title: Effects of sericin on the testicular growth hormone/insulin-like growth factor-1 axis in a rat model of type 2 diabetes.
abstract: This study investigated the effects of sericin on the testicular growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis in rats with type 2 diabetes mellitus. Forty rats were randomly assigned to normal control, type 2 diabetes mellitus, sericin and metformin treated groups. Type 2 diabetes was established by repeated intraperitoneal injection of streptozotocin, and identified by blood glucose ≥16.7 mmol/L at 1 week. The diabetic rats were given no other treatment, these rats in the sericin group were intragastrically perfused with 2.4 g/kg sericin and the metformin treated rats were intragastrically perfused with 55.33 mg/kg Metformin daily for 35 consecutive days. Enzyme-linked immunosorbent assays were used to determine serum testosterone, growth hormone and IGF-1 levels. Immunohistochemical staining, western blotting and reverse transcription-PCR were used to determine testicular growth hormone, growth hormone receptor and IGF-1 expression. The sericin significantly reduced serum growth hormone levels, downregulated growth hormone expression, increased serum testosterone and IGF-1 levels, and upregulated testicular growth hormone receptor and IGF-1 expression. Moreover, there were no significant differences in any of the parameters between the sericin and metformin treated groups. These findings indicated that sericin improved spermatogenic function through regulating the growth hormone/IGF-1 axis, thereby protecting reproductive function against diabetes-induced damage.
authors.affiliation: Department of Anatomy, Chengde Medical College Chengde, Hebei, P. R. China.
authors.forename: Cheng-Jun
authors.initials: CJ
authors.lastname: Song
authors.affiliation: Department of Anatomy, Chengde Medical College Chengde, Hebei, P. R. China.
authors.forename: Zhen-Jun
authors.initials: ZJ
authors.lastname: Yang
authors.affiliation: Department of Anesthesiology, Suzhou BenQ Medical Center, Nanjing Medical University Suzhou, Jiangsu, P. R. China.
authors.forename: Qi-Feng
authors.initials: QF
authors.lastname: Tang
authors.affiliation: Department of Anatomy, Chengde Medical College Chengde, Hebei, P. R. China.
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Chen
keywords: Sericin; growth hormone; insulin-like growth factor-1; testis; type 2 diabetes