Optimization of a locomotion-based zebrafish seizure model

BACKGROUND

Locomotor assays in zebrafish have emerged as a screening test in early drug discovery for antiseizure compounds. However, parameters differ considerably between published studies, which may explain some discrepant results with (candidate) antiseizure medications.

NEW METHOD

We optimized a locomotor-based seizure assay in zebrafish with pentylenetetrazol (PTZ) as the pharmacological proconvulsant to generate a therapeutic window in which proconvulsant-treated zebrafish larvae could be discriminated from a non-treated control. To generate a reliable control, exposure time and concentration of valproate (VPA, anticonvulsant) was optimized.

RESULTS

Wells with one or three larvae show a similar PTZ dose-dependent increase in locomotion with less variability in motility for the latter. Zebrafish immersed in 10 mM PTZ showed a significant increase in movement with a sustained effect, without any indication of toxicity. Animals treated with 3 mM VPA showed the strongest reduction of PTZ-induced movement without toxicity. The decrease in PTZ-induced locomotion was greater after 18 h versus 2 h.

COMPARISON WITH EXISTING METHOD(S)

For the larval zebrafish PTZ-induced seizure model, varying experimental parameters have been reported in literature. Our results show that PTZ is often used at toxic concentrations, and we provide instead reliable conditions to quantify convulsant behaviour using an infrared-beam motility assay.

CONCLUSIONS

We recommend using three zebrafish larvae per well to quantify locomotion in 96-multiwell plates. Larvae should preferably be exposed to 10 mM PTZ for 1 h, consisting of 30 min acclimation and 30 min subsequent recording. As positive control for anticonvulsant activity, we recommend exposure to 3 mM VPA for 18 h before administration of PTZ.

Alonso S, Prieto MJ. Combined Therapy for Alzheimer's Disease: Tacrine and PAMAM Dendrimers Co-Administration Reduces the Side Effects of the Drug without Modifying its Activity

Alzheimer's disease has become a public health priority, so an investigation of new therapies is required. Tacrine (TAC) was licensed for treatments; however, its oral administration caused hepatotoxicity, so it is essential to reduce the side effects. PAMAM dendrimer generation 4.0 and 4.5 (DG4.0 and DG4.5) can be used as drug delivery systems and as nanodrugs per se. Our work aims to propose a combined therapy based on TAC and PAMAM dendrimer co-administration. TAC and dendrimer interactions were studied by in vitro drug release, drug stability, and FTIR. The toxicity profile of co-administration was evaluated in human red blood cells, in Neuro-2a cell culture, and in zebrafish larvae. Also, the anti-acetylcholinesterase activity was studied in cell culture. It was possible to obtain DG4.0-TAC and DG4.5-TAC suspensions, without reducing the drug solubility and stability. FTIR and in vitro release studies confirmed that interaction between TAC and DG4.5 was of the electrostatic type. No toxicity effects on human red blood cells were observed, whereas the co-administration with DG4.5 reduced cytotoxicity of TAC on the Neuro-2a cell line. Moreover, in vivo co-administration of both DG4.0-TAC and DG4.5-TAC reduced the morphological and hepatotoxic effects of TAC in zebrafish larvae. The reduction of TAC toxicity was not accompanied by a reduction in its activity since the anti-acetylcholinesterase activity remains when it is co-administrated with dendrimers. In conclusion, the co-administration of TAC with both DG4.0 and DG4.5 is a novel therapy since it was less-toxic, was more biocompatible, and has the same effectiveness than the free drug. Graphical abstract.

Persistent and transgenerational effects of risperidone in zebrafish

Since behavior is the connection between the internal physiological processes of an animal and its interaction with the environment, a complete behavioral repertoire is crucial for fish survival and fitness, at both the individual and population levels. Thus, unintended exposure of non-target organisms to antipsychotic residues in the environment can impact their normal behavior, and some of these behavioral changes can be seen during the entire life of the animal and passed to subsequent generations. Although there are some reports related to transgenerational toxicology, little is known of the long-term consequences of exposure to pharmaceutical compounds such as risperidone. Here, we show that zebrafish exposed to risperidone (RISP) during embryonic and larval stages presented impaired anti-predatory behavior during adulthood, characterizing a persistent effect. We also show that some of these behavioral changes are present in the following generation, characterizing a transgenerational effect. This suggests that even short exposures to environmentally relevant concentrations, at essential stages of development, can persist throughout the whole life of the zebrafish, including its offspring. From an environmental perspective, our results suggested possible risks and long-term consequences associated with drug residues in water, which can affect aquatic life and endanger species that depend on appropriate behavioral responses for survival.

Biological response and developmental toxicity of zebrafish embryo and larvae exposed to multi-walled carbon nanotubes with different dimension

The development and use of nanomaterials are increasing significantly. Among nanomaterials, carbon nanotubes are of particular interest due to its distinctive physicochemical properties. This material composed of sheets of graphite has very high thermal conductivity, metallic-type electrical conductivity, stiffness, toughness and unique ability to bond to itself in an extended network with extraordinary strength. Its application in the industry is continuously growing, which could lead to the accumulation in the environment and a consequent impact on both humans and ecosystems. Considering that environmental systems are dynamic, it is difficult to predict the risks associated with the release of nanomaterials to the environment. Bioindicators are useful tools as primary signals of environmental risk, and their responses reveal the organism and ecosystem health.

In the present study, we evaluated the impact of multi-walled carbon nanotubes with different dimensions and agglomeration pattern on zebrafish embryo and larvae; mainly, studies were focused on physiological and behavioral responses. In embryos, measurements were hatching rate, morphology changes, and viability. In larvae, locomotor activity, heart rate, innate inflammatory response, general and tissue-specific morphology were measured. MWCNT-S (short, wide and mostly dispersed) caused depression of the locomotor activity of larvae, indicating an alteration of the central nervous system, and depression of neutrophil migration activity. MWCNT-L (long, thin and agglomerated) caused malformations during larval development, a decrease of neutrophil migration and alteration of cardiac rhythm. Results obtained for both carbon nanotubes were different, highlighting the importance of dimensions of the same nanomaterial, and also the kind of agglomeration and shape adopted, for the toxic effects on organisms.

Synthesis, Characterisation and In Vitro Permeation, Dissolution and Cytotoxic Evaluation of Ruthenium(II)-Liganded Sulpiride and Amino Alcohol

Sulpiride (SPR) is a selective antagonist of central dopamine receptors but has limited clinical use due to its poor pharmacokinetics. The aim of this study was to investigate how metal ligation to SPR may improve its solubility, intestinal permeability and prolong its half-life. The synthesis and characterisation of ternary metal complexes [Ru(p -cymene)(L)(SPR)]PF6 (L1 = (R)-(+)-2-amino-3-phenyl-1-propanol, L2 = ethanolamine, L3 = (S)-(+)-2-amino-1-propanol, L4 = 3-amino-1-propanol, L5 = (S)-(+)-2-pyrrolidinemethanol) are described in this work. The stability constant of the [Ru(p -cymene)(SPR)] complex was determined using Job's method. The obtained value revealed higher stability of the metal complex in the physiological pH than in an acidic environment such as the stomach. The ternary metal complexes were characterised by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermal analyses, Ultraviolet-Visible (UV-Vis). Solubility studies showed higher aqueous solubility for complexed SPR than the free drug. Dissolution profiles of SPR from the metal complexes exhibited slower dissolution rate of the drug. Permeation studies through the pig's intestine revealed enhanced membrane permeation of the complexed drug. In vitro methyl thiazolyl tetrazolium (MTT) assay showed no noticeable toxic effects of the ternary metal complexes on Caco-2 cell line.

Nano-formulation for topical treatment of precancerous lesions: skin penetration, in vitro, and in vivo toxicological evaluation

With the aim of improving the topical delivery of the antineoplastic drug 5-fluorouracil (5FU), it was loaded into ultradeformable liposomes composed of soy phosphatidylcholine and sodium cholate (UDL-5FU). The liposome populations had a mean size of 70 nm without significant changes in 56 days, and the ultradeformable formulations were up to 324-fold more elastic than conventional liposomes. The interaction between 5FU and the liposomal membrane was studied by three methods, and also release profile was obtained. UDL-5FU did penetrate the stratum corneum of human skin. At in vitro experiments, the formulation was more toxic on a human melanoma-derived than on a human keratinocyte-derived cell line. Cells captured liposomes by metabolically active processes. In vivo toxicity experiments were carried out in zebrafish (Danio rerio) larvae by studying the swimming activity, morphological changes, and alterations in the heart rate after incubation. UDL-5FU was more toxic than free 5FU. Therefore, this nano-formulation could be useful for topical application in deep skin precancerous lesions with advantages over current treatments. This is the first work that assessed the induction of apoptosis, skin penetration in a Saarbrücken penetration model, and the toxicological effects in vivo of an ultradeformable 5FU-loaded formulation.

Psychotropic in the environment: risperidone residues affect the behavior of fish larvae

The ability to avoid and escape from predators are clearly relevant behaviors from the ecological perspective and directly interfere with the survival of organisms. Detected in the aquatic environment, risperidone can alter the behavior of exposed species. Considering the risk of exposure in the early stages of life, we exposed zebrafish embryos to risperidone during the first 5 days of life. Risperidone caused hyperactivity in exposed larvae, which in an environmental context, the animals may be more vulnerable to predation due to greater visibility or less perception of risk areas.

Skin penetration and UV-damage prevention by nanoberries

BACKGROUND

Ethanolic extract from blueberry (Vaccinium myrtillus) is rich in anthocyanins and thus exhibits antioxidant activity. On the other hand, ultradeformable liposomes are capable of penetrating to the impermeable barrier of skin. Nanoberries are ultradeformable liposomes carrying blueberry extract.

OBJECTIVES

In this study, their capacity to penetrate the stratum corneum and photodamage prevention were tested, with the aim of developing a topical formulation for skin protection from environmental damage.

METHODS

Nanoberries were prepared by lipid film resuspension with ethanolic extract from blueberry, followed by sonication and incorporation to a gel. Size, zeta potential, deformability, rheology, and viscoelasticity were determined. Toxicity was assessed in vivo in zebrafish model, while in vitro cytotoxicity assay was performed on HaCaT and HEK-293T cell lines. Skin penetration was evaluated with the Saarbrücken penetration model followed by tape stripping, cryosection, or optical sectioning. UV-damage protection and photoprotection were determined by ad hoc methods with UVA, UVB, and UVC radiation on HaCaT cells. Wound assay was performed on HaCaT cells.

RESULTS

Nanoberries of about 100 nm, with differential elastic properties, did penetrate the stratum corneum, with low toxicity. When HaCaT cells were exposed to UV radiation in the presence of nanoberries, their viability was maintained.

CONCLUSIONS

Nanoberries could be effective to protect the skin from sun photodamage.

VY6, a β-lactoglobulin-derived peptide, altered metabolic lipid pathways in the zebra fish liver

Today enormous research efforts are being focused on alleviating the massive, adverse effects of obesity. Short peptides are key targets for research as they can be generated from natural proteins, like milk. Here we conducted trypsinogen digestion of beta-lactoglobulin (β-lg), the major mammalian milk protein, to release the hexamer VY6. It was assayed in vivo for its activities on lipid metabolism using zebra fish as a vertebrate model. Zebra fish juveniles were injected with two different doses of the peptide: 100 and 800 μg per g fish and left for 5 days before sacrificing. Lipid measurements showed significant reduction in liver triglycerides and free cholesterol, as well as increased liver HDL cholesterol. Dose-dependent increases of the mRNA levels of the genes coding for the enzymes acyl coenzyme A oxidase 1 (acox1) and lipoprotein lipase (lpl) were also found. The complete results suggest significant anti-obesity activity of the β-lg-derived VY6 peptide. Its use as a nutraceutical has been discussed.