OBJECTIVE To explore the characteristics of hot flushes and the effect of Erxian Decoction in rats after bilateral oophorectomy.

METHODS Forty-eight female SD rats were randomly divided into 4 groups: sham operation group, bilateral ovariectomy group, 17β-estradiol treatment group and Erxian Decoction treatment group, with 12 rats in each group. After bilateral ovariectomy, rats were gavaged with 17β-estradiol (0.1 mg ·kg^-1 ·d^-1) and Erxian Decoction (8 g ·kg^-1 ·d^-1) for 6 weeks. On the 21st and 42nd days of modeling, the body weight, rectal temperature, infrared thermography of the body surface and other characteristic information of the rats were detected. Serum E₂ content was detected by ELISA. The pathological changes of the uterus and foot pad sweat glands of the rats were observed by HE staining. The hypothalamic estrogen receptor (ER) and thermoreceptor transient receptor potential vanilloid 3 (TRPV3) and transient receptor potential vanilloid 4 (TRPV4) were detected by immunohistochemistry. The protein expression of ERβ, PAC1R and PKA was detected by Western blot.

RESULTS Compared with the sham operation group during the same period, the body weight of the rats in the bilateral ovariectomy group increased significantly (P < 0.01), while the body weight of the rats in the 17β-estradiol group and Erxian Decoction group increased slowly. Compared with the sham operation group, the rectal temperature of the bilateral ovariectomy group and the 17β-estradiol group increased significantly on the 21st day after modeling (P < 0.01), and decreased significantly on the 42nd day after modeling (P < 0.05); on the 21st and 42nd days after modeling, the maximum body surface temperature of the rats in the bilateral ovariectomy group, the 17β-estradiol group and the Erxian Decoction group decreased significantly (P < 0.01), and on the 42nd day after modeling, the tail/body temperature ratio of the rats in the bilateral ovariectomy group increased significantly (P < 0.05); the number of sweat points in the bilateral ovariectomy group increased significantly (P < 0.01); the uterine index of the bilateral ovariectomy group, the 17β-estradiol group and the Erxian Decoction group decreased significantly (P < 0.01); the serum E2 in the bilateral ovariectomy group decreased significantly (P < 0.05); the number of ER-positive cells in the hypothalamus of the rats in the bilateral ovariectomy group decreased significantly (P < 0.01), while the number of TRPV3 positive cells increased significantly (P < 0.05); the number of ER and TRPV3 positive cells decreased in the 17β-estradiol group (P < 0.05), and the number of TRPV4 positive cells increased (P < 0.01); 17β-estradiol inhibited the expression of PAC1R and PKA proteins (P < 0.05), and Erxian Decoction significantly inhibited the expression of PAC1R, PKA and ERβ proteins (P < 0.01). Compared with the bilateral ovariectomy group, the rectal temperature of the Erxian Decoction group decreased significantly on the 21st day (P < 0.01); the number of sweat spots in the 17β-estradiol group and the Erxian Decoction group decreased significantly (P < 0.01); the E₂ level in the Erxian Decoction group increased significantly (P < 0.05), the number of ER positive cells in the hypothalamus increased significantly (P < 0.01), and the expression of ERβ and PAC1R proteins decreased significantly (P < 0.01).

CONCLUSION Bilateral oophorectomy rat model is associated with hot flashes, and its symptom characteristics are yin deficiency and internal heat, as well as insufficient yang qi, resulting in a yin-yang imbalance; Erxian Decoction affects the sensitivity of temperature changes by promoting estrogen secretion and its receptor expression.