Effect of kinins on the central action of serotonin.

Kinins, the biologically active peptides, potentiate the central stimulatory effects of NA and depressant action of acetylcholine as have been shown by the authors previously. The aim of the work has been to study the effects of these peptides on the central action of 5-HT. For experiments female Wistar rats were used. 5-HT given ivc to the animals and 5-HTP applied ip resulted in an increase of the pain threshold to the electrical stimuli and in a worse motor coordination. Bradykinin injected ivc or kallikrein ip to some extent abolished these effects. The biochemical tests revealed that bradykinin ivc lead to a significant decrease in 5-HT content in the midbrain. In experiments in vitro this peptide increased markedly the release of the platelets 5-HT and inhibited the uptake of this mediator to platelets. The results have shown that kinins can attenuate the central action of 5-HT. This effect can be ascribed, at least in part to a kinin-induced changes of 5-HT concentration in some structures of the central nervous system.