Publications (2)5.88 Total impact
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ABSTRACT: To explore the effects of cannabinoid 2 receptor (CB2) in the development of bone cancer pain in mice. A total of 84 mice (C3H/HeJ) were randomly divided into 4 groups:tumor group (Group T, n = 30), medication administration group (Group J, n = 12), vehicle group (Group D, n = 12) and sham group (Group S, n = 30). And 2 × 10(5) osteolytic NCTC2472 cells in α-MEM were injected into medullary cavity of right distal femur to induce bone cancer pain in a murine model while sham mice received an injection of only α-MEM. All mice were tested for pain-related behaviors at pre-inoculation and at Days 5, 7, 10 and 14 post-inoculation. The tests included paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). Group J and Group D were injected intrathecally with 2 µg JWH015 dissolved in 4% DMSO and only 4% DMSO respectively in a 5 µl. volume. Pain behavior tests were performed before and at 1, 6, 24, 48 and 72 h after an intrathecal injection. Lumbar intumescentia of mice in each group were harvested to examine the expression level of CB2 by Western blot after pain behavior tests at Days 5, 7, 10 and 14 post-inoculation and 12 h after an intrathecal injection. (1) Pain behavior tests:Mechanical allodynia appeared at Day 7 post-inoculation. The value of PWMT was (1.27 ± 0.28) g (P < 0.05) and it declined gradually to (0.53 ± 0.20) g at Day 14. The threshold of mechanical hyperalgesia increased to (1.00 ± 0.20) g at 6 h after an intrathecal injection of JWH015, peaked at (1.40 ± 0.39) g at 12 h, became alleviated after 48 h and recovered to the pre-dosing levels at 72 h. Thermal hyperalgesia appeared at Day 10 post-inoculation. The value of PWTL was (16.9 ± 0.4) s (P < 0.05) at Day 10 and declined to (11.5 ± 0.7) s at Day 14 post-inoculation. The threshold of thermal hyperalgesia increased to (15.7 ± 1.9) g at 6 h after an intrathecal injection of JWH015, peaked at (18.6 ± 2.3) g at 12 h, became alleviated after 48 h and recovered to the pre-dosing levels at 72 h. (2) Western blot: From Day 5 post-inoculation, the ratio of CB2/β-actin increased gradually. Compared with the ratio of 0.190 ± 0.010 at Day 5 post-inoculation, the ratio of CB2/β-actin increased to 0.660 ± 0.010 at Day 14 post-inoculation (P < 0.05); compared with the ratio of 0.903 ± 0.006 in group D at 12 h after an intrathecal injection of JWH015, the ratio of CB2/β-actin 0.510 ± 0.010 significantly decreased (P < 0.05). The cannabinoid 2 receptor plays an important role in the formation of bone cancer pain.
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ABSTRACT: Astrocytes and metabotropic glutamate receptors play important roles in nociceptive processing. However, their roles in bone cancer pain were not well understood. This study sought to investigate whether selective mGluR3 and mGluR5 agonist or antagonist develop antinociceptive effects on bone cancer pain by inhibition of spinal astrocyte activation. C3H/HeNCrlVr mice were inoculated into the intramedullary space of the femur with sarcoma NCTC 2472 cells to induce bone cancer pain. Quantitative real-time reverse transcription-polymerase chain reaction and Western blot experiments examined messenger RNA and protein expression of spinal glial fibrillary acidic protein, mGluR3, and mGluR5. The authors further investigated effects of intrathecal treatment with the mGluR3 agonist (APDC), the mGluR3 antagonist (LY341495), the mGluR5 agonist (CHPG), or the mGluR5 antagonist (MTEP) on nociceptive behaviors and spinal astrocyte activation associated with bone cancer pain. Inoculation of sarcoma cells, but not α-MEM solution, induced progressive bone cancer pain and resulted in up-regulation of glial fibrillary acidic protein, mGluR3, and mGluR5 expression on days 10, 14, and 21 postinoculation. Intrathecal administration of APDC and MTEP attenuated bone cancer-evoked spontaneous pain, mechanical allodynia, thermal hyperalgesia, and reduced spinal glial fibrillary acidic protein expression. However, treatment with LY341495 and CHPG induced thermal hyperalgesia and spinal glial fibrillary acidic protein expression in control mice. Spinal mGluR3 activation or mGluR5 inhibition reduced bone cancer pain. Inhibition of spinal astrocyte activation may contribute to the analgesic effects. These findings may lead to novel strategies for the treatment of bone cancer pain.
Nanjing UniversityNan-ching, Jiangsu Sheng, China