Electroacupuncture reduces stress-induced expression of c-fos in the brain of the rat

We have previously shown that electroacupuncture (EA) at Shaohai and Neiguan (HT3-PC6) points significantly attenuated stress-induced peripheral responses, including increases in blood pressure, heart rate and plasma catecholamines. In this study, we examined the central effect of EA on the expression of c-fos, one of the immediate-early genes in the brain of rats subjected to immobilization stress. Immobilization stress (180 minutes) preferentially produced a significant increase in Fos-like immunoreactivity (FLI) in stress-relevant regions including the paraventricular hypothalamic nucleus (PVN), arcuate nucleus (ARN), supraoptic nucleus (SON), suprachiasmatic nucleus (SCN), medial amygdaloid nucleus (AMe), bed nucleus of the stria terminalis (BST), hippocampus, lateral septum (LS), nucleus accumbens, and the locus coeruleus (LC). EA (3 Hz, 0.2 ms rectangular pulses, 20 mA) at HT3-PC6 on the heart and pericardium channels for 30 minutes during stress, significantly attenuated stress-induced FLI in the parvocellular PVN, SON, SCN, AMe, LS and the LC. However, EA stimulations at HT3-PC6 had no effect on FLI in the magnocelluar PVN, ARN, BST or the hippocampus. EA stimulation at HT3-PC6 had a greater inhibitory effect on stress-induced FLI than that at TE5-LI11, the triple energizer and large intestine meridian, or non-acupoints. These results demonstrated that EA attenuated stress-induced c-fos expression in brain areas. These results suggest that decreased c-fos expression in hypothalamic and LC neurons, among stress-related areas, may reflect the integrative action of acupuncture in stress response.