Long-term electrical stimulation at ear and electro-acupuncture at ST36-ST37 attenuated COX-2 in the CA1 of hippocampus in kainic acid-induced epileptic seizure rats

Abstract

Seizures produce brain inflammation, which in turn enhances neuronal excitability. Therefore, anti-inflammation has become a therapeutic strategy for antiepileptic treatment. Cycloxygenase-2 (COX-2) plays a critical role in postseizure brain inflammation and neuronal hyperexcitability. Our previous studies have shown that both electrical stimulation (ES) at the ear and electro-acupuncture (EA) at the Zusanli and Shangjuxu acupoints (ST36-ST37) for 6 weeks can reduce mossy fiber sprouting, spike population, and high-frequency hippocampal oscillations in kainic acid (KA)-induced epileptic seizure rats. This study further investigated the effect of long-term ear ES and EA at ST36-ST37 on the inflammatory response in KA-induced epileptic seizure rats. Both the COX-2 levels in the hippocampus and the number of COX-2 immunoreactive cells in the hippocampal CA1 region were increased after KA-induced epileptic seizures, and these were reduced through the 6-week application of ear ES or EA at ST36-ST37. Thus, long-term ear ES or long-term EA at ST36-ST37 have an anti-inflammatory effect, suggesting that they are beneficial for the treatment of epileptic seizures.

Figure 1

Kainic acid (KA)-induced epileptic seizures in rats. The counts of KA-induced wet-dog shakes, facial myoclonia, and paw tremors were similar among the KA group (KA), sham group (Sham), auricular group (Ear), and Zusanli group (Zusanli).

Figure 2

Western blot findings for the effects of electrical stimulation at the ear and electro-acupuncture at ST36–ST37 on the levels of COX-2, GFAP, S-100B, RAGE, mGluR3, MCP-1, and CCR2 in kainic acid (KA)-induced epileptic seizure rats. The levels of COX-2 increased in the KA group (K) and sham group (S), and decreased in the auricular group (E) and Zusanli group (Z) (A and B). The levels of GFAP increased in the KA group and sham group and decreased in the auricular group and Zusanli group (A and C). The levels of S100-B (A and D), RAGE (A and E), mGluR3 (A and F), MCP-1 (A and G), and CCR2 (A and H) among the normal group (N) and the KA, sham, auricular, and Zusanli groups. ^¶p < 0.05 compared with the value of N; *p < 0.05 compared with the value of K; ^#p < 0.05 compared with the value of S; n = 6.

Figure 3

Effects of electric stimulation at the ear and electro-acupuncture at ST36–ST37 on the counts of COX-2, GFAP, S100-B, RAGE, mGluR3, MCP-1, and CCR2 immunoreactive cells in kainic acid (KA)-induced epileptic seizure rats. The CA1, CA2, CA3, and hilus regions of the hippocampus (A). The counts of COX-2, GFAP, and S100-B immunoreactive cells were higher in the KA group (KA) and sham group (Sham) than in the normal group (Normal), whereas these counts were decreased in the auricular group (Ear) and Zusanli group (Zusanli). The counts of RAGE, mGluR3, MCP-1, and CCR2 immunoreactive cells were similar among the normal, KA, sham, and auricular groups (B). Immunoreactive cell (arrowhead); B image is 400× in the CA1 region; n = 6.

Figure 4

Effect of electrical stimulation at the ear and electro-acupuncture at ST36–ST37 observed on double immunofluorescence analysis in kainic acid-induced epileptic seizure rats. Double immunofluorescence analysis revealed the co-localization of GFAP (green) and S-100B (red) immunoreactive cells; the co-localization is marked with yellow (GFAP and S-100B).