[Introduction] 5-aminolevulinic acid (ALA) is a precursor of heme and is involved in mitochondrial activation. It has been suggested that mitochondrial dysfunction in the brain is associated with chronic fatigue. To clarify the anti-fatigue effect of ALA, we used the established chronic fatigue model mice and examined the effects of ALA on fatigue and noradrenaline (NA) level in the frontal cortex (FCX).
[Methods] Female C57BL/6N mice were orally given ALA hydrochloride or DW for 8 weeks. The fatigue model mice were developed by housing them in a cage filled with water to a height of 1.5 cm for 4 days. The fatigue was evaluated using the running distance in the treadmill test. After the test, their brains were quickly dissected and NA in the FCX were quantified by HPLC.
[Results and Discussion] The running distance in the treadmill test were significantly reduced in the fatigue group. In addition, the running distance in the ALA-treated fatigue group was significantly increased as compared with DW-treated fatigue group. In the fatigue group, NA contents in the FCX were significantly decreased and ALA treatment canceled it. These results suggested that chronic ALA treatment produced the anti-fatigue effect and the protective effects on NA neurons in the FCX which may be involved in the mechanisms of the effect of ALA.