Chemogenetic inhibition of the lateral hypothalamus in rats: A simple but robust tool with high translational relevance to facilitate the development of central nervous system-targeted gene therapies

Abstract Aims Despite the therapeutic potential of chemogenetics, the method lacks comprehensive preclinical validation, hindering its progression to human clinical trials. We aimed to validate a robust but simple in vivo assay in rats, which could support chemogenetic drug discovery. We also aimed to establish the proof-of-concept for the chemogenetic approach in obesity indication. Methods Key methodological parameters such as adeno-associated virus (AAV) serotype, actuator drug, dose, and application routes were investigated by measuring the food-intake-reducing effect of chemogenetic inhibition of the lateral hypothalamus (LH) by hM4D(Gi) designer receptor stimulation. Results Subcutaneous deschloroclozapine in rats transfected with AAV9 resulted in a substantial reduction of food-intake, comparable to the efficacy of exenatide. We estimated that the effect of deschloroclozapine lasts for 1–3 hours post-administration. AAV5, oral administration of deschloroclozapine, and clozapine-n-oxide were also effective but with slightly less potency. The strongest effect on food-intake occurred within the first 30 min after re-feeding, suggesting this as the optimal experimental endpoint. Conclusion This study demonstrates that the chemogenetic silencing of the LH is a potential strategy in obesity treatment. The study also supports the development of chemogenetics by providing a “first in vivo” tool for the validation of new chemogenetic constructs.