Browsing by Author "Rinne, Meri"

Parkison's disease is a progressive neurodegenerative disorder that is characterized by degeneration of dopaminergic neurons in the nigrostriatal dopamine pathway. This is responsible for the major symptoms of Parkinson's disease. The current therapies only treat symptoms without being able to slow down, or reverse, the neurodegenerative process. Therefore current research is directed toward prevention of dopaminergic neuron degeneration. Prolyl oligopeptidase (POP) is a serine peptidase which cleaves small proline-containing peptides. A number of neuropeptides are affected in Parkinson's disease and POP contributes to the degradation of many of these neuropeptides. Reduction in POP activity has observed in Parkinson's disease. However, it is not known if changes in POP activity were a cause or a consequence of Parkinson's disease. POP inhibitors are substrate-like compounds. In our study we used KYP-2047, a novel brain-penetrating POP inhibitor. Administration of KYP-2047 has previously been shown to increase slightly neurotensin levels after a single dose. Neurotensin is an endogenous neuropeptide that has antidopaminergic actions in the brain. A number of neurotensin receptors has been observed to decrease in substantia nigra and striatum after degeneration of nigrostriatal pathway in laboratory animals or Parkinson patients. When given into the brain, neurotensin and neurotensin analogs have decreased rigidity and tremor caused by 6-hydroxydopamine (6-OHDA). The aim of this study was to determine the interactions between POP and neurotensin and their connections with dopamine deficit in a rat model of Parkinson's disease (the turning model of Ungerstedt). POP activity was also studied. In this study two different kinds of lesions were used. Intracerebral injections of 6-OHDA were given either into the MFB (medial forebrain bundle) or striatum. Rotational behaviour was measured five weeks post-lesion. The MFB lesion Wistar rats were given levodopa/carbidopa -suspension with KYP-2047 or entacapone or both of them. The striatum lesion rats were given amphetamine with KYP-2047. Studies were organized in a cross-over manner once a week. Rotational behaviour did not change when a POP inhibitor was given suggesting that neurotensin levels were apparently not much changed. Differences in POP activity assay were not noticed when compared to normal and lesioned cerebral hemisphere. This indicates that there is no POP in long dopaminergic neurons.