Age-Dependent Effects of Caffeine on Physiological, Behavioral, and Circadian Gene Changes in Young and Mature C57BL/6 Male Mice.

BACKGROUND: Caffeine, a widely consumed psychoactive substance, has known effects on physiological and behavioral processes. Recent studies report that caffeine can influence the circadian rhythm, which is linked to many aspects of physiology, energy metabolism, and homeostasis. Therefore, we examined the arousal effects of caffeine via behavioral tests and assessed its impact on the circadian rhythm by measuring clock gene and clock-controlled gene expression in the brains of mice and Neuro 2a (N2a) cells. METHODS: Male C57BL/6 mice from two age groups, young (1 month 2 weeks) and mature (10 months 2 weeks), were randomly divided into four subgroups: control, vehicle, caffeine, and caffeine with adenosine (n = 8 each). After inducing fatigue through forced treadmill exercise, we performed balance beam and foot fault tests, and measured the mRNA expression and protein levels of circadian genes (circadian locomotor output cycles kaput (Clock), brain and muscle ARNT-like 1 (Bmal1), period circadian regulator 2 (Per2), cryptochrome circadian regulator 1 (Cry1), and Cry2) in the brain and N2a cells treated with caffeine. RESULTS: Caffeine treatment showed a trend toward reduced body weight gain in both young and mature mice. Behavioral tests indicated improvements in balance and coordination across both age groups. After 16 days of treatment, circadian genes showed significant differences in expression, and adenosine receptor levels changed notably, especially after long-term exposure. In N2a cells, caffeine decreased viability in a dose-dependent manner and affected circadian gene expression. CONCLUSIONS: The study demonstrates that caffeine influences body weight, behavior, circadian rhythms, and adenosine receptor protein levels, with age-related variations. These findings deepen the understanding of caffeine's effects on physiological and molecular functions and suggest possible age-specific therapeutic implications or precautions related to caffeine intake.