Abnormal Expression Of Lin28a And Lin28b MRNA In Hypothalamus-Pituitary-Ovary Axis Of Female Precocious Puberty Sprague-Dawle Rat Induced By Estrogen

Objective:To investigate expression and significance of Lin28a and Lin28b mRNA in hypothalamus-pituitary-ovary axis of female SD rats at various stages of development and precocious puberty induced by estrogen.Methods:1) Analyze expression of Lin28a and Lin28b mRNA in hypothalamus, pituitary and ovary of SD rats with Real-time PCR on postnatal day15(PND15), PND23and PND35, meanwhile examine level of serum LH and E2with ELISA;2)EB(estradiol benzoate)-induced precocious puberty rats are divided into EB-1and EB-2groups and are respectively sacrificed at the time of vaginal opening (VO) and PND56, at the same time respectively controlled with OIL-1and OIL-2groups which are induced by sesame oil (OIL). Analyze expression of Lin28a and Lin28b mRNA in hypothalamus, pituitary and ovary with Real-time PCR, examine level of serum LH and E2with ELISA and observe influence of precious puberty on VO, weight, crown-rump length, tibia length at the same time.Results:1) Level of serum LH and E2, expression of Lin28a and Lin28b mRNA in hypothalamus and pituitary and expression of Lin28b mRNA in ovary among PND15, PND23and PND35groups are not statistically significant respectively (P>0.05),while expression of Lin28a mRNA within ovary in group PND23and PND35is higher than group PND15,respectively (P<0.05); 2) Expression of Lin28a and Lin28b mRNA within hypothalamus and expression of Lin28a mRNA within pituitary in EB-1is higher than OIL-1, respectively (P<0.05), however expression of Lin28b mRNA within ovary in EB-1is lower than OIL-1(P<0.05), while expression of Lin28b mRNA in pituitary, expression of Lin28a mRNA in ovary and level of serum LH and E2between two groups is not statistically significant, respectively (P>0.05); Expression of Lin28a and Lin28b mRNA in EB-2is higher than OIL-2(P<0.05), however expression of Lin28a and Lin28b mRNA in pituitary and ovary between two groups is not statistically significant (P>0.05), meanwhile level of serum LH and E2between two groups is statistically significant (P<0.05);3) Time of VO in EB-2group is earlier than OIL-2group (P<0.01), while weight,crown-rump length, tibia length between two groups is not statistically significant (P>0.05).Conclusions:Precious puberty induced by Exogenous Estrogen could result in abnormal expression of Lin28a and Lin28b mRNA in hypothalamus-pituitary-ovary axis, especially in hypothalamus.