The proneurogenic and microglial modulatory properties of botulinum toxin in the hippocampus of aging experimental mice

Abstract This study explored the neurogenic and microglial modulatory properties of botulinum toxin in the hippocampus of aging experimental mice. Therapeutic botulinum toxin (BoNT) treatment is widely practiced to reduce the excessive discharge of acetylcholine (ACh) in the management of aging and neurological deficits. While the production of new neurons in the adult brain contributes to cognitive functions, age-related diseases with excessive release of ACh and progressive neuroinflammation have been characterized by impaired hippocampal neurogenesis and memory loss. Therefore, we investigated the effect of BoNT on the regulation of hippocampal neurogenesis, focusing on doublecortin (DCX)-positive immature neurons in the hippocampus of aging experimental mice. We also assessed ionized calcium-binding adapter molecule 1 (Iba1)-positive microglia and the expression of cyclooxygenase (COX)-2, a key inflammatory response element, using reverse transcription polymerase chain reaction (RT-PCR). Results revealed a prominent increase in DCX-positive cells in the BoNT-treated animals compared to the control group. Additionally, the reduced number of microglia accompanied by decreased mRNA expression of COX-2 was evident in the BoNT-treated animals. These dual effects suggest that BoNT could be a promising therapeutic agent for mitigating age-related neuroregenerative decline and neuroinflammation responsible for cognitive impairments.