Emerging role of microglia and astrocyte in the affective-motivational response induced by a rat model of persistent orofacial pain

Author(s)

Nascimento, Glauce Crivelaro ; Lucas, Guilherme ; Andrade Leite-Panissi, Christie Ramos

• Document type: Journal article
• Source: Brain Research Bulletin; v. 195, p. 13-pg., 2023-02-20.

Abstract

Few studies are approaching the neural basis underlying the aggregation of emotional disorders in orofacial pain despite the stress, depression, and anxiety are some of the most commonly reported risk factors. Using a persistent orofacial pain rat model induced by complete Freund's adjuvant (CFA) injection into the temporomandibular joint, we have investigated the plasticity astrocytes and microglia key brain regions for the affectiveemotional component of pain. We measured the expression and morphologic pattern of reactivation of glial fibrillary acidic protein (GFAP, astrocyte marker) and Iba-1 (microglial marker) by western blotting and immunohistochemistry analysis. The results showed no alterations on motor activity during inflammatory pain, indicating an exclusive effect of nociceptive behavior on the plasticity of limbic regions. CFA-induced temporomandibular inflammation changed GFAP and Iba-1 expression in distinct regions related to emotional behavior in a time-dependent manner. A significant increase in GFAP and Iba-1 expression was observed in the central nucleus of the amygdala, hippocampus and periaqueductal grey matter from day 3 to day 10 post-CFA injection. Moreover, a positive correlation between GFAP and Iba-1 upregulation and an increased mechanical hypersensitivity was observed. Conversely, no change on GFAP and Iba-1 expression was observed in the hypothalamus and colliculus during orofacial inflammatory pain. Our data suggest an important role for glial cells in the affective-motivational dimension of orofacial pain beyond their well-explored role in the traditional nociceptive transmission circuits. (AU)

• FAPESP's process: 15/03053-3 - Evaluation of medial pterygoid muscle and brain structures related to orofacial nociception and emotional behavior in an animal model of chronic stress and masticatory hypofunction
• Grantee: Glauce Crivelaro Do Nascimento
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 11/07718-9 - Behavioral analysis of rats with persistent inflammation of the temporomandibular joint: correlation with the quantification of metalloproteinases in the structures of the brain aversive system
• Grantee: Glauce Crivelaro Do Nascimento
• Support Opportunities: Scholarships in Brazil - Doctorate