title: Surgical castration but not immuncastration is associated with reduced hypothalamic GnIH and GHRH/GH/IGF-I axis function in male rats.
abstract: Gonadotropin-inhibitory hormone (GnIH) is a potent positive regulator of the growth axis. The present study was aimed to comparatively investigate the effects of surgical and immunologic castration on hypothalamic GnIH expression and endocrine function of the growth axis. Thirty-six prepubertal male rats were randomly allocated into three groups (n = 12): control, surgically castrated or immunized against 100-μg D-Lys6-GnRH-tandem peptide conjugated to ovalbumin in Specol adjuvant at 6 weeks of age (with a booster 8 weeks later). Blood samples were collected (for hormone and urea nitrogen concentrations) at 2-week intervals, and growth performance was evaluated. Compared to intact controls, surgical castration reduced (P < 0.05) messenger RNA (mRNA) expressions of hypothalamic GnIH and growth hormone-releasing hormone (GHRH), pituitary growth hormone (GH), and liver insulin-like growth factor-1 (IGF-1), reduced (P < 0.05) serum concentrations of GH and IGF-1 and increased (P < 0.05) serum concentrations of urea nitrogen. In contrast, immunocastration did not alter messenger RNA expressions of hypothalamic GnIH, GHRH and pituitary GH, and the serum concentrations of GH (P > 0.05). Moreover, serum concentrations of IGF-1 and urea nitrogen in immunocastrates were substantially higher and lower than those in surgical castrates, respectively (P < 0.05). Compared to surgical castrates, immuncastrates had superior feed conversion efficiency and faster daily weight gain (P < 0.05). We concluded that surgical castration but not immunocastration is associated with reduced hypothalamic GnIH and GHRH/GH/IGF-I axis function in male rats.
authors.affiliation: Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, People's Republic of China.
authors.forename: Xingfa
authors.initials: X
authors.lastname: Han
authors.affiliation: Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, People's Republic of China.
authors.forename: Junli
authors.initials: J
authors.lastname: Li
authors.affiliation: Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, People's Republic of China.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Cao
authors.affiliation: Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, People's Republic of China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Du
authors.affiliation: Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, People's Republic of China.
authors.forename: Fengyan
authors.initials: F
authors.lastname: Meng
authors.affiliation: Isotope Research Lab, Biological Engineering and Application Biology Department, Sichuan Agricultural University, Ya'an, People's Republic of China. Electronic address: xyzeng1966@163.com.
authors.forename: Xianyin
authors.initials: X
authors.lastname: Zeng
mesh_terms: D000818:Animals; D000906:Antibodies; D001806:Blood Urea Nitrogen; D005786:Gene Expression Regulation / Q000502:physiology; D013006:Growth Hormone / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D007028:Hypothalamic Hormones / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009919:Orchiectomy / Q000379:methods*; D009929:Organ Size; D011897:Random Allocation; D051381:Rats; D013737:Testis / Q000033:anatomy & histology / Q000473:pathology; D022642:Vaccines, Contraceptive
chemical_list: D000906:Antibodies; D007028:Hypothalamic Hormones; C000588859:RFamide-related peptide-3, rat; D022642:Vaccines, Contraceptive; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone
keywords: GnRH; Gonadotropin-inhibitory hormone; Growth hormone–releasing hormone; Immunocastration; Performance; Rat