3 research outputs found
Pentylenetetrazol and Morphine Interaction in a State-dependent Memory Model: Role of CREB Signaling
Introduction: State-dependent (STD) memory is a process, in which the learned information can be optimally retrieved only when the subject is in the state similar to the encoding phase. This phenomenon has been widely studied with morphine. Several studies have reported that Pentylenetetrazole (PTZ) impairs memory in experimental animal models. Due to certain mechanistic interactions between morphine and PTZ, it is hypothesized that PTZ may interfere with the morphine-STD. The cyclic adenosine monophosphate Response Element-Binding (CREB) is considered as the main downstream marker for long-term memory. This study was designed to determine the possible interaction between PTZ and morphine STD and the presumable changes in CREB mRNA.
Methods: In an Inhibitory Avoidance (IA) model, posttraining morphine (2.5, 5, and 7.5 mg/kg-i.p.) was used. The pre-test morphine was evaluated for morphine-induced STD memory. Moreover, the effect of a pre-test PTZ (60 mg/kg-i.p.) was studied along with morphine STD. Locomotion testing was carried out using open-field. Eventually, using real-time-PCR, the CREB mRNA changes in the hippocampus were evaluated.
Results: Posttraining MOR (7.5 mg/kg-i.p.) impaired IA memory (P<0.001). The pre-test injection of similar doses of morphine recovered the morphine-induced memory impairment (P<0.001). The pre-test PTZ impaired the IA memory recall (P<0.001); however, the pre-test PTZ along with morphine STD potentiated the morphine-induced STD (P<0.001). Alterations in CREB mRNA were observed in all groups. No difference was seen in the locomotor activity.
Conclusion: Presumably, the certain interactive effect of PTZ on morphine-induced STD is mediated through gamma-aminobutyric acid and opioid systems via CREB signaling
Effect of Pentylenetetrazol on Morphine State-Dependent Memory in Rat
Abstract
Background: Learning and memory are among the higher functions of the brain. State-dependent memory (STM) is a type of memory in which the recall of a learned behavior is happend only in the same sensory and physiologic condition in which the behavior is encoded. The STM is seen with some drugs, e.g. the morphine. The pentylenetetrazol (PTZ) is a durg which is used for the induction of seizure in experimental models. Some studies have been revealed different effects of the PTZ on brain higher function (learning, memory …). The aim of present study was to explore the effect of PTZ on morphine-induced STM.
Materials and Methods: In this study, male adult Wistar rats (190-220 g) were used. Animals in 3 groups (n=8) during 3 sessions (learning/memory, STM and interaction) were studied. During 48 hour (training and test) the learning and memory of animals were studied in inhibitory avoidance apparatus. The step-through latency in the test day was used as a criterion for memory. Post-training injection of saline or morphine (2.5, 5 and 7.5 mg/kg-ip) in different groups was carried out. In addition, the pre-test injection of morphine at the same doses was made to study the STM. Moreover, the interaction of pre-test single-dose PTZ (60 mg/kg-ip) on STM was studied. The locomotion of the animals was measured using the open field.
Results: The post-training injection of morphine (2.5, 5 and 7.5 mg/kg-ip) impaired the inhibitory memory of rats compared to control group (p<0.001). The post-training and pre-test injections of the same dose of morphine (7.5 mg/kg-ip) reversed the impaired memory compared to morphine (2.5 and 5 mg/kg-ip), (p<0.001). The pre-test PTZ (60 mg/kg-ip) maintained the morphine (7.5 mg/kg-ip) STM (p<0.001).
Conclusion: The present study revealed that the post-training ip injection of different doses of morphine results in the impairment of inhibitory avoidance memory in rat. In addition, the pre-test injection of the same doses of morphine reverses the impaired memory. This process is called STM. Consequently, the pre-test injection of PTZ maintains the morphine STM
Effects of Ethanol Preconditioning on Pentylenetetrazole-induced Memory Impairment and Expression of NMDA Receptor NR1 Subunit mRNA in Rat
Abstract
Background: Neuronal damage following seizures and epilepsy is one of the main causes of disabilities and mortality worldwide. In recent years, preconditioning has been introduced as a novel strategy for the prevention of brain damage. Preconditioning is a phenomenon in which a minor noxious stimulus protects from a subsequent more severe insult. The aim of present study was to examine the effect of ethanol (Eth) preconditioning on pentylenetetrazole (PTZ)-induced impairment memory in the inhibitory avoidance model.
Material and Methods: This study was carried out on 45 adult male Wistar rats (180-200 g). Animals were assigned into five groups: Control, Eth 0.25, Eth 0.5, PTZ and Eth (0.5) +PTZ (n=9, for all groups). Eth-preconditioning was induced 6 days before the injection of PTZ. The animals were tested in a single trial step-through inhibitory test in two sessions (train and test). Then locomotor activity of rats was recorded in the open-field apparatus and NR1 mRNA expression in the hippocampus was measured by real-time PCR technique.
Results: One-way ANOVA revealed that the Ethanol preconditioning did not impair inhibitory memory. Further, post-test analyses showed that Ethanol preconditioning significantly prevented from PTZ-induced memory impairment, and increased NR1 subunit mRNA expression in PTZ-induced memory impairment group. In addition, one-way ANOVA for the locomotor activity showed no significant difference between the groups.
Conclusion: Our results showed that a pre-conditioning treatment with Ethanol
(0.5g/kg/day), 6 days before PTZ-induced memory impairment may provide a kind of neuroprotection in rats