Gavage/oral lyophilized royal jelly (50 and 100 mg/kg body weight/d/8 weeks)  18-months old (naturally aging) Wistar male rats as a model of aging  EG1 and EG2: aged rats on royal jelly 50 and 100 mg, respectivelyCG: aged rats on gavage solution of 0.9% NaCl.  Learning, spatial memory, and motor performance on Morris water maze.  Royal jelly improved learning, spatial memory, and motor performance e.g., increased the number of crossings, swimming speed, and swimming distance.  [98,99]