Alex Poplawsky

ACTH4–10 produces a transient decrease in septal hyperemotionality

The administration of doses of ACTH4-10 that have been shown to be effective in producing enhanced peripheral nerve regeneration did not produce the enhanced rate of decline in hyperemotionality produced by administration of the ACTH4-9 variant Org 2766. Long-term changes in septal reactions in training situations were likewise not affected by ACTH4-10. These results indicate that, despite similar peripheral nerve growth effects, these two ACTH-related agents (ACTH4-10 and Org 2766) produce quite different long- and short-term effects on rats with septal area damage.

The GM1 ganglioside hastens the reduction of hyperemotionality after septal lesions

The purpose of the present study was to assess the effects of ganglioside treatment on changes in emotional, activity, and avoidance behaviors following septal brain damage. Rats were treated with GM1-gangliosides either before and after septal lesions, or only after septal lesions and tested for emotionality on 10 consecutive days beginning on the second day after surgery. The ganglioside treatment decreased the emotionality of rats with septal damage on the first test day, and enhanced their rate of recovery to control levels of emotionality. Septal rats treated with gangliosides had activity, rearing, and avoidance behaviors equivalent to nontreated septal rats; however, lesioned rats treated with GM1 showed reduced intertrial crossings during avoidance conditioning. These results suggest that the changes in emotional behavior of septal rats treated with GM1 occur shortly after the lesion.

Autoshaping a leverpress in rats with lateral, medial, or complete septal lesions

Rats with either control operations or lateral, medial, or complete septal lesions received 600 trials of leverpress training using an autoshaping procedure, i.e., food delivery followed a 10 s illuminated lever presentation, or occurred immediately after a leverpress. Rats with complete septal lesions acquired the leverpress faster than controls and had more food-tray entries per minute during the first 100 trials than the other groups. Rats with lateral or medial septal lesions had leverpress and food-tray entries equivalent to controls. The facilitation of autoshaping a leverpress may partially be explained by the general increase in motor reactivity to stimuli found following septal lesions.

Nimodipine accelerates recovery from the hyperemotionality produced by septal lesions.

Rats with large electrolytic lesions of the septal area were given the calcium channel antagonist nimodipine (70 micrograms/kg, ip) or its vehicle on the day of surgery and for 3 subsequent days. They were tested for emotionality and compared to control rats for 10 days beginning on the third day after surgery. Forty days after surgery all animals were trained in a two-way active avoidance task for 120 trials. Nimodipine reduced the hyperemotionality found after septal lesions as early as the first test day, and increased the rate of recovery toward control levels on subsequent days. Both septal-lesion groups exhibited more avoidance responses than controls, even though the intertrial crossings were enhanced only in rats with septal lesions that did not receive nimodipine.

Brief ganglioside treatment produces delayed enhancement of functional recovery after medial septal lesions

The effects of a 5-day ganglioside (GM1) treatment (30 mg/kg) on body weight and water intake subsequent to medial septal lesions were evaluated for 44 consecutive days. In addition, activity, rearing, and repetitive motor acts were measured on postsurgery days 5, 10, 40, and 60. The rate of increase in the body weights of rats with medial septal lesions treated with GM1 was equivalent to that of controls, while untreated rats with such lesions had reduced body weights. Rats with medial septal lesions treated with GM1 also exhibited movement times and frequency of repetitious motor acts similar to those of control rats by postsurgery day 60. No differences were found in water intake between any of the groups. Rats with medial septal lesions, whether treated with GM1 or not, had equivalent frequencies of rearings that were lower than control rats. This study emphasizes that even brief regimes of GM1 administration can exert behavioral changes in brain-damaged rats well after the treatment was administered, i.e. 40-60 days after surgery.

The effect of training procedures on fixed-interval responding following septal lesions in rats.

Two experiments were conducted to assess the effects of training procedures on fixed-interval (FI) performance of rats with septal lesions. In Experiment 1, rats with septal lesions that had extensive preoperative FI experience responded at higher rates than did control rats in early periods of the FI and at lower rates during the later period of the FI for the first 10 sessions after surgery. Their subsequent FI behavior became equivalent to that of control rats. In Experiment 2, septal rats that were trained on an FI schedule of reinforcement entirely after surgery by gradually increasing the FI requirements had FI performance equivalent to that of rats with control operations. The results suggest that septal lesions result in a transient disruption in the FI performance of rats with previous FI experience without affecting the acquisition of appropriate FI behavior.

Responding on a multiple schedule of reinforcement as a function of different septal lesions in the rat

The response rates of rats with either control operations or lateral, medial, or complete septal lesions were compared on a multiple fixed-interval (FI)/random-interval (RI) 40-sec schedule of reinforcement in which the rat was required to respond on a different lever for each alternating schedule component. Rats with lateral septal lesions responded at higher rates during the first 8-sec period of the FI component and had poorer response patterning than rats with control operations on the FI 40-sec reinforcement schedule. On the other hand, rats with medial septal lesions responded at higher rates than controls during the RI 40-sec component. Rats with complete septal lesions switched levers more than did controls before the ongoing schedule was completed. The results suggest that the lateral and medial septum have different functional roles mediating responding for food on interval schedules of reinforcement.

Long-term maintenance of shuttlebox avoidance behavior before and after septal lesions

Twenty-four rats were given 1,800 trials in a two-way avoidance chamber. Rats that avoided shock on more than 50% of the trials were categorized as high avoiders, while the others were categorized as low avoiders. Half the animals in each group received septal lesions, while the remaining animals received control operations. These four groups of animals were then observed postoperatively for another 1,800 trials of signaled avoidance. Preoperative low avoiders exhibited a large postoperative increase in avoidances, while high avoiders continued to avoid shock after septal lesions. Animals with septal lesions maintained a high level of avoidance throughout the postoperative testing period. Intertrial crossing had an initial postoperative increase in animals with lesions, which gradually decreased over days. Septal lesions interfered with the suppression of freezing behavior, thereby facilitating the performance of low avoiders without changing high-avoider performance. Comparisons of septal lesions and scopolamine were discussed.

Low-dose oral caffeine induces a specific form of behavioral sensitization in rats

The present study assessed the effects of a low dose of orally administered caffeine on sensitization of open-field behavior in rats. Rats had free access to untreated water every day or water containing 0.2 mg/ml of caffeine every other day of the 14-day experiment. On alternate days discrete movements (horizontal and vertical) and ambulatory distance were measured in open-field activity monitors. Although caffeine intake significantly decreased across test sessions in caffeine-treated rats, the number of discrete horizontal movements significantly increased. These findings suggest that low doses of orally administered caffeine induce a specific form of behavioral sensitization in rats.

Nimodipine's functional benefits depend on lesion completeness in medial septal area.

The effects of a 4-day nimodipine treatment (70 micrograms/kg IP beginning on the day of surgery) given to rats with lesions directed at the medial septal area were monitored for 120 days. Body weight, water intake, open-field activity, rearing, hole-poking, and repetitive motor acts were periodically measured through 120 postsurgical days. Although no differences were found in water intake between any of the groups, the body weights of rats with any medial septal damage, whether treated with nimodipine or not, were lower than rats with control operations by postsurgery day 120. Rats with any medial septal damage, whether treated with nimodipine or not, had lower rearing frequencies, rearing durations, and hole-poking frequencies than controls on all test days. However, rats with complete medial septal lesions treated with nimodipine exhibited movement in the open field and frequencies of stereotyped, species-typical acts similar to those of control rats by postsurgery day 60. This nimodipine effect was not observed in rats with partial lesions of the medial septal region. This study emphasizes that a brief administration of nimodipine shortly after brain damage can influence behavioral changes 40-60 days after surgery, but that this effect was not apparent in rats with only partial medial lesions.