There is no evidence of sexual dimorphism in platelet reactivity in the rat.

Changes in platelet reactivity (in vivo) to adenosine diphosphate (ADP) were evaluated in intact male and female rats, gonadectomized rats (with or without hormonal treatment with oestradiol or testosterone), feminized and androgenized rats (with or without hormonal treatment with oestradiol and testosterone). The 3',5'-cyclic adenosine monophosphate (cAMP) content of the respective platelet suspensions was also determined simultaneously. Changes recorded in platelet reactivity to ADP showed striking changes unreflective of endocrine status. No consistent concomitant changes were observed in the cAMP content of the respective platelet suspensions. The data obtained casts doubts on the presence of sexual dimorphism in platelet reactivity. A dependence of platelet reactivity on hormones per se as well as the second messenger role for cAMP in platelet reactivity also raises some doubts.