Khadijeh Sedaghat - Ferdowsi University of Mashhad, Mashhad, Iran
Morteza Behnam Rasoouli - Ferdowsi University of Mashhad, Mashhad, Iran
Nasser Mahdavi Shahri - Ferdowsi University of Mashhad, Mashhad, Iran
Masoumeh Kheirabadi - Ferdowsi University of Mashhad, Mashhad, Iran

Tamoxifen is a nonsteroidal anti-estrogen which is prescribed for treatment of breast cancer.It is an estrogen receptor modulator. Dependent on the target tissue, It may be estrogenagonist or antagonist. Some effects of the reproductive tract have been observed. Thepurpose of this study was to investigate the tumorigenesis effects of neonatala dministrationof tamoxifen on endometrium in female mice. In this study 10 females were examined.Female mice were divided into test and control groups. Control group received sesame oiland treatment groups received tamoxifen (400 Âμg/kg/days) per 1 to 5 days after birthsubcutaneously. All animals were perfused with paraformaldehyde in 70 days and uteruswere removed and post-fixed in paraformaldehyde and cross-section of uterus stained withhematoxyline and eosine and were evaluated histologically. In results, we found thikness inendometrium stroma. Morphological and histological studies showed that tamoxifen affectson endometrium stroma and causes of its thickness and decrease body weight (p ≤o.oo1). Tamoxifen, a selective estrogen modulator (SERM) is an agonist in the uterus. Theseagonist actions in the uterus may cause an increased risk of endometrial cancer. Howsoever,many studies have shown that tamoxifen can act as an estrogen agonist in the female genitaltract leading to the development of endometrial hyperplasia and sometimes malignancy. Inmany patients, tamoxifen has an antiestrogenic effect on the uterus, and patients can developinactive or atrophic endometrium. Further studies are essential to investigate other effects oftamoxifen on the female uterus.

Tamoxifen, Uterus, Mice, Endometrial Cancer, Tumorigenesis