Medial septal dysfunction by A beta-induced KCNQ channel-block in glutamatergic neurons

• Amyloid beta (A beta) peptides play a central role in the pathophysiology of Alzheimer's disease (AD). The cellular mechanisms underlying A beta toxicity, however, are poorly understood. Here we show that A beta 25-35 and A beta 1-40 acutely and differentially affect the characteristics of 3 classes of medial septum (MS) neurons in mice. In glutamatergic neurons A beta increases firing frequency and blocks the A-and the M-current (I-A and I-M, respectively). While the I-A block is similar in other MS neuron classes, the block of I-M is specific to glutamatergic neurons. I-M block and a simulated A beta block mimic the A beta-induced increase in spontaneous firing in glutamatergic neurons. Calcium imaging shows that under control conditions glutamatergic neurons rarely fire while nonglutamatergic neurons fire coherently at theta frequencies. A beta increases the firing rate of glutamatergic neurons while nonglutamatergic neurons lose theta firing coherence. Our results demonstrate that A beta-induced dysfunction of glutamatergic neurons via I-M decrease diminishes MS rhythmicity, which may negatively affect hippocampal rhythmogenesis and underlie the memory loss observed in Alzheimer's disease.

Nyckelord

Amyloid beta peptide

Medial septum

Theta oscillations

Glutamatergic neurons

Cholinergic neurons

GABAergic neurons

M-current

A-current

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)