Mice selected for low and high blood magnesium levels: a new model for stress studies.

Extra- and intracellular magnesium levels have previously been shown to be genetically controlled in humans and in the mouse. To further study this genetic regulation, mice were selected from a heterogeneous population, for low (MGL mice) and high (MGH mice) red blood cell (RBC) magnesium values. These values diverged rapidly in the two strains, to reach a stable difference between the 14th and 18th generations. MGL mice also exhibited significantly lower plasma, kidney, and skull bone magnesium contents and higher urinary magnesium excretion and total brain weights. Moreover, in stressful conditions, MGL mice displayed a more aggressive behavior that the control MGH strain. Altogether, MGL mice showed a more restless behavior, a higher rectal temperature, and much higher brain (+17%) and urine (+200%) noradrenaline levels than the MGH animals. These strains, thus, constitute a new animal model for the study of magnesium metabolism and its relationships with catecholamines, stress sensitivity, and aggressive behavior.