2Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: (495) 939-3181; E-mail: email@example.com
* To whom correspondence should be addressed.
Received January 22, 2010; Revision received March 9, 2010
Using a specific fluorescent probe of mitochondrial membrane potential (tetramethylrhodamine ethyl ester), we have shown that glucose deprivation (GD) of cultured cerebellar granule neurons (CGN) for 3 h lowers mitochondrial membrane potential in these cells. Longer glucose starvation (24 h) causes CGN death that is not prevented by blockers of ionotropic glutamate receptors (MK-801 (10 µM) and NBQX (10 µM)). Glutamine or pyruvate (2 mM) maintain membrane potential of mitochondria and decrease CGN death under GD conditions. In the presence of glucose the mitochondrial respiratory chain blocker rotenone induces neuron death potentiated by glutamine. The potentiation effect is completely prevented by blockers of ionotropic glutamate receptors. These results show that glutamine under conditions of GD can be utilized by mitochondria as substrate, but at the same time, in the case of mitochondrial function deterioration, metabolism of this amino acid results in glutamate accumulation to toxic level.
KEY WORDS: glutamine, cerebellar granule neurons, glutamate, mitochondria, glucose deprivation, chemical hypoxia