A DEVELOPMENTAL PERSPECTIVE TO STUDY THE ROLE OF DIFFERENT GLUTAMATERGIC NEURONS OF THE AMYGDALA IN BEHAVIOR

The amygdala contains multiple neuron subtypes with different embryonic origins, which conditions much of their mature phenotype. We studied two subtypes of glutamatergic neurons; those derived from the pallium and expressing the transcription factor Emx1, and those derived from the telencephalon-opto-hypothalamic domain expressing Otp. To identify these subtypes, we used triple transgenic Emx1-Cre/Rpl22HA/Otp-eGFP mice. HA/Emx1 neurons were mostly found in the pallial amygdala, representing 40-64% of neurons depending on the subdivision. GFP/Otp neurons were mostly found in some subdivisions of the medial amygdala, representing half of all neurons in the anteroventral subnucleus and 7-15% in the posterior subnuclei. Some pallial amygdala subdivisions contained a few Otp cells, and the medial amygdala contained minor subpopulations of Emx1 cells. By way of triple immunofluorescence, we found that in most subdivisions more than two thirds of the HA/Emx1 and GFP/Otp neurons coexpressed the transcription factor COUP-TFII (NR2F2). We also found coexpression of calcium binding proteins calretinin and calbindin in some subsets of Otp and Emx1 neurons. We analyzed the role of these different glutamatergic neurons in anti-predator and social contexts, exposing mice to odorants with different biological relevance (neutral, fruity or predator) or performing tests of social recognition. Following the tests, we studied the expression of cFos in Emx1 and Otp neurons. We observed activation of distinct subdivisions and neuron subtypes of the medial amygdala and cortical areas. Our results help to identify different glutamatergic neurons of the amygdala, and to better understand their involvement in odor-mediated and social behaviors.
Funding: AEI/MICIU_PID2023-151927OB-I00; FPU22/03133