Effects of median raphe region on social behaviour, locomotion and body temperature
Csilla Lea Fazekas1, 2,Mannon Bellardie1, 3, Bibiána Török1, 2, Eszter Sipos1, Blanka Tóth4, Mária Baranyi1, Beáta Sperlágh1, Elodie Chaillou-Sagon3, Dóra Zelena1
Numerous, translationally relevant behaviours have been linked to the median raphe region (MRR) (e.g.: depressive, anxious, social) involving locomotion and body temperature (BT) regulation. Our aim was to confirm these findings by combining pharmacogenetic technique and telemetry in mice. With the help of adeno-associated virus vectors MRR neurons were infected with control (no receptor), excitatory (Gq) or inhibitory (Gi) DREADDs. Telemetric devices were implanted into the abdominal cavity for measuring locomotion and BT. The following behavioural tests were conducted: sociability (social interest), social interaction (SIT; social and anxiety-like behaviour), resident intruder (RIT; aggressive behaviour) and forced swim test (FST; depressive-like behaviour). The ligand of DREADDs, clozapine-N-oxide (1mg/kg) was injected intraperitoneally 30 mins before the tests or alone to measure a 24-hour effect. In sociability all three groups showed intact social interest and there were no differences between them. In SIT there was a marginal group effect: both excitatory and inhibitory group showed increased frequency of friendly social behaviour, while in RIT the excitatory group spent significantly more time with friendly social behaviour. In FST the excitatory group spent more time floating. Additionally, their BT decrease was smaller. The 24-hour monitoring showed that the excitatory group moved less between 6-10 hours after injection. In sum, we confirmed the positive effect of MRR stimulation on friendly social behaviour and its negative effect on locomotion. Moreover, excitation resulted in depressive-like behaviour with smaller BT decrease giving translational value to our findings.