Both, Sprague-Dawley rats and Han Wistar rats show a very intersting phenomenon in the context of metabonomics. Thereby, usually two types types of patterns of metabolites of the phenylalanine metabolism pathway are excreted into urine. These metabolites and changes of the excretion of the metabolites are attributed to the gut microflora and changes of the gut microflora. The concentrations of the corresponding metabolites in urine are rather high. Therefore, changes of the type of gut microflora can dominate the variance of the patterns of metabolites in urine. In the figure both types of gut microflora are shown, which are normal for healthy non treated animals. The first type of gut microflora can be characterized by high levels of Hippurate and low levels of trans-2-Hydroxycinnamate and 3-Hydroxyphenylpropanoate in urine. The second type is characterized by low levels of Hippurate and high levels of trans-2-Hydroxycinnamate and 3-Hydroxyphenlypropanoate in urine. These two profiles are usually exclusive. This means, that an animal shows either the first or the second type of gut microflora. Intermediate concentraton levels of the metabolites are only visible at the moment, when animals switch the typ of gut microflora. It is often visible that Han Wistar animals begin with a low-Hippurate type of gut microflora at the beginning of a study and switch to a high-Hippurate type of gut microflora. The exact relationships and mechanism of the gut microflora, the types of metabolites, the reabsorption of the metabolites in the gut and the importance of the symbiotic system are not known yet, but are of great interest in metabonomics.
Population of control rats with two different types of gut microflora and part of the Phenylalanine pathway, which represents the analytes involved in the differences of the types of gut microflora. The PCA was performed for a group of control animals using only the spectral variables covering the metabolites Hippurate, 3-Hydroxyphenylpropanoate and trans-2-Hydroxycinnamte. The first type is characterized by low levels of trans-2-Hydroxycinnamate and 3-Hydroxyphenylpropanoate and high levels of Hippurate in urine. The second type of gut microflora is characterized by high levels of trans-2-Hydroxycinnamate and 3-Hydroxyphenylpropanoate and low levels of Hippurate in urine.