Liu Y N, Yang X, Suo Z W, Xu Y M, Hu X D
Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Gansu, China; College of Chemistry and Chemical Engineering, Lanzhou University, Gansu, China.
Eur J Pain. 2014 Sep;18(8):1120-8. doi: 10.1002/j.1532-2149.2014.00455.x. Epub 2014 Jan 20.
Inhibition of Src-family protein tyrosine kinases (SFKs) in spinal dorsal horn has been established as an effective strategy for the alleviation of chronic pathological pain. As one of the important SFKs members, Fyn kinase is critical for synaptic plasticity and many pathophysiological processes. However, whether Fyn is involved in spinal sensitization is far from being elucidated.
We manipulated Fyn activity by expressing a constitutively active Fyn mutant [Fyn(Y528F) ] or a catalytically null mutant [Fyn(K296M) ] in the spinal dorsal horn of mice, and performed behavioural and biochemical experiments to investigate the role of Fyn in regulating the nociceptive responses and the synaptic expression of ionotropic glutamate receptors.
Spinal expression of Fyn(Y528F) alone in intact mice was sufficient to elicit persistent mechanical allodynia and thermal hyperalgesia, which lasted for at least 12 days. Fyn(Y528F) simultaneously enhanced the concentrations of N-methyl-D-aspartic acid (NMDA)-subtype and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-subtype glutamate receptors at synaptosomal membrane fraction. Pharmacological inhibition of NMDA receptors or AMPA receptors greatly alleviated Fyn(Y528F)-induced pain hypersensitivity. To evaluate the contribution of Fyn to inflammatory pain, we expressed Fyn(K296M) before intradermal injection of complete Freund's adjuvant (CFA), finding that Fyn(K296M) had no effect on the induction of inflammatory pain within 3 h post-CFA injection, which, however, repressed the synaptic accumulation of NMDA receptors and AMPA receptors to attenuate the maintenance of chronic pain states.
Fyn played a key role in the sustained sensitization of nociceptive behaviours by up-regulating the functions of ionotropic glutamate receptors in spinal dorsal horn.
脊髓背角中Src家族蛋白酪氨酸激酶（SFKs）的抑制已被确立为缓解慢性病理性疼痛的有效策略。作为重要的SFKs成员之一，Fyn激酶对突触可塑性和许多病理生理过程至关重要。然而，Fyn是否参与脊髓敏化作用仍远未阐明。
我们通过在小鼠脊髓背角中表达组成型活性Fyn突变体[Fyn(Y528F)]或催化失活突变体[Fyn(K296M)]来操纵Fyn活性，并进行行为学和生化实验，以研究Fyn在调节伤害性反应和离子型谷氨酸受体的突触表达中的作用。
在完整小鼠中单独脊髓表达Fyn(Y528F)足以引发持续的机械性异常性疼痛和热痛觉过敏，持续至少12天。Fyn(Y528F)同时提高了突触体膜组分中N-甲基-D-天冬氨酸（NMDA）亚型和α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）亚型谷氨酸受体的浓度。对NMDA受体或AMPA受体的药理抑制大大减轻了Fyn(Y528F)诱导的疼痛超敏反应。为了评估Fyn对炎性疼痛的作用，我们在皮内注射完全弗氏佐剂（CFA）之前表达Fyn(K296M)，发现Fyn(K296M)在CFA注射后3小时内对炎性疼痛的诱导没有影响，然而，它抑制了NMDA受体和AMPA受体的突触积累，以减轻慢性疼痛状态的维持。
Fyn通过上调脊髓背角中离子型谷氨酸受体的功能，在伤害性感受行为的持续敏化中起关键作用。
