Figure 4.

Inherent impulsive action predicts 5-HT_2AR binding density and protein expression in whole frontal cortex. (a) Following 1-CSRT task training and phenotypic identification (cohort 4), whole frontal cortex was collected and a crude synaptosomal preparation analyzed for single-point radioligand binding ([³H]-ketanserin, 10 nM) to approximate saturation binding. Specific [³H]-ketanserin binding positively correlated with premature responses during stable ITI5 performance in the 1-CSRT task (n=28; r=0.508, p<0.01). Error bars (±SEM) represent results from three independent experiments run in triplicate. (b) The subset of HI and LI samples from the same frontal cortex crude synaptosomal preparations were then analyzed by capillary gel-based immunodetection. Quantitation of 5-HT_2AR immunoreactivity (normalized to cadherin loading control) revealed elevated 5-HT_2AR protein expression in HI (n=6, black bar) relative to LI rats (n=6, white bar; *p<0.05 vs. LI). The inset presents representative electrophoretic bands. Arbitrary units (AU) of normalized densitometry are presented (see Materials and Methods).