Effect of acupuncture at Renying (ST 9) on gene expression profile of hypothalamus in spontaneously hypertensive rats

Influence of electroacupuncture on ghrelin and the phosphoinositide 3-kinase/protein kinase B/endothelial nitric oxide synthase signaling pathway in spontaneously hypertensive rats

OBJECTIVE

To investigate the influence of electroacupuncture (EA) on ghrelin and the phosphoinositide 3-kinase/protein kinase B/endothelial nitric oxide synthase (PI3K/Akt/eNOS) signaling pathway in spontaneously hypertensive rats (SHRs).

METHODS

Eight Wistar-Kyoto rats were used as the healthy blood pressure (BP) control (normal group), and 32 SHRs were randomized into model group, EA group, EA plus ghrelin group (EA + G group), and EA plus PF04628935 group (a potent ghrelin receptor blocker; EA + P group) using a random number table. Rats in the normal group and model group did not receive treatment, but were immobilized for 20 min per day, 5 times a week, for 4 continuous weeks. SHRs in the EA group, EA + G group and EA + P group were immobilized and given EA treatment in 20 min sessions, 5 times per week, for 4 weeks. Additionally, 1 h before EA, SHRs in the EA + G group and EA + P group were intraperitoneally injected with ghrelin or PF04628935, respectively, for 4 weeks. The tail-cuff method was used to measure BP. After the 4-week intervention, the rats were sacrificed by cervical dislocation, and pathological morphology of the abdominal aorta was observed using hematoxylin-eosin (HE) staining. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of ghrelin, nitric oxide (NO), endothelin-1 (ET-1) and thromboxane A2 (TXA2) in the serum. Isolated thoracic aortic ring experiment was performed to evaluate vasorelaxation. Western blot was used to measure the expression of PI3K, Akt, phosphorylated Akt (p-Akt) and eNOS proteins in the abdominal aorta. Further, quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to measure the relative levels of mRNA expression for PI3K, Akt and eNOS in the abdominal aorta.

RESULTS

EA significantly reduced the systolic BP (SBP) and diastolic BP (DBP) (P < 0.05). HE staining showed that EA improved the morphology of the vascular endothelium to some extent. Results of ELISA indicated that higher concentrations of ghrelin and NO, and lower concentrations of ET-1 and TXA2 were presented in the EA group (P < 0.05). The isolated thoracic aortic ring experiment demonstrated that the vasodilation capacity of the thoracic aorta increased in the EA group. Results of Western blot and qRT-PCR showed that EA increased the abundance of PI3K, p-Akt/Akt and eNOS proteins, as well as expression levels of PI3K, Akt and eNOS mRNAs (P < 0.05). In the EA + G group, SBP and DBP decreased (P < 0.05), ghrelin concentrations increased (P < 0.05), and the concentrations of ET-1 and TXA2 decreased (P < 0.05), relative to the EA group. In addition, the levels of PI3K and eNOS proteins, the p-Akt/Akt ratio, and the expression of PI3K, Akt and eNOS mRNAs increased significantly in the EA + G group (P < 0.05), while PF04628935 reversed these effects.

CONCLUSION

EA effectively reduced BP and protected the vascular endothelium, and these effects may be linked to promoting the release of ghrelin and activation of the PI3K/Akt/eNOS signaling pathway.

Electroacupuncture Attenuated Phenotype Transformation of Vascular Smooth Muscle Cells via PI3K/Akt and MAPK Signaling Pathways in Spontaneous Hypertensive Rats

OBJECTIVE

To investigate whether the antihypertensive mechanism of electroacupuncture (EA) is associated with attenuating phenotype transformation of vascular smooth muscle cells (VSMCs) via phosphoinositide3-kinase (PI3K)/protein kinase B (Akt) and mitogen-activated protein kinase (MAPK) signaling pathways.

METHODS

Eight Wistar-ktoyo (WKY) rats were set as normal blood pressure group (normal group). A total of 32 spontaneous hypertensive rats (SHRs) were randomly divided into 4 groups using random number tables: a model group, an EA group, an EA+PI3K antagonist group (EA+P group), and an EA+p38 MAPK agonist+extracellular signal-regulated kinase (ERK) agonist group (EA+M group) (n=8/group). SHRs in EA group, EA+P group and EA+M group received EA treatment 5 sessions per week for continuous 4 weeks, while rats in the normal and model groups were bundled in same condition. The systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) of each rat was measured at 0 week and the 4th week. After 4-week intervention, thoracic aorta was collected for hematoxylin-eosin (HE) staining, immunohistochemistry [the contractile markers α-smooth muscle actin (α-SMA) and calponin and the synthetic marker osteopontin (OPN)] and Western blot [α-SMA, calponin, OPN, PI3K, phosphorylated-Akt (p-Akt), Akt, p-p42/44 ERK, total p42/44 ERK, p-p38 MAPK and total p38 MAPK].

RESULTS

EA significantly reduced SBP, DBP and MAP (P<0.01). HE staining showed that the wall thickness of thoracic aorta in EA group was significantly decreased (P<0.01). From results of immunohistochemistry and Western blot, EA increased the expression of α-SMA and calponin, and decreased the expression of OPN (P<0.01). In addition, the expression of PI3K and p-Akt increased (P<0.01), while the expression of p-p42/44 ERK and p-p38 MAPK decreased in EA group (P<0.01). However, these effects were reversed by PI3K antagonist, p38 MAPK agonist and ERK agonist.

CONCLUSIONS

EA was an effective treatment for BP management. The antihypertensive effect of EA may be related with inhibition of phenotypic transformation of VSMCs, in which the activation of PI3K/Akt and the repression of MAPK pathway were involved.