Deep brain stimulation of subthalamic nucleus modulates cortical auditory processing in advanced Parkinson's Disease

Deep brain stimulation (DBS) has proven its clinical efficacy in Parkinson's disease (PD), but its exact mechanisms and cortical effects continue to be unclear. Subthalamic (STN) DBS acutely modifies auditory evoked responses, but its long-term effect on auditory cortical processing remains ambiguous. We studied with magnetoencephalography the effect of long-term STN DBS on auditory processing in patients with advanced PD. DBS resulted in significantly increased contra-ipsilateral auditory response latency difference at similar to 100 ms after stimulus onset compared with preoperative state. The effect is likely due to normalization of neuronal asynchrony in the auditory pathways. The present results indicate that STN DBS in advanced PD patients has long-lasting effects on cortical areas outside those confined to motor processing. Whole-head magnetoencephalography provides a feasible tool to study motor and non-motor neural networks in PD, and to track possible changes related to cortical reorganization or plasticity induced by DBS.Peer reviewe

Exposure to Environmental Radionuclides Associates With Tissue-Specific Impacts on Telomerase Expression and Telomere Length

Telomeres, the protective structures at the ends of chromosomes, can be shortened when individuals are exposed to stress. In some species, the enzyme telomerase is expressed in adult somatic tissues, and potentially protects or lengthens telomeres. Telomeres can be damaged by ionizing radiation and oxidative stress, although the effect of chronic exposure to elevated levels of radiation on telomere maintenance is unknown for natural populations. We quantified telomerase expression and telomere length (TL) in different tissues of the bank vole Myodes glareolus, collected from the Chernobyl Exclusion Zone, an environment heterogeneously contaminated with radionuclides, and from uncontaminated control sites elsewhere in Ukraine. Inhabiting the Chernobyl Exclusion Zone was associated with reduced TL in the liver and testis, and upregulation of telomerase in brain and liver. Thus upregulation of telomerase does not appear to associate with longer telomeres but may reflect protective functions other than telomere maintenance or an attempt to maintain shorter telomeres in a stressful environment. Tissue specific differences in the rate of telomere attrition and apparent radiosensitivity weaken the intra-individual correlation in telomere length among tissues in voles exposed to radionuclides. Our data show that ionizing radiation alters telomere homeostasis in wild animal populations in tissue specific ways

The Effects of Ionizing radiation on bank vole in Chernobyl Exclusion Zone

The Chernobyl disaster in 1986 created an environment that provides unique opportunity to explore the eco-evolutionary impacts of chronic exposure to low-dose radioactive contaminants on wild animals. Studying the key species in the area could help determine the effects of radiation on species interactions and thus improve the radiation impact assessment. The bank vole (Myodes glareolus) was chosen as study species as it combines ecological relevance with laboratory tractability. Multi-generational experiments were conducted to test the wild populations exposed to long-term low-level ionizing radiation by analysing: the impact of added food sources on population sizes, the effects of radiation on reproduction of males and females, and radiation induced effects on organs. In the first study, bank vole abundances decreased with increasing radiation. Adding food sources to the field increased vole abundances only in low radiation environments. To find out whether lower abundances result from problems in male reproduction, in the second study, properties of the bank vole sperm were investigated. Sperm mid-pieces got shorter with increasing radiation. In addition, the proportion of static sperm increased in higher radiation areas. Thus, there were some negative effects on male reproduction. In the third study, reciprocal transplant experimental design was used to find study female reproduction. Females tended to survive better when moved to similar type of radiation environment indicating a possible adaptation to radiation in the environments. However, their pups survived better if the female was pregnant when living in the clean sites. Finally, in the fourth study, differences in various organ masses between the contaminated and clean sites were investigated. Results revealed smaller brain mass in the contaminated sites, and increased heart and spleen masses in the contaminated sites. In this thesis many correlative radiation effects were found, however the strength of the radiation in large areas of Chernobyl are very low. It is still unclear whether these effects are really radiation induced or do they come from combined stress effects in the area.Tšernobylin ydinkatastrofi vuonna 1986 on luonut ainutlaatuisen ympäristön kroonisen säteilyaltistuksen tutkimiselle. Tutkimalla alueen avainlajeja on mahdollista selvittää säteilyvaikutuksia myös eliöryhmätasolla ja täten kehittää ympäristövaikutusten arviointia. Tutkimuslajina oli metsämyyrä (Myodes glareolus), joka on yksi runsaslukuisimmista lajeista alueella ja sietää lisäksi hyvin laboratorio-oloja. Matalatasoisen ionisoivan säteilyn vaikutusta metsämyyräpopulaatioon testattiin useilla sukupolvilla. Tutkin säteilyn vaikutusta populaatiokokoon, lisääntymistä molemmilla sukupuolilla ja vaikutusta ruumiinkokoon ja sisäelinten kokoon. Ensimmäisessä osakokeessa havaittiin negatiivinen korrelaatio säteilyn ja yksilömäärän välillä. Edes ravinnon lisääminen alueelle ei auttanut kasvattamaan populaatiokokoa korkean säteilyn alueella. Väitöskirjassa tutkittiin yksilömäärän harventumista korkean säteilyn alueella, sekä säteilyn vaikutusta molempien sukupuolten lisääntymisominaisuuksiin. Toisessa osakokeessa havaittiin, että metsämyyräkoiraiden siittiöiden keskikappale pienentyi säteilyn kasvaessa. Lisäksi säteilymäärän kasvaessa liikkumattomien siittiöiden määrä kasvoi. Tämä saattaa vaikuttaa koiraiden lisääntymiskykyyn, mutta tässä väitöskirjassa asiaa ei olla tarkemmin tutkittu. Kolmannessa osakokeessa naaraita siirrettiin poikasten kanssa joko matalan tai korkean säteilyn alueelle ja niiden havaittiin selviytyvän paremmin, jos siirtyminen tapahtui samankaltaiselle alueelle, jolta yksilöt oli alun perin pyydetty. Toisaalta poikasten selviytyminen parani, jos emo oli pyydetty alun perin puhtaalta alueelta. Viimeisessä osakokeessa tutkittiin metsämyyrien ruumiinkokoa ja sisäelinten massoja. Tulokset paljastivat aivojen massan pienentyvän säteilyn kasvaessa. Lisäksi sydän ja perna olivat suurempia korkean säteilyn alueella. Tutkimuksessa löydettiin useita negatiivisia säteilyvaikutuksia, mutta koska säteilyn voimakkuus alueella on paikoin suhteellisen alhainen, ei ole varmaa johtuvatko tulokset suorasta säteilyvaikutuksesta vai useammasta kroonisesta stressitekijästä alueella

Supplementary material for article "Exposure to environmental radionuclides is associated with altered metabolic and immunity pathways in a wild rodent".

Electronic material for Kesäniemi J, Jernfors T, Lavrinienko A, Kivisaari K, Kiljunen M, Mappes T & Watts PC. 2019. Exposure to environmental radionuclides is associated with altered metabolic and immunity pathways in a wild rodent. Molecular Ecology 28: 4620–4635. Contains transcriptome annotation data and output of differential expression and gene ontology enrichment analyses. Parts of the dataset originally published in DRYAD (https://doi.org/10.5061/dryad.j3c6r69)

Data from: Exposure to environmental radionuclides is associated with altered metabolic and immunity pathways in a wild rodent

Wildlife inhabiting environments contaminated by radionuclides face putative detrimental effects of exposure to ionizing radiation, with biomarkers such as an increase in DNA damage and/or oxidative stress commonly associated with radiation exposure. To examine the effects of exposure to radiation on gene expression in wildlife, we conducted a de novo RNA sequencing study of liver and spleen tissues from a rodent, the bank vole Myodes glareolus. Bank voles were collected from the Chernobyl Exclusion Zone (CEZ), where animals were exposed to elevated levels of radionuclides, and from uncontaminated areas near Kyiv, Ukraine. Counter to expectations, we did not observe a strong DNA damage response in animals exposed to radionuclides, although some signs of oxidative stress were identified. Rather, exposure to environmental radionuclides was associated with upregulation of genes involved in lipid metabolism and fatty acid oxidation in the livers – an apparent shift in energy metabolism. Moreover, using stable isotope analysis, we identified that fur from bank voles inhabiting the CEZ had enriched isotope values of nitrogen: such an increase is consistent with increased fatty acid metabolism, but also could arise from a difference in diet or habitat between the CEZ and elsewhere. In livers and spleens, voles inhabiting the CEZ were characterized by immunosuppression, such as impaired antigen processing, and activation of leukocytes involved in inflammatory responses. In conclusion, exposure to low dose environmental radiation impacts pathways associated with immunity and lipid metabolism, potentially as a stress-induced coping mechanism