0

Spinal sigma-1 Receptor Activation Increases the Production of D-serine in Astrocytes Which Contributes to the Development of Mechanical Allodynia in a Mouse Model of Neuropathic Pain

Ji-Young Moon, Sheu-Ran Choi, Dae-Hyun Roh, Seo-Yeon Yoon, Soon-Gu Kwon, Hoon-Seong Choi, Suk-Yun Kang, Ho-Jae Han, Hyun-Woo Kim, Alvin J Beitz, Seog-Bae Oh, Jang-Hern Lee

Pharmacol Res. 2015 Oct;100:353-64.

PMID: 26316425

Abstract:

We have previously demonstrated that activation of the spinal sigma-1 receptor (Sig-1R) plays an important role in the development of mechanical allodynia (MA) via secondary activation of the N-methyl-d-aspartate (NMDA) receptor. Sig-1Rs have been shown to localize to astrocytes, and blockade of Sig-1Rs inhibits the pathologic activation of astrocytes in neuropathic mice. However, the mechanism by which Sig-1R activation in astrocytes modulates NMDA receptors in neurons is currently unknown. d-serine, synthesized from l-serine by serine racemase (Srr) in astrocytes, is an endogenous co-agonist for the NMDA receptor glycine site and can control NMDA receptor activity. Here, we investigated the role of d-serine in the development of MA induced by spinal Sig-1R activation in chronic constriction injury (CCI) mice. The production of d-serine and Srr expression were both significantly increased in the spinal cord dorsal horn post-CCI surgery. Srr and d-serine were only localized to astrocytes in the superficial dorsal horn, while d-serine was also localized to neurons in the deep dorsal horn. Moreover, we found that Srr exists in astrocytes that express Sig-1Rs. The CCI-induced increase in the levels of d-serine and Srr was attenuated by sustained intrathecal treatment with the Sig-1R antagonist, BD-1047 during the induction phase of neuropathic pain. In behavioral experiments, degradation of endogenous d-serine with DAAO, or selective blockade of Srr by LSOS, effectively reduced the development of MA, but not thermal hyperalgesia in CCI mice. Finally, BD-1047 administration inhibited the development of MA and this inhibition was reversed by intrathecal treatment with exogenous d-serine. These findings demonstrate for the first time that the activation of Sig-1Rs increases the expression of Srr and d-serine in astrocytes. The increased production of d-serine induced by CCI ultimately affects dorsal horn neurons that are involved in the development of MA in neuropathic mice.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP138356215 BD 1047 dihydrobromide BD 1047 dihydrobromide 138356-21-5 Price
AP17436021 L-Serine O-sulfate potassium salt L-Serine O-sulfate potassium salt 17436-02-1 Price
qrcode