valerenic-acid and Seizures

Gamma-aminobutyric acid type A (GABA

Topics: Animals; Blood-Brain Barrier; Molecular Structure; Pentylenetetrazole; Plant Extracts; Plant Roots; Receptors, GABA-A; Seizures; Valerian; Xenopus laevis; Zebrafish

Valerenic acid (VA)-a β2/3-selective GABA type A (GABAA) receptor modulator-displays anxiolytic and anticonvulsive effects in mice devoid of sedation, making VA an interesting drug candidate. Here we analyzed β-subunit-dependent enhancement of GABA-induced chloride currents (IGABA) by a library of VA derivatives and studied their effects on pentylenetetrazole (PTZ)-induced seizure threshold and locomotion. Compound-induced IGABA enhancement was determined in oocytes expressing α1β1γ2S, α1β2γ2S, or α1β3γ2S receptors. Effects on seizure threshold and locomotion were studied using C57BL/6N mice and compared with saline-treated controls. β2/3-selective VA derivatives such as VA-amide (VA-A) modulating α1β3γ2S (VA-A: Emax = 972 ± 69%, n = 6, P < 0.05) and α1β2γ2S receptors (Emax = 1119 ± 72%, n = 6, P < 0.05) more efficaciously than VA (α1β3γ2S: VA: Emax = 632 ± 88%, n = 9 versus α1β2γ2S: VA: Emax = 721 ± 68%, n = 6) displayed significantly more pronounced seizure threshold elevation than VA (saline control: 40.4 ± 1.4 mg/kg PTZ versus VA 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ versus VA-A 3 mg/kg: 57.9 ± 1.9 mg/kg PTZ, P < 0.05). Similarly, VA's methylamide (VA-MA) enhancing IGABA through β3-containing receptors more efficaciously than VA (Emax = 1043 ± 57%, P < 0.01, n = 6) displayed stronger anticonvulsive effects. Increased potency of IGABA enhancement and anticonvulsive effects at lower doses compared with VA were observed for VA-tetrazole (α1β3γ2S: VA-TET: EC50 = 6.0 ± 1.0 μM, P < 0.05; VA-TET: 0.3 mg/kg: 47.3 ± 0.5 mg/kg PTZ versus VA: 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ, P < 0.05). At higher doses (≥10 mg/kg), VA-A, VA-MA, and VA-TET reduced locomotion. In contrast, unselective VA derivatives induced anticonvulsive effects only at high doses (30 mg/kg) or did not display any behavioral effects. Our data indicate that the β2/3-selective compounds VA-A, VA-MA, and VA-TET induce anticonvulsive effects at low doses (≤10 mg/kg), whereas impairment of locomotion was observed at doses ≥10 mg/kg.

Topics: Animals; Behavior, Animal; Dose-Response Relationship, Drug; Female; Indenes; Mice; Pentylenetetrazole; Receptors, GABA-A; Seizures; Sesquiterpenes; Xenopus laevis

Anticonvulsant properties have been attributed to extracts of the herbal medicine Valeriana officinalis. Our aims were to examine the anticonvulsant properties of valerenic acid and valerian extracts and to determine whether valerian preparations interact with the activity of other anti-epileptic drugs (phenytoin or clonazepam). To achieve these goals, we validated the adult zebrafish, Danio rerio, as an animal model for studying anticonvulsant drugs.. All drug treatments were administered by immersion in water containing the drug. For assays of anticonvulsant activity, zebrafish were pretreated with: anti-epileptic drugs, valerenic acid, aqueous or ethanolic valerian extracts, or mixtures (phenytoin or clonazepam with valerenic acid or valerian extracts). Seizures were then induced with pentylenetetrazole (PTZ). A behavioral scale was developed for scoring PTZ-induced seizures in adult zebrafish. The seizure latency was evaluated for all pretreatments and control, untreated fish. Valerenic acid and both aqueous and ethanolic extracts of valerian root were also evaluated for their ability to improve survival after pentylenetetrazole-challenge. The assay was validated by comparison with well-studied anticonvulsant drugs (phenytoin, clonazepam, gabapentin and valproate). One-way ANOVA followed by Tukey post-hoc test was performed, using a p < 0.05 level of significance. All treatments were compared with the untreated animals and with the other pretreatments.. After exposure to pentylenetetrazole, zebrafish exhibited a series of stereotypical behaviors prior to the appearance of clonic-like movements--convulsions. Both valerenic acid and valerian extracts (aqueous and ethanolic) significantly extended the latency period to the onset of seizure (convulsion) in adult zebrafish. The ethanolic valerian extract was a more potent anticonvulsant than the aqueous extract. Valerenic acid and both valerian extracts interacted synergistically with clonazepam to extended the latency period to the onset of seizure. Phenytoin showed interaction only with the ethanolic valerian extracts.. Valerenic acid and valerian extracts have anticonvulsant properties in adult zebrafish. Valerian extracts markedly enhanced the anticonvulsant effect of both clonazepam and phenytoin, and could contribute to therapy of epileptic patients.

Topics: Animals; Anticonvulsants; Behavior, Animal; Indenes; Pentylenetetrazole; Plant Extracts; Seizures; Sesquiterpenes; Valerian; Zebrafish

Valerenic acid (VA) is a β2/3 subunit-specific modulator of γ-aminobutyric acid (GABA) type A (GABAA) receptors inducing anxiolysis. Here we analyze if VA-esters can serve as prodrugs and if different ester structures have different in vitro/in vivo effects. Modulation of GABAA receptors expressed in Xenopus oocytes was studied with 2-microelectrode-voltage-clamp. Anxiolytic effects of the VA-esters were studied on male C57BL/6N mice by means of the elevated plus maze-test; anticonvulsant properties were deduced from changes in seizure threshold upon pentylenetetrazole infusion. VA was detected in plasma confirming hydrolysis of the esters and release of VA in vivo. Esterification significantly reduced the positive allosteric modulation of GABAA (α1β3γ2S) receptors in vitro. in vivo, the studied VA-ester derivatives induced similar or even stronger anxiolytic and anticonvulsant action than VA. While methylation and propylation of VA resulted in faster onset of anxiolysis, the action of VA-ethylester was longer lasting, but occurred with a significant delay. The later finding is in line with the longer lasting anticonvulsant effects of this compound. The estimated VA plasma concentrations provided first insight into the release kinetics from different VA-esters. This might be an important step for its future clinical application as a potential non-sedative anxiolytic and anticonvulsant.

Topics: Animals; Anti-Anxiety Agents; Anticonvulsants; Anxiety; Behavior, Animal; Esters; GABA Agents; Indenes; Male; Mice, Inbred C57BL; Oocytes; Pentylenetetrazole; Prodrugs; Receptors, GABA-A; Seizures; Sesquiterpenes; Xenopus