Serotoninergic neurotransmission is known as a neuromodulatory system which is involved in the elaboration of an adapted response of the central nervous system to external stimuli. Accordingly, the 5-hydroxytryptamine (5-HT) system is structured in an appropriate manner being very centralized and present in almost all brain areas via a very high number of terminals able to release 5-HT. The autoreceptors 5-HT1B, present on these terminals, precisely control the release of the amine through a negative-feedback loop. Moreover, a novel endogenous peptide, 5-HT-moduline, regulates the efficacy of 5-HT1B receptors and thus participates in the control of 5-HT activity. Somatodendritic autoreceptors (5-HT1A) also participate in this control via their regulatory activity on the electrical activity of the 5-HT neurons. EGb 761 prevents the desentization of 5-HT1A receptors observed 24 h (not immediately) after an acute stress. More interestingly, the chronic treatment of rats with EGb 761 prevents the rapid desensitization of 5-HT1B receptors induced by an acute stress. These results suggest that Ginkgo biloba extracts may interact with the mechanisms controlling the serotoninergic activity and particularly those related to stressful situations. Therefore, Ginkgo biloba extracts may play a role in the modulation of the mechanisms involved in the adaptation of the organism to various sensory stimuli.
