Effect of orotic acid on the excitability processes in central nervous system and on cerebral circulation in cats.

The influence of orotic acid on cortical excitability processes and cerebral circulation was studied in acute experiments in cats. The effect on CNS excitability was assessed by examination of the cortical visual-evoked potentials and the recovery cycles. The flash-evoked responses were recorded from visual cortex (VC), associative cortex (AsC) and auditory cortex (AuC). The recovery cycles were determined as the ratio of the average response to the test stimulus and those to the conditioning stimulus depending on the interstimulus interval duration. For investigation of cerebral circulation the method of local cerebral rheoencephalography (REG) was used. The following REG parameters were assessed: amplitude, anacrotic sections of the curve and its relative part, and duration of the wave. The arterial blood pressure was monitored continuously. Orotic acid administration (50 mg/kg i.v.) induced a significant increase in the amplitude of the primary response from VC and AsC. Significant shortening of the peak latency of the second wave of the response in the VC was also observed. The recovery cycles examination showed a facilitation of the test response. The changes observed indicate an increase of excitability processes in the CNS. The REG changes after orotic acid indicate a cerebrovascular resistance decrease and increase in cerebral blood volume. It is assumed that increased cortical activity by orotic acid may lead to an improvement of cerebral circulation.