Baratzadeh M, Danialy S, Abtin S, Manaheji H. Naloxone could limit morphine hypersensitivity: Considering the molecular mechanisms.
Neuropeptides 2023;
100:102345. [PMID:
37172403 DOI:
10.1016/j.npep.2023.102345]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/18/2023] [Accepted: 05/01/2023] [Indexed: 05/15/2023]
Abstract
BACKGROUND
Naloxone has been used as an opioid antagonist to prevent multiple adverse side effects of opioid-like tolerance and hyperalgesia. This study has investigated naloxone combined with morphine to limit pain hypersensitivity. In addition, the expression of brain-derived neurotrophic factor (BDNF) and K+ Cl- cotransporter2 (KCC2) were also studied.
METHODS
Forty-eight adult male Wistar rats (180-220 g) were divided into eight groups, with six rats in each group. Rats were divided into two tolerance and hyperalgesia groups; the sham group, the morphine group, the treatment group (naloxone along with morphine), and the sham group (naloxone along with saline) for eight consecutive days. Tail-flick test was performed on days 1, 5, and 8, and the plantar test on days 1 and 10. On days 8 and 10, the lumbar segments of the spinal cord were collected, and BDNF and KCC2 expression were analyzed using western blotting and immunohistochemistry, respectively.
RESULTS
Results showed that tolerance and hyperalgesia developed following eight days of repeated morphine injection. BDNF expression significantly increased, but KCC2 was downregulated. Co-administration of naloxone and morphine decreased tolerance and hyperalgesia by decreasing BDNF and increasing KCC2 expression, respectively.
CONCLUSION
This study suggests that BDNF and KCC2 may be candidate molecules for decreased morphine tolerance and hyperalgesia.
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