T Petteri Piepponen

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Glial cell line-derived neurotrophic factor (GDNF) has been shown to be involved in the maintenance of striatal dopaminergic neurons. To study whether reduced levels of endogenous GDNF affect the striatal dopaminergic transmission we estimated the basal extracellular levels of dopamine in vivo, the basal expression of FosB-related proteins in striatal brain(More)
In vertebrates the development and function of the nervous system is regulated by neurotrophic factors (NTFs). Despite extensive searches no neurotrophic factors have been found in invertebrates. However, cell ablation studies in Drosophila suggest trophic interaction between neurons and glia. Here we report the invertebrate neurotrophic factor in(More)
Gdnf, its binding receptor Gfrα1 or its main signaling receptor Ret die after birth mainly as a result of the lack of kidneys, but with intact catecholamine system, rendering postnatal analysis impossible4. However, conditional ablation using a loxP-Cre system (referred to as floxed) of GDNF main signaling receptor Ret and Gdnf have yielded conflicting(More)
The role of nicotinic acetylcholine receptor (nAChR) activation in accumbal dopamine (DA) release during chronic continuous nicotine treatment was studied by in vivo microdialysis in freely-moving mice. Nicotine was administered chronically to NMRI mice in their drinking water. On the 50th day of nicotine administration microdialysis samples were collected(More)
The effects of acute morphine on the release of dopamine (DA) in the striatum and limbic forebrain of rats upon 48 h withdrawal from 20-day morphine treatment were studied using 3-methoxytyramine (3-MT) in tissue as an index of DA release. Homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were also measured. The chronic morphine treatment(More)
The role of dopamine in opioid reward is unresolved. Furthermore, the issue is somewhat unclear regarding cocaine and the place preference paradigm. In the present study we investigated whether the drugs activating dopamine autoreceptors affect cocaine- and morphine-induced place preference in rats. Neither the dopamine D2/D3 receptor agonist, quinpirole(More)
Effects of ethanol on the accumbal extracellular concentrations of dopamine, as well as of the amino acid transmitters gamma-amino butyric acid (GABA), glutamate and taurine, were studied in the alcohol-insensitive (alcohol-tolerant, AT) and alcohol-sensitive (alcohol-nontolerant, ANT) rats selected for low and high sensitivity to ethanol-induced motor(More)
The interaction of dopamine (DA) precursor L-dopa and catechol-O-methyltransferase (COMT) inhibitor, entacapone, was examined in rats using conditioned place preference (CPP) paradigm to assess reinforcement, and by measuring DA metabolism in the striatum and the limbic forebrain. Neither L-dopa (100 mg/kg i.p.) nor entacapone (30 mg/kg i.p.) alone induced(More)
Ret is the common signaling receptor for glial cell line-derived neurotrophic factor (GDNF) and other ligands of the GDNF family that have potent effects on brain dopaminergic neurons. The Met918Thr mutation leads to constitutive activity of Ret receptor tyrosine kinase, causing the cancer syndrome called multiple endocrine neoplasia type B (MEN2B). We used(More)
Degeneration of nigrostriatal dopaminergic system is the principal lesion in Parkinson's disease. Because glial cell line-derived neurotrophic factor (GDNF) promotes survival of dopamine neurons in vitro and in vivo, intracranial delivery of GDNF has been attempted for Parkinson's disease treatment but with variable success. For improving GDNF-based(More)