Oxidative stress may cause various neuronal dysfunctions and modulate responses to many centrally acting drugs. This study examines
the effects of oxidative stress produced by hydrogen peroxide (H2O2) on sedation induced by diazepam or xylazine as assessed in
7–14 day-old chicks. Day-old chicks were provided with either plane tap water (control group) or H2O2 in tap water as 0.5% v/v drinking
solution for two weeks in order to produce oxidative stress. Spectrophotometric methods were used to determine glutathione
and malondialdehyde concentrations in plasma and whole brain. Drug-induced sedation in the chicks was assessed by monitoring
the occurrence of signs of sedation manifested as drooping of the head, closed eyelids, reduced motility or immotility, decreased
distress calls, and recumbency. The latency to onset of sedation and its duration were also recorded. H2O2 treatment for two weeks
significantly decreased glutathione and increased malondialdehyde concentrations in plasma and whole brain of the chicks on days
7, 10 and 14 as compared with respective age-matched control groups. H2O2 decreased the median effective doses of diazepam and
xylazine for the induction of sedation in chicks by 46% and 63%, respectively. Injection of diazepam at 2.5, 5 and 10 mg/kg, i.m. or
xylazine at 2, 4 and 8 mg/kg, i.m. induced sedation in both control and H2O2-treated chicks in a dose dependent manner, manifested
by the above given signs of sedation. H2O2 significantly decreased the latency to onset of sedation in chicks treated with diazepam at
5 and 10 mg/kg, increased the duration of sedation and prolonged the total recovery time in comparison with respective non-stressed
control chicks. A similar trend occurred with xylazine in the H2O2-treated chicks, though the differences from control counterparts did
not attain the statistical significance, except for the recovery time of the lowest dose of the drug. The data suggest that H2O2-induced
oxidative stress sensitizes the chicks to the depressant action of the sedatives diazepam and xylazine. Further studies are needed to
examine the potential role of oxidative stress in modulating the actions of therapeutic agents on the brain.
يعرب جعفر موسى | Yaareb Jaafar Mousa | 5709