Maternal influences on adult blood pressure of SHRS: A single pup cross-fostering study

To examine the effects of the preweanling maternal environment on the development of adult blood pressure, individual spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) normotensive pups were reciprocally cross-fostered between mothers of the same or opposite strain. With this design, each SHR and WKY foster mother reared 7 of her own pups and 1 SHR or WKY foster pup. All litters were weaned at 21 days of age and body weights were obtained. At 110 days of age, SHR and WKY males were weighed and surgically prepared with chronic tail artery catheters. One day later, basal measures of mean arterial pressure (MAP, mmHg) and heart rate (HR, beats per min) were obtained while animals were resting and undisturbed in their home cages. Our findings indicate that adult SHRs reared by WKY foster dams displayed significant reductions in MAP compared to SHRs that were reared by their natural mothers or by SHR foster mothers. In contrast, MAPs of WKYs did not differ across rearing conditions. Weanling body weights of cross-fostered SHRs were significantly greater than control-reared SHRs while weanling body weights of cross-fostered WKYs were significantly lower than control-reared WKYs. However, by 110 days of age, there were no treatment-related effects on body weights of males of either strain. These findings underscore the importance of genotype x maternal environment interactions during the preweanling period for the development of cardiovascular phenotype in SHRs.