TCPL delivery system as a model for E + P replacement therapy in post-ovariectomized adult rats mimicking a...

The specific aim of this investigation was to utilize TCPL delivery system as a model for estrogen (E) plus progesterone (P) replacement therapy in post-ovariectomized adult rats mimicking a postmenopausal condition. A total of 20 adult female rats were used in this study. The animals were randomly divided into four different groups: groups II, III and IV were ovariectomized (OVX), OVX plus E (40 mg loaded TCPL), and OVX plus E (TCPL, 40 mg) plus P (TCPL, 80 mg) treatment. Group I animals (n = 5) served as intact control group. Blood samples were collected biweekly for 30 days. Vaginal smears were taken and screened daily during the entire investigation. The total serum levels of E, P, luteinizing hormone (LH), and follicle stimulating hormone (FSH) were measured by means of radioimmunoassay procedure. Data obtained from this study suggest the followings: (I) OVX resulted in an increase in total serum levels of LH and FSH within 2 days post-ovariectomy, (II) TCPL were capable of releasing sustained levels of E (10-40 pg/ml) and P (2.30-3.75 ng/ml) at the end of second day and continued until the 30th day, (III) the sustained levels of E plus P were able to suppress the post ovariectomy rise of LH and FSH to almost physiological levels, (IV) sustained delivery of E resulted in maturation of vaginal epithelium and the smears exhibited the estrus phase throughout the investigational period, and (V) sustained delivery of E + P induced no estrus and the epithelial changes resembled the OVX group.