GABAa receptor subunits expression in silver catfish (Rhamdia quelen) brain and its modulation by Nectandra grandiflora Nees essential oil and isolated compounds.

Studies using silver catfish (Rhamdia quelen) as experimental models are often applied to screen essential oils (EO) with GABAergic-mediated effects. However, the expression of GABAa receptors in the silver catfish brain remains unknown. Thus, we assessed whether silver catfish express GABAa receptor subunits associated with sedation/anesthetic process and/or neurological diseases. Additionally, we evaluated the brain expression of GABAa receptor subunits in fish sedated with Nectandra grandiflora EO and its isolated compounds, the fish anesthetic (+)-dehydrofukinone (DHF), and dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL), which have GABAa-mediated anxiolytic-like effects in mice. The expression of the subunits gabra1, gabra2, gabra3, gabrb1, gabrd and gabrg2 in the silver catfish brain were assessed after a 24h-sedation bath by real time PCR. Since qPCR data rarely describes mechanisms of action, which are usually found through interactions with receptors, we also performed an antagonist-driven experiment using flumazenil (FMZ). Real-time PCR detected the mRNA expression of all targeted genes in R. quelen brain. The expression of gabra1 was decreased in fish sedated with ERM; EO increased gabra2, gabra3, gabrb1 and gabrg2 expression; SEL increased gabrb1, gabrd and gabrg2 expression. EO and compounds DFX, SEL and ERM induced sustained sedation in fish and FMZ-bath prompted the recovery from ERM- and DFX-induced sedation. Our results suggest that the EO, SEL, ERM and DFX sedative effects involve interaction with the GABAergic system. Our findings support the use of the silver catfish as robust and reliable experimental model to evaluate the efficacy of drugs with putative GABAergic-mediated effects.

Anxiolytic effect of fatty acids and terpenes fraction from Aloysia triphylla: Serotoninergic, GABAergic and glutamatergic implications.

Aloysia triphylla (Verbenaceae) is an aromatic medicinal plant, and it is used for the treatment of "nervous" problems as, "sadness" and "nervousness". While, there are no reports about its pharmacological activity in animal models. The objective of this work was to evaluate the anxiolytic effect of the extracts and fractions of this species and to measure the interaction of the most active fraction with serotonergic, glutamatergic and GABAergic drugs. An elevated plus maze test was carried ought where the methanol (AtM), dicloromethane (AtD) and hexanic (AtH) extracts presented anxiolytic activity in mice when exposed to the test. Also, different fractions obtained from the AtD were evaluated (AtF1, AtF2 and AtF3, 15mg/kg), and showed that fraction AtF1 possessed the anxiolytic activity, in the same model. Then, AtF1 was co-administered with different drugs, which act on GABAergic (bicuculline, picrotoxin, pentylenetetrazol, baclofen and phaclofen), or serotononinergic (DOI, 8-OH-DPAT, WAY 100635 and ketanserine) or glutamatergic (NMDA, MPEP and MK-801) systems. The anxiolytic activity of AtF1 was modified by GABAergic and serotoninergic drugs. Chemical analysis of this fraction by using GC-MS, showed that it contains hexadecanoic acid, hexadecanoic acid methyl ester, octadecanoic acid methyl ester, eicosanoic acid methyl ester, vitamin E, α-amiryn, campesterol, sitosterol, stigmastan-2,22, dien-3-ol (4) and stigmasta 5, 24 (28) dien-3-ol.

HPLC-Based Activity Profiling for GABAA Receptor Modulators in Searsia pyroides Using a Larval Zebrafish Locomotor Assay.

A dichloromethane extract from leaves of Searsia pyroides potentiated gamma aminobutyric acid-induced chloride currents by 171.8 ± 54% when tested at 100 µg/mL in Xenopus oocytes transiently expressing gamma aminobutyric acid type A receptors composed of α1ß2γ2s subunits. In zebrafish larvae, the extract significantly lowered pentylenetetrazol-provoked locomotion when tested at 4 µg/mL. Active compounds of the extract were tracked with the aid of HPLC-based activity profiling utilizing a previously validated zebrafish larval locomotor activity assay. From two active HPLC fractions, compounds 1 - 3 were isolated. Structurally related compounds 4 - 6 were purified from a later eluting inactive HPLC fraction. With the aid of 1H and 13C NMR and high-resolution mass spectrometry, compounds 1 - 6 were identified as analogues of anacardic acid. Compounds 1 - 3 led to a concentration-dependent decrease of pentylenetetrazol-provoked locomotion in the zebrafish larvae model, while 4 - 6 were inactive. Compounds 1 - 3 enhanced gamma aminobutyric acid-induced chloride currents in Xenopus oocytes in a concentration-dependent manner, while 4 - 6 only showed marginal enhancements of gamma aminobutyric acid-induced chloride currents. Compounds 2, 3, and 5 have not been reported previously.

Multisite organic-inorganic hybrid catalysts for the direct sustainable synthesis of GABAergic drugs.

Multisite organic-inorganic hybrid catalysts have been prepared and applied in a new general, practical, and sustainable synthetic procedure toward industrially relevant GABA derivatives. The domino sequence is composed of seven chemical transformations which are performed in two one-pot reactions. The method produces both enantiomeric forms of the product in high enantiopurity as well as the racemate in good yields after a single column purification step. This protocol highlights major process intensification, catalyst recyclability, and low waste generation.

Gomisin N isolated from Schisandra chinensis augments pentobarbital-induced sleep behaviors through the modification of the serotonergic and GABAergic system.

The fruits of Schisandra chinensis have been used for the treatment of insomnia in oriental countries for more than thousands of years. However, the pharmacological properties and the mechanism of sedative and hypnotic effects have not yet been studied. Gomisin N is one of the major bioactive constituents from the fruits of Schisandra chinensis, and in this paper we reported a detailed study on the effects and mechanisms of Gomisin N on its sedative and hypnotic activity for the first time. These results implied that Gomisin N possessed weak sedative effects on locomotion activity in normal mice, and produced a dose-dependent(5-45 mg/kg, i.p.) increase in sleep duration in pentobarbital-treated mice, thus, itself did not induce sleep at higher dose which was used in this experiment (45 mg/kg, i.p.). It also can reverse the rodent models of insomnia induced by p-chlorophenylalanine (PCPA) and caffeine, which could exhibit a synergistic effect with 5-hydroxytryptophan (5-HTP) as well; furthermore, the hypnotic effects of Gomisin N were inhibited by flumazenil (a specific GABAA-BZD receptor antagonist). Altogether, these results indicated that Gomisin N produced beneficial sedative and hypnotic bioactivity, which might be mediated by the modification of the serotonergic and GABAergic system.

Identification of GABA A receptor modulators in Kadsura longipedunculata and assignment of absolute configurations by quantum-chemical ECD calculations.

A petroleum ether extract of Kadsura longipedunculata enhanced the GABA-induced chloride current (I(GABA)) by 122.5±0.3% (n=2) when tested at 100 µg/ml in Xenopuslaevis oocytes expressing GABA A receptors (α(1)ß(2)γ(2S) subtype) in two-microelectrode voltage clamp measurements. Thirteen compounds were subsequently identified by HPLC-based activity profiling as responsible for GABA A receptor activity and purified in preparative scale. 6-Cinnamoyl-6,7-dihydro-7-myrceneol and 5,6-dihydrocuparenic acid were thereby isolated for the first time. The determination of the absolute stereochemistry of these compounds was achieved by comparison of experimental and calculated ECD spectra. All but one of the 13 isolated compounds from K. longipedunculata potentiated I(GABA) through GABA A receptors composed of α(1)ß(2)γ(2S) subunits in a concentration-dependent manner. Potencies ranged from 12.8±3.1 to 135.6±85.7 µM, and efficiencies ranged from 129.7±36.8% to 885.8±291.2%. The phytochemical profiles of petroleum ether extracts of Kadsura japonica fruits (114.1±2.6% potentiation of I(GABA) at 100 µg/ml, n=2), and Schisandra chinensis fruits (inactive at 100 µg/ml) were compared by HPLC-PDA-ESIMS with that of K. longipedunculata.