Animal studies demonstrated thattryptophan supplementation improved embryo survival in mice exposed to pseudorabiesvirus-induced pregnancy failure,14 and fetal growth inruminants,15,16 potentially through the role of KP metabolites in boneremodeling.82 Furthermore, the development of hypertension in the pups ofrats with experimental chronic kidney disease was prevented by supplementing thesepregnant rats with tryptophan.17 Here, NPPA is linked to hypertensive disorder.