Cathepsin K deficiency in mice induces structural and metabolic changes in the central nervous system that are associated with learning and memory deficits

<p>Abstract</p> <p>Background</p> <p>Cathepsin K is a cysteine peptidase known for its importance in osteoclast-mediated bone resorption. Inhibitors of cathepsin K are in clinical trials for treatment of osteoporosis. However, side effects of first generation inhibitors included altered levels of related cathepsins in peripheral organs and in the central nervous system (CNS). Cathepsin K has been recently detected in brain parenchyma and it has been linked to neurobehavioral disorders such as schizophrenia. Thus, the study of the functions that cathepsin K fulfils in the brain becomes highly relevant.</p> <p>Results</p> <p>Cathepsin K messenger RNA was detectable in all brain regions of wild type (WT) mice. At the protein level, cathepsin K was detected by immunofluorescence microscopy in vesicles of neuronal and non-neuronal cells throughout the mouse brain. The hippocampus of WT mice exhibited the highest levels of cathepsin K activity in fluorogenic assays, while the cortex, striatum, and cerebellum revealed significantly lower enzymatic activities. At the molecular level, the proteolytic network of cysteine cathepsins was disrupted in the brain of cathepsin K-deficient (<it>Ctsk</it>^-/-) animals. Specifically, cathepsin B and L protein and activity levels were altered, whereas cathepsin D remained largely unaffected. Cystatin C, an endogenous inhibitor of cysteine cathepsins, was elevated in the striatum and hippocampus, pointing to regional differences in the tissue response to <it>Ctsk </it>ablation. Decreased levels of astrocytic glial fibrillary acidic protein, fewer and less ramified profiles of astrocyte processes, differentially altered levels of oligodendrocytic cyclic nucleotide phosphodiesterase, as well as alterations in the patterning of neuronal cell layers were observed in the hippocampus of <it>Ctsk</it>^-/-mice. A number of molecular and cellular changes were detected in other brain regions, including the cortex, striatum/mesencephalon, and cerebellum. Moreover, an overall induction of the dopaminergic system was found in <it>Ctsk</it>^-/-animals which exhibited reduced anxiety levels as well as short- and long-term memory impairments in behavioral assessments.</p> <p>Conclusion</p> <p>We conclude that deletion of the <it>Ctsk </it>gene can lead to deregulation of related proteases, resulting in a wide range of molecular and cellular changes in the CNS with severe consequences for tissue homeostasis. We propose that cathepsin K activity has an important impact on the development and maintenance of the CNS in mice.</p

No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice

BACKGROUND: Several reports indicated that non-thermal electromagnetic radiation such as from mobile phones and base stations may promote cancer. Therefore, it was investigated experimentally, whether 900 MHz electromagnetic field exposure influences lymphoma development in a mouse strain that is genetically predisposed to this disease. The AKR/J mice genome carries the AK-virus, which leads within one year to spontaneous development of thymic lymphoblastic lymphoma. METHODS: 320 unrestrained female mice were sham-exposed or exposed (each n = 160 animals) to GSM like 900 MHz electromagnetic fields for 24 hours per day, 7 days per week, at an average whole body specific absorption rate (SAR) value of 0.4 W/kg. Animals were visually checked daily and were weighed and palpated weekly. Starting with an age of 6 months, blood samples were taken monthly from the tail. Animals with signs of disease or with an age of about 46 weeks were sacrificed and a gross necropsy was performed. RESULTS: Electromagnetic field exposure had a significant effect on body weight gain, with higher values in exposed than in sham-exposed animals. However, survival rate and lymphoma incidence did not differ between exposed and sham-exposed mice. CONCLUSION: These data do not support the hypothesis that exposure to 900 MHz electromagnetic fields is a significant risk factor for developing lymphoma in a genetically predisposed species, even at a relatively high exposure level

Effects of Weak Alternating Magnetic Fields on Nocturnal Melatonin Production and Mammary Carcinogenesis in Rats

Since extremely low frequency (i.e., 50- or 60-Hz) magnetic fields (MFs) from overhead power lines and other electromagnetic sources are ubiquitous in modern societies, the possible carcinogenic effect of such fields recently suggested by epidemiological studies has engendered much concern. However, in view of various unknown and uncontrolled variables which may bias epidemiological studies on MF interactions, a causal relationship between MFs and tumorigenesis can only be determined precisely in animal experiments. The goal of the study reported here was to determine if low frequency MFs at the low flux densities which are relevant for human populations induce tumor-promoting or copromoting effects in a model of breast cancer. Furthermore, since reduction in pineal production of melatonin has been implicated as a cause of tumor promotion by electromagnetic fields, determinations of nocturnal melatonin peak levels in serum were performed during MF exposure. Mammary tumors were induced by intragastric administration of 20 mg (5 mg/week) 7,12-dimethylbenz(a)anthracene (DMBA) in female Sprague-Dawley rats. Groups of 36 rats were either sham-exposed or exposed for 91 days at a 50-Hz gradient MF of 0.3-1 microT, which is a relevant range for elevated domestic MF exposure as arising from neighboring power lines. Nocturnal melatonin levels were significantly reduced by exposure to this weak alternating MF. However, histopathological evaluation of mammary lesions did not disclose any significant difference between MF- and sham-exposed animals. Incidence of mammary tumors was 61% in controls versus 67% in MF-exposed rats. The predominant tumor type was the invasive adenocarcinoma, which was found in 21 rats of both groups. Examination of tumor size did not indicate significant differences in tumor burden between both groups. Furthermore, the incidence of preneoplastic lesions was not altered by MF exposure. Thus, the data of this study indicate that alternating MF do not exert significant tumor promoting or copromoting effects at environmentally relevant flux densities in the rat mammary cancer system

Children's health and RF EMF exposure

$\textbf{Aim}$ The report is reviewing and evaluating the current state of the scientific evidence of the effects of EMF exposure from cell phones and base stations on children’s health. Three main areas of children’s health were assessed: - Cancer (brain cancer and leukaemia) and health disturbances, - Effects on embryonic development, offspring, and blood-brain barrier investigated by animal research, - Effects on cognition and the central nervous system (CNS). Additionally, dosimetry issues were considered, i.e. whether children do absorb more power than adults when exposed to RF EMF. $\textbf{Procedure}$ The report is based on the scientific opinions of 7 international recognized experts and 4 advisory experts from Australia, Austria, Belgium, Germany, Italy and Switzerland as well as on a series of workshop discussion. An important criterion for the selection of the experts was that they have a strong record in EMF research, as documented by publications in internationally recognized and peer-reviewed academic journals. Advisory expert panelists supported the discussions of the expert opinions during the workshops. For their selection, it was not required that the scientific research of the advisory experts focuses specifically on the EMF field. Rather, the selection depended on their theoretical and methodological knowledge for the respective topic area to critically review the expert opinion reports. Subsequently, for all relevant endpoints evidence maps were constructed, i.e. graphical representations of the main arguments on which the conclusions are based as well as a description of the remaining uncertainties. The dialogue project was initiated in October 2007 and completed in August 2009. $\textbf{Results}$ Dosimetry For children under 8 years no conclusive evidence exists for the assumption that the SAR level in children’s head is higher than for adults. For whole body exposure, there is some evidence that the ICNIRP reference level cannot ensure that basic restrictions are not exceeded under any circumstances. This applies for children younger than 8 years at specific frequency bands, e.g. around 100 MHz and 1.8 GHz. However, even if further research would prove this it has to be taken into account that ICNIRP basic restrictions comprise large safety factors and real-world [...