Expression of functional GABAc receptors in the brain

γ-aminobutyric acid (GABA) is the main inhibitory transmitter in the nervous system and acts via three distinct receptor classes: A, B, and C. GABAC receptors are ionotropic receptors comprising ρ subunits. In this work, we aimed to elucidate the expression of ρ subunits in the postnatal brain, the characteristics of ρ2 homo-oligomeric receptors, and the function of GABAC receptors in the hippocampus. In situ hybridization on rat brain slices showed ρ2 mRNA expression from the newborn in the superficial grey layer of the superior colliculus, from the first postnatal week in the hippocampal CA1 region and the pretectal nucleus of the optic tract, and in the adult dorsal lateral geniculate nucleus. Quantitative RT-PCR revealed expression of all three ρ subunits in the hippocampus and superior colliculus from the first postnatal day. In the hippocampus, ρ2 mRNA expression clearly dominated over ρ1 and ρ3. GABAC receptor protein expression was confirmed in the adult hippocampus, superior colliculus, and dorsal lateral geniculate nucleus by immunohistochemistry. From the selective distribution of ρ subunits, GABAC receptors may be hypothesized to be specifically involved in aspects of visual image motion processing in the rat brain. Although previous data had indicated a much higher expression level for ρ2 subunit transcripts than for ρ1 or ρ3 in the brain, previous work done on Xenopus oocytes had suggested that rat ρ2 subunits do not form functional homo-oligomeric GABAC receptors but need ρ1 or ρ3 subunits to form hetero-oligomers. Our results demonstrated, for the first time, that HEK 293 cells transfected with ρ2 cDNA displayed currents in whole-cell patch-clamp recordings. Homomeric rat ρ2 receptors had a decreased sensitivity to, but a high affinity for picrotoxin and a marked sensitivity to the GABAC receptor agonist CACA. Our results suggest that ρ2 subunits may contribute to brain function, also in areas not expressing other ρ subunits. Using extracellular electrophysiological recordings, we aimed to study the effects of the GABAC receptor agonists and antagonists on responses of the hippocampal neurons to electrical stimulation. Activation of GABAC receptors with CACA suppressed postsynaptic excitability and the GABAC receptor antagonist TPMPA inhibited the effects of CACA. Next, we aimed to display the activation of the GABAC receptors by synaptically released GABA using intracellular recordings. GABA-mediated long-lasting depolarizing responses evoked by high-frequency stimulation were prolonged by TPMPA. For weaker stimulation, the effect of TPMPA was enhanced after GABA uptake was inhibited. Our data demonstrate that GABAC receptors can be activated by endogenous synaptic transmitter release following strong stimulation or under conditions of reduced GABA uptake. The lack of GABAC receptor activation by less intensive stimulation under control conditions suggests that these receptors are extrasynaptic and activated via spillover of synaptically released GABA. Taken together with the restricted expression pattern of GABAC receptors in the brain and their distinctive pharmacological and biophysical properties, our findings supporting extrasynaptic localization of these receptors raise interesting possibilities for novel pharmacological therapies in the treatment of, for example, epilepsy and sleep disorders.

Ethics in a Technological World : Framing the Questions and Three Approaches

This study addresses the following question: How to think about ethics in a technological world? The question is treated first thematically by framing central issues in the relationship between ethics and technology. This relationship has three distinct facets: i) technological advance poses new challenges for ethics, ii) traditional ethics may become poorly applicable in a technologically transformed world, and iii) the progress in science and technology has altered the concept of rationality in ways that undermine ethical thinking itself. The thematic treatment is followed by the description and analysis of three approaches to the questions framed. First, Hans Jonas s thinking on the ontology of life and the imperative of responsibility is studied. In Jonas s analysis modern culture is found to be nihilistic because it is unable to understand organic life, to find meaning in reality, and to justify morals. At the root of nihilism Jonas finds dualism, the traditional Western way of seeing consciousness as radically separate from the material world. Jonas attempts to create a metaphysical grounding for an ethic that would take the technologically increased human powers into account and make the responsibility for future generations meaningful and justified. The second approach is Albert Borgmann s philosophy of technology that mainly assesses the ways in which technological development has affected everyday life. Borgmann admits that modern technology has liberated humans from toil, disease, danger, and sickness. Furthermore, liberal democracy, possibilities for self-realization, and many of the freedoms we now enjoy would not be possible on a large scale without technology. Borgmann, however, argues that modern technology in itself does not provide a whole and meaningful life. In fact, technological conditions are often detrimental to the good life. Integrity in life, according to him, is to be sought among things and practices that evade technoscientific objectification and commodification. Larry Hickman s Deweyan philosophy of technology is the third approach under scrutiny. Central in Hickman s thinking is a broad definition of technology that is nearly equal to Deweyan inquiry. Inquiry refers to the reflective and experiential way humans adapt to their environment by modifying their habits and beliefs. In Hickman s work, technology consists of all kinds of activities that through experimentation and/or reflection aim at improving human techniques and habits. Thus, in addition to research and development, many arts and political reforms are technological for Hickman. He argues for recasting such distinctions as fact/value, poiesis/praxis/theoria, and individual/society. Finally, Hickman does not admit a categorical difference between ethics and technology: moral values and norms need to be submitted to experiential inquiry as well as all the other notions. This study mainly argues for an interdisciplinary approach to the ethics of technology. This approach should make use of the potentialities of the research traditions in applied ethics, the philosophy of technology, and the social studies on science and technology and attempt to overcome their limitations. This study also advocates an endorsement of mid-level ethics that concentrate on the practices, institutions, and policies of temporal human life. Mid-level describes the realm between the instantaneous and individualistic micro-level and the universal and global macro level.

Sostdc1 Plays an Essential Role in Mammalian Tooth Patterning : Insight into the Rodent Dental Evolution

This thesis work focuses on the role of TGF-beta family antagonists during the development of mouse dentition. Tooth develops through an interaction between the dental epithelium and underlying neural crest derived mesenchyme. The reciprocal signaling between these tissues is mediated by soluble signaling molecules and the balance between activatory and inhibitory signals appears to be essential for the pattern formation. We showed the importance of Sostdc1 in the regulation of tooth shape and number. The absence of Sostdc1 altered the molar cusp patterning and led to supernumerary tooth formation both in the molar and incisor region. We showed that initially, Sostdc1 expression is in the mesenchyme, suggesting that dental mesenchyme may limit supernumerary tooth induction. We tested this in wild-type incisors by minimizing the amount of mesenchymal tissue surrounding the incisor tooth germs prior to culture in vitro. The cultured teeth phenocopied the extra incisor phenotype of the Sostdc1-deficient mice. Furthermore, we showed that minimizing the amount of dental mesenchyme in cultured Sostdc1-deficient incisors caused the formation of additional de novo incisors that resembled the successional incisor development resulting from activated Wnt signaling. Sostdc1 seemed to be able to inhibit both mesenchymal BMP4 and epithelial canonical Wnt signaling, which thus allows Sostdc1 to restrict the enamel knot size and regulate the tooth shape and number. Our work emphasizes the dual role for the tooth mesenchyme as a suppressor as well as an activator during tooth development. We found that the placode, forming the thick mouse incisor, is prone to disintegration during initiation of tooth development. The balance between two mesenchymal TGF-beta family signals, BMP4 and Activin is essential in this regulation. The inhibition of BMP4 or increase in Activin signaling led to the splitting of the large incisor placode into two smaller placodes resulting in thin incisors. These two signals appeared to have different effects on tooth epithelium and the analysis of the double null mutant mice lacking Sostdc1 and Follistatin indicated that these TGF-beta inhibitors regulate the mutual balance of BMP and Activin in vivo. In addition, this work provides an alternative explanation for the issue of incisor identity published in Science by Tucker et al. in 1998 and proposes that the molar like morphology that can be obtained by inhibiting BMP signaling is due to partial splitting of the incisor placodes and not due to change in tooth identity from the incisor to the molar. This thesis work presents possible molecular mechanisms that may have modified the mouse dental pattern during evolution leading to the typical rodent dentition of modern mouse. The rodent dentition is specialized for gnawing and consists of two large continuously growing incisors and toothless diastema region separating the molars and incisors. The ancestors of rodents had higher number of more slender incisors together with canines and premolars. Additionally, murine rodents, which include the mouse, have lost their ability for tooth replacement. This work has revealed that the inhibitory molecules appear to play a role in the tooth number suppression by delineating the spatial and temporal action of the inductive signals. The results suggest that Sostdc1 plays an essential role in several stages of tooth development through the regulation of both the BMP and Wnt pathway. The work shows a dormant sequential tooth forming potential present in wild type mouse incisor region and gives a new perspective on tooth suppression by dental mesenchyme. It reveals as well a novel mechanism to create a large mouse incisor through the regulation of mesenchymal balance between inductive and inhibitory signals.

Nature of chemistry in the national frame curricula for upper secondary education in Finland, Norway and Sweden

The aim of this study was to discover how current chemistry syllabi in the frame curricula for up- per secondary education in three Nordic countries (Finland, Norway, and Sweden) take into account topics related to the nature of chemistry. By qualitative content analysis, the statements related to the nature of chemistry were divided into categories. Conclusions and implications for improving the frame curricula under study were made by comparing results with research into the nature of science. Chemistry syllabi from the Nordic frame curricula analyzed take into account the aims related to the nature of chemistry in a very similar manner. The ideas that should be made more explicit in all of the analyzed curricula are: i) the limits of the chemical models and theories, ii) the relationship between chemistry and other natural sciences, iii) the importance of creativity in chemical research, iv) the concepts of evidence in science texts, v) the social nature of chemical research, and vi) chemistry as a technological practice.

Monumenttikuvista elämyskuviin : Helsinki matkaesitteiden kuvituksessa 1895 - 2005

The purpose of this study is to define how Helsinki has been presented in the pictures of tourist brochures and how their illustration has changed over time. Attention is also paid to the values and meanings that the pictures mediate, as well as their historical and societal connections. The pictures are approached as representations selectively interpreting and illustrating the reality of Helsinki, while constructing mental images of it. An iconological framework structures the study. It proceeds from the description and classification of the physical features towards an analysis of time- and culture-specific meanings. The emergence of meanings and their historical and cultural underpinnings are examined from the perspectives of humanistic geography, semiotics and constructionism. In the analysis attention is paid to the discourses, myths and ideologies that underlie the representations. Information on the physical features of the pictures and their changes is collected with a content analysis. The classified data consists of 1377 photographs. These pictures are collected from 75 tourist brochures of Helsinki that have been published between 1895 and 2005. The deeper meanings of the pictures are studied qualitatively, by paying attention to the mental images that the content elements and visual effects evoke. Research studies, contemporary literature and the texts of the tourist brochures are utilised in the interpretation of the meanings. There has been a permanent core to objects of the pictures during the entire study period. It has consisted mainly of sights that are located close to the Senate and Market Squares. In addition, marine elements have been popular. The area of Helsinki represented in the brochures has extended from the Senate Square towards Töölö Bay. Pictures of monumental buildings and statues have been complemented with snapshots and portraits. In the beginning of the 20th century, brochures were mainly produced for the travelling, educated elite. The style of the pictures was declaratory and educative. They aimed at medating an objective image of the reality that prevailed in Helsinki. In practice, the pictures were connected to a patriotic ideology and the corresponding myth of Finnishness. In the second half of the 20th century the improvement of the standard of living led to a democratisation of consumers and an increase in the tourism demand. Local culture and the everyday life of "ordinary" people became popular themes in the pictures. A new welfare ideology manifested itself in the people of the local residential areas, for instance. The increase in the cultural diversity has led to the recognition of new target groups, expecially since the 1980s. The human figures in the pictures have started to function as objects of identification and a means of constructing mental images. A pronounced emphasis on experience and individuality in the illustration of the tourist brochures mirrors the post-modern change and a new ideology based on consumption. The construction and consumption of the pictures in the tourist brochures is governed by the conventions of representation and interpretaion that are typical of the genre of tourist brochures. The pictures emphasize the perceived positive characteristics of Helsinki and thus construct a skewed view of the reality. However, consumers can knowingly use the pictures as a means of dreaming and detaching themselves from their everyday reality.