Einsatz von L-Glutamin und seine Wirkung auf den antioxidativen Status bei Galopprennpferden

Strong physical exertion causes an increased production of oxygen
radicals in humans as well as in animals. The maximum training of
race horses also causes a strong oxidative stress. The protection
of the organism could be improved by the diatary intake of
antioxidants and therefore oxidative stress is reduced. The aim of
this study was to prove the hypothesis that through the oral
supplement of the aminoacid L-glutamine, the intra-cellular
concentration of the antioxidant glutathione (GSH) could be
increased and the result is less oxidative stress. Glutamine serves
as a substrate for glutathione-synthesis, the most important
intra-cellular antioxidative system and has numerous other
metabolic functions. In order to examine the protective effects of
glutamine on the antioxidant status, steeple chase horses at peak
training levels which are under extreme physical exertion were
given a supplement of the aminoacid L-glutamine in their food. The
examination were focused on an intensive training programme on the
grass track on a 3000-metres distance with horses ridden at high
speed and over hurdles. The horses were devided into a glutamine
supplemented group (G, 20 g/100Kg for a duration of four days
before and on the actual day of training) and a control group (K).
The process of Glutamine concentration within the serum was
defined. The parameters for observation of the antioxidant status
(GSH and GSSG, TEAC, Vitamine C, Vitamine E,) and for tissue damage
of liver and muscles as well as possible side effects (activities
of enzymes: CK, LDH, AST, GLDH; other clinical parmeters: lactate,
bilirubin, urea, creatinine, total proteins and hemogram) were
determined. Four blood samples were taken from each horse within a
certain period ie.: Pre-samples four days before the next grass
track training (vw), samples shortly before (vT) and after (nT1)
and finally 20 houres after exercise (nT2). The following results
have been identified: All glutamine-supplementation was well
tolerated without recognizable side effects neither in behaviour
nor in hemogram. Through the supplementation of glutamine,
significant increase of glutamine in the blood of the G-group was
identified and therefore an increased glutamine availability for
GSH-synthesis was evident (G vw: 400 ± 54µmol/l; G vT: 600 ±
80µmol/l). The parameters concerning tissue damage, like the medium
activities of GLDH and LDH as well as medium concentrations of
creatinine after training were higher (statistically insignificant)
while the level of lactate, was as anticipated, increased. The
other measured parameters (urea, total proteine, AST) were not
effected by glutamine supplementation. The parameters for the
observation of the antioxidative status showed higher GSH (KnT1:
803 ± 182µmol/l; GnT1: 891 ± 277µmol/l) and lower medium GSSG
concentrations (K nT1: 116 ± 79µmol/l; G nT1: 101 ± 65mmol/l) in
the glutamine-supplemented group. Also the values of medium TEAC (K
nT1: 0,290 ± 0,048 mmol/l; G nT1: 0,321 ±0,026 mmol/l) and medium
Vitamine C concentrations (K nT2: 11,23 ± 5,53µmol/l; G nT2: 13,46
± 2,99µmol/l) were higher in the glutamine group. Even though the
differences are not statistically significant, the plurality of the
expected changes of the single parameters of the antioxidative
status support the hypothesis of the increased GSH synthesis due to
glutamine supplementation. Of practical relevance were the results
of creatine kinase (CK, K nT1: 5559 ± 2484 nkat/l; G nT1: 3622 ±
627 nkat/l) which showed a significant reduction in the
glutamine-supplemented group which could prove a decrease in the
muscle tissue damage. It would be interesting to test the effects
of glutamine in a larger number of horses under maximal exertion
such as a racing situation followed by regeneration phase because
this could prove the actual effects of glutamine.