Figure 3. HTT phosphorylation at S421 increases short-term plasticity in the corticostriatal network ex vivo.

(A) Schematic of medium-sized spiny neurons (MSNs) recording in the dorsolateral striatum (DLS) after paired-pulse stimulations in S2 cortex of mice at 2–3 months of age. (B) Representative traces of the paired-pulse ratio per interstimulus interval of electrophysiological response of MSNs in the DLS after stimulation in S2 in 2- to 3-month-old wild-type (WT) (gray), HTT-SD (pink), and HTT-SA (orange) mice (C). Quantification of (B). In contrast to WT and HTT-SA MSNs, HTT-SD MSN responses from 25 to 50 ms showed no facilitation (paired-pulse ratio~1) but only depression from 100 ms (*p<0.05, **p<0.001, and ***p<0.0001; ns means non-significant). Paired-pulse ratios were recorded from 13 WT, 12 HTT-SD, and 12 HTT-SA MSNs from at least N=3 mice.

Figure 3—figure supplement 1. HTT phosphorylation does not regulate the spontaneous excitatory postsynaptic currents (sEPSCs) in the corticostriatal synapse.

(A) Schematic of the procedure for sEPSC recording in medium-sized spiny neurons (MSNs) within the dorsolateral striatum (DLS). (B) Representative traces, cumulative probability of the mean amplitude, and mean interevent intervals (p<0.05) of sEPSCs in MSNs within the DLS in 2- to 3-month-old wild-type (WT) and HTT-SD mice. sEPSCs were recorded from WT (10 MSN) and HTT-SD mice (10 MSN). There were no significant differences in cumulative probability between WT, HTT-SD, and HTT-SA mice (ns: non-significant).