Ornithine alpha-ketoglutarate supplementation influences motor activity in healthy rats

Ornithine alpha-ketoglutarate (OKG) improves nutritional status in malnourished patients. Published and unpublished data suggest OKG may have effects on the central nervous system that may contribute to its action.

We investigated the effect of an OKG-enriched diet on behaviour in healthy rats.

Thirty male Wistar rats were randomised in three groups: the OKG group was fed for 5 days (D0-D5) at 90% of spontaneous food intake with an OKG-enriched diet (5 g/kg/d). The non-essential amino acids (NEAA) group was fed similarly with a regimen enriched with NEAA (glycine, alanine, histidine and serine) to be isonitrogenous to OKG group. The ad libitum (AL) group had no treatment and was fed ad libitum with a standard regimen throughout. Rats were tested at D4 for motor activity by actimetry, and at D5 first for spontaneous alternation behaviour measured in the Y-maze, and then for exploratory behaviour measured using the open-field test (stressful environment).

We found that OKG supplementation enhanced global motricity by actimetry (AL 772 +/- 55, NEAA 811 +/- 54 vs. OKG 966 +/- 24 arbitrary units, P < 0.05) and total numbers of arms visited in the Y-maze (AL 26 +/- 2, NEAA 30 +/- 3 vs. OKG 38 +/- 3, P < 0.05). The lack of any effect of the OKG-enriched diet in the open-field test shows that the enhancement of locomotion activity was most probably not due to an increase in anxiety or fear in the rats.

An OKG-enriched diet can induce beneficial stimulant effects that may be involved in the mechanism of action of OKG.