Involvement of signaling pathways in bovine sperm motility, and effect of ergot alkaloids

• Published in: In vitro cellular & developmental biology. Animal 2009-09, Vol.45 (8), p.483-489
• Main Authors: Wang, Hehai, Looper, Michael L, Johnson, Zelpha B, Rorie, Rick W, Rosenkrans, Charles F. Jr
• Format: Article
• Language: English
• Subjects: Adrenergic receptors; Alkaloids; alpha-adrenergic receptors; Animal Genetics and Genomics; Animals; Arithmetic mean; Biomedical and Life Sciences; Calcium; Cattle; Cell Biology; Cell Culture; Chelating Agents - pharmacology; Cholera Toxin - pharmacology; Cyclic AMP - analogs & derivatives; Cyclic AMP - pharmacology; Developmental Biology; dihydroergotamine; Dihydroergotamine - pharmacology; Egtazic Acid - analogs & derivatives; Egtazic Acid - pharmacology; Ergot alkaloids; Ergot Alkaloids - pharmacology; ergotamine; Ergotamine - pharmacology; inhibitors; Life Sciences; Male; mechanism of action; Pertussis Toxin - pharmacology; Prazosin - pharmacology; Receptors; Receptors, Adrenergic, alpha - drug effects; Receptors, Adrenergic, alpha - metabolism; Signal Transduction; Signal Transduction - drug effects; Sperm motility; Sperm Motility - drug effects; Sperm Motility - physiology; Spermatozoa; Spermatozoa - drug effects; Stem Cells; Toxins; Ungulates; Yohimbine - pharmacology
• ISSN: 1071-2690; 1543-706X
• DOI: 10.1007/s11626-009-9191-8

There is evidence that ergot alkaloids can directly interact with mammalian spermatozoa affecting sperm functions. Ergot alkaloids exert their toxic or pharmaceutical effects through membrane receptor-mediated activities. This study investigated the signaling pathways involved in the in vitro inhibitory effects of both ergotamine (ET) and dihydroergotamine (DEHT) on the relative motility of bovine spermatozoa using specific inhibitors. Motile bovine spermatozoa were prepared using a Percoll gradient and incubated with ergot alkaloids with and without signaling pathway inhibitors. Co-incubation of ET or DHET with 100 μM prazosin (alpha 1-adrenergic receptor inhibitor) decreased (p < 0.05) relative motility of spermatozoa when compared with controls. In addition, preincubation of spermatozoa with 10 or 20 μM prazosin and DHET also reduced (p < 0.05) the number of motile spermatozoa. Relative sperm motility (motility of treated spermatozoa normalized to control sperm motility) was increased (p < 0.05) when co-incubations included ET and yohimbine (alpha 2-adrenergic receptor inhibitor); conversely, co-incubation of yohimbine (100 μM) and DHET decreased (p < 0.05) the percentage of motile spermatozoa when compared with controls. Pertussis toxin and cholera toxin (effectors of inhibitory and stimulatory G-proteins, respectively) altered (p < 0.05) relative sperm motility in a concentration dependent manner; however, co-incubation of pertussis or cholera toxin with ergot alkaloids had no interactive (p = 0.83) effects on the relative motility of spermatozoa. Co-incubation of Rp-cAMP (a membrane-permeable cAMP inhibitor) with 50 μM DHET had no effect (p > 0.05) on relative sperm motility; whereas, the co-incubation of 22.4 or 44.8 μM Rp-cAMP with 50 μM ET increased (p < 0.05) the percentage of motile spermatozoa when compared with 0 or 224 μM Rp-cAMP (49%, 65%, 59%, and 54%, respectively, for 0, 22.4, 44.8, and 224 μM of Rp-cAMP. An interaction between BAPTA-AM (a chelator of intracellular calcium) and alkaloids also impacted (p < 0.05) relative sperm motility. Generally, co-incubating spermatozoa with BAPTA-AM and ET increased the percentage of motile spermatozoa; however, co-incubation with DHET decreased relative sperm motility except with 41 μM BAPTA-AM. Collectively, these observations suggest that ET and DHET decreased the percentage of motile bovine spermatozoa via alpha adrenergic receptors. However, the second messenger systems involved with ergot alkalo