Baclofen Influences Acquisition and MMP-2, MMP-9 Levels in the Hippocampus of Rats After Hypoxia

Background: Baclofen, the agonist of GABA(B) receptors, influences hypoxia-induced deficits in learning and memory processes.

Methods: We studied the effects of baclofen on acquisition in the passive avoidance test and in the Morris water maze in groups of rats without or after hypoxia as well as the influence of baclofen on MMP-2 and MMP-9 levels in the hippocampus.

Results: Even though baclofen itself impaired the acquisition in the passive avoidance, it improved the hypoxia-induced deficit of acquisition in the passive avoidance test and in the Morris water maze. There was a significant decrease in the level of the active form of MMP-2 as well as an increase in the level of pro-MMP-9 in the hippocampus of rats without hypoxia 30 min after the administration of baclofen. Furthermore, an elevated level of pro-MMP-9 was observed 30 min after hypoxia. Baclofen used before the deprivation of oxygen, decreased the level of the active form of MMP-2 and pro-MMP-9.

Conclusions: These results show that MMP-2 and MMP-9 activities in the hippocampus can be regulated by baclofen in non-pathological conditions and very shortly after hypoxia induction. We suggest that the changes in MMP-2 and MMP-9 levels are the mechanism activities of baclofen in the acquisition process.