Endocrine Abstracts

Introduction: Neurodegeneration is one of the most common condition accompanied Diabetes Mellitus, Parkinson’s and Alzheimer’s diseases. Although its mechanisms intensively studied for many years, some questions of pathogenesis remain unclear. The aim of the study was investigate the effects of thyroid hormones and some neurotransmitters on the cerebral cortex of rats with experimental neurodegeneration.

Materials and methods: Series of experiments were carried out on 45 purebred white rats were divided into 3 groups: control, animals given a neurotoxins such as thiamazole (second group) and AlCl3 (third group) for neurodegeneration models. In the end of experiments rats were sacrified, blood samples taken by cardiac puncture, hippocampus, cortex and other parts of the brain taken separately and homogenised. In blood serum T3, T4, TTG and tau protein concentrations were determined, also in samples from hippocampus, cortex and other part of the brain based on enzyme immunoassay kits. Determination of the content of neurotransmitters aspartate, glutamate, gamma-aminobutyric acid (GABA) level in samples were measured using thin-layer chromatography. The amount of dopamine and noradrenaline in the homogenate of the hippocampus and cortex of the brain determined by column chromatography, and acetylcholine was determined spectrophotometrically.

Results: Rat models with neurodegeneration were obtained 14th day after taken of neurotoxins. Blood serum T3, T4 levels were not significantly differs between the groups and were in normal ranges. Interestingly, in rats with both neurodegeneration models significant decreasing in the level of T3 in the homogenate of the hippocampus and cortex, but not in other parts of the brain were found. Moreover, neurotransmitters level were disturbed i.e. increasing of glutamate and aspartate, GABA level, also decreasing of amount of noradrenaline and dopamine in the homogenates of the hippocampus and cortex of the brain were determined in rats with neurodegeneration. Decreasing level of thyroid hormones locally in hippocampus and cortex of the brain and abnormal neurotransmitters level probably was one of the main causes of the disturbance of cognitive functions in the rats.

Conclusion: Experimental neurodegeneration in rats revealed decreasing of thyroid hormones level locally in the homogenates of the hippocampus and cortex of the brain, which accompanied with disturbed level of glutamate and aspartate, GABA levels, also decreasing of amount of noradrenaline and dopamine, which affected rats cognitive function.