A threshold for the protective effect of over-reinforced passive avoidance against scopolamine-induced amnesia

Cruz-Morales, Sara E.; Duran-Arevalo, Martha; Guante, Miguel A. Diaz Del; Quírarte, Gina L.; Prado‐Alcalá, Roberto A.

doi:10.1016/0163-1047(92)90248-3

Cited by 27 publications

(12 citation statements)

References 20 publications

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“…The higher number and intensity of footshocks during the IA training may have led to the occurrence of a ceiling effect on the IA performance. For example, Cruz-Morales et al (1992) found that the amnesic effect triggered by systemic administration of scopolamine, a cholinergic antagonist, was not present when the intensity of footshocks was increased during IA training. Therefore, it is possible that the observed absence of differences between the Ex and SC groups in the present study was due to the occurrence of a ceiling effect.…”

Section: Discussionmentioning

confidence: 99%

Aerobic exercise attenuates inhibitory avoidance memory deficit induced by paradoxical sleep deprivation in rats

et al. 2013

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The deleterious effects of paradoxical sleep deprivation (SD) on memory processes are well documented. Physical exercise improves many aspects of brain functions and induces neuroprotection. In the present study, we investigated the influence of 4 weeks of treadmill aerobic exercise on both long-term memory and the expression of synaptic proteins (GAP-43, synapsin I, synaptophysin, and PSD-95) in normal and sleep-deprived rats. Adult Wistar rats were subjected to 4 weeks of treadmill exercise training for 35 min, five times per week. Twenty-four hours after the last exercise session, the rats were sleep-deprived for 96 h using the modified multiple platform method. To assess memory after SD, all animals underwent training for the inhibitory avoidance task and were tested 24h later. The aerobic exercise attenuated the long-term memory deficit induced by 96 h of paradoxical SD. Western blot analysis of the hippocampus revealed increased levels of GAP-43 in exercised rats. However, the expression of synapsin I, synaptophysin, and PSD-95 was not modified by either exercise or SD. Our results suggest that an aerobic exercise program can attenuate the deleterious effects of SD on long-term memory and that this effect is not directly related to changes in the expression of the pre- and post-synaptic proteins analyzed in the study.

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Section: Discussionmentioning

confidence: 99%

Aerobic exercise attenuates inhibitory avoidance memory deficit induced by paradoxical sleep deprivation in rats

et al. 2013

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“…As soon as the animal crossed to the aversive compartment with its four paws, the door was closed, the latency to enter was recorded, and the animal received one footshock. Considering that high-intensity shock can suppress scopolamine-induced amnesia in rats [ 17 ], we tested the aversive memory of our animals with two footshock intensities: one group of offspring animals was tested with 0.4 mA for 1 sec (n = 14 for the exercise group and n = 13 for the control group), and a different set of animals was tested with 0.6 mA for 1 sec (n = 15 for both the exercise and control groups). After the shock, the animal was removed from the apparatus and returned to the home cage.…”

Section: Methodsmentioning

confidence: 99%

Maternal Exercise during Pregnancy Increases BDNF Levels and Cell Numbers in the Hippocampal Formation but Not in the Cerebral Cortex of Adult Rat Offspring

et al. 2016

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Clinical evidence has shown that physical exercise during pregnancy may alter brain development and improve cognitive function of offspring. However, the mechanisms through which maternal exercise might promote such effects are not well understood. The present study examined levels of brain-derived neurotrophic factor (BDNF) and absolute cell numbers in the hippocampal formation and cerebral cortex of rat pups born from mothers exercised during pregnancy. Additionally, we evaluated the cognitive abilities of adult offspring in different behavioral paradigms (exploratory activity and habituation in open field tests, spatial memory in a water maze test, and aversive memory in a step-down inhibitory avoidance task). Results showed that maternal exercise during pregnancy increased BDNF levels and absolute numbers of neuronal and non-neuronal cells in the hippocampal formation of offspring. No differences in BDNF levels or cell numbers were detected in the cerebral cortex. It was also observed that offspring from exercised mothers exhibited better cognitive performance in nonassociative (habituation) and associative (spatial learning) mnemonic tasks than did offspring from sedentary mothers. Our findings indicate that maternal exercise during pregnancy enhances offspring cognitive function (habituation behavior and spatial learning) and increases BDNF levels and cell numbers in the hippocampal formation of offspring.

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“…Although amnestic influences have been rarely studied in experiments using intensive training, the available findings have consistently indicated that amnestic treatments become ineffective or less effective when animals are extensively trained or given relatively high intensities of foot‐shock for training (Prado‐Alcalá et al, ). This effect has been observed after systemic administration of amnestic treatments (Durán‐Arévalo et al, ; Cruz‐Morales et al, ; Solana‐Figueroa et al, ; Díaz‐Trujillo et al, ) as well as localized treatments affecting the striatum (STR), amygdala (AMY), substantia nigra (SN), and hippocampus, among other cerebral structures (Thatcher and Kimble, ; Prado‐Alcalá and Cobos‐Zapiaín, , ; Prado‐Alcalá et al, ; Parent et al, , ; Cobos‐Zapiaín et al, ; Lazaro‐Muñoz et al, ). Such findings have been interpreted as suggesting that the affected structures are not critical sites for the changes mediating associations based on overtraining or strong aversive stimulation, which engages other brain regions subserving memory processing.…”

Section: Introductionmentioning

confidence: 96%

Intense aversive training protects memory from the amnestic effects of hippocampal inactivation

et al. 2013

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There is extensive evidence that amnestic treatments are less effective, or ineffective when administered to subjects that have been overtrained or subjected to high foot-shock intensities in aversively motivated learning. This protective effect has been found with a variety of learning tasks and with treatments that disrupt activity in several regions of the brain, including the hippocampus, amygdala, striatum, and substantia nigra. Such findings have been interpreted as suggesting that the brain regions disrupted are not critical sites for the memory processes induced by these types of training. In most experiments investigating this issue the amnestic treatments were administered after training. Thus, it might be less amnesia was induced because the training accelerated memory consolidation and, thus, the maximum effect of the amnestic treatment occurred after memory of the learning experience was consolidated. This study investigated this issue by inactivating the hippocampus of rats bilaterally with tetrodotoxin (TTX) (10 ng/side) 30 min before one-trial inhibitory avoidance training using relatively low (1.0 mA), medium (2.0 mA), or high (3.0 mA) foot-shock intensities. Retention of the task was measured 48 h after training. TTX produced a profound retention deficit, a mild deficit, and no deficit at all in the 1.0, 2.0, and 3.0 mA groups, respectively. These data confirm the protective effect of training with relatively high foot-shock intensity against experimentally induced amnesia, and suggests that this protection is not due to accelerated consolidation. Rather, the findings suggest that strong training activates brain systems other than those typically involved in mediating memory consolidation.

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A threshold for the protective effect of over-reinforced passive avoidance against scopolamine-induced amnesia

Cited by 27 publications

References 20 publications

Aerobic exercise attenuates inhibitory avoidance memory deficit induced by paradoxical sleep deprivation in rats

Aerobic exercise attenuates inhibitory avoidance memory deficit induced by paradoxical sleep deprivation in rats

Maternal Exercise during Pregnancy Increases BDNF Levels and Cell Numbers in the Hippocampal Formation but Not in the Cerebral Cortex of Adult Rat Offspring

Intense aversive training protects memory from the amnestic effects of hippocampal inactivation

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