Browsing by Author "Viljakainen, Tuulikki"

Parkinson’s disease is a progressive neurodegenerative disease, in which dopamine neurons are dying in the nigrostriatal dopaminergic pathway. This causes motor symptoms such as slowness of movement, tremor, and rigidity. In addition, various non-motor symptoms appear. All currently used medicines are symptomatic, and there are no disease modifying treatment available for Parkinson’s disease. Several neurotrophic factors have shown promise in animal models of Parkinson’s disease. One of those is cerebral dopamine neurotrophic factor (CDNF) which has been studied in different animal models, including rodents and non-human primates. CDNF is a secreted protein but it is also localized in endoplasmic reticulum (ER). CDNF has two domains, N-terminal and C-terminal, which may have distinct functions. CDNF can be retained in the ER by the ER retention sequence at the end of the C-terminal domain. The C-terminal domain also has an evolutionarily conserved disulfide bridge which is crucial for the biological activity of CDNF. The exact mechanism of CDNF is still unknown. However, it has been shown that CDNF affects the unfolded protein response (UPR) in the presence of ER stress. Neurotrophic factors do not penetrate blood-brain barrier (BBB), for this reason, they need to be injected directly to the brain. Penetration of the BBB is also a problem in the treatment of many other diseases. Various methods for enhancing the BBB penetration of drugs have been studied. For example, permeability of the BBB can be temporarily increased by focused ultrasound combined with microbubbles. Another possibility is the use of a carrier molecule, which can be transported through BBB via specific transport mechanisms. Furthermore, molecule modification offers many applications to achieve enhanced BBB penetration. In view of peripheral administration, a next generation variant of CDNF (ngCDNF) has been developed. The efficacy of this novel variant after intrastriatal injection is equal to that of CDNF in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson’s disease. Systemic administration could also enable treatment of non-motor symptoms of Parkinson’s disease. The aim of this experiment was to study the effects of subcutaneously injected ngCDNF on rotation behaviour, and nigrostriatal TH-positive cells in rats with 6-OHDA lesions. 6-OHDA was injected unilaterally to three different sites in the striatum. Two weeks later, the lesion size was estimated, via amphetamine- induced rotation test. ngCDNF, at two dose levels, was injected twice weekly for three weeks. Amphetamine-induced rotation test was assessed every other week, until week 12. At the end, optical density of tyrosine hydroxylase (TH) was measured from sections of the striatum, and TH positive cells in the substantia nigra were counted. In addition, the effect of ngCDNF on anxiety and depression like behaviour, learning, and locomotor activity were studied at three different levels in naïve mice. Behaviour was analyzed by open field test, forced swim test, and fear conditioning test. The ngCDNF did not seem to have clear effect on rats’ behaviour or TH positive cells and fibers compared to the control group, but positive tendency was found in the group with lower dose. The reduced efficacy of ngCDNF,via subcutaneous administration, is likely due to rapid metabolism and insufficient entry of the active form to the brain. In naïve mice, ngCDNF did not reduce anxiety-like behaviour and did not affect locomotor activity after subcutaneous injections. This result supports previous findings, which suggest that the effects of CDNF are specific to the toxin treated cells and CDNF has no effect in naïve animals.