Functional and anatomical study of the medial nucleus of the amygdala in the organization of social defense.

Author(s)

Gabriela Gonçalves Nunes

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2021-04-26

Examining board members

Simone Cristina Motta; Patricia Pereira Coltri; Carolina Demarchi Munhoz; Christie Ramos Andrade Leite Panissi

• Advisor: Simone Cristina Motta

Abstract

An a important sensory information for the expression of defensive behaviors is olfactory, and the medial nucleus of the amygdala (MeA) is an important structure for conveying information from the conspecific, since it is anatomically connected to olfactory sensory structures, such as the accessory olfactory bulb (AOB). However, little is known about how this information reaches important neural structures in the mouse for the organization of these behaviors and what the chemical identity of these projections would be. Thus, the present work aims to clarify the functional and anatomical aspects of this neural circuit, mapping areas involved in social defensive behavior and inhibiting the medial nucleus of the amygdala (MeApd). For this inhibition, we used bilateral viral injections to express inhibitory DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) in MeA of male C57BL/6J mice. The experimental group received intraperitoneal injections of clozapine N-oxide (CNO), which act specifically on DREADD receptors, and the control group received saline, then both groups were exposed to a dominant conspecific. Then to anatomically clarify the chemical identity of the MeA projections, we used transgenic V-glut2-ires-cre knock-in (C57BL/6J) males and females, that received viral injection of the cre-dependent virus into MeA subdivisions. This virus was only expressed in glutamatergic neurons, favoring the identification of only glutamatergic projections. The results of the functional study showed a significant decrease in active defense behavior (student\'s t-test, p <0.05) in the experimental group, when compared to the control group. The result of the anatomical mapping showed efferent glutamatergic projections from the anterodorsal MeA towards the VMHc/dm/vl, PMv and BSTpr/if/tr. As for the anteroventral MeA and posteroventral MeA, glutamatergic efferent projections were found in the VMHc/dm/vl nuclei and BSTpr/if/tr, but not in the PMV. Ethics in animal research approval (CEUA, ICB-USP)#58/2016. (AU)

• FAPESP's process: 18/15757-3 - The role of the ventral pre-mammillary nucleus of the hypothalamus, the ventrolateral part of the ventromedial nucleus of the hypothalamus and the principal part of the bed nucleus of the stria terminalis in the organization of the social defense
• Grantee: Gabriela Gonçalves Nunes
• Support Opportunities: Scholarships in Brazil - Master