The effect of a subchronic post-lesion treatment with (−)-deprenyl on the sensitivity of 6-OHDA-lesioned rats to apomorphine and d-amphetamine

Summary.

The effects of a subchronic post-lesion treatment of 14 days with (−)-deprenyl or its solvent on the rotational response to apomorphine (0.1 mg/kg) and d-amphetamine (2.5 mg/kg) in 6-OHDA- and SHAM-lesioned rats were investigated. Rats received a local injection of 6-OHDA (9 μg/0.7 μl) or its solvent into the medial forebrain bundle. Following the (SHAM or 6-OHDA) lesion the animals were randomly assigned to one of the two post-lesion treatment groups, viz. vehicle or (−)-deprenyl (0.1 mg/kg, 2 × day, i.p.) and treated for 14 days. After a wash out period of 6 weeks the number of rotations in response to apomorphine (0.1 mg/kg) and d-amphetamine (2.5 mg/kg) were compared. Seven days following the final behavioural experiments the animals were sacrificed and the striatal dopamine, DOPAC and HVA levels were determined. The (−)-deprenyl-treated 6-OHDA-lesioned rats responded with a reduced number of rotations in response to apomorphine but not to d-amphetamine as compared to vehicle-treated 6-OHDA-lesioned rats. However the two lesion groups did not differ in striatal dopamine, DOPAC and HVA concentrations; the levels were below or close to the detection limit ipsilateral to the 6-OHDA injections. Thus a post-lesion treatment with (−)-deprenyl reduced the dopaminergic supersensitivity without a concomitant increase in striatal dopamine content. The data are discussed in the light of the previously described neurorescue properties of (−)-deprenyl.