Biology subjects

Pyterson, M. P.

Publications and source records attributed to Pyterson, M. P..

3 recordsLinked to original sources

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

Phasic and tonic serotonin modulate alarm reactions and post-exposure behavior in zebrafish

Current theories on the role of serotonin (5-HT) in vertebrate defensive behavior suggest that this monoamine increases anxiety but decreases fear, by acting at different levels of the neuroaxis. This paradoxical, dual role of 5-HT suggests that a serotonergic tone inhibits fear responses, while an acute increase in 5-HT would produce anxiety-like behavior. However, so far no evidence for a serotonergic tone has been found. Using zebrafish alarm responses, we investigate the participation of phasic and tonic 5-HT levels in fear-like behavior, as well as in behavior after stimulation. Conspecific alarm substance (CAS) increased bottom-dwelling and erratic swimming, and animals transferred to a novel environment after CAS exposure (post-exposure behavior) showed increased bottom-dwelling and freezing. Clonazepam blocked CAS effects during and after exposure. Acute fluoxetine dose-dependently decreased fear-like behavior, but increased post-exposure freezing. Metergoline had no effect on fear-like behavior, but blocked the effects of CAS on post-exposure behavior; similar effects were observed with pCPA. Finally, CAS was shown to decrease the activity of monoamine oxidase in the zebrafish brain after exposure. These results suggest that phasic and tonic serotonin encode an aversive expectation value, switching behavior towards cautious exploration/risk assessment/anxiety when the aversive stimulus is no longer present.

neuroscience↗