- 作者: Pao-Luh TAO ; Ho-Shan NIU ; Wei-Ming LUE ; Shwun-De WANG
- 中文摘要: Previously, we have used the biochemical receptor binding method to investigate whether down-regulation of the opioid receptor is a mechanism for morphine tolerance, and we were led to a negative conclusion. In the current study, we further used immunohistochemistry to reinvestigate this issue. Male Sprague-Dawley rats (250-300 g) were chronically treated with morphine s.c. for 2, 4 or 6 days, using an escalating dosage paradigm (5-45 mg), which resulted in a 1.8 to 4.0-fold increase in AD50. Rat brains were removed, frozen, coronally sectioned (14 .mu.m) and processed for .mu.- or .delta.-opioid receptor immunohistochemistry using the Avidin-Biotin Complex (ABC) method. No significant decrease in .mu.-opioid receptor (MOR) immunodensity was found in most of the brain regions, which were enriched with MOR after chronic treatment with morphine except for the anteroventral thalamic nucleus in the ventrolateral part (AVVL). No significant change in .delta.-opioid receptor (DOR) immunodensity after chronic treatment with morphine was found either. Therefore, our conclusion is that down regulation of opioid receptors may not be an important mechanism for morphine tolerance.
- 英文摘要: --
- 中文關鍵字: morphine, antinociception, tolerance, opioid receptor, down-regulation, immunohistochemistry
- 英文關鍵字: --