Animal groups
Thirty 10-months-old male Sprague-Dawley rats weighing 522 ± 50 g were obtained from Harlan (Indianapolis, IN, USA). At 10 months, Sprague-Dawley rats are considered not yet senescent but rather “middle-aged”. Previous studies found that the main effects of age on neurogenesis were evident at this time point (McDonald and Wojtowicz, 2005). The animals were allowed to acclimatize for 1 week prior to surgery and divided into the following groups: 10 days sham, 10 day ischemic, 35 day sham, 35 day ischemic (n = 6 each), 90 days sham and 90 days ischemic (n = 3 each).