Injection of specific amyloid-beta oligomers (beta_1-40:beta_1-42 = 10:1) into rat medial septum impairs memory retention without inducing hippocampal apoptosis

Abstract

Objectives: Because of the well-known neurochemical interactions between the septum and hippocampus during memory processes, we investigated the effect of amyloid-beta (A-beta) injection into the medial septum (MS) on the behavior in Wistar rats. We also assessed whether the observed effects were functional or due to apoptosis.

Methods: Specific A-beta oligomers (beta_1-40:beta_1-42  = 10:1) were injected into MS for seven consecutive days. Behavior was assessed with the Morris water maze task.

Results: Compared with the control group, rats that received A-beta oligomers exhibited significant memory retention impairment (P < 0·05) without apoptosis in the cornu ammonis (CA)1 and CA3 regions of the dorsal hippocampus.

Discussion: These data indicate that septal injection of A-beta impairs memory retention, even in the absence of hippocampal apoptosis. This result might bring new insight to spatial memory-related disorders like Alzheimer’s disease (AD).

Keywords:

• A-beta
• Apoptosis
• Medial septal area
• Memory retention
• Water maze

This study was supported by Advanced Material Institute, University of Fukuoka 814–0180, Japan.