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Shirin Babri , Naser Khalajy ,
Volume 6, Issue 4 (12-2006)
Background & Objectives : Piracetam is a nootropic compound, which acts as a nervous system enhancer. Different processes are involved in memory formation and various parameters are able to disturb it. Due to increase of exposure possibility to electromagnetic fields in recent years and the effects of theses fields on memory consolidation, this investigation designed to clear the relation between these parameters and memory consolidation.
Methods: In this research eleven groups of male wistar rats (ten rats in each group) with a mean weight of 275±25 gr aging 3-4 months were studied. To evaluate the effects of electromagnetic field, four groups of rats were exposed to 5mT/50HZ electromagnetic field for 1,4,6 and 8 hours respectively immediately after training. In other six groups 250mg/kg or 500 mg/kg piracetam were administered orally one hour before training. They were also exposed to electromagnetic field for 4,6,8 hours respectively immediately after training,. Retrieval test was performed 24 hours later in all groups.
Results: 1 hour exposure on EMF had no meaningful effect on memory consolidation, however, in other three groups the electromagnetic fields impaired memory consolidation significantly compared to the control group (p<0.05). Piracetam administration with two mentioned doses significantly improved memory consolidation (p<0.05).
Conclusions: Acute exposure to low intensity magnetic field can disturb memory consolidation and piracetam administration can prevent it.
Sana Mollahoseini , Lotfollah Khajehpour, Mahnaz Kesmati, Abdolrahman Rasekh,
Volume 12, Issue 3 (9-2012)
Background & Objectives: Several studies have shown that Glucocorticoids affect learning and memory processes by influences on limbic structures such as amygdala. The amygdala is an important region for memory formation. Considering the existence of the muscarinic acetylcholine receptors in the basolateral amygdala (BLA), the aim of the present study was to investigate the effect of intra-BLA microinjection of pilocarpine on the effect of dexamethasone on memory retrieval .
Methods: As a model of learning, using a step-through apparatus , inhibitory avoidance was used for assessment of long-term memory in 80 adult male Wistar rats . All animals were bilaterally implanted with cannulas into the BLA and were trained and tested (with 24 h interval) 7 days after surgery. Memory retrieval was evaluated by recording of the step-through latencies and the time spent in dark chamber of apparatus in the testing day.
Results: Pre-test subcutaneous (s.c) administration of dexamethasone (2 mg/kg) impaired memory retrieval in animals when trained 24 h in advance. Co-pretest microinjection of different doses of pilocarpine (1 , 2 μg/rat, intra-BLA ), a muscarinic acetylcholine receptor agonist, with the dexamethasone (2 mg/kg, s.c) caused enhancement of memory retrieval.
Conclusion: Results of this research indicate that impairment effect of dexamethasone on memory processes may be mediates by decrease of mechanisms of BLA muscarinic cholinergic.
Shima Abtin, Lotfollah Khajehpour, Mahnaz Kesmati, Hosein Najafzadeh,
Volume 15, Issue 4 (1-2016)
Background & objectives: Salvia officinalis is one of the memory-enhancing herbs that were used in the past. On the other hand, iron oxide nanoparticles which are widely used in medicine and industry may impair the brain process related to memory. In this investigation, the effect of hydro-alcoholic extract of Salvia officinalis on iron oxide nanoparticle induced memory impairment and the role of beta-adrenergic receptors in this effect were studied.
Methods: To assess the inhibitory avoidance memory, animals were trained in the step-down task and drugs (saline, hydro-alcoholic extract of sage leaves, nanoparticles of iron oxide and propranolol) were injected immediately after training by intraperitoneal (ip) injections. Long-term memory was tested 24 hours later and step-down latencies were recorded.
Results: Administration of iron oxide nanoparticles (5 mg/kg, ip) impaired memory retrieval. Salvia officinalis extract (40 mg/kg, ip) also prevented iron oxide nanoparticle induced long-term memory impairment. On the other hand, administration of propranolol (5, 10 mg/kg, ip) before Salvia officinalis extract (40 mg/kg, ip) and iron oxide nanoparticles (5 mg/kg, ip) attenuated the effect of Salvia officinalis extract.
Conclusion: It seems that extract of Salvia officinalis leaves decreases iron oxide nanoparticle induced memory impairment. Beta-adrenergic mechanisms are possibly involved in these effects of Salvia officinalis extract.