Effects of glucose on responsiveness to change in young adult and middle-aged rats

After a 0.5-, 15-, or 30-min intertrial interval, first entries of a novel Y-maze arm that had changed in brightness, percent entries of the arm, and percent time spent in this arm during a 1-min period were recorded in 4-month-old hooded rats following 6 or 30 min of free exploration of both arms. From the results, it was concluded that maximal responsiveness to the changed (or novel) arm occurred after 6 min of exploration and a 30-min intertrial interval. In a second experiment, responsiveness to change was assessed in young adult (4 months) and middle-aged (18 months) rats after 6 min of free exploration followed by an intraperitoneal injection of distilled water, or 50 or 100 mg/kg d-glucose before testing 20 min later. While glucose increased first entries of the changed arm in all rats, longer-term responsiveness in the form of percent entries of the novel arm and time spent in the novel arm was increased only for young adults. Although the results suggested age-specific glucose-enhanced consolidation or retrieval of change-related information, it was also possible that the treatment had differentially increased preferences for novelty in the two age groups. This possibility should be addressed in future research.