Fig. 4.

Microinjections of clonidine into the A7 group reduced Fos expression in NE A7 neurons. (A) Example of Fos expression in A7 cells on the control side and the side injected with clonidine (0.75 mM, 40 nl) in the same experiment. On the control side, arrows point to each of the five Fos-positive TH cells of the 22 TH cells present in this frame; none of the 16 TH-positive cells present on the injected side had Fos-positive nuclei. (B) The mean percentages of Fos-positive TH cells in the A7 group on the control and injected sides in the four experiments with clonidine injections into the A7 group (bars on the left) and in another five experiments with clonidine injections placed more than 0.5 mm away from the A7 group. Only the injections placed within 0.4 mm from the A7 group significantly decreased Fos expression in A7 neurons. The percentage of Fos-positive TH cells on the injected side in the four experiments with clonidine injections into the A7 group was significantly lower than the percentages Fos-positive TH cells on the control side, whereas the latter was not different from the percentages of Fos-positive TH cells on either the control or injected side in the five experiments with clonidine injections placed more than 0.5 mm away from the A7 group. (C) Mean counts of Fos+ nuclei in non-TH cells located within a 0.5×0.5 mm counting box centered on the “loose” A7 group was not different between the injected and control side in the four experiments in which clonidine was injected less than 0.4 mm away from the A7 group.