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Front. Behav. Neurosci. | doi: 10.3389/fnbeh.2018.00284

Modulation of Fear and Arousal Behavior by Serotonin Transporter (5-HTT) Genotypes in Newly Hatched Chickens

  • 1UniversitätsSpital Zürich, Switzerland
  • 2Institut für Tierschutz und Tierhaltung, Friedrich Loeffler Institut, Germany

The serotonin transporter (5-HTT) plays a key role in regulating serotonergic transmission via removal of serotonin (5-HT) from synaptic clefts. Alterations in 5-HTT expression and 5-HT transmission have been shown to cause changes to adult behavior including fear. The objective of the present study was to investigate the 5-HTT role in fear in birds at the very early stages of post-hatching life. Using an avoidance test with an elevated balance beam, which was based on depth perception and the respective fear of heights, we assessed fear-related avoidance behaviors of newly hatched chicks of the three functional 5-HTT genotypes W/W, W/D and D/D. Newly hatched chicks of the genotype D/D, which was linked to high 5-HTT expression, showed less intensive avoidance responses as measured by decreased latency to jump than W/W and W/D chicks. Further, significantly fewer D/D hens than W/W hens showed fear-like behavior that resembled a freezing response. Furthermore, in an arousal test the arousal reaction of the chicks in response to an acute short-term visual social deprivation in the home compartment was assessed 5 weeks after hatching, which also revealed that D/D chicks exhibited decreased arousal reaction, compared to W/W chicks. Thus, the results indicate that fear responses differ in D/D chicks in the early post-hatching periods, possibly due to the different expression of 5-HTT respectively 5-HT levels in this strain.

Keywords: Serotonin transporter (5-HTT), 5-HTT, Fear, Early conditions, Gallus gallus

Received: 16 Sep 2018; Accepted: 05 Nov 2018.

Edited by:

Walter Adriani, Istituto Superiore di Sanità (ISS), Italy

Reviewed by:

Lesley J. Rogers, University of New England, Australia
Giorgio Vallortigara, University of Trento, Italy  

Copyright: © 2018 Phi van, Krause and Phi Van. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Loc Phi Van, Institut für Tierschutz und Tierhaltung, Friedrich Loeffler Institut, Celle, Germany,