Neural correlates of food allergy: role of IgE-dependent mechanisms and sensory C-fibers

Author(s)

Alexandre Salgado Basso

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2004-08-20

Examining board members

João Palermo Neto; Luciano Freitas Felicio; Roberto Frussa Filho; Wothan Tavares de Lima; Wilson Savino

• Advisor: João Palermo Neto

Abstract

Although many authors have considered the possibility of a direct interaction between food allergy and behavioral changes, the evidence supporting this hypothesis is elusive. Here we show that after oral OVA challenge allergic mice present higher levels of anxiety, increased serum corticosterone, and increased Fos expression in the paraventricular nucleus of the hypothalamus (PVN) and in the central nucleus of the amygdala (CeA), which are both emotionality-related brain areas. Food allergy-activated neurons in the PVN and in the CeA are able to produce CRF. We found that food allergy also induced enhanced Fos immunoreactivity in the nucleus of tractus solitarii (NTS) of OVA-immunized animals. Besides that, OVA-immunized animals developed aversion to an antigen-containing solution. Treatment with anti-IgE antibody, or induction of oral tolerance abrogated both food aversion and the expression of c-fos in the central nervous system. In order to investigate the brain-gut communication in allergic animals, we have employed destruction of sensory C fibers by neonatal capsaicin treatment. Although this treatment did not block development of food aversion, it decreased the magnitude of such aversion. Moreover, we observed that while the degree of Fos staining in the NTS of allergic mice was only diminished by neonatal capsaicin, it was completely blocked in the PVN. However, capsaicin did not modify food alergy-induced c-fos expression in the CeA. Besides establishing a direct relationship between brain function and food allergy, our findings provide evidence showing that IgE-dependent mechanisms and the sensory C fibers play an important role in food allergy signaling to the mouse brain. Finally, this study creates a solid ground for understanding the etiology of psychological disorders in allergic patients. (AU)