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The long-lasting effect of morphine on the neuropathic pain sensitivity
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Kawsar Alami   , Hossein Azizi , Yaghoub Fathollahi , Saeed Semnanian |
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Abstract: (241 Views) |
Introduction: The intensity of pain sensitivity due to nerve injury varies among individuals, with reports suggesting that both genetic and environmental factors contribute to these individual differences. Opioid use disorder, particularly in early life, is one known environmental factor that affects the pain matrix. Studies suggest that opioid use during adolescence has long-lasting impacts on subsequent behaviors. However, it remains unknown whether adolescent morphine exposure affects neuropathic pain sensi
tivity in adulthood. Therefore, this study aims to investigate the pain sensitivity in a sciatic nerve injury model in adult rats following adolescent morphine exposure.
Methods and Materials: Adolescent male rats were administered escalating doses of morphine (2.5-25 mg/kg, s.c.) or an equivalent volume of saline, twice daily for 10 days (PND 28-37). After a washout period of 30 days, the basal pain sensitivity of adult rats was evaluated using Von-Frey filaments and Hargreaves plantar tests. Subsequently, the rats underwent either a sham procedure or surgery to induce chronic constrictive injury (CCI) in the sciatic nerve and were examined for pain sensitivity on days 1, 3, 5, 7, 14, 21, and 28 after the surgery.
Results: The results demonstrated a significant decrease in basal paw withdrawal threshold and latency in adolescent rats treated with morphine, compared to those treated with saline. Additionally, CCI surgery induced a significant reduction in paw withdrawal threshold and latency in rats. Furthermore, rats that received morphine during adolescence (but not saline) exhibited lower paw withdrawal threshold and latency following a sciatic nerve injury.
Conclusion: These findings suggest that exposure to morphine during adolescence may increase sensitivity to pain, including both baseline pain perception and the response to neuropathic pain conditions.
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| Keywords: opioid, sciatic nerve injury, adolescence, CCI |
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Full-Text [PDF 247 kb]
(36 Downloads)
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Type of Study: Research |
Subject:
General
Received: 2024/02/9 | Accepted: 2023/08/23 | Published: 2023/08/23
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