Norepinephrine-induced downregulation of GLT-1 mRNA in rat astrocytes

Masako Kurita, Yoshikazu Matsuoka, Kosuke Nakatsuka, Daisuke Ono, Noriko Muto, Ryuji Kaku, Hiroshi Morimatsu

Research output: Contribution to journalArticle

Abstract

Aim of the research: Glutamate transporter-1 (GLT-1; also known as excitatory amino acid transporter 2) plays an important role in the maintenance of glutamate homeostasis in the synaptic cleft. Downregulation of GLT-1 in the spinal cord has been reported in chronic pain models, which suggests that GLT-1 is involved in the development of chronic pain. However, the mechanism by which GLT-1 is downregulated in the spinal cord is still unknown. We hypothesized that norepinephrine is involved in the regulation of GLT-1. The aim of this study was to investigate the effect of norepinephrine on GLT-1 expression in cultured astrocytes. Methods: This study involved both in vivo and in vitro experiments. We first validated changes in GLT-1 mRNA expression in the spinal cord of rats with spared nerve injury (SNI) using real-time RT-PCR. Next, cultured primary astrocytes from the rat spinal cord were stimulated with norepinephrine, and GLT-1 mRNA was subsequently quantitated. RNB cells, an astrocytic cell line, were also stimulated with norepinephrine and other α-adrenoceptor agonists. Results: SNI resulted in bilateral downregulation of GLT-1 in rat spinal cord. The in vitro study showed that norepinephrine and phenylephrine dose-dependently downregulated GLT-1 in primary astrocytes and RNB cells. Furthermore, the effect of norepinephrine was reversed by an α-adrenoceptor antagonist. Conclusion: Norepinephrine downregulates GLT-1 mRNA expression in astrocytes via the α1-adrenoceptor. Our results provide new insight into the mechanisms involved in downregulation of GLT-1 in the chronic pain models.

Original languageEnglish
Pages (from-to)103-108
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume504
Issue number1
DOIs
Publication statusPublished - Sep 26 2018

Fingerprint

Astrocytes
Rats
Norepinephrine
Down-Regulation
Messenger RNA
Spinal Cord
Chronic Pain
Adrenergic Receptors
Excitatory Amino Acid Transporter 2
Amino Acid Transport System X-AG
Wounds and Injuries
Phenylephrine
Real-Time Polymerase Chain Reaction
Glutamic Acid
Homeostasis
Cells
Maintenance
Cell Line
Research
Experiments

Keywords

  • Astrocyte
  • Descending inhibitory pathway
  • Glutamate transporter
  • Neuropathic pain
  • Norepinephrine
  • Spinal cord

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Norepinephrine-induced downregulation of GLT-1 mRNA in rat astrocytes. / Kurita, Masako; Matsuoka, Yoshikazu; Nakatsuka, Kosuke; Ono, Daisuke; Muto, Noriko; Kaku, Ryuji; Morimatsu, Hiroshi.

In: Biochemical and Biophysical Research Communications, Vol. 504, No. 1, 26.09.2018, p. 103-108.

Research output: Contribution to journalArticle

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abstract = "Aim of the research: Glutamate transporter-1 (GLT-1; also known as excitatory amino acid transporter 2) plays an important role in the maintenance of glutamate homeostasis in the synaptic cleft. Downregulation of GLT-1 in the spinal cord has been reported in chronic pain models, which suggests that GLT-1 is involved in the development of chronic pain. However, the mechanism by which GLT-1 is downregulated in the spinal cord is still unknown. We hypothesized that norepinephrine is involved in the regulation of GLT-1. The aim of this study was to investigate the effect of norepinephrine on GLT-1 expression in cultured astrocytes. Methods: This study involved both in vivo and in vitro experiments. We first validated changes in GLT-1 mRNA expression in the spinal cord of rats with spared nerve injury (SNI) using real-time RT-PCR. Next, cultured primary astrocytes from the rat spinal cord were stimulated with norepinephrine, and GLT-1 mRNA was subsequently quantitated. RNB cells, an astrocytic cell line, were also stimulated with norepinephrine and other α-adrenoceptor agonists. Results: SNI resulted in bilateral downregulation of GLT-1 in rat spinal cord. The in vitro study showed that norepinephrine and phenylephrine dose-dependently downregulated GLT-1 in primary astrocytes and RNB cells. Furthermore, the effect of norepinephrine was reversed by an α-adrenoceptor antagonist. Conclusion: Norepinephrine downregulates GLT-1 mRNA expression in astrocytes via the α1-adrenoceptor. Our results provide new insight into the mechanisms involved in downregulation of GLT-1 in the chronic pain models.",
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