Tryptophan (Trp) metabolism primarily involves the kynurenine, 5-hydroxytryptamine, and
indole pathways. A variety of bioactive compounds produced via Trp metabolism can …

The brain-gut axis is a bidirectional communication system between the central nervous
system and the gastrointestinal tract. Serotonin functions as a key neurotransmitter at both …

The kynurenine pathway (KP) plays a critical role in generating cellular energy in the form of
nicotinamide adenine dinucleotide (NAD+). Because energy requirements are substantially …

NAD+ is a pivotal metabolite involved in cellular bioenergetics, genomic stability,
mitochondrial homeostasis, adaptive stress responses, and cell survival. Multiple NAD+ …

The tryptophan (TRP)-kynurenine (KYN) metabolic pathway is a main player of TRP
metabolism through which more than 95% of TRP is catabolized. The pathway is activated …

Together with aspartate, glutamate is the major excitatory neurotransmitter in the brain.
Glutamate binds and activates both ligand-gated ion channels (ionotropic glutamate …

Huntington disease is devastating to patients and their families—with autosomal dominant
inheritance, onset typically in the prime of adult life, progressive course, and a combination …

Background Disturbance in the equilibrium of the gut microbiota has been involved in the
pathophysiology of depression. Probiotics have the potential to healthfully modulate the gut …

Neurotransmitters, including catecholamines and serotonin, play a crucial role in
maintaining homeostasis in the human body. Studies on these neurotransmitters mainly …

We survey the historical development of scientific knowledge surrounding Vitamin B3, and
describe the active metabolite forms of Vitamin B3, the pyridine dinucleotides NAD+ and …