Figure 3.

Stereotactic infusion of activin A into the hippocampal dentate gyrus exerts antidepressant-like behavioural effects in the forced swim test (FST) paradigm. (a) A strong antidepressant-like effect of activin A injection into the hippocampal dentate gyrus could be observed: animals bilaterally injected with activin A showed a significant increase in struggling (*P<0.05) and a significant decrease in floating behaviour (*P<0.01) with no change in swimming 15 min after treatment. The significant difference in struggling behaviour between the treatment groups could still be observed 24 h after activin A injection. To investigate whether the behavioural effects of activin A injection are dependent on the neuroanatomical region, we bilaterally injected activin A into the amygdala (b) Acute injection of activin A into the amygdala did not significantly alter any of the behavioural parameters measured in the FST. However, 24 h after the activin A injection, we observed a trend (P=0.056) towards an increase in swimming behaviour in animals that had been injected with activin A into the amygdala on the day before.