Influence of CCK-8 and yohimbine on supraspinal modulation of nociceptive process.

We studied the effect of cholecystokinin (CCK-8) and yohimbine-alpha-2-adrenoreceptor antagonist administered locally into lateral reticular formation (LRF) on the bioelectrical response to the pain stimulation. The experiments were carried out on 8 conscious rabbits with bilaterally implanted electrodes into: motor-sensory cortex, ventro-postero-lateral thalamic nuclei, hippocampus and LRF. Nociceptive stimulation was performed by means of electrical pulses applied to the front paw. Bioelectrical activity (BA) of the chosen brain structures was analysed by means of spectral analysis (FFT) and directed transfer function (DTF). The results of our study may suggest that supraspinal administration of CCK-8 together with yohimbine have inhibitory effect on nociceptive transmission.