[Respective effects on locomotor activity of injections of 5, 7-DHT in median raphe nucleus and of 6-OHDA in the mesolimbic dopaminergic group area in the rat].

This experiment was performed in order to demonstrate that the locomotor hyperactivity provoked by a radiofrequency lesion of the ventral mesencephalic tegmentum-A10 DA group area was not due to a 5-HT fiber damage. Four groups of Rats were used. First groups II and IV received a 5, 7-DHT injection in the median raphe; groups I and III received the vehicle. Locomotor activity was measured in a circular corridor 10 and 30 days; no hyperactivity was obtained. Then the same groups received a 6-OHDA injection, bilaterally in the A 10 area (groups III and IV) or the vehicle (groups I and II); the activity was measured 10 days later: significant hyperactivity was obtained with groups III and IV, without statistical differences between these two groups. In conclusion (i) 5-HT neurons are not directly involved in the VMT-hyperactivity, (ii) the DA A 10 neurons seem to be a critical anatomical target for this symptom.