"We decided to confirm the previous result using the mouse model Andressoo developed, and noticed that the complete absence of GDNF did not cause significant changes to the amount or function of dopamine neurons. Since the result surprised us, we wanted to verify it using two alternative methods, one of which was identical to the method in the previously published article," explains Dr Jaan-Olle Andressoo.
In addition, some of the experiments were conducted in parallel at Professor Anders Björklund's laboratory at Lund University. The Lund tests similarly indicated no changes to the dopamine systems or the behaviour of the mice. This clearly established that GDNF is not a necessary component of the dopamine system.