Time course changes of the striatum neuropil after unilateral dopamine depletion and the usefulness of the contralateral striatum as a control structure.

Introduction: After unilateral dopamine depletion, some ipsilateral alterations occur and the contralateral structure has been utilized as control.
Objective: Our aim is to analyse the evolution of the ultrastructural alterations of the ipsilateral and contralateral striata of the 6-hydroxydopamine lesioned rats to demonstrate that the contralateral striatum should not be used as control structure.
Methods: After the surgery and the rotation behavior evaluation, animals were killed from 3 to 120 days after lesioning, and their striata were compared with those of aged rats.
Results: The ultrastructural analysis shows increased diameter of the synaptic ending in ipsilateral (since the third day) and contralateral striata (since day 30) and an increase in perforated synaptic contacts.
Conclusion: Our data suggest that the contralateral striatum should not be taken as control structure at least after 20-30 days after lesioning, as the alterations found here may result in wrong interpretations when comparing with the ipsilateral-lesioned one.