Anatomical and functional study of the efferent gabaergic projections of the medial amygdala nucleus mobilized in the organization of social defense.

Author(s)

Érika Tissiana Sterde

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2021-04-23

Examining board members

Simone Cristina Motta; Newton Sabino Canteras; Antonio de Pádua Carobrez; Miguel Antonio Xavier de Lima

• Advisor: Simone Cristina Motta

Abstract

The medial nucleus of the amygdala (MeA) plays a fundamental role in social behaviors, as it processes olfactory cues, and projects them to hypothalamic regions to organize suitable behavioral responses according to the received information. In our study, we mapped the efferent gabaergic projections of the different subdivisions of MeA and functionally investigated the gabaergic MeA neurons in social defense. The results showed that MeApd sends gabaergic projections to the bed nucleus of the stria terminalis, principal part (BSTpr), to the ventral premammillary nucleus (PMV) and to the medial preoptic nucleus (MPN). We did not find gabaergic projections from the anterior MeA (MeAa) or posteroventral MeA (MeApv) to MPN, as previously described in the literature. Also different to the literature, we hardly found gabaergic projections from MeA to the ventromedial nucleus of the hypothalamus (VMH). The results of the functional studies showed behavioral changes in the total time spent in social and exploratory behaviors, which were greater in the experimental group when compared to the control group and we observed a reduction in the time spent in defensive behaviors, such as total defense and passive defense, in the experimental group. We did not see any differences between the groups regarding the bites received from the resident and the total time of active defense. Our results indicate that MeApd gabaergic neurons modulate social defense, and the loss of gabaergic function directly affects the behaviors expressed in the face of an agonistic encounter with a conspecific. We also saw that it is possible for MeApd to exert its functions in social defense through BST or PMV. (AU)

• FAPESP's process: 18/12763-2 - Importance of the medial amygdala nucleus efferent projections in the organization of social defense
• Grantee: Erika Tissiana Sterde
• Support Opportunities: Scholarships in Brazil - Master