Dual effects of the lichen glucan PB-2, extracted from Flavoparmelia baltimorensis, on the induction of long-term potentiation in the dentate gyrus of the anesthetized rat: Possible mediation via adrenaline β- and interleukin-1 receptors

Yoshikuni Edagawa, Fumiyuki Sato, Hiroshi Saito, Tadahiro Takeda, Noriko Shimizu, Takao Narui, Shoji Shibata, Yoshihisa Ito

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

We have previously found that oral or intravenous (i.v.) administration of the polysaccharide fraction PB-2, extracted from the lichen Flavoparmelia baltimorensis, facilitated the induction of long-term potentiation (LTP) in the dentate gyrus (DG) in vivo. In this study, the mechanism underlying the effect of PB-2 on the induction of LTP was investigated in the DG of anesthetized rat focusing on the contribution of the interleukin-1 (IL-1) receptor and the adrenaline β-receptor. An i.v. injection of IL-1ra (10-9 g/kg), an antagonist of the IL-1 receptor, had no effect on the basal response in the DG; however, this treatment augmented the enhancement of LTP induced by a single i.v. injection of PB-2 (10-3 g/kg). This potentiating effect was also observed following intracerebroventricular (i.c.v.) injection of IL-1ra (10-15-10-11 g). An i.v. injection of IL-1β (3.5×10-15-3.5×10-9 g/kg) inhibited the induction of LTP, which was diminished by the previous application of IL-1ra. These results suggest that the activation of the IL-1 receptor induces the suppression of LTP in PB-2-treated rats, and that endogenous IL-1β contributes to the IL-1 receptor activation. An i.c.v. infusion of metoprolol (7.5 × 10-6 g), an antagonist of the adrenaline β1-receptor, attenuated the enhancement of LTP induced by an i.v. injection of PB-2. These results suggest that PB-2 has two different effects on the LTP, an enhancing effect and an inhibiting one, and that it exhibited the significant enhancing effect on the LTP as a total balance of these effects.

Original languageEnglish
Pages (from-to)183-192
Number of pages10
JournalBrain Research
Volume1032
Issue number1-2
DOIs
Publication statusPublished - 2005 Jan 25
Externally publishedYes

Keywords

  • Adrenaline β-receptor
  • Hippocampus
  • Interleukin-1β
  • Lichen
  • Long-term potentiation
  • Polysaccharide

ASJC Scopus subject areas

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

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