Brain metabolites in ISIAH and Wistar rats

Abstract

Hypertension is one of the most common human diseases, which leads to serious disturbances, such as myocardial infarction and stroke. A decrease in the neuron viability in different parts of the brain in humans with hypertension has been shown by nuclear magnetic resonance spectroscopy (NMRS). Translation of NMRS tools to the clinical practice requires the accumulation of empirical data on neurometabolic changes in a strictly controlled experiment. It is particularly interesting to compare the metabolic parameters of laboratory animals with the normal and high blood pressure maintained under standard conditions on the same diet. In this study, we examined the cortex and hypothalamus metabolites of ISIAH and Wistar male rats at the age of 8–9 weeks. The cortex and hypothalamus metabolites were measured in animals under isoflurane anesthesia using proton magnetic resonance spectroscopy (1Н MRS). Processing the primary data using the Partial Least Squares Discriminant Analysis (PLS-DA) allowed us to identify the main discriminating axis (Y1) and its variations, which showed the predominance of the excitatory neurometabolites (glutamine and glutamate) over the inhibitory ones (GABA and glycine). In the cortex, the Y1 axis values were lower in ISIAH rats than in Wistar rats. This indicates a decrease in the cortical excitability in hypertensive animals. In contrast, in the hypothalamus, the Y1 axis values were higher in ISIAH rats than in Wistar rats, and the predominance of the excitatory neurometabolites was positively correlated to the level of the mean blood pressure, which agrees well with the idea of caudal hypothalamic activation in hypertensive animal models.