How 5-HT1A agonists are useful in anxiety disorders?

5-Hydroxy tryptamine (5-HT) is one of the important chemical mediators within the CNS. Normally it is released by exocytosis and increases neuronal activation within the CNS. The released 5-HT then acts on various types of 5-HT receptors mainly including 5-HT_1A , 5-HT_1D, 5-HT_2A, 5-HT₃ and 5-HT₄ etc.

Among these 5-HT_1A receptors are mostly autoinhibitory receptors that present presynaptically within the CNS. Few of 5-HT_1A receptor are also present post synaptically particularly at hippocampus.

The presynaptic 5-HT_1A receptors play key role in controlling serotoninergic transmission within the CNS. When these receptors are activated they inhibit the release of 5-HT from nerve endings.

Serotonine has several functions in the CNS and one of the important role is increasing anxiety. Since 5-HT_1Areceptors decrease seroninergic transmission they decrease anxiety and improve the sleep.

Buspirone is one of the agents that acts as 5-HT_1A agonist hence indicated for anxiety. It has few advantages compared with benzodiazepines.

It shows less motor disturbances, less sedation and less amnesia compared with benzodiazepines.

Even it has few advantages over benzodiazepines with respect to unwanted effects, it cann’t be used for acute anxiety disorders. Buspirone shows it beneficial effects after 2-4 weeks of the treatment. Hence it cannot be used for acute conditions.