Effects of intercostal nerve transection on hyperplasia of mammary glands in rats

Abstract:

Objective：To study the effects of cutting off the seventh and the eighth intercostal nerve in the right side on hyperplasia of mammary gland（HMG） in SD rats. Methods：Totally 60 SD rats were randomly divided into 4 groups：normal group，model group，in－tercostal nerve transection group and ovariectomized group. Intramuscular injection of estradiol benzoate combinng with progesterone was provided to establish a rat model HMG. Diameter and height of the third nipple by right side in each group were measured at 2，4，6 weeks，respectively. Moreover，morphological changes and Ki-67 expression of the breast tissues were observed. mRNA levels and protein levels of estradiol receptor（ER） and progestogen receptor（PR） in breast tissues were measured by real time PCR and West－ern blot; protein levels of proliferating cell nuclear antigen（PCNA） were measured by Western blot respectively. Results：Diameter and height of the third nipple at the right side were measured. Diameter and height were lower in intercostal nerve transection group than in model group（P<0.05）. Layers of epithelial cell，numbers of acinus，diameter of acinus and diameter of duct of mammary gland were markedly reduced in intercostal nerve transection group than in model group（P<0.05）. In addition，mRNA and protein levels of ER and PR and the protein levels of PCNA in breast tissues were lower in intercostal nerve transection group than in model group（P<0.05）. Conclusions：Intercostal nerve transection could reduce pathological changes of HMG and reduce mRNA and protein ex－pressions of ER and PR as well as protein expressions of PCNA in rat mammary gland.