Neural regeneration dynamics of Xenopus laevis olfactory epithelium after zinc sulfate-induced damage

• Zinc sulfate induces glial and neuronal degeneration s of Xenopus laevis olfactory epithelium.
• Neural progenitors in the basal layer of the olfactory epithelium regenerate both neuronal and glial cells.
• Mature olfactory neurons and sustentacular cells were restored after seven days of severe damage.
• Seven days after massive destruction the olfactory epithelium recovers its normal function.

Neural stem cells (NSCs) of the olfactory epithelium (OE) are responsible for tissue maintenance and the neural regeneration after severe damage of the tissue. In the normal OE, NSCs are located in the basal layer, olfactory receptor neurons (ORNs) mainly in the middle layer, and sustentacular (SUS) cells in the most apical olfactory layer. In this work, we induced severe damage of the OE through treatment with a zinc sulfate (ZnSO4) solution directly in the medium, which resulted in the loss of ORNs and SUS cells, but retention of the basal layer. During recovery following injury, the OE exhibited increased proliferation of NSCs and rapid neural regeneration. After 24 h of recovery, new ORNs and SUS cells were observed. Normal morphology and olfactory function were reached after 168 h (7 days) of recovery after ZnSO4 treatment. Taken together, these data support the hypothesis that NSCs in the basal layer activate after OE injury and that these are sufficient for complete neural regeneration and olfactory function restoration. Our analysis provides histological and functional insights into the dynamics between olfactory neurogenesis and the neuronal integration into the neuronal circuitry of the olfactory bulb that restores the function of the olfactory system.