The viscero-vagal-cerebral axis in homeostatic regulation and non-homeostatic reinforcement

Abstract

The vagal-brain axis is considered an important two-way communication highway between the viscera and the brain. The vagus nerve carries information relevant to homeostatic behaviours such as food intake and hydromineral regulation, but its terminals also contain chemical receptors for various hormones and substances of abuse. By using animal models and CNS intervention techniques (chemical and electrolytic lesions, electrical and chemical brain activation, systemic administration of products...), together with behavioural recording, the Psychobiology research group (CTS-430) has been focused on the study of this axis through three lines of research: (A) One line of research focuses on their involvement in the rapid processing of satiety-relevant signals, the reinforcing value of nutrients, and the role of the cephalic phase of ingestion. B) Another line of research examines the role of the tuberomammillary nuclei and the median eminence in regulating water and mineral salt intake and excretion, as well as the compensatory effects of oxytocin, a natriuretic hormone. C) A third line focuses on the functional characterisation of a circuit running through the visceral-vagal-brain system involved in processing the hedonic-affective component of reward, which may be common to substances of abuse. Disruption to these pathways can result in severe behavioural and mood disorders, such as obesity, anorexia, diabetes insipidus, and the compulsive seeking behaviours typical of addictions and depression. Therefore, research in this area has significant implications for human health.