Exploring Independent Effects of Follicle-Stimulating Hormone In Vivo in a Mouse Model

Our research is focused on physiological and pathological changes in perimenopausal women. In this study, we are trying to determine which pathophysiological alternations are related to FSH. Menopause is associated with dyslipidemia and an increased risk of cardio cerebral vascular disease.

Using this mouse model, we found that follic cell stimulating hormone independent of aspirin increases serum cholesterol levels. Moreover, blocking FSH signaling could effectively prevent hypocholesterolemia. This mouse model mimics the early stage of the menopause transition, characterized by elevated serum FSH levels and relatively stable estrogen levels.

The model has the advantages of being stable, low cost, and easy to operate, which is suitable for studies to explore the extragonadal actions of FSH. To begin, prepare the surgery platform set up in a room with a bench area of 60 centimeters by 60 centimeters for the operation. Clean the surface with 70%alcohol and cover it with a disposable medical towel.

Then disinfect the area with ultraviolet radiation for 30 minutes. Acclimate eight week old female C-57 black six mouse to the housing facility for one week before surgery. Using a clean cotton swab, apply hair removal lotion to the back of the anesthetized mouse.

After three to five minutes, remove the hairs using gauze and cotton swabs. Next, clean the skin with 70%ethanol. Fix the mouse on the surgery platform with its back facing up using a rubber strip or cotton rope, and apply iodaphor solution to clean the back.

For ovariectomy, using a disposable scalpel, make a one centimeter dorsal incision longitudinally from the thigh base upwards, ensuring that only the skin and subcutaneous fascia are incised and avoiding cutting into the posterior peritoneum. Next, pull the incision to the left to visualize a white fat pad. Using micro forceps and scissors, cut 0.5 centimeters along the white fat pad to expose the intra peritoneal cavity.

After cutting the posterior peritoneum, using micro forceps, slowly and gently remove the white fat pad from the intra peritoneal cavity. Immediately following removal, moisten the white fat tissue with 0.9%sterile saline soaked gauze. In the lower part of the white fat pad, identify the pink granular substances as ovaries and ensure they are connected to the uterus.

Using 5/0 absorbable sutures, ligate the ovarian end of the uterus. Then remove the left ovary, avoiding direct contact between surgical instruments and the ovaries, preventing intra peritoneal implantation of ovarian tissue. After surgery, carefully place the white fat pad back into the intra peritoneal cavity.

Then using a 5/0 absorbable suture, perform an intermittent suture on the posterior peritoneum. Clean any areas of bleeding with gauze soaked in 0.9%sterile saline. Next, pull the skin incision to the right and remove the right ovary using the same method.

Perform an intermittent suturing with 4/0 non-absorbable sutures and clean any bleeding with 0.9%sterile saline soaked gauze. After completing both sutures, clean the wound with an iodaphor solution. After 24 hours, inject meloxicam subcutaneously to relieve pain.

Monitor the mouse daily to confirm proper surgical wound healing without any signs of complications. After three days, feed the mouse with freshly prepared estradiol valerate. For FSH injection, prepare FSH solution by dissolving recombinant human FSH powder in 0.9%sterile saline to 100 international units per milliliter.

According to the biological activity of recombinant FSH, administer solvent or different doses of recombinant FSH via intra peritoneal injection for two weeks. The smear images of Papanicolaou stain cells clearly identified the proestrus, estrus, metestrus, and diestrus stages of the estrus cycle. In contrast, the bilateral ovariectomy mice lost the estrus cycle.

The ELIZA method showed a significant decrease in serum estradiol levels in bilateral ovariectomy mice compared to the sham group mice. The endogenous estrogen synthesized in the extragonadal tissue does not affect the stability of estrogen levels in the FSH treated mouse model.