The magnitude of TBS-induced long-term potentiation is
significantly reduced in ArcKR mice
Although the expression of Arc protein plays an important role in
mGluR-mediated LTD (Wall et al. ,
2018), the involvement of Arc in potentiation: (long term (LTP) and
short term (STP)) is more contentious. Previous studies have shown a
role for Arc in LTP, particularly in the dentate gyrus (see
introduction). In contrast, (Kyrke-Smithet al. , 2021) showed that LTP at SC-CA1 synapses was unaffected
by an inducible deletion of Arc. To further investigate the role of Arc
in potentiation at SC-CA1 synapses we have compared potentiation induced
in ArcKR Vs. WT mice. Since Arc protein expression is enhanced and
longer lasting in ArcKR mice (Wallet al. , 2018), any effects of Arc on LTP might be expected to be
increased in ArcKR mice. Potentiation was evoked using theta burst
stimulation (TBS, 4 bursts as in
(Kyrke-Smith et al. , 2021).
Following induction, there was no significant difference in the
amplitude of STP between the genotypes (measured 2-3 minutes after
induction, Fig 2A, B). However, LTP measured 2 hours after induction was
significantly reduced in ArcKR mice (Fig 2A, C). This was not a
consequence of a difference in synaptic activation, as there was no
significant difference in the mean slope of baseline fEPSPs between
ArcKR and WT mice (p = 0.409, Z = 0.825, U = 108, Mann Whitney).