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Olfactory dysfunction is a common outcome of brain injuries, negatively affecting quality of life. The adult mammalian nervous system has limited capacity for olfactory recovery, making it challenging to study olfactory regeneration and recovery. In contrast, zebrafish are ideal for such studies due to its extensive and lifelong regenerative abilities. In this work, we describe a model of excitotoxic injury in the olfactory bulb (OB) using quinolinic acid lesions in adult zebrafish of both sexes. We observed extensive neurodegeneration in both the OB and olfactory epithelium, including a reduction of bulbar volume, neuronal death, and impaired olfactory function. Recovery mechanisms involved tissue remodeling, cell proliferation, and neurogenesis, leading to full restoration of olfactory function by 21 d. This study provides a model to further investigate the effects of excitotoxicity on olfactory dysfunction and highlights zebrafish's remarkable regenerative abilities, providing insights into potential therapeutic strategies for restoring olfactory function following brain injuries. 

The olfactory system, composed of the olfactory organs and the olfactory bulb, allows organisms to interact with their environment and through the detection of odor signals. Olfaction mediates behaviors pivotal for survival, such as feeding, mating, social behavior, and danger assessment. The olfactory organs are directly exposed to the milieu, and thus are particularly vulnerable to damage by environmental pollutants and toxicants, such as heavy metals, pesticides, and surfactants, among others. Given the widespread occurrence of olfactory toxicants, there is a pressing need to understand the effects of these harmful compounds on olfactory function. Zebrafish (Danio rerio) is a valuable model for studying human physiology, disease, and toxicity. Additionally, the anatomical components of the zebrafish olfactory system are similar to those of other vertebrates, and they present a remarkable degree of regeneration and neuroplasticity, making it an ideal model for the study of regeneration, reorganization and repair mechanisms following olfactory toxicant exposure. In this review, we focus on (1) the anatomical, morphological, and functional organization of the olfactory system of zebrafish; (2) the adverse effects of olfactory toxicants and injury to the olfactory organ; and (3) remodeling and repair neuroplasticity mechanisms following injury and degeneration by olfactory toxicant exposure.