CHEMOGENETIC ANALYSIS OF AN ASCENDING THALAMIC PATHWAY CONVEYING SOCIAL INFORMATION OF CONSPECIFIC RATS
1 Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 2MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Eötvös Loránd University and the Hungarian Academy of Sciences, Budapest
In a previous study, we determined the Posterior intralaminar complex of the thalamus (PIL) as a relay station of socially relevant sensory information innervating and activating oxytocin-secreting neurons upon social encounter. Our present aim was to identify and functionally characterize neuronal projections from the PIL during stress-free social interaction in rats. The brain activation patterns were determined following direct interaction of familiar female rats. We also determined the effect of chemogenetic stimulation of the PIL on the social behavior and the brain activation pattern. In addition, anterograde tract-tracing from the PIL was performed. We found that neurons in the PIL projected to different elements of the social brain network, such as the lateral septal nucleus, the amygdala, the preoptic area and the infralimbic cortex. Significantly higher level of activation upon social encounter was found in the medial amygdala, the somatosensory and infralimbic cortices, compared with separated animals. The chemogenetic stimulation of the PIL resulted in the activation of three brain regions, the medial amygdala, the medial preoptic area and the infralimbic cortex. Double immunohistochemistry suggested that the fibers of PIL neurons closely apposed the neurons activated upon social interactions. Chemogenetic stimulation of the PIL also increased the duration of social interactions between the animals. The results suggest that the PIL may convey socially relevant information to several other brain regions, which may participate in the control of social behaviors. Support: New National Excellence Program of the Ministry of Human Capacities, Excellence Program of the Semmelweis University, NKFIH-4300-1/2017-NKP_17 and OTKA K116538.