Action of carbamazepine (50 mg/kg i.p.) and phenytoin (60 mg/kg i.p.) on the activity of cerebellar neurones was studied in rats under urethane anaesthesia. Carbamazepine markedly decreased the firing frequency of all ten neurones recorded continually before and after drug administration. The same conclusion was reached when a group of 53 cells recorded before drug administration was compared with 48 neurones recorded after carbamazepine administration only. The effects of phenytoin were ambiguous - a decrease as well as an increase in frequency was recorded. The solvent used did not change cerebellar unit activity. Cerebellum cannot be considered as a possible target structure for phenytoin but it might be a target for carbamazepine action.
In vitro binding of specific opioid ligands to their respective sites in membrane fractions and the contribution of individual receptor classes (mu, delta, kappa) was studied in rats after longlasting (up to 22 months) section of spinal dorsal roots at the cervical (C5.8) or thoracic (Th^) level. This procedure leads to autotomy or scratching of the skin on the operated side. The total number of receptors in the cervical and thoracic spinal cord was more than doubled in both operated and contralalteral part of the cord in comparison with intact controls of the same age. In the cervical region, this increase mainly represented a rise in the number of free receptors, whilst in the thoracic region both free and saturated receptors were increased. On the deafferented side, receptor selectivity, especially in the delta and kappa types was decreased.