Gender and inter-species influence on coagulation tests of rats and mice.

INTRODUCTION Rats and mice have been used to evaluate effects of natural and synthetic oestrogens. However, data about oestrogen's effects on haemostasis in rodents is very limited. The aim of this work was to standardize blood coagulation screening tests in adult male, female, and ovariectomized (Ovx) Wistar rats and CD1 mice in an effort to evaluate the influence of gender and species differences on haemostasis. MATERIALS AND METHODS Values were obtained for the following haemostatic parameters: prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin clotting time (TT), and fibrinogen (FIB), through modifications of the conventional techniques used for human blood coagulation analysis. RESULTS Both rats and mice showed gender intra-species and inter-species differences of high significance in PT, aPTT, TT, and FIB values. Intra-species differences were found in TT (+10% p<0.01) and FIB concentration (-21% p<0.001) between male and Ovx rats. Male vs. Ovx mice showed a TT difference of -20% (p<0.001). The main inter-species differences found were PT values of male rats vs. male mice (-39%) and female rats vs. female mice (-35%, both p<0.001). Female rats and mice aPTT values vs. those corresponding to Ovx animals showed differences of +15% and +32% (p<0.001), respectively. CONCLUSIONS These data reveal the great importance of gender intra- and inter-species differences on the values of haemostatic screening tests, which should be taken into consideration when evaluating the effects of oestrogens and other drugs on the coagulation system.