Biology subjects

de Siqueira-Silva, D. H.

Publications and source records attributed to de Siqueira-Silva, D. H..

4 recordsLinked to original sources

bioRxiv2024

Flavonoids as anxiolytics in animal tests: Bibliometry and meta-analysis of the effects of flavonoids on anxiety-like behavior in animal tests

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/596117v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@177bd39org.highwire.dtl.DTLVardef@27f63forg.highwire.dtl.DTLVardef@197a43aorg.highwire.dtl.DTLVardef@9f0ad0_HPS_FORMAT_FIGEXP M_FIG C_FIG Flavonoids are natural secondary compounds of plants with a basic composition derived from polyphenols that can produce a plethora of different neurochemical effects, some of which are relevant to anxiety disorders. As such, many flavonoids have been evaluated in behavioral screens in preclinical research on anxiolytics. Given the many different molecular subclasses of flavonoids, the many different molecular targets that have been proposed for these compounds, and the different research priorities that arise in preclinical research, we sought to map the potential of flavonoids as anxiolytics by bibliometric analysis and a meta-analysis of animal tests using these compounds. Bibliometric analysis suggest that the field is highly concentrated on few research groups that are mostly located in the Global South, suggesting the need to improve international collaborations. The themes which emerged in the bibliometric analysis are driven by the exploratory steps of pharmacological research, including finding anxioselective effects and looking for dose-response patterns; this suggests that the field, as a whole, could benefit from more mechanistic and confirmatory research. The meta-analysis showed strong evidence for an anxiolytic-like effect of flavonoids on animal tests, including assays made in rats, mice, and zebrafish (SMD = -1.4398, 95%CI[-1.7319, - 1.1477]). Subgroup analysis suggested that this effect is present in acute treatment (SMD = -1.14, 95%CI[-1.36, -0.93]), but not after chronic treatment (SMD = -1.96, 95%CI[-4.93; 1.01]). For all molecule subclasses included in the study, only isoflavones, glycoside derivatives, and flavanolignans did not show evidence of an anxiolytic-like effect, although the low number of studies including these subclasses is low. We finish with a set of recommendations for preclinical research on the anxiolytic potential of flavonoids.

pharmacology and toxicology↗

bioRxiv2023

Serotonergic mediation of orienting and defensive responses in zebrafish

Serotonin (5-HT) is involved in arousal and defensive responses, both of which represent modulators of attention and orienting. Orienting responses (ORs), considered as a unit of attentional processing, are elicited by novel innocuous stimuli, differ from defense reflexes (DR)s, as the latter are elicited by painful and threatening stimuli. When zebrafish (Danio rerio) are exposed to a conspecific alarm substance (CAS), visual stimuli elicit a DR instead of ORs, suggesting a state of hypervigilance. CAS elicited an OR-to-DR shift, as shown both by the shift from an approach to an escape response when the stimulus was turned on and by the changes in directional focus. Both pCPA and 5-HTP attenuated the CAS-elicited OR-to-DR shift . While pCPA did not alter ORs in animals which were not exposed to CAS, 5-HTP abolished those responses, suggesting that the serotonergic tone is important in regulating the general arousal levels in zebrafish.

neuroscience↗

bioRxiv2022

Roles of the 5-HT2C receptor on zebrafish sociality

Serotonin (5-HT) receptors have been implicated in social behavior in vertebrates. Zebrafish (Danio rerio) have been increasingly being used behavioral neuroscience to study the neurobiological correlates of behavior, including sociality. Nonetheless, the role of 5-HT2C receptors in different social functions were not yet studied in this species. Zebrafish were treated with the agonist MK-212 (2 mg/kg) or the antagonist RS-102221 (2 mg/kg) and tested in the social interaction and social novelty tests, conditional approach test, or mirror-induced aggressive displays. MK-212 increased preference for an unknown conspecific in the social investigation test, but also increased preference for the known conspecific in the social novelty test; RS-102221, on the other hand, decreased preference in the social investigation test but increased preference for the novel conspecific in the social novelty test. MK-212 also decreased predator inspection in the conditional approach test. While RS-102221 decreased time in the display zone in the mirror-induced aggressive display test, it increased display duration. Overall, these results demonstrate the complex role of 5-HT2C receptors in different social contexts in zebrafish, revealing a participation in social plasticity in vertebrates.

neuroscience↗

bioRxiv2019

A model to study orienting responses in zebrafish, and applications towards the emotion-cognition interaction

Orienting responses (ORs) are whole-organism reflexes that are elicited by innocuous stimuli, and which decrease in magnitude after stimulus repetition. ORs represent relatively simple responses that can be used to study attentional processes, and are modulated by the organism’s state, including arousal and activation levels, as well as by emotional processes. Here we describe a simple method to study ORs in zebrafish, a model organism increasingly being used in behavioural neuroscience. After presentation of a static visual stimulus, an OR is elicited, characterized by approaching the stimulus and orienting towards it. After repeated stimulation, OR decreases, suggesting habituation. These responses are qualitatively altered by exposure to a fear-eliciting alarm substance (i.e., derived from the skin of a conspecific), since exposed animals avoid the visual stimulus and orient either away from the stimulus or towards it, but at a distance. The protocol can be used to study orienting responses, as well as the impact of fear and arousal on these reflexes.Competing Interest StatementThe authors have declared no competing interest.View Full Text

animal behavior and cognition↗