Astrocytic control in in vitro and simulated neuron-astrocyte networks

acceptedVersionPeer reviewe

Astrocytes in modulating subcellular, cellular and intercellular molecular neuronal communication

Astrocytes are one of the most abundant cell types in our brain. They modulate the brain homeostasis and play a role in the synaptic signalling and thus the molecular propagation inside the brain. Moreover, they form communication networks that co-localise with the neuronal networks with comparable topological complexity. There is an increasing piece of evidence that astrocytes are important in plasticity and learning from the level of the single synapse to the entire network. Moreover, several diseases are molecular communications on different scales from the synaptic to network level.acceptedVersionPeer reviewe

Astrocytes Exhibit a Protective Role in Neuronal Firing Patterns under Chemically Induced Seizures in Neuron-Astrocyte Co-Cultures.

Astrocytes and neurons respond to each other by releasing transmitters, such as γ-aminobutyric acid (GABA) and glutamate, that modulate the synaptic transmission and electrochemical behavior of both cell types. Astrocytes also maintain neuronal homeostasis by clearing neurotransmitters from the extracellular space. These astrocytic actions are altered in diseases involving malfunction of neurons, e.g., in epilepsy, Alzheimer's disease, and Parkinson's disease. Convulsant drugs such as 4-aminopyridine (4-AP) and gabazine are commonly used to study epilepsy in vitro. In this study, we aim to assess the modulatory roles of astrocytes during epileptic-like conditions and in compensating drug-elicited hyperactivity. We plated rat cortical neurons and astrocytes with different ratios on microelectrode arrays, induced seizures with 4-AP and gabazine, and recorded the evoked neuronal activity. Our results indicated that astrocytes effectively counteracted the effect of 4-AP during stimulation. Gabazine, instead, induced neuronal hyperactivity and synchronicity in all cultures. Furthermore, our results showed that the response time to the drugs increased with an increasing number of astrocytes in the co-cultures. To the best of our knowledge, our study is the first that shows the critical modulatory role of astrocytes in 4-AP and gabazine-induced discharges and highlights the importance of considering different proportions of cells in the cultures

The Effects of Intensive Weight Reduction on Body Composition and Serum Hormones in Female Fitness Competitors

Worries about the potential negative consequences of popular fat loss regimens for aesthetic purposes in normal weight females have been surfacing in the media. However, longitudinal studies investigating these kinds of diets are lacking. The purpose of the present study was to investigate the effects of a 4-month fat-loss diet in normal weight females competing in fitness-sport. In total 50 participants finished the study with 27 females (27.2 +/- 4.1 years) dieting for a competition and 23 (27.7 +/- 3.7 years) acting as weight-stable controls. The energy deficit of the diet group was achieved by reducing carbohydrate intake and increasing aerobic exercise while maintaining a high level of protein intake and resistance training in addition to moderate fat intake. The diet led to a similar to 12% decrease in body weight (P <0.001) and a similar to 3550% decrease in fat mass (DXA, bioimpedance, skinfolds, P <0.001) whereas the control group maintained their body and fat mass (diet x group interaction P <0.001). A small decrease in lean mass (bioimpedance and skinfolds) and in vastus lateralis muscle cross-sectional area (ultrasound) were observed in diet (P <0.05), whereas other results were unaltered (DXA: lean mass, ultrasound: triceps brachii thickness). The hormonal system was altered during the diet with decreased serum concentrations of leptin, triiodothyronine (T3), testosterone (P <0.001), and estradiol (P <0.01) coinciding with an increased incidence of menstrual irregularities (P <0.05). Body weight and all hormones except T3 and testosterone returned to baseline during a 34 month recovery period including increased energy intake and decreased levels aerobic exercise. This study shows for the first time that most of the hormonal changes after a 3550% decrease in body fat in previously normal-weight females can recover within 34 months of increased energy intake.Peer reviewe

Osallistamisen ja omaneduntavoittelun rajat : Tutkimus uusliberalistisista taloudellisista intresseistä Euroopan unionin itäisiin naapurimaihinsa kohdistamassa liikkuvuuspolitiikassa

Pro gradu -tutkielmassa tarkastellaan Euroopan unionin (EU) liikkuvuuspolitiikkaan sisältyviä taloudellisia intressejä. Liikkuvuuspolitiikkaa on aikaisemmin tarkasteltu pääsääntöisesti turvallisuuteen liittyvänä kysymyksenä. Muualla maailmassa tehdyn tutkimuksen valossa on kuitenkin syytä selvittää, onko liikkuvuuden kontrolloinnissa myös taloudellisen eduntavoittelun piirteitä. Tutkimuskohteena on kuusi itäistä EU:n naapurimaata, jotka kuuluvat alueellista yhdentymistä edistävän Euroopan naapuruuspolitiikka -instrumentin (ENP) piiriin. Kohdemaat ovat Valko-Venäjä, Ukraina, Moldova, Georgia, Armenia ja Azerbaidzhan. Maiden kansalaiset ovat viisumivelvollisia Schengen-liikkuvuusalueelle. Tutkimus koostuu kahdesta osasta. Ensimmäisessä vaiheessa esitetään tutkimusaineiston laadullisen sisällönanalyysin avulla, että Euroopan naapuruuspolitiikka pyrkii edistämään alueellista integraatiota. Samalla osoitetaan kuitenkin, että liikkuvuuspolitiikka, joka on tärkeä osa yhdentymistä, tukee lähinnä markkinatalouden kannalta keskeisten ihmisryhmien matkustamisen vapautta. Sisällönanalyysin tutkimusaineistona on käytetty neljää Euroopan naapuruuspolitiikkaa käsittelevää tiedonantoa sekä yhteensä kuutta EU:n ja ENP-maiden välistä liikkuvuuskumppanuus- ja viisumihelpotussopimusta. Tutkimusaineiston avulla voidaan peilata retoriikkaa politiikan käytäntöihin ja havaita tutkimuksellisesti mielenkiintoinen ristiriita. Tutkimuksen toisessa osassa liikkuvuuden painottumista markkinatalouden tukemiseen on tulkittu kahden teorian – uusliberalismin ja osallistavan uusliberalismin – avulla. Molempien teorioiden globaaleista vaikutuksista on käyty runsaasti keskustelua. Teoriat on tässä tutkimuksessa ymmärretty käsitejärjestelmiksi, joiden avulla voidaan hahmottaa – ei niinkään selittää – poliittisia käytäntöjä. Teoreettisten erojen pohjalta on muotoiltu kuusi tutkimushypoteesia, joiden avulla on testattu, kuinka hyvin liikkuvuuspolitiikka vastaa kumpaakin teoreettista diskurssia. Hypoteesit liittyvät 1) markkinatalouden rooliin, 2) sosiaaliseen vastuuseen ja 3) kehitykseen. Hypoteesien vertailun perusteella voidaan havaita, että taloudellisessa liikkuvuudessa on niin osallistavan uusliberalismin kuin uusliberalisminkin piirteitä. Osallistava uusliberalismi esiintyy kuitenkin lähinnä retorisena keinona, ei niinkään johdonmukaisesti toteutettuna politiikkana. Liikkuvuus heijastaa sen sijaan vahvasti uusliberalismille tyypillistä EU:n taloudellista omaneduntavoittelua, joka on markkinoiden avaamistakin keskeisemmässä asemassa. Tulosten perusteella voidaan havaita, että uusliberalistiset käytännöt ovat saaneet jalansijaa EU:n liikkuvuuspolitiikassa, jolle taloudellisen eduntavoittelun arvot ovat lähtökohtaisesti vieraita. Uusliberalismi herättää myös kysymyksen demokratiaperiaatteen toteutumisesta. Jatkotutkimuksen selvitettäväksi jää, miten uusliberalistinen diskurssi on muodostunut

Citizens’ preferences for policies to conserve agricultural genetic resources

The intensification of agriculture has led to remarkable changes in the utilization of agricultural genetic resources and many previously common breeds and varieties have become rare or even endangered (FAO 2007, 2010, Drucker, Gomez &amp; Anderson 2001). In Finland, Eastern and Northern Finncattle, the Kainuu Grey Sheep and the Åland Sheep are endangered according to the FAO classification (FAO 2003) and, for example, majority of the old Finnish crop varieties and Finnish landrace pig are already extinct. Making informed decisions on the appropriate focus and extent of conservation of agricultural genetic resources requires information on both the costs and benefits of conservation. Economic analyses involving the valuation of conservation benefits can guide resource allocation of various types of genetic resources and conservation methods (Artuso 1998). The value of genetic resources is not typically revealed by markets, as they are not directly traded in the markets or the prices of agricultural products do not completely indicate their value (Oldfield 1989, Brown 1990, Drucker et al. 2001). Although the importance of economic analyses has been recognized, the literature on the monetary value of genetic resources in agriculture is relatively limited (see e.g. Evenson et al. 1998 and Rege and Gibson 2003, Ahtiainen &amp; Pouta 2011). Currently the conservation policy of farm agricultural genetic resources in Finland is based on international agreements such as the Convention on Biological Diversity (1992) and the Global Plan of Action for Animal Genetic resources (FAO 2007). National genetic resource programs were initiated for plants in 2003 and for farm animals in 2005 to strengthen the conservation of genetic resources in Finland. Although there has been some progress in the implementation of the programs, they have also suffered from shortage of funds and lack of political interest in conservation. To re-evaluate the conservation policy, there is a need to use valuation methods capable of estimating also the non-use value components of genetic resources, i.e. stated preference methods. The choice experiment (CE) method has been found suitable to valuing genetic resources due to its flexibility and ability to value the traits of breeds or varieties and their attributes. Choice experiment makes it possible to value benefits of both plant genetic resources (PGR) and animal genetic resources (AnGR). The terms refer to all cultivated plant species and varieties, as well as all animal species and breeds that are of interest in terms of food and agricultural production. The CE method can also be used to evaluate the means of conservation in situ (live animals and plants) and ex situ (as seeds, cryopreserved embryos and other genetic material). Previous choice experiments have focused on valuing breeds or varieties and their attributes, especially on attributes that are related to the use of the breed or variety in agriculture (Birol et al. 2006, Ouma et al. 2007). In this study we present the results of a choice experiment valuing the benefits of a genetic resource conservation program in Finland. We test the effect of in situ and ex situ conservation on citizen choices between programs. We also analyse whether the plant varieties and animal breeds are perceived equally valuable by citizen. As the conservation of agricultural genetic resources (AgGR) cannot be expected to be equally valuable to all citizens, we analyse the existence of citizen segments that value differently the conservation of genetic resources. We can assume that AgGR is a rather unknown good for some of the respondents of the valuation survey. However, in valuation surveys respondents are assumed to make “informed” choices when responding to value elicitation questions (e.g. Blomquist &amp;Whitehead 1998). Therefore, we offered an opportunity for respondents to obtain further information on AgGR. In our case, the internet-based survey allowed us also to measure how much time respondents took in reading the information and responding to questions. Furthermore, we also measured response certainty and tested the effects of uncertainty and information as reasons for heterogeneity