Summary: | 碩士 === 國防醫學院 === 生物及解剖學研究所 === 100 === Calcitonin is a polypeptide hormone that is produced by the parafollicular cells of thyroid gland. It acts to reduce blood calcium concentration and inhibit osteoclast activity in bones. Because of these features, clacitonin is used as a treatment of hypercalcaemia and postmenopausal osteoporosis. The analgesic effect of calcitonin has been observed and reported in clinical situations, but the mechanism is still unclear. Studies reported that the descending inhibitory serotonergic system may be involved in the analgesic mechanism of calcitonin. The purpose of this study is to evaluate the antinociceptive effect of calcitonin by investigating serotonin activity in the brain of ovariectomized rats. Rats were divided into four groups: OVX-CT, OVX-SDCP, OVX-con and sham-con groups. For each group evaluate their serotonin transporter (SERT) activity in the living rat brain were evaluated with newly developed 18F-labeled PET radioligand. After sacrified, we reserved brains and collected blood. Immunohistochemical stain of serotonin neuron, SERT western blot were performed. According to the result of PET image, OVX-con group showed that SERT ratio decreased in cortex, striatum and hippocampus, and increased in thalamus, hypothalamus and midbrain. OVX-CT Group showed decrease SERT ratio in all six regions. In Western blot analysis, OVX-con group SERT expression decreased in cortex and brainstem, and increased in midbrain. OVX-CT group showed decreased SERT expression in all three regions. Analysis of serotonin fiber density, OVX-con showed lower fibers density than sham in cortex, hippocampus, striatum, thalamus, hypothalamus and raphe. In the future, we will increase sample number and analysis statistically to confirm whether calcitonin affect serotonin system of ovariectomized rats in the brain.
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