Variation of InsP4,InsP5 and InsP6 levels in tissues and biological fluids depending on dietary phytate

Due to the increasing interest of InsP6 on human health, the aim of this paper is to compare the levels of highly phosphorilated inositols (InsP4, InsP5 and InsP6) in organs and biological fluids of rats and to study the influence of the presence and absence of InsP6 in diets. Thus, for this purpose, the variation of InsP4, InsP5 and InsP6 levels in organs and biological fluids of rats submitted to two different diets were studied. In the AIN-76A diet no InsP6 was present, yet the other was a 1% InsP6 modified diet (AIN-76A + 1% InsP6). The highest InsP4, InsP5 and InsP6 levels were found to be 10-fold superior in the brain than those found in the kidney. When the InsP6 was eliminated from the diet, the InsP6 levels decreased dramatically (97.2% in kidney, 89.8% in brain, 100% in bone, 90.5% in plasma and 98.1% in urine), the InsP5 levels showed an important decrease (61.2% in kidney, 45.5% in brain, 28.1% in bone, 30% in plasma and 88.6% in urine) and the InsP4 levels in organs only changed slightly. From these results, it can be deduced that the majority of InsP6 present in the organism is of dietary origin and its endogenous synthesis is not important. According to the results, it can be evidenced that the endogenous synthesis of InsP5 can occur, besides InsP6 can be transformed by enzymatic dephosphorilation in InsP5.