Zebrafish is becoming a popular animal model in neuropharmacology and drug discovery, mainly due to its ease of handling and low costs involved in maintenance and experimental work. This animal displays a series of complex behaviours that makes it useful for assessing the effects of psychoactive drugs. Here, adult zebrafish were used for assessment of the anxiolytic and anti-addictive properties of UFR2709, a nicotinic receptor (nAChR) antagonist, using two behavioural paradigms to test for addiction, the novel tank diving test to assess anxiety and the conditioned place preference (CPP). Furthermore, the expression of nAChR subunits α4 and α7 was measured in the zebrafish brain. The results show that UFR2709 exhibits an anxiolytic effect on zebrafish and blocks the effect evoked by nicotine on CPP. Moreover, UFR2709 significantly decreased the expression of α4 nicotinic receptor subunit. This indicates that UFR2709 might be a useful drug for the treatment of nicotine addiction.

Insect nicotinic acetylcholine receptors (nAChRs) are molecular targets of highly effective insecticides such as neonicotinoids. Functional expression of these receptors provides useful insights into their functional and pharmacological properties. Here, we report that the α5 nAChR subunit of the honey bee, Apis mellifera, functionally expresses in Xenopus laevis oocytes, which is the first time a homomeric insect nAChR has been robustly expressed in a heterologous system without the need for chaperone proteins. Using two-electrode voltage-clamp electrophysiology we show that the α5 receptor has low sensitivity to acetylcholine with an EC₅₀ of 2.37 mM. However, serotonin acts as an agonist with a considerably lower EC₅₀ at 119 μM that is also more efficacious than acetylcholine in activating the receptor. Molecular modelling indicates that residues in the complementary binding site may be involved in the selectivity towards serotonin. This is the first report of a ligand-gated ion channel activated by serotonin from an insect and phylogenetic analysis shows that the α5 subunit of A. mellifera and other non-Dipteran insects, including pest species, belong to a distinct subgroup of subunits, which may represent targets for the development of novel classes of insecticides.

Nicotinic acetylcholine receptors (nAChRs) are best known for mediating the fast actions of acetylcholine. However, the spectrum of other neurotransmitters possibly acting on these receptors is not well understood. Here, we report that the α5 nAChR subunit of the honey bee, Apis mellifera , when expressed in Xenopus laevis oocytes, has unusual pharmacological properties in that it has high sensitivity towards dopamine, tyramine and octopamine with EC ₅₀ values of 3.37 μM, 91.1 μM and 378 μM, respectively, whereas the EC ₅₀ for acetylcholine is 2.37 mM. The biogenic amines are also considerably more efficacious than acetylcholine in activating the receptor. Molecular dynamics simulations and expression of α5 mutants identify the lack of a proline doublet in loop E as playing a major role in determining dopamine efficacy. Together with phylogenetic analysis using homologous receptors from other species, this study enhances our understanding of how ligand-gated ion channels evolve functional diversity.

Potato (Solanum tuberosum) is one of the most important food crops worldwide, and Rhizoctonia solani infection is one of the most common diseases. The objective of this study was to evaluate the antifungal activity of Vitis vinifera byproducts (VIDES) and flesh-coloured potato (FCP) extracts against Rhizoctonia sp. in potato crops. Photosynthetic traits, phenolic profiles, and antioxidant and enzymatic activities were determined. The VIDES extract showed a 151.4% improvement in stomatal conductance and a 258.5% improvement in the photosynthetic rate compared to the plants without infection. Regarding the enzymatic antioxidant activity, the best response was found in the FCP treatments with 30 min of application, with increases of 25%, 161%, and 450% in ascorbate peroxidase, catalase (CAT), and glutathione reductase (GR) activities, respectively, compared to plants without infection. For the VIDES extract, a 15 min application produced an 83% increase in CAT activity, whereas a 181% increase in GR activity compared to plants without infection was produced after a 30 min application. A similar behaviour was observed for antioxidant compounds, where FCP had a higher concentration of compounds and antioxidant activity. This finding suggests that FCP and VIDES promote the synthesis of plant-defence compounds against Rhizoctonia sp. in potato crops, in which the application time is a determining factor.

Neuronal α4β2 nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels (LGIC) that have been implicated in nicotine addiction, reward, cognition, pain disorders, anxiety, and depression. Nicotine has been widely used as a template for the synthesis of ligands that prefer α4β2 nAChRs subtypes. The most important therapeutic use for α4β2 nAChRs is as replacement therapy for smoking cessation and withdrawal and the most successful therapeutic ligands are partial agonists. In this case, we use the N-methylpyrrolidine moiety of nicotine to design and synthesize new α4β2 nicotinic derivatives, coupling the pyrrolidine moiety to an aromatic group by introducing an ether-bonded functionality. Meta-substituted phenolic derivatives were used for these goals. Radioligand binding assays were performed on clonal cell lines of hα4β2 nAChR and two electrode voltage-clamp experiments were used for functional assays. Molecular docking was performed in the open state of the nAChR in order to rationalize the agonist activity shown by our compounds.

Nicotinic acetylcholine receptors (nAChRs), serotonin transporters (SERT) and dopamine transporters (DAT) represent targets for the development of novel nicotinic derivatives acting as multiligands associated with different health conditions, such as depressive, anxiety and addiction disorders. In the present work, a series of functionalized esters structurally related to acetylcholine and nicotine were synthesized and pharmacologically assayed with respect to these targets. The synthesized compounds were studied in radioligand binding assays at α4β2 nAChR, h-SERT and h-DAT. SERT experiments showed not radioligand [³H]-paroxetine displacement, but rather an increase in the radioligand binding percentage at the central binding site was observed. Compound 20 showed K_i values of 1.008 ± 0.230 μM for h-DAT and 0.031 ± 0.006 μM for α4β2 nAChR, and [³H]-paroxetine binding of 191.50% in h-SERT displacement studies, being the only compound displaying triple affinity. Compound 21 displayed K_i values of 0.113 ± 0.037 μM for α4β2 nAChR and 0.075 ± 0.009 μM for h-DAT acting as a dual ligand. Molecular docking studies on homology models of α4β2 nAChR, h-DAT and h-SERT suggested potential interactions among the compounds and agonist binding site at the α4/β2 subunit interfaces of α4β2 nAChR, central binding site of h-DAT and allosteric modulator effect in h-SERT.