Identification of insulin-like growth factor I in bovine seminal plasma and its receptor on spermatozoa: influence on sperm motility

• Published in: Biology of reproduction 1998-08, Vol.59 (2), p.330-337
• Main Authors: Henricks, D.M. (Clemson University, Clemson, SC.), Kouba, A.J, Lackey, B.R, Boone, W.R, Gray, S.L
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Monoclonal - drug effects; BINDING SITES; Biological and medical sciences; BULLS; Cattle; Fundamental and applied biological sciences. Psychology; HORMONE RECEPTORS; IMMUNOCYTOCHEMISTRY; Immunohistochemistry; IMMUNOLOGY; In Vitro Techniques; INSULIN-LIKE GROWTH FACTOR; Insulin-Like Growth Factor I - analysis; Insulin-Like Growth Factor I - metabolism; Insulin-Like Growth Factor I - pharmacology; INSULIN-LIKE GROWTH FACTOR II; Insulin-Like Growth Factor II - pharmacology; INSULIN-LIKE GROWTH FACTOR RECEPTOR; LOCALIZATION; Male; Mammalian male genital system; Morphology. Physiology; MOVEMENT; Radioimmunoassay; Receptor, IGF Type 1 - chemistry; Receptor, IGF Type 1 - metabolism; SEMEN; Semen - chemistry; Semen - metabolism; Sperm Motility - drug effects; Sperm Motility - physiology; SPERMATOZOA; Spermatozoa - chemistry; Spermatozoa - metabolism; Vertebrates: reproduction
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod59.2.330

Insulin-like growth factor I (IGF-I) has been identified in human seminal plasma. This study was conducted to determine whether IGF-I is present in bovine seminal plasma, whether sperm cells express the IGF-I receptor (IGF-IR), and whether IGF-I affects sperm motility. Semen samples were collected from bulls by electroejaculation and maintained at 37°C, and motility of sperm was assessed. After centrifugation to separate sperm cells from seminal plasma, the seminal plasma was submitted to a validated heterologous RIA for IGF-I. Significant concentrations of IGF-I (116.29 ± 40.83 ng/ml expressed as mean ± SD) were measured in bovine seminal plasma. Sperm cells were washed with buffer and subjected to either radioreceptor assay (RRA) or immunocytochemistry (IC). RRA revealed a single high affinity for the IGF-IR with a K d of 0.83 nM as determined by the computer program LIGAND. IC, using three monoclonal antibodies, localized the IGF-IR to the acrosomal region of the sperm. Computer-assisted sperm-motion analysis was used to determine the effects of IGF-I and IGF-II on bovine sperm motility parameters. Both IGF-I and IGF-II increased sperm motility and straight-line velocity ( p < 0.05) relative to the control. The presence of IGF-IR on sperm, the presence of IGF-I in semen, and the ability of IGF-I to stimulate sperm motility provide evidence that the IGF system may be involved in the fertilization process in the bovine species.