Influence of α₂-Adrenoreceptor Antagonists on Electroencephalogram Characteristics after Dexmedetomidine Administration in Rabbits

The humane treatment of laboratory animals is an integral part of good laboratory practice. It remains relevant to study the anaesthetic effects of various medicinal products helping to reduce pain and distress in laboratory animals.

The aim of the study was to compare the effects of the α₂ blockers proroxan and atipamezole on changes in electroencephalogram rhythm index ratios after dexmedetomidine administration.

Materials and methods. The study used male Soviet chinchilla rabbits weighing 3.0±0.3 kg (n=12). Study animals received single injections of 100 μg/kg dexmedetomidine subcutaneously, 50 μg/kg atipamezole intramuscularly, and 170 μg/kg proroxan intravenously (equimolar to the dose of dexmedetomidine). The effects of these medicinal products were evaluated by pharmacoelectroencephalography. The authors recorded electroencephalograms using cup electrodes and a Neuron-Spectrum-1 8-channel encephalograph (Neurosoft, Russia)  with  a  bandwidth of 0.5–35 Hz and a sampling frequency of 500 Hz. The distribution of quantitative characteristics was checked for normality using the Shapiro–Wilk W test. The authors used one-way ANOVA with Dunnett’s post hoc test to evaluate the significance of differences for the normal distribution of quantitative characteristics; they used the nonparametric Kruskal–Wallis test with  Dunn’s  post  hoc  test  for the non-normal one.

Results. Dexmedetomidine administration resulted in significant two-hour changes in the rabbit brain, and the authors observed an increase in the delta rhythm and     a decrease in the theta rhythm. At equimolar doses, atipamezole returned the ratios of the wave rhythm indices to the baseline values, whereas proroxan had no effect on the ratios.

Conclusions. As demonstrated by the neutralisation of dexmedetomidine sedative and hypnotic effects, atipamezole can be used in veterinary for recovery from anaesthesia. Proroxan, on the contrary, is not effective in reversing the sedative effect of dexmedetomidine.

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