Figure 1. Experimental scheme.

The newborn rat pups were reared either by their genetic mother (control) or exposed to a fostering procedure where on the first postnatal day (P1), the pups were transferred to a foster mother. A foster mother of the same rat strain (intra‐strain fostering) or of the other rat strain (cross‐strain fostering) reared the pups until weaning (P30) or the pups were exposed to cross‐strain fostering until P10 and then returned to their original mother for the rest of the lactation period (until P30).