Figure 2.

Fear conditioning regulates Arc/Arg3.1 protein in the lateral amygdala. a, Schematic of the behavioral protocol. Rats were habituated to handling for 2 d, trained with 3 pairings of a tone and shock (Paired), and killed 2 h later. Control animals received handling for 2 d followed by 3 immediate shocks (Imm. Shock) and were killed 2 h later. A third group consisted of naive rats that had been handled but given no further stimulation (Naive). b, Western blot analysis of Arc/Arg3.1 protein in the LA of Paired (n = 6), Imm. Shock (n = 7), and Naive (n = 6) groups after fear conditioning. *p < 0.05 relative to Naive and Imm. Shock groups. Representative blots can be seen in the inset. c–e, Representative 10× photomicrographs of immunolabeled Arc/Arg3.1 neurons in a Paired, Imm. Shock, and Naive rat, respectively. f, g, Higher level (20 and 40×, respectively) magnifications of Arc/Arg3.1 labeled neurons from the box in the Paired rat in c. Note that Arc/Arg3.1 label is present throughout the soma, dendrites, and nucleus of LA cells. h, Quantification of Arc/Arg3.1 labeled cells in the LA, CE, and basal nucleus (B) of the amygdala of Paired (n = 3), Imm. Shock (n = 3), and Naive (n = 3) groups after fear conditioning. *p < 0.05 relative to Naive and Imm. Shock groups.