The effects of Chamaecyparis obtusa essential oil on pain-related behavior and expression of pro-inflammatory cytokines in carrageenan-induced arthritis in rats

Figures & data

Fig. 1. Experimental flowchart for carrageenan (CGN)-induced arthritis in rats. Drugs were administered intra-articularly to the knee joint 4.5 h after CGN injection.

Notes: The expression of pro-inflammatory cytokines and cyclooxygenase (COX)-2 in both the synovial membrane and meniscus of drug-treated groups was measured using Western blotting 5–8 h after CGN injection. The weight load of drug-treated groups was evaluated before as well as 4–8 h after CGN injection.

Table 1. Chemical components of Chamaecyparis obtusa essential oil (COE) and the relative percentages using peak area normalization.

Peak no.	Molecular formula	Compound	RT (s)	Peak area percentage
1	C10H16	α-Thujene	16.7	1.2
2	C10H16	α-Pinene	17	3.3
3	C10H16	Camphene	17.4	0.6
4	C10H16	β-Myrcene	17.8	26.4
5	C10H16	1-β-Pinene	18	0.5
6	C10H16	1-Phellandrene	18.4	0.3
7	C10H16	α-Terpinolene	18.6	2.5
8	C10H16	l-Limonene	18.8	11.2
9	C10H16	β-Phellandrene	19	0.4
10	C10H16	γ-Terpinene	19.3	6.8
11	C10H18O2	1-Octen-3yl-acetate	20.1	0.3
12	C10H18O	Terpinene-4-ol	22	5.3
13	C10H18O	α-Terpineol	22.3	0.5
14	C12H20O2	1,7,7-Trimethyl-bicyclo	23.7	10.2
15	C12H20O2	α-Terpinenyl acetate	24.5	12.6
16	C15H24	Epi-bicyclosesquiphellandrene	26.4	1.3
17	C15H24	Widdrene	26.5	3.2
18	C15H24	Epizonaren	27.1	0.7
19	C15H24	δ-Cadinene	27.5	0.7
20	C15H24	δ-Himachalene	27.7	0.5
21	C15H26O	Elemol	29.1	4.2
22	C15H26O	10-epi-γ-Eudesmol	31.4	1.1
23	C15H26O	β-Eudesmol	32.4	1.1

Fig. 2. Inhibitory effects of 10% Chamaecyparis obtusa essential oil (COE; 50 μL, intra-articularly) and indomethacin (INDO; 10 mg/kg, 50 μL, i.a.) on weight load in carrageenan (CGN)-induced arthritic rats.

Notes: A time course of the weight load on the inflamed joint (open circle) was shown. Reduction of weight load on the inflamed joint was significantly attenuated in the 10% COE (closed circle, n = 9)- and INDO-treated group (positive control; closed triangle, n = 9) compared to the vehicle-treated group (open circle, n = 9) 6–8 h after CGN injection. (a) p < 0.05 indicated comparison made with CGN + vehicle (VEH) groups; (b) p < 0.05 indicates comparison made with CGN + INDO groups; (c) p < 0.05 indicates comparison made with CGN + 10% COE groups.

Fig. 3. Inhibitory effects of 10% Chamaecyparis obtusa essential oil (COE; 50 μL, intra-articularly) and indomethacin (INDO; 10 mg/kg, 50 μL, i.a.) on inflamed synovial membrane 5–8 h after carrageenan (CGN) injection.

Notes: (A) Representative images for Western blot data in inflamed synovial membrane. (B) The group treated with 10% COE had significantly reduced levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6 (at 6–8 h), and cyclooxygenase (COX)-2 (at 8 h) compared with vehicle (VEH)-treated group after CGN injection. INDO-treated group (positive control) showed a significant reduction in IL-1β and COX-2 (at 5–8 h), TNF-α (at 6–7 h), and IL-6 (at 6–8 h) after CGN injection compared with VEH-treated group. The INDO-treated group was significantly reduced in the levels of IL-1β (at 5 and 8 h), TNF-α (at 6 and 7 h), COX-2 (at 6 and 8 h), and IL-6 (at 6 and 7 h) compared with 10% COE-treated group. Values are means ± standard error of the means, n = 3. (a) p < 0.05 indicated comparison made with CGN + vehicle (VEH) groups; (b) p < 0.05 indicates comparison made with CGN + INDO groups; (c) p < 0.05 indicates comparison made with CGN + 10% COE groups.

Fig. 4. Inhibitory effects of 10% Chamaecyparis obtusa essential oil (COE; 50 μL, intra-articularly) and indomethacin (INDO; 10 mg/kg, 50 μL, i.a.) on inflamed meniscus 5–8 h after carrageenan (CGN) injection.

Notes: (A) Representative images for Western blot data in inflamed meniscus. (B) The group treated with 10% COE had significantly reduced levels of interleukin (IL)-1β and cyclooxygenase (COX)-2 (at 6–8 h), and IL-6 (at 5–7 h), but not tumor necrosis factor (TNF)-α, compared with vehicle (VEH)-treated group after CGN injection. INDO-treated group (positive control) showed a significant reduction of IL-1β and IL-6 (at 5–8 h), TNF-α (at 6–7 h), and COX-2 (at 7 and 8 h) after CGN injection compared with VEH-treated group. The INDO-treated group was significantly reduced in the levels of IL-1β and IL-6 (at 5–8 h), TNF-α (at 6–7 h), and COX-2 (at 7–8 h) compared with 10% COE-treated group. Values are means ± standard error of the means, n = 3. (a) p < 0.05 indicated comparison made with CGN + vehicle (VEH) groups; (b) p < 0.05 indicates comparison made with CGN + INDO groups; (c) p < 0.05 indicates comparison made with CGN + 10% COE groups.