title: Effect of growth hormone and induced IGF-I release on germ cell population and apoptosis in the bovine testis.
abstract: Bovine growth hormone has been used in dairy cattle to increase milk production,but it also increases the twin parturition rate. This effect is mediated by insulin-like growth factor-I (IGF-I), which prevents follicular atresia by hindering apoptosis of granulosa cells. The action of GH and IGF-I on testicular function remains unclear. The goal of this study, therefore, was to verify the effects of short-term administration of GH and induced IGF-I release on the number of testicular germ cells, testicular morphology, and apoptosis in the bovine testis. Twenty Zebu bulls were split into 2 groups. The bulls in Group 1 (n = 10) were treated with 2 subcutaneous injections of bovine GH (500 mg/bull) 7 d apart. Group 2 bulls (n = 10) received placebos under the same protocol. All of the bulls were slaughtered 14 d after the start of treatment. Fragments of the testis were collected, fixed in Bouin's solution, embedded in paraffin, and the sections stained with hematoxilin and eosin. The paraffin-embedded sections were also used for in situ detection of apoptotic cells. Blood samples were collected at slaughter to measure serum levels of IGF-I, FSH and LH. Neither the number of Stage I seminiferous epithelium germ cells and the morphometric parameters (tubular diameter, seminiferous epithelium height, and volumetric proportions of structural components) nor the blood levels of FSH and LH showed a significant difference between the 2 groups. However, the treated animals showed an increase in serum IGF-I (P<0.01). Apoptotic germ cells were detected in the testis of both groups, showing the same pattern and a stage-specific apoptosis pattern. Most of the labeled cells were spermatocytes. The localization of apoptotic germ cells did not differ between groups. These results suggest that short-term administration of GH does not affect bovine spermatogenesis in adult bulls.
authors.affiliation: Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil.
authors.forename: R L
authors.initials: RL
authors.lastname: Santos
authors.forename: C M
authors.initials: CM
authors.lastname: Silva
authors.forename: A F
authors.initials: AF
authors.lastname: Ribeiro
authors.forename: A C
authors.initials: AC
authors.lastname: Vasconcelos
authors.forename: J L
authors.initials: JL
authors.lastname: Pesquero
authors.forename: S G
authors.initials: SG
authors.lastname: Coelho
authors.forename: R
authors.initials: R
authors.lastname: Serakides
authors.forename: S R
authors.initials: SR
authors.lastname: Reis
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000097:blood; D013006:Growth Hormone / Q000097:blood / Q000494:pharmacology* / Q000502:physiology; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D008163:Luminescent Measurements; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011863:Radioimmunoassay / Q000662:veterinary; D013091:Spermatogenesis; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
chemical_list: D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone