Rodriguez-Cedres, C.; Sangroniz-Beltran, L.; Lopez, N.; Delgado-Martin, N.; Andueza-Peral, G.; Mugica-Susaeta, P.; Ospital, P.; Beriain, S.; Ceprian, M.; Egana-Huguet, J.; Piriz, J.; Ferreira, G.; Ducourneau, E. G.; Mato, S.; Soria-Gomez, E.

The medial habenula (MHb) is an epithalamic structure involved in aversive processing and emotional regulation, notable for its marked cellular heterogeneity and high astrocyte density. This cellular composition suggests that astrocytes may play an important role in MHb structure and plasticity, potentially contributing to the regulation of emotional states. The aim of this study is to characterize sex-dependent astrocytic morphology in the MHb and determine how it is modulated by peripheral alterations and direct central manipulations. A high-fat diet (HFD) was used as a model of metabolic stress, and systemic lipopolysaccharide (LPS) administration was used to induce a peripheral inflammatory challenge. At the central level, a chemogenetic approach using Gi-DREADDs under the GFAP promoter allowed selective modulation of astrocytic intracellular signaling independently of peripheral influences. Preliminary results indicate sex-dependent morphological differences in MHb astrocytes across all these experimental conditions, supporting the idea that MHb astrocytes are sensitive to both peripheral and central disturbances and may represent a key cellular substrate linking body-brain interactions with emotional regulation.