Differential effects of corticosterone on the colocalization of reelin and neuronal nitric oxide synthase in the adult hippocampus in wild type and heterozygous reeler mice

• CORT has a main effect in reelin and nNOS changes in both WTM and HRM.
• CORT decreases Reelin and nNOS colocalization in the SGZ in WTM.
• CORT increases Reelin and nNOS colocalization in the SGZ in HRM.

Repeated corticosterone (CORT) treatment induces a deficit in dentate gyrus subgranular zone reelin-positive cells, in maturation of newborn neurons, and results in a consistent depressive-like behavior. However, the molecular mechanisms underlying these processes are not known in detail. The purpose of the present study was to characterize the effect of three weeks of 20 mg/kg CORT injections in the number of reelin and neuronal nitric oxide synthase (nNOS), as well as their colocalization, in hippocampal regions in wild type (WTM) and heterozygous reeler mice (HRM). ANOVA analysis shows a CORT×genotype interaction in the density of reelin+ cells co-localizing nNOS in the dentate subgranular zone and stratum-lacunosum moleculare, and in the density of nNOS+ cells in the hilus. There is a main effect of CORT in the density of both reelin+ and nNOS+ cells in the dentate subgranular zone and hilus, and in reelin+ cells in the molecular layer and CA3 stratum radiatum; and a main effect of genotype on the co-localization of both markers in the dentate subgranular zone, and in the density of reelin+ cell sin the stratum lacunosum moleculare. These alterations suggest a possible interconnection between reelin and nNOS expression that is altered by repeated CORT treatment.