & biological psychiatry March 20, 2025 Kristýna Štefková-mazochová, Hynek Danda, Vladimír Mazoch et al. 3 citations

Methoxphenidine (MXP), a new psychoactive substance, rapidly crosses the blood-brain barrier in Wistar rats, reaching peak concentrations in serum and brain 30 minutes after injection, with a half-life of 2.15 hours. Low to moderate doses (10-20 mg/kg) increase locomotor activity in an open field test, while a higher dose (40 mg/kg) decreases it. All doses disrupt sensorimotor gating (prepulse inhibition), an effect linked to psychosis. MXP shows moderate acute toxicity with an estimated LD50 of 500 mg/kg subcutaneously. The drug exhibits a profile similar to dissociative anesthetics, producing stimulant and anxiogenic effects at lower doses and sedative effects at higher doses, indicating risks of serious adverse health outcomes from recreational use.

Hexahydrocannabinol: pharmacokinetics, systemic toxicity, and acute behavioral effects in Wistar rats.

The international journal of neuropsychopharmacology August 1, 2025 Klára Šíchová, Barbara Mallarino, Lucie Janečková et al. 1 citation

Hexahydrocannabinol (HHC), a new psychoactive substance used as a legal alternative to ∆9-tetrahydrocannabinol, crosses the blood-brain barrier, exhibits mild toxicity, and induces behavioral effects similar to tetrahydrocannabinol in male Wistar rats. A 1:1 mixture of (9R)-HHC and (9S)-HHC was given at doses of 1, 5, and 10 mg/kg. Two hours after the highest dose, peak concentrations appeared in blood and brain tissue. The OECD 423 test classified HHC as Category 4, with an estimated lethal dose of 1000 mg/kg. Compared to controls, 10 mg/kg HHC reduced movement, increased anxiety, and impaired sensory processing, highlighting dose-dependent anxiogenic properties and impact on information processing.

Behavioural and pharmacological evaluation of the psilocybin analogue baeocystin in Wistar rats.

Progress in neuro-psychopharmacology & biological psychiatry July 5, 2025 Hynek Danda, Kristýna Mazochová, Klára Šíchová et al. 1 citation

Baeocystin, a compound found in psychoactive mushrooms, has minimal to no behavioral effects in rats, likely because it poorly crosses the blood-brain barrier. After subcutaneous doses of 1.25 or 5 mg/kg, baeocystin and its metabolite norpsilocin showed very limited brain penetration. Consistent with this, the compound had no significant effects on locomotor activity, exploratory behavior, anxiety-like responses, or sensorimotor gating in Wistar rats. The findings suggest baeocystin's negligible neurobiological and psychedelic activity is due to its poor permeability across the blood-brain barrier.

Effects of serotonergic psychedelics on synaptogenesis and immediate early genes expression - comparison with ketamine, fluoxetine and lithium.

Journal of psychopharmacology (Oxford, England) May 28, 2025 Yana Vella, Kateřina Syrová, Aneta Petrušková et al. 1 citation

Psilocin, the active compound in magic mushrooms, promotes the formation of new synapses in rat brain cells, an effect comparable to ketamine and lithium. In laboratory experiments on rat cortical cultures, psilocin increased the number of synaptic puncta and boosted expression of the immediate early gene Arc after acute treatment. Lysergic acid diethylamide (LSD) and N,N-dimethyltryptamine (DMT) did not produce significant synaptogenic effects. Fluoxetine, a common antidepressant, had no effect on synapse formation but upregulated other immediate early genes. These findings add evidence that psilocin may be a promising therapeutic agent for psychiatric conditions.

Metabolic profile of 25E-NBOH in human liver microsomes, rat urine, and fungus Cunninghamella elegans.

Journal of pharmaceutical and biomedical analysis August 1, 2026 Magdaléna Vágnerová, Petr Palivec, Monika Mrňavá et al.

The metabolism of the recreational drug 25E-NBOH was investigated in human liver microsomes, rat urine, and Cunninghamella elegans fungus. Using untargeted LC-HRMS/MS, 56 metabolites were annotated, many as isomers. Primary metabolic pathways included hydroxylation, O-demethylation, and N-debenzylation, followed by conjugation. Ten reference substances were synthesized; seven matched detected metabolites by retention time and MS/MS spectra, enabling structural assignment. The known psychoactive substance 2C-E was confirmed as a metabolite. Three main biomarkers are proposed. This work provides the first comprehensive metabolic profile of 25E-NBOH, supporting future pharmacological and toxicological studies and aiding clinical diagnosis of intoxication.

Chronic psilocin microdosing produces limited behavioral effects and does not enhance neurogenesis in rats.

Pharmacology, biochemistry, and behavior June 30, 2026 Lucie Ladislavová, Viera Kútná, Kristýna Mazochová et al.

Chronic microdosing of psilocin (0.05 or 0.075 mg/kg) in adult male Wistar rats over five weeks did not alter locomotor activity, depressive-like behavior, sociability, or novelty seeking, and did not increase cell proliferation in the dentate gyrus of the hippocampus. A small anxiogenic effect was detected in the Elevated Plus Maze. The findings suggest that, under this dosing schedule, psilocin microdosing produces limited behavioral effects and does not enhance hippocampal progenitor proliferation.

Psilocybin and Ibogaine in Cocaine‐Seeking: Extinction Enhancement Without Relapse Prevention

Addiction Biology March 1, 2026 Isis Koutrouli, Vojtěch Brejtr, Marek Schwendt et al.

Psilocybin and ibogaine, given in a dose-escalation protocol, facilitated extinction learning in male rats that had self-administered cocaine. Psilocybin reduced active lever pressing one day after the second dose, with a nonsignificant reduction after the first dose; ibogaine significantly reduced pressing even after the first administration. Neither drug significantly altered cue-induced reinstatement of drug-seeking, though psilocybin showed a trend toward attenuation. The treatments had no side effects on general locomotor activity or anxiety-like behavior in the open field test. These results suggest psilocybin and ibogaine may support extinction learning and possibly protect against relapse, warranting further research into their antiaddictive potential.

Behavioral pharmacology of mescaline - the role of serotonin 5-HT2A, 5-HT2B, 5-HT2C and 5-HT1A receptors

bioRxiv Preprint Server August 28, 2024 Lucie Olejníková-Ladislavová, Michaela Fujáková-Lipski, Klára Šíchová et al. preprint

Mescaline, a classical psychedelic with a phenylethylamine structure, primarily acts on serotonin 5-HT2A/C receptors but also binds to 5-HT1A and 5-HT2B receptors. Although it was the first psychedelic ever isolated and synthesized, the precise role of these different serotonin receptor subtypes in its behavioral pharmacology remains not fully understood.