Abstract
Paraxanthine (PXN) is the main metabolite of caffeine (CAF). PXN supplementation has been shown to increase measures of cognition, memory, reasoning, response time, and sustained attention; however, no preclinical study has compared the effects of PXN with those of CAF. The aim of this study was to compare the effects of PXN and CAF on memory and related biomarkers in rats. The effects of two different doses of PXN (PXN LOW, PXN HIGH), CAF (CAF HIGH), and a control group on cognition (escape latency in the Morris water maze test), neurotransmitters (acetylcholine, dopamine, and gamma-aminobutyric acid), and neurochemicals (BDNF, catalase, glutathione, and cyclic GMP) were analyzed from whole brain samples in young (8 weeks old) and aged (16 months old) rats. Compared to the control group, escape latency improved in PXN LOW, PXN HIGH, and CAF HIGH (all P < 0.05) in young animals, and in PXN HIGH and CAF HIGH in older animals (P < 0.001). PXN HIGH improved escape latency compared to CAF HIGH in both young (P < 0.001) and old animals (P = 0.003). BDNF levels increased in PXN LOW, PXN HIGH, and CAF HIGH (all P < 0.001), with PXN HIGH increasing BDNF to a greater extent compared to CAF HIGH (P = 0.03). PXN HIGH also significantly increased BDNF levels compared to PXN LOW (P < 0.001). All other neurotransmitters and neurochemicals significantly increased in the PXN HIGH and CAF HIGH groups compared to the control. In conclusion, PXN showed greater improvements in cognition and BDNF levels compared to CAF, further substantiating PXN as a nootropic with greater benefits compared to CAF.