Maternal behavior in F344/N and LEW/N rats: Effects on carrageenan-induced inflammatory reactivity

Inbred Fischer and Lewis rats differ on inflammatory, startle and drug responsivity. These differences point to underlying genetic differences between both strains. Genetic models of hypertension have shown the importance of maternal environment in the development of high blood pressure, suggesting that maternal influences might also play a role in adult phenotypes in these strains. To determine maternal influences on these two strains, Lewis pups were cross-fostered to Fischer dams (F/L) and vice versa (L/F) (these litters were compared to in-fostered pups, L/L and F/F). Lewis dams were faster to initiate retrieval and to retrieve the whole litter than Fischer dams, independent of the strain of the pups. Cross-fostering affected body weight of the two strains (at two months of age). However cross-fostering did not affect inflammatory reactivity to carrageenan, suggesting that differences in the inflammatory response between these two strains are under a high degree of genetic control.