To observe the effects of insulin resistance on gonadal steroid hormone stimulation and the myometrial growth of female rats in order to elucidate the relationship between insulin resistance and the development of uterine leiomyomas. We divided 180 nonpregnant female Wistar rats into three groups as follows: group A, as the control group; group B, as the "model by exogenous sex hormone" group; and group C, as the "model by exogenous sex hormone plus insulin-resistance" group. All the animals were raised for 16 weeks. Uterine coefficient and homeostasis model assessment of insulin resistance (HOMA-IR) index were calculated. Myometrial depth and expression levels of the oestrogen receptor (ER), progesterone receptor (PR), and proliferating cell nuclear antigen (PCNA) were measured. HOMA-IR index, serum oestrogen level, uterine coefficient, and myometrial depth were lower in group B than in group C (P < 0.05). The expression levels of ER, PR, and PCNA were higher in group C than in group B (P < 0.05). An auxo-action of insulin resistance in myometrial growth was observed when exogenous oestrogen and progesterone were administered to the female rats in this study. Thus, we suspected that insulin resistance may affect the development of uterine leiomyomas.
Keywords: Myometrium; gonadal steroid hormones; insulin resistance; laboratory rats; uterine leiomyomas.