Therapeutic potential of Syzygium cumini L. extract in treating anxiety in adult zebrafish (Danio rerio): Behavioral, toxicological, and molecular evidence involving the GABAergic and serotonergic pathways.

Anxiolytic-like effect of brominated compounds from the marine sponge Aplysina fulva on adult zebrafish (Danio rerio): Involvement of the GABAergic system

Antibacterial activity and anxiolytic-like effect of Ziziphus joazeiro Mart. leaves in adult zebrafish (Danio rerio)

Structural and spectroscopic analysis, ADMET study, and anxiolytic-like effect in adult zebrafish (Danio rerio) of 4′-[(1E,2E)-1-(2-(2′,4′-dinitrophenyl)hydrazone-3-(4-methoxyphenyl)allyl)aniline

General anxiety disorders are among the most prevalent mental health problems worldwide. The emergence and development of anxiety disorders can be due to genetic (30–50%) or non-genetic (50–70%) factors. Despite medical progress, available pharmacotherapies are sometimes ineffective or can cause undesirable side effects. Thus, it becomes necessary to discover new safe and effective drugs against anxiety. This study evaluated the anxiolytic effect in adult zebrafish (Danio rerio) of a natural pyrroloformamide (PFD), N-(4,5-dihydro-5-oxo-1,2-dithiolo-[4,3,b]-pyrrole-6-yl)-N-methylformamide, isolated from a Streptomyces sp. bacterium strain recovered from the ascidian Eudistoma vannamei. The complete structure of PFD was determined by a detailed NMR analysis, including 1H–13C and 1H–15N-HBMC data. In addition, conformational and DFT computational studies also were performed. A group of fishes (n = 6) was treated orally with PFD (0.1, 0.5 and 1.0 mg/mL; 20 μL) and subjected to locomotor activity and light/dark tests, as well as, acute toxicity 96 h. The involvement of the GABAergic and serotonergic (5-HT) systems was investigated using flumazenil (a silent modulator of GABA receptor) and 5-HT1, 5-HT2A/2C and 5-HTR3A/3B receptors antagonists, known as pizotifen, granisetron and cyproheptadine, respectively. PFD was nontoxic, reduced locomotor activity and promoted the anxiolytic effect in zebrafish. Flumazenil did not inhibit the anxiolytic effect of the PFD via the GABAergic system. This effect was reduced by a pretreatment with pizotifen and granisetron, and was not reversed after treatment with cyproheptadine. Molecular docking and dynamics studies confirmed the interaction of PFD with the 5-HT receptor. Communicated by Ramaswamy H. Sarma

Metabolic profile of pitaya (Hylocereus polyrhizus (F.A.C. Weber) Britton & Rose) by UPLC-QTOF-MSE and assessment of its toxicity and anxiolytic-like effect in adult zebrafish.

Zebrafish is an excellent model that can be utilized as an adjunct to current rodent models for studies of eye diseases because the anatomy and ultrastructural characterization of its cornea show much similarity with the human cornea. Therefore, we developed a behavioral model of corneal nociception using the adult zebrafish (Danio rerio). We analyzed the nociceptive effect of hypertonic saline (0.15-5.0 M sodium chloride [NaCl]) applied to the surface of the right or left cornea, on the animals' gender and locomotor activity through the open-field test. The behavioral model of corneal nociception was characterized by the antinociceptive effect of morphine (8.0 or 16 mg/kg; intraperitoneally [i.p.]), an opioid analgesic, and capsazepine, an antagonist of transient receptor potential vanilloid type 1 channels. We also tested whether the corneal antinociceptive effect of morphine could be modulated by naloxone, an opioid antagonist. Finally, we used the light and dark test to assess the anxiolytic effect of hypertonic saline (5.0 M NaCl; 5 μL) applied to the right or left cornea of the animals. As a result, hypertonic saline significantly increased (p < 0.01 vs. control) the corneal nociceptive behavior of adult zebrafish (D. rerio). Morphine significantly inhibited (p < 0.01 vs. 5.0 M NaCl) the hypertonic saline-induced corneal nociception and this effect was blocked by naloxone. Capsazepine (20 mg/kg; i.p.) significantly inhibited (p < 0.05 vs. control) the corneal nociception induced by hypertonic saline. Hypertonic saline, applied to the surface of the right or left cornea of the animals, induced nociception and did not cause a presumptive anxiolytic effect. Gender and site of application did not affect the profile of response to hypertonic saline. The results suggest that the adult zebrafish can also be used as a behavioral model of corneal nociception, with the advantages of significant homology with the human genome and low cost.

This study evaluated the anxiolytic and memory-protective effects of withanolide D in adult zebrafish (Danio rerio). The compound was administered at doses of 4, 20, and 40mg/kg and showed no signs of toxicity after 96h of observation at any of the doses tested. In the open field test, withanolide D reduced locomotor activity, indicating a sedative-like effect. Nevertheless, in the light/dark test, doses of 20 and 40mg/kg produced an anxiolytic-like response, suggesting that anxiolytic and motor effects may partially overlap depending on dose. The anxiolytic effect observed at the minimum effective dose (20mg/kg) was reversed by flumazenil (FMZ), supporting the involvement of a benzodiazepine-sensitive GABAA modulatory domain. Furthermore, withanolide D, at a dose of 4mg/kg, prevented ethanol-induced memory impairment in the inhibitory avoidance task, suggesting a protective effect on memory consolidation. Molecular docking analyses revealed favorable interactions of withanolide D at the extracellular α1γ2 interface of the GABAA receptor, supporting a putative allosteric interaction in a functionally related modulatory region rather than definitive occupation of the classical diazepam site. Consistently, normal mode analysis (NMA) showed that withanolide D increases receptor mobility compared to diazepam, with RMSF values reaching up to 0.98 Å, indicating enhanced structural flexibility and dynamic modulation of the protein. Thus, these findings suggest that withanolide D has therapeutic potential for the treatment of anxiety, in addition to providing protective effects on memory.

Introduction: Generalized anxiety disorder is a neurological condition that can lead to cardiovascular disease and type II diabetes mellitus. Physical activity and the consumption of foods rich in antioxidant compounds are strategies that substantially improve anxiety. Purpose: This study aimed to assess the cytotoxic potential of methanolic extracts obtained from the pulp and seeds of Annona squamosa using different analytical approaches, in addition to investigating their anxiolytic and anticonvulsant effects in adult zebrafish. Methods: For toxicity in Artemia salina, eggs were incubated and, after hatching, the larvae were exposed to concentrations of extracts (0.06-5 μg/mL) for 24 hours. Toxicity in Drosophila melanogaster involved exposure to different concentrations of extracts (125-2000 μg/mL) with mortality readings every 3, 6, 12, 24, and 48 hours. Locomotor damage was assessed using the negative geotaxis test. In Danio rerio, anxiolytic activity was investigated through open field, light/dark, and PTZ-induced convulsion tests, where fish were exposed to oral extracts at different concentrations (40, 200, and 400 mg/kg). GABAergic neuromodulation was analyzed using benzodiazepine antagonists. Results: The extracts demonstrated high cytotoxicity against A. salina, with LD50 values of 2.24 μg/mL for the pulp extract and 1.64 μg/mL for the seed extract. In D. melanogaster, toxic effects were limited, with mild toxicity observed for the seed extract at high concentrations. In the zebrafish model, the seed extract showed toxicity at doses higher than 200 mg/kg, while the pulp extract was non-toxic. In terms of locomotor activity, both extracts affected the locomotor behavior of fish and D. melanogaster, with the seed exhibiting more pronounced effects. In the anxiolytic test, the extracts displayed effects similar to diazepam, modulating behavior via GABAergic neurotransmission. Finally, the seed extract demonstrated anticonvulsant activity in zebrafish, particularly in the acute and chronic stages of PTZ-induced seizures, indicating specific therapeutic potential. Discussion: The pulp and seed extracts have different toxicological profiles, with greater toxicity associated with the seed extract, especially at high concentrations. The changes in locomotor behavior and the anxiolytic effects observed in both models suggest that they act on neuromodulatory pathways, possibly mediated by the GABAergic system. The anticonvulsant activity of the seed extract in the acute and chronic stages of PTZ-induced seizures in zebrafish points to a potential therapeutic use in neurological disorders. Conclusion: The study revealed that the methanolic extract from the pulp of A. squamosa exhibited a safe anxiolytic effect, while the seed extract showed both anxiolytic and anticonvulsant effects, albeit with acute toxicity. New formulations are suggested to reduce the toxicity of the seeds and explore the plant’s therapeutic potential.

Phytoceutical isoquercitrin and ethanolic extracts from pequi (Caryocar coriaceum Wittm) reverse alcohol withdrawal-induced anxiety in adult zebrafish (Danio rerio).

Background This work presents the development of functional beverages for brain health support formulated with matcha, sugarcane juice, and medicinal plants chamomile (CT) and lemon balm (LB) tea extracts Methods For this, the anxiolytic-like effects were assessed using the in vivo adult zebrafish (Danio rerio) model for behavioral and toxicological analyses, as well as the in vitro bioactivity and total phenolic content TPC. Initially, three beverage bases with matcha and sugarcane juice were tested. Based on the positive anxiolytic-like effects, the prioritized beverage base BB3 (35% matcha and 65% sugarcane juice, v/v, 10.2 °Brix) was selected to produce three experimental beverages BBC (70% BB3, 30% CT), BBLB (70% BB3, 30% LB) and BBCLB (70% BB3, 15% LB and 15% CT). Results Prioritized beverages BBLB and BBCLB had no effect on the adult zebrafish locomotion behavior and showed similar anxiolytic-like effects and phenolics bioaccessibility (29.8% and 30.8% for BBLB and BBCLB, respectively), as well as no toxicity. BBLB and BBCLB also showed similarly high phenolic content (669.84 ± 19.47 mg GAE/L and 729.43 ± 41.49 mg GAE/L, respectively). Conclusion A complex phenolic profile was observed for both beverages and myricetin, and chlorogenic acid was the predominant phenolic compound detected. Overall, this study demonstrated the successful development of safe, functional polyphenol-rich beverages with anxiolytic-like effects using readily available plant-based materials.

Azadirachta indica A. Juss is known as the tree of life for its diverse pharmacological applications. This study evaluated the effect of the anxiolytic type of bark of A. indica and mechanisms of action on adult zebrafish. Initially, EtCNeem toxicity was detected against Artemia salina, eliminated with the saponification reaction. The antioxidant potential of the fractions was evaluated. The fraction with higher antioxidant potential was submitted to the preliminary chemical prospecting, FT-IR, and the phenol and flavonoid content was determined. The animals were treated with the most promising antioxidant fraction (1.0; 2.5 or 5.0 mg/mL, i.p.) and underwent acute toxicity, open field tests and Light &amp; Dark Test, evaluating the participation of serotonergic and GABAergic systems in the anxiolytic test. As a result, we selected the fraction of ethyl acetate (F-EtOAc) rich in phenolic and flavonoid compounds with antioxidant potential, which had a sedative and anxiolytic effect on adult zebrafish through serotonergic and GABAergic systems. F-EtOAc prevented alcohol-induced chronic anxiety in adult zebrafish. The results suggest that F-EtOAc is an anxiolytic agent mediated via the GABAergic and serotonergic system

The zebrafish (Danio rerio) has been proposed as a low-cost and simple alternative to the use of higher vertebrates in laboratory research on novel compounds with antinociceptive potential. In this study, we tested adult zebrafish (Danio rerio) as an alternative behavioral model of formalin-induced nociception. We evaluated the nociceptive effect of 0.1% formalin (3 or 5 μL; intramuscularly [i.m.]), applied into the tail or lips, on locomotor activity, using as parameter the number of times the fish crossed the lines between the quadrants of a glass Petri dish during the neurogenic stage (0-5 min) and the inflammatory stage (15-30 min). The behavioral model was validated by testing the antinociceptive effect of morphine and indomethacin (standard analgesic drugs used in the formalin test of rodents). We also tested whether the effect of morphine could be modulated by naloxone, an opioid antagonist. The effect of morphine and indomethacin on zebrafish locomotor behavior was evaluated with the open field test. The white/black test was used to rule out the anxiolytic effect of 0.1% formalin injected into the tail on adult zebrafish. Formalin (0.1%; 3 and 5 μL injected into the tail) increased significantly the nociceptive behavior of the adult zebrafish in both stages (p < 0.001 vs. control). Morphine and indomethacin (both 0.2 mg/mL; 20 μL; intraperitoneally [i.p.]) significantly inhibited nociception induced with formalin (5 μL injected i.m. into the tail) in both stages (p < 0.001). Naloxone blocked the antinociceptive effect of morphine. No influence on locomotion was observed. Locally administered formalin (injected into the tail) induced nociception, but not anxiety. The results suggest that the adult zebrafish behavioral model is a feasible alternative to more conventional laboratory models used in research on novel compounds with antinociceptive potential.

Lipopolysaccharide-induced abdominal nociception behavioral model in adult zebrafish (Danio rerio).

Structural characterization, electronic properties, and anxiolytic-like effect in adult zebrafish (Danio rerio) of cinnamaldehyde chalcone

Anxiolytic-like effect of chalcone N-{(4′-[(E)-3-(4-fluorophenyl)-1-(phenyl) prop-2-en-1-one]} acetamide on adult zebrafish (Danio rerio): Involvement of the GABAergic system