Search for Magnetite Nanoparticles in the Rats’ Brain

Various animals (bacteria, bees, fishes, birds, etc.) show the ability to find orientation in the geomagnetic field. This magnetoreception effect can be explained by the presence of small biogenic magnetite crystals in their organisms that interact with the geomagnetic field. Some studies carried out on rodents show that they respond to magnetic stimulation in the earth’s magnetic field by the expression of activity genes like C-fos, but the mechanism of magnetoreception for them it is still unknown. In this paper, the amount of magnetite of two brains and two cerebellums of Sprague-Dawley rats was measured using ferromagnetic resonance spectroscopy. No presence of magnetite (with a limit of a few picograms) was found. This means that either biogenic magnetite is not located in the brain, but somewhere else, or that the magnetic field sensibility in rats is not related to biogenic magnetite.

I. Introduction

Magnetorreception is the ability to orient in the geomagnetic field. This ability is present in various animals, as bees, saumons, turtles, pigeons, and in the so called magnetotactic bacteria. In most cases, the mechanism of the magnetorreception seems based on the presence of biomineralized magnetite nanoparticles, which constitute small compasses within the body of the animal or bacteria. In magnetotactic bacteria [1], long strings of nanoparticles, with diameters between 40 and 120 nm, do provide enough force as to direct the organism movement toward the desired places, usually low oxygen concentration zones where food is available.