(K141934) Támogató: Hungarian National Research, Development and Innovation Office
(K138763) Támogató: NKFIH
Gamma-aminobutyric acid (GABA) is a well-known inhibitory neurotransmitter implicated
in numerous physiological and pathological behaviors including social interest. Dysregulation
of the median raphe region (MRR), a main serotoninergic nucleus, is also characterized
by increased social problems. As the majority of MRR cells are GABAergic, we aimed
to reveal the social role of these cells. Chemogenetic techniques were used in vesicular
GABA transporter Cre mice and with the help of adeno-associated virus vectors artificial
receptors (DREADDs, stimulatory, inhibitory or control, containing only a fluorophore)
were expressed in MRR GABAergic cells confirmed by immunohistochemistry. Four weeks
after viral injection a behavioral test battery (sociability; social interaction;
resident-intruder) was conducted. The artificial ligand (clozapine-N-oxide, 1 mg/10
ml/kg) was administrated 30 min before the tests. As possible confounding factors,
locomotion (open field/OF), anxiety-like behavior (elevated plus maze/EPM), and short-term
memory (Y-maze) were also evaluated. Stimulation of the GABAergic cells in MRR had
no effect on locomotion or working and social memory; however, it increased social
interest during sociability and social interaction but not in resident-intruder tests.
Accordingly, c-Fos elevation in MRR-GABAergic cells was detected after sociability,
but not resident-intruder tests. In the EPM test, the inhibitory group entered into
the open arms later, suggesting an anxiogenic-like tendency. We confirmed the role
of MRR-GABAergic cells in promoting social interest. However, different subpopulations
(e.g. long vs short projecting, various neuropeptide containing) might have divergent
roles, which might remain hidden and requires further studies.
