ABSTRACT
Objective: To study the effects of different niacin nutritures on behaviors of stressed rats. Methods: 100 Wistar male rats were assigned into 10 groups:control, pair-fed, nicotinamide (NAM) deficiency (ND), low-dose NAM supplement (LNS 40 mg/kg diet) and high-dose NAM supplement (HNS 500 mg/kg diet), and the corresponding restrained groups. 24 h urinary excretion of N1-methylnicotinamide (NMN), body weight changes, behaviors in the open-field test, plasma cortisol, nitric oxide(NO) and liver nitric oxide synthase(NOS) were determined. Results: Compared with the control group, restrained rats had relatively lower urinary NMN. Both ND and restrainted stress retarded the body weight gains . Rats in the control and LNS groups had relatively shorter latency time in the open-field test. Restrained rats had higher plasma cortisol and NO than those in the corresponding control group. However, rats with HNS had the lowest plasma cortisol concentrations. Dietary supplement of NAM increased liver NOS . Conclusions: Restraint stress may increase niacin depletion and appropriate NAM supplement has positive effects on stress adaptation in rats.