EFFECTS OF XENOBIOTICS ON MILK SECRETION AND COMPOSITION

The effect of xenobiotics on milk secretion and composition has receiv ed limited systematic study This review highlights current understandi ng of the mechanisms and regulation of milk secretion and indicates po tential sites of xenobiotic perturbation. Major emphasis includes revi ew of the cellular architecture and biochemical mechanisms of the diff erentiated mammary alveolar cell in relation to secretion of lipid, la ctose, milk proteins, electrolytes, trace elements, host defense syste ms, vitamins, hormones, growth factors, and antioxidant enzyme systems . The regulation of milk secretion by oxytocin, prolactin, steroid hor mones, and thyroxine is reviewed in the context of potential or known modulation by xenobiotics. Lastly, the impact of xenobiotic-induced ch anges in nutrient delivery to the mammary gland from altered mammary b loodflow or malnutrition are considered. This review also summarizes t he limited current knowledge of the impact of selected xenobiotics of environmental concern on milk secretion and composition. Attention is directed to alcohol, polychlorinated biphenyls, phthalate plasticizers , pharmacologic agents, tumor promotors, insecticides, heavy metals, a nd vitamins. The critical need for additional research is addressed, w ith proposals for epidemiologic studies in the human population and fu rther development of animal and tissue culture models for mechanistic investigations.