The retired breeder rat as a new model for antiplatelet drug discovery

Spontaneous circulating platelet aggregates were observed in male retired breeder rats but in nonbred males of the same age and strain. Fasting serum lipid, platelet serotonin, and platelet rich plasma cyclic guanosine monophosphate levels were similar in retired breeders and nonbred rats. The in vitro response of platelets from retired breeder and nonbred rats to adenosine diphosphate and collagen were also similar. Administration of prostaglandin E1 and antiplatelet drugs (acetylsalicylic acid, sulfinpyrazone, and dipyridamole) reduced the number of circulating platelet aggregates in the breeder rats. It was concluded that the retired breeder rat may be a useful model for identification of new anti-platelet drugs.