3.3 Intra-PrL or IL injection of 1-MT blocks depressive behaviors induced by ICV-STZ.
To directly evaluate whether the activation of IDO in the PrL and IL was responsible for the depressive- and anxiety-like behaviors in ICV-STZ rats, we observed the effects of IDO inhibitor 1-MT on the behaviors of ICV-STZ rats. Depressive-like behaviors induced by ICV-STZ, including the increase in immobility time in the FST( F(5,30)=34.96, Figure 4A), the decrease in sucrose preference rate in the SPT( F(5,30)=11.37, Figure 4B) and latency time to feed in the NSFT ( F(5,30)=16.20, Figure 4C) were reversed by intra-PrL or IL injection of 1-MT. Food consumption after NSFT was no difference across the groups (Figure 4D). The result of time in center showed that intra-PrL or IL injection of 1-MT could not reverse the anxiety-like behavior in ICV-STZ rats (Figure 4E). Results of locomotor activity in total distance in the OFT did not reveal significant differences among the various groups ( Figure 4F, G). Based on these results, intra-PrL or IL injection of 1-MT both prevented depressive-like behaviors in ICV-STZ rats but failed to produce an anxiolytic effect.