Zoltán Kristóf Varga1,2; László Bíró1,2, Diána Pejtsik1, Áron Zsigmond3, Máté Varga3, Éva Mikics1, Blanka Tóth4, Vilmos Salamon1, Manó Aliczki1
1 Laboratory of Translational Behavioral Neuroscience, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest
2 Doctoral School of Neurosciences (János Szentágothai), Semmelweis University, Budapest
3 Eötvös Loránd University, Budapest
4 Budapest University of Technology and Economics, Budapest
Introduction: Effectively responding environmental threats requires the emergence of stress-induced internal states. Such ability depends on early experiences and, in connection, the adequate formation of central modulatory systems, particularly the development of serotonergic pathways.
Aims: In the current study we use zebrafish (Danio rerio) as a model to unravel the serotonergic background of experience-dependent behavioural responsiveness due to its relatively simple vertebrate central nervous system and robust behavioural stress responses.
Materials: First, we characterised a highly reactive period during development in which we subjected individuals to social isolation i.e. chronic deprivation of environmental stimuli, than described the connection between serotonergic changes and behavioural endpoints.
Results: Socially isolated fish showed delayed avoidance and lowered sensory responsiveness during novel stressful conditions compared to socially reared subjects. In line with such decreased reactivity, isolation exerted lower basal and increased stress-induced whole-brain serotonin content compared to controls. We detected similar differences on the level of forebrain limbic structures, e.g. structures homologous to the mammalian amygdala and hippocampus. Acute pharmacological blockade of serotonergic signalling through 5HT1A autoreceptor agonism prevented isolation-induced physiological and behavioural effects as well. Interestingly, the isolation-induced decrease in reactivity was specific to novelty-induced visually-driven challenges. In summary, we found that the absence of adequate stimuli in a sensitive developmental period impairs stress-induced but not basal responsiveness through the emergence of an atypical hyper-serotonergic phenotype.
Conclusion: Our results support the idea, that serotonergic signalling is one fundamental and ancient channel that transmits early-life information to the adult phenotype, establishing contextually relevant challenge coping.
Doctoral School: Neurosciences (“János Szentágothai”)
Supervisor: Manó Aliczki
E-mail address: email@example.com