Evaluation of inositol phosphates in urine after topical administration of myo-inositol hexaphosphate to female Wistar rats.

AIMS

Previous studies demonstrated a remarkable increase of urinary InsP by topical administration. However, the methodology used for InsP analysis was not specific. The aim of this paper is to measure urinary inositol phosphates InsPs using more advanced methodologies and to compare the results with those obtained by the non-specific method.

MATERIALS AND METHODS

We fed 12 female rats with a diet without InsP for 16days. Then, we administered a topical InsP gel at high doses for 7days (50mgInsP/day) or at low doses for 28days (20mgInsP/day). We measured urine levels InsPs using a nonspecific method (based on the ability of InsPs to complex Al) and levels of InsP by a specific method (using polyacrylamide gel electrophoresis). Identification of different InsPs was performed by MS.

KEY FINDINGS

At baseline, after dietary deprivation of InsP, rats only excreted InsP in their urine, and there was no detectable InsP or other InsPs. Rats given the high dose treatment for 7days had abundant urinary InsP, but also had other InsPs in their urine; cessation of InsP administration led to decreased levels of urinary InsPs. Rats given the low dose treatment for 28days had increasing levels of urinary InsPs over time. The maximum urinary InsP was at 21days, after which InsPs excretion decreased.

SIGNIFICANCE

We conclude that the skin can absorb InsP from a topical gel, and that InsP is excreted in the urine, along with other InsPs (InsP, InsP, InsP, and InsP).