%0 Journal Article
%T Impaired Fear Extinction Recall in Serotonin Transporter Knockout Rats Is Transiently Alleviated during Adolescence
%A Beenish Asrar
%A David de Leest
%A Federica Rebuglio
%A Francesca Calabrese
%A Judith R. Homberg
%A Leonie Madder
%A Marco A. Riva
%A Marloes J. A. G. Henckens
%A Michel M. M. Verheij
%A Paola Brivio
%A Pieter Schipper
%A Tamas Kozicz
%J Brain Sciences | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/brainsci9050118
%X Adolescence is a developmental phase characterized by emotional turmoil and coincides with the emergence of affective disorders. Inherited serotonin transporter (5-HTT) downregulation in humans increases sensitivity to these disorders. To reveal whether and how 5-HTT gene variance affects fear-driven behavior in adolescence, we tested wildtype and serotonin transporter knockout (5-HTT £¿/£¿) rats of preadolescent, adolescent, and adult age for cued fear extinction and extinction recall. To analyze neural circuit function, we quantified inhibitory synaptic contacts and, through RT-PCR, the expression of c-Fos, brain-derived neurotrophic factor (BDNF), and NDMA receptor subunits, in the medial prefrontal cortex (mPFC) and amygdala. Remarkably, the impaired recall of conditioned fear that characterizes preadolescent and adult 5-HTT £¿/£¿ rats was transiently normalized during adolescence. This did not relate to altered inhibitory neurotransmission, since mPFC inhibitory immunoreactivity was reduced in 5-HTT £¿/£¿ rats across all ages and unaffected in the amygdala. Rather, since mPFC (but not amygdala) c-Fos expression and NMDA receptor subunit 1 expression were reduced in 5-HTT £¿/£¿ rats during adolescence, and since PFC c-Fos correlated negatively with fear extinction recall, the temporary normalization of fear extinction during adolescence could relate to altered plasticity in the developing mPFC. View Full-Tex
%U https://www.mdpi.com/2076-3425/9/5/118