Do cathine and noradrenaline stimulate protein tyrosine phosphorylation in uncapacitated spermatozoa?
Our earlier investigation of responses to cathine demonstrated that the acceleration of capacitation seen in response to cathine, adrenaline and noradrenaline using CTC analysis correlated with a significant increase in cAMP production (Adeoya-Osiguwa and Fraser, 2005). We therefore hypothesized that such responses would also cause an increase in protein tyrosine phosphorylation. Filtered uncapacitated sperm suspensions containing 100 µmol/l sodium orthovanadate were mixed well, divided into three aliquots and treated with: (i) nothing (control); (ii) 100 nmol/l noradrenaline; (iii) 100 nmol/l cathine. Samples were again mixed gently, gassed for 15 s and incubated for 10 min at 37°C and then evaluated using gel electrophoresis and western blotting as described in Materials and Methods. Three different samples were evaluated, with each being used for two or three replicate gels; Figure 6 shows a representative result. As can be seen, both noradrenaline and cathine did stimulate tyrosine
