Type 1 diabetes mellitus in mice increases hippocampal d-serine in the acute phase after streptozotocin injection

Masataka Suzuki, Jumpei Sasabe, Shigeki Furuya, Masashi Mita, Kenji Hamase, Sadakazu Aiso

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Diabetes mellitus (DM) is known to be a risk factor in the development of deficits in cognition, learning, and memory. In DM animal models, including the streptozotocin (STZ)-induced diabetic rodent model, abnormalities in the regulation of several neurotransmitters have been reported. However, the role in DM of d-serine, an endogenous co-agonist of glutamatergic N-methyl-d-aspartate receptors, remains unknown. Here, we measured the amounts of d-/l-serine and l-glutamate in the hippocampi of STZ-treated mice using a 2D-HPLC system from acute to chronic phases after the induction of DM. STZ treatment significantly increased the d-serine level by 23.7% in the hippocampus compared with vehicle treatment at 1 week after the injection, whereas it did not affect the levels of l-serine. In contrast, l-glutamate levels in the hippocampus were elevated at 3 days after STZ injection and rather decreased at 1 week after that. Such alterations in the amino acids were not evident in the chronic phases. We further tested whether the STZ-induced d-serine increase was caused by DM pathophysiology. In vivo, subcutaneous insulin implants into STZ-treated mice restored the elevated d-serine levels in the hippocampus. An in vitro study using primary cultured hippocampal neurons revealed that treatments of STZ did not directly affect the level of d-serine secreted in the cultured media. These results indicate that DM pathology caused by insulin deficiency triggers transient d-serine increase and l-glutamate alteration in the hippocampus. Such aberrant regulations of excitatory neurotransmitters may be relevant to the formation of DM-related dysfunction of the central nervous system (CNS).

Original languageEnglish
Pages (from-to)167-176
Number of pages10
JournalBrain Research
Volume1466
DOIs
Publication statusPublished - 2012 Jul 23
Externally publishedYes

Keywords

  • d-Serine
  • Diabetes mellitus
  • Glucose metabolism
  • l-Glutamate
  • Serine racemase
  • Streptozotocin

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

Cite this

Type 1 diabetes mellitus in mice increases hippocampal d-serine in the acute phase after streptozotocin injection. / Suzuki, Masataka; Sasabe, Jumpei; Furuya, Shigeki; Mita, Masashi; Hamase, Kenji; Aiso, Sadakazu.

In: Brain Research, Vol. 1466, 23.07.2012, p. 167-176.

Research output: Contribution to journalArticle

Suzuki, Masataka ; Sasabe, Jumpei ; Furuya, Shigeki ; Mita, Masashi ; Hamase, Kenji ; Aiso, Sadakazu. / Type 1 diabetes mellitus in mice increases hippocampal d-serine in the acute phase after streptozotocin injection. In: Brain Research. 2012 ; Vol. 1466. pp. 167-176.
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abstract = "Diabetes mellitus (DM) is known to be a risk factor in the development of deficits in cognition, learning, and memory. In DM animal models, including the streptozotocin (STZ)-induced diabetic rodent model, abnormalities in the regulation of several neurotransmitters have been reported. However, the role in DM of d-serine, an endogenous co-agonist of glutamatergic N-methyl-d-aspartate receptors, remains unknown. Here, we measured the amounts of d-/l-serine and l-glutamate in the hippocampi of STZ-treated mice using a 2D-HPLC system from acute to chronic phases after the induction of DM. STZ treatment significantly increased the d-serine level by 23.7{\%} in the hippocampus compared with vehicle treatment at 1 week after the injection, whereas it did not affect the levels of l-serine. In contrast, l-glutamate levels in the hippocampus were elevated at 3 days after STZ injection and rather decreased at 1 week after that. Such alterations in the amino acids were not evident in the chronic phases. We further tested whether the STZ-induced d-serine increase was caused by DM pathophysiology. In vivo, subcutaneous insulin implants into STZ-treated mice restored the elevated d-serine levels in the hippocampus. An in vitro study using primary cultured hippocampal neurons revealed that treatments of STZ did not directly affect the level of d-serine secreted in the cultured media. These results indicate that DM pathology caused by insulin deficiency triggers transient d-serine increase and l-glutamate alteration in the hippocampus. Such aberrant regulations of excitatory neurotransmitters may be relevant to the formation of DM-related dysfunction of the central nervous system (CNS).",
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