Impact of neonatal imprinting with vitamin A or D on the hormone content of rat immune cells

Neonatal single vitamin A (retinol; 3 mg) or vitamin D3 (cholecalciferol; 0.05 mg) treatment (imprinting) was done in male and female rats and 2 months later the endorphin, triiodothyronine (T3) and ACTH content of immune cells (peritoneal lymphocytes, monocyte-granulocyte-macrophage group [mo-gran], mast cells and thymic lymphocytes) were studied immunocytochemically by using flow cytometry and confocal microscopy. The T3 content was significantly decreased in peritoneal lymphocytes and in mo-gran and the endorphin content decreased in thymocytes of male animals, while ACTH was decreased in female lymphocytes and mo-gran. Vitamin D treatment was absolutely ineffective. The imprinting effects of vitamins A and D and their differences are discussed. The results call attention to the possible harmful effect of vitamin treatments during the perinatal critical period.