gms | German Medical Science

Objective: The 6-hydroxydopamine (6-OHDA) Parkinson (PD) rat model is based on specific dopamine depletion in the nigrostriatal pathway, which subsequently leads to hyperactivity of the subthalamic nucleus (STN). Chronic rotenone injections similarly lead to loss of dopaminergic neurons in the substantia nigra but in addition also to loss of cholinergic neurons in the pedunculopontine nucleus (PPN), which has been thought to underly certain components of parkinsonian gait. We here evaluated the motor disability and the neuronal firing activity of the STN in the rotenone rat model of PD.

Method: Male Sprague Dawley rats were treated with chronic rotenone injections (2.5 mg / kg bodyweight, i.p.) for 60 days. Control rats received vehicle injections. After the end of the treatment motor coordination was assessed by using the Rotarod test. Thereafter, single unit activities and local field potentials were recorded in the STN during anesthesia with urethane 1.2 g/kg.

Results: Rotenone injected rats spent significantly less time on the Rotarod as compared to vehicle treated rats (p < 0.05). Further, electrophysiological data showed a higher firing rate and higher beta oscillatory activity in the STN (p < 0.05).

Conclusions: Similar as in 6-OHDA injection we found enhanced STN neuronal firing rates as well as increased beta oscillatory activity, key features of PD, in this model. The rotenone-induced rat model of PD should deserve further attention since it covers more aspects than just the dopamine depletion.