Study on the detrimental ramifications of stress in the brain has mainly focused on the hippocampus. of several aversive stimuli [cold water (18C), vibration, restraint, overcrowding, exposure to a hot air stream]; the stressors were presented in random order for the duration of the experiment. This stress paradigm was shown previously to result in persistently elevated plasma levels of corticosterone, the primary glucocorticoid of the rat (for details, see Sousa et al., 1998). Another group of 10 rats were handled daily and served as controls (CONs). Body weights were recorded on a weekly basis throughout the study as an indication of treatment efficacy; postmortem thymus weights also provided information on treatment efficacy. Corticosterone levels were measured in blood serum sampled between 8:00 and 9:00 A.M. (3 h before the electrophysiological recordings and 12 h after the last exposure to stress) using a commercially available ELISA kit (R & D Systems, Minneapolis, MN). To determine the sequential pattern of chronic stress-induced disturbances in the hippocampusCPFC system, we Sorafenib kinase inhibitor submitted a different set of rats to shorter periods of the same stress paradigm: 10 animals were exposed to unpredictable stress for 3 d and another 10 rats were stressed for 6 d. Two groups of 10 animals, handled daily for the same period, served as controls. Behavioral testing Behavioral tests were conducted in a circular black tank (170 cm diameter) filled to a depth of 31 cm with water at 22C, colored with a black nontoxic dye (Jazz Gloss Tempera black ink; Van Aken International, Rabbit polyclonal to USF1 Rancho Cucamonga, CA) and placed in a dimly lit room with extrinsic clues. The tank was divided in imaginary quadrants and had a black platform (12 cm diameter, 30 cm high) placed in one of them. Data were collected using a video camera fixed to the ceiling and connected to a video-tracking system (Viewpoint, Champagne au mont d’or, France). Working memory task. The test used was described by Kesner (2000) as a test of PFC function: its goal is to assess the ability of rats to learn the position of the hidden platform and to keep this information online during four consecutive trials. This working memory task, a modification of the spatial reference memory space test (Morris, 1984), includes 4 d of acquisition. The positioning of the system is Sorafenib kinase inhibitor kept continuous through the four trials of every day, but differs on each successive day time such that all quadrants are utilized. Rats are put, facing the wall structure of Sorafenib kinase inhibitor the maze, at a different starting place (north, east, south, or west) at the start of each one of the four daily trials. A trial is known as full when the rat escapes onto the system; when this get away fails to happen within 120 s, the pet is lightly guided to the system and a getaway latency of 120 s is documented for that trial. Rats are permitted to spend 30 s on the get away platform before becoming positioned at a fresh starting point. Amount of the road described (range swam) and period spent to attain the system (get away latency) are documented in the consecutive trials. Sorafenib kinase inhibitor Reference memory space task. Following the working memory space procedure (days 1C4), the system remained in the same quadrant as on day time 4 and pets were examined for yet another 3 d (times 5C7) to make sure that they had properly learnt the positioning of the system before evaluation Sorafenib kinase inhibitor of reversal learning (de Bruin et al., 1994). All the remaining methods were like the ones referred to for the operating memory space.