Tamás Láng 1, Dávid Keller 1, Árpád Dobolyi 1,2
1 Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Hungary,
2 MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Eötvös Loránd Research Network and Eötvös Loránd University
In a previous study, we established the activation of the posterior intralaminar thalamic (PIL) neurons during social interactions between adult female rats. In this study we focused on the role of PIL in intermale aggressive behavior.
For manipulation of PIL neurons, adeno-associated virus was injected into the PIL using stereotaxic apparatus. The virus expressed mCherry and a DREADD in the infected cells. We used excitatory and inhibitory DREADDs, which were activated by clozapine-N-oxide (CNO). Behavioral tests were recorded during the chemogenetic manipulation. After perfusion of the animals, we performed histological analysis. We identified the brain areas activated by aggressive behavior using c-Fos method. We found neuronal activation in the infralimbic cortex (ILC), the medial preoptic area (MPOA) and in the lateral septum (LS). Chemogenetic stimulation of the axonal terminals of the PIL neurons in the MPOA was also performed using local CNO administration in the medial preoptic area.
To induce aggression, the animals were separated at an early age. The behavioral tests were performed at the age of 5 month. On the first day of the experiment, vehicle was injected to the animal. We performed aggressive behavioral test, where an unfamiliar intruder was placed in the subject animal’s cage resulting in an aggressive response. On the second day, the same test was repeated starting 1,5 hours after CNO administration. Chemogenetic stimulation significantly decreased aggression and increased the duration of positive valance contact, while inhibiting the PIL resulted in the increase of aggression and decreased the duration of positive valance contact. On the third day, we repeated the vehicle injection. The chemogenetic activation of axonal terminals of PIL neurons in the MPOA increased the duration of positive valance contact, and decreased aggression.
Based on these results, PIL neurons participate in the regulation of aggressive behavior conveying sensory inputs from the conspecific to higher brain areas, possibly by its projection to the medial preoptic area
Grant support: ÚNKP-22-2-I-SE-23; EFPO-3.6.3-VEKOP-16-2017-00009, MTA Nemzeti Agykutatási Program 3.0, NKFIH OTKA K134221.