The Role of the Serotonin Pathway of Tryptophan Metabolism in the Development of Neuroinflammation in Alzheimer’s Disease

Despite the fact that more than 90% of tryptophan is metabolized via the kynurenine pathway, the serotonin pathway is of great importance for the functioning of the central nervous system. The main products of this pathway are serotonin and melatonin. They provide maintenance of the sleep–wake mode, modulation of oxidative stress activity, apoptosis of neurons and glial elements, regeneration and neuroinflammation. In the pathogenesis of Alzheimer’s disease, neuroinflammation plays one of the main roles. Melatonin and serotonin, being modulators of its intensity, as well as an important component of neurochemical interactions that provide cognitive functions, can be considered as targets for preventive and therapeutic effects.