5 research outputs found
GABA, glutamine, glutamate oxidation and succinic semialdehyde dehydrogenase expression in human gliomas
Bioenergetic characterisation of malignant tissues revealed that different tumour cells can catabolise multiple substrates as salvage pathways, in response to metabolic stress. Altered metabolism in gliomas has received a lot of attention, especially in relation to IDH mutations, and the associated oncometabolite D-2-hydroxyglutarate (2-HG) that impact on metabolism, epigenetics and redox status. Astrocytomas and oligodendrogliomas, collectively called diffuse gliomas, are derived from astrocytes and oligodendrocytes that are in metabolic symbiosis with neurons; astrocytes can catabolise neuron-derived glutamate and gamma-aminobutyric acid (GABA) for supporting and regulating neuronal functions.Metabolic characteristics of human glioma cell models - including mitochondrial function, glycolytic pathway and energy substrate oxidation - in relation to IDH mutation status and after 2-HG incubation were studied to understand the Janus-faced role of IDH1 mutations in the progression of gliomas/astrocytomas. The metabolic and bioenergetic features were identified in glioma cells using wild-type and genetically engineered IDH1-mutant glioblastoma cell lines by metabolic analyses with Seahorse, protein expression studies and liquid chromatography-mass spectrometry.U251 glioma cells were characterised by high levels of glutamine, glutamate and GABA oxidation. Succinic semialdehyde dehydrogenase (SSADH) expression was correlated to GABA oxidation. GABA addition to glioma cells increased proliferation rates. Expression of mutated IDH1 and treatment with 2-HG reduced glutamine and GABA oxidation, diminished the pro-proliferative effect of GABA in SSADH expressing cells. SSADH protein overexpression was found in almost all studied human cases with no significant association between SSADH expression and clinicopathological parameters (e.g. IDH mutation).Our findings demonstrate that SSADH expression may participate in the oxidation and/or consumption of GABA in gliomas, furthermore, GABA oxidation capacity may contribute to proliferation and worse prognosis of gliomas. Moreover, IDH mutation and 2-HG production inhibit GABA oxidation in glioma cells. Based on these data, GABA oxidation and SSADH activity could be additional therapeutic targets in gliomas/glioblastomas
PHARMACOKINETICS OF INTRAMUSCULAR ADMINISTERED BETA-CAROTENE AND ITS EFFECTS ON REPRODUCTION IN SHEEP
In the first experiment, blood levels of p-carotene were determined after i.m. administration of 7.4, 14.9, 22.3, 27.9 and 37.2 mu mol beta-carotene/kg BW3/4 (metabolic body weight), once a month in foursheep of the same breed and age. Blood samples were drawn 1 day after each injection and continued in two day intervals for 21 days. The lowest dose, leading to a detectable serum concentration, was 14.9 mu mol beta-carotene/kg BW3/4. AS th, higher dosages were given, higher blood levels were determined and the p-carotene remained longer in the circulation. In lactating sheep P-carotene was also found in milk