Genetic models in brain and behavior research, part IV

Abstract

Four reviews on the the role of developmental factors in hypertension are introduced and set in historical context. Recent research in the laboratory rat has shown that the preweaning environment makes an important contribution to the level of blod-pressure reached in adult life in genetic models of hypertension. Both of the most commonly used models of hypertension, the SHR and SS/Jr rat strains, exhibit lower BP in adult life, if they are fostered shortly after birth to mothers from their normotensive control strains. It has been suggested that it is the idiosyncratic maternal behavior of the hypertensive mothers which contributes to the elevated BP of their offspring, and it has been amply demonstrated that there is an association between a constellation of behaviors emitted by rat mothers and the adult BP of their offspring in a wide variety of genetic groups (inbred hypertensive animals, F1's and F2's). In addition to the above, maternal environment has been demonstrated to have a significant impact on the pathophysiological response of hypertensive animals to a high salt diet. Being raised by an SHR mother, versus an SS/Jr mother, increases the magnitude of BP increases to a high salt diet, susceptibility to hemorrhagic stroke, body weight loss and the risk of mortality. A variety of physiological systems are undergoing rapid change during the preweaning period and may mediate the effects of differences in the maternal environment. These include the renin-angiotensin system and the peripheral sympathetic nervous system. Nutritional factors may be involved in all of the phenomena referred to above. Thus, any physiological mechanisms that are proposed to link maternal behavior to its effects on the physiology of adult animals should recognize the involvement of nutritional factors. Research on the role of developmental factors such as maternal behavior in genetic models of hypertension is at the interface of two growing disciplines: behavior genetics and developmental psychobiology. The methodological and conceptual contributions of these fields to advancing our understanding of these phenomena is emphasized.