RESUMEN
Dor é uma experiência pessoal e subjetiva que pode apenas ser sentida pelo sofredor. A dor aguda tem a finalidade de avisar o indivíduo que algo está errado. Contudo, a dor crônica (DC) é um problema global de saúde, que afeta a qualidade de vida e torna o indivíduo parcial ou totalmente incapacitado. A pesquisa básica utiliza diversos modelos animais para o estudo da dor aguda ou crônica, bem como para o estudo das principais comorbidades oriundas de sua cronificação como a ansiedade e a depressão. Esta revisão aborda os modelos animais mais comumente utilizados neste contexto.
Pain is a personal and subjective experience that can only be felt by the sufferer. Acute pain is intended to warn the individual that something is wrong. However, chronic pain (CP) is a global health problem, affecting the quality of life and making the individual parts or disabled. Basic research uses several animal models for the study of acute or chronic pain, as well as for the study of the main comorbidities arising from their chronicity, such as anxiety and depression. This review focuses on the animal models most commonly used in this context.
El dolor es una experiencia personal y subjetiva que solo puede sentir la víctima. El dolor agudo está destinado a advertir al individuo que algo está mal. Sin embargo, el dolor crónico (EC) es un problema de salud global, que afecta la calidad de vida y hace que el individuo esté parcial o totalmente discapacitado. La investigación básica utiliza varios modelos animales para el estudio del dolor agudo o crónico, así como para el estudio de las principales comorbilidades resultantes de su cronicidad, como la ansiedad y la depresión. Esta revisión se centra en los modelos animales más utilizados en este contexto.
RESUMEN
BACKGROUND: The endogenous opioid peptide system has been implicated in the neural modulation of fear and anxiety organised by the dorsal midbrain. Furthermore, previous results indicate a fundamental role played by inferior colliculus (IC) opioid mechanisms during the expression of defensive behaviours, but the involvement of the IC µ1-opioid receptor in the modulation of anxiety- and panic attack-related behaviours remains unclear. Using a prey-versus-snake confrontation paradigm, we sought to investigate the effects of µ1-opioid receptor blockade in the IC on the defensive behaviour displayed by rats in a dangerous situation. METHODS: Specific pathogen-free Wistar rats were treated with microinjection of the selective µ1-opioid receptor antagonist naloxonazine into the IC at different concentrations (1.0, 3.0 and 5.0 µg/0.2 µL) and then confronted with rattlesnakes ( Crotalus durissus terrificus). The defensive behavioural repertoire, such as defensive attention, flat back approach (FBA), startle, defensive immobility, escape or active avoidance, displayed by rats either during the confrontations with wild snakes or during re-exposure to the experimental context without the predator was analysed. RESULTS: The blockade of µ1-opioid receptors in the IC decreased the expression of both anxiety-related behaviours (defensive attention, FBA) and panic attack-related responses (startle, defensive immobility and escape) during the confrontation with rattlesnakes. A significant decrease in defensive attention was also recorded during re-exposure of the prey to the experimental apparatus context without the predator. CONCLUSION: Taken together, these results suggest that a decrease in µ1-opioid receptor signalling activity within the IC modulates anxiety- and panic attack-related behaviours in dangerous environments.