Transforming Growth Factor-β1 and Cortisol in Differentially Reared Primates

Abstract

Exposure of primate infants to adverse rearing conditions during the first half year of life can result in enduring behavioral, neuroendocrine, and immunologic abnormalities. However, the effects of differential rearing on cytokines, some of which can regulate immune and inflammatory responses and modulate activity of the central nervous system and the hypothalamic-pituitary-adrenal (HPA) axis, are largely unexamined. The present study explored the relationship between circulating levels of transforming growth factor-β1 (TGF-β1) and cortisol in macaques reared either normally or under conditions of variable foraging demand (VFD). Under VFD rearing, for a period of 4 months, the infants' mothers intermittently had to expend more time and effort to obtain food than did the mothers of normally reared control subjects. Two years after cessation of the rearing experience, exposure to a moderate stressor (confinement in an unfamiliar room for 90 min) induced elevated levels of serum TGF-β1 and plasma cortisol in VFD-reared monkeys compared to normally reared controls. The correlation between TGF-β1 and cortisol levels was substantially higher in the normally reared subjects. Examination of the relationship between HPA axis and immune function will improve our understanding of the pathophysiological consequences of adverse rearing.