ARTICLE INFO

Article Type

Original Research

Authors

Asadollahi   Z. (* )
Papahn   A.A. (1 )
Moazedi   A.A. (2 )
Najafzadeh Varzi   H. (3 )






(* ) Physiology Department, Veterinary Faculty, Shahid Chamran University, Ahvaz, Iran
(1 ) Physiology Department, Veterinary Faculty, Shahid Chamran University, Ahvaz, Iran
(2 ) Biology Department, Basic Science Faculty, Shahid Chamran University, Ahvaz, Iran
(3 ) Pharmacology Department , Veterinary Faculty, Shahid Chamran University, Ahvaz, Iran

Correspondence

Address: Physiology Department, Veterinary Faculty, Shahid Chamran University of Ahvaz, Golestan Bolevard, Ahvaz, Iran. Post Box: 71355-145
Phone: +986113330010
Fax: +986113360807
zahra.asadollahi@gmail.com

Article History

Received:  May  25, 2013
Accepted:  March 20, 2014
ePublished:  July 1, 2014

BRIEF TEXT


… [1-3] Through classical conditioning, every animal learns to predict any unconditioned stimulus by conditioned one [4]. In passive avoidance conditioning, learning is associated with reduced spike amplitude [5]. Cholinergic neurotransmitter, glutamatergic, serotonergic, and GABAergic systems play important roles in passive avoidance conditioning [6]. According to conducted studies, glucose is one of the learning modulators [7].

… [8, 9] Many evidences show that learning processing is affected by glucose leading to memory and learning increase and reduction in human beings and rodents [10-16].

The aim of this study was to investigate the effect of intravenous injection of glucose on passive avoidance learning in adult male rats using shuttle box apparatus.

Non-declared

Adult male Wistar rats (170g to 220g) obtained from Center for Laboratory Animals Breeding and Reproduction (Ahvaz Jundishapur University,Iran) were studied.

21 rats were brought under study.

Brought into Animal Home one week before experiment and for adaptation with the experiment environment, the rats were housed in standard conditions (standard temperature, wet, and light/dark cycle, as well as free access to water and food) and in special cages. The rats were divided into 3 groups of 7, including control group (no treatment), saline group, glucose receiving group. 10 minutes before shock receiving (training), glucose receiving group received 500mg/kg rat body weight glucose (Merck; Germany) as intraperitoneal [17, 18]. Injection of this amount of glucose was done to determine the effect of glucose on passive avoidance learning in shuttle box apparatus. In addition, to ensure from no effect of glucose solvent on learning in the mentioned conditions, the saline group received glucose solvent (saline) in the same amount and conditions. Shuttle box apparatus (Iran), working based on punishment (applying electrical shock), was used to assess passive avoidance learning. Learning test method in shuttle box apparatus contained 3 stages, as follows: Adaptation; training; retrieval At adaptation stage, the intermediate guillotine door of two boxes having been opened, the animal was put into the apparatus for 3 minutes, in order to be familiar with the environment. 24 hours after adaptation stage and 10 minutes before shock receiving (training), glucose receiving group received 500mg/kg rat body weight glucose (Merck; Germany) as intraperitoneal; and after 10 minutes, the guillotine door having been closed, the animal was put into the apparatus. After 30 seconds, the guillotine door having been opened slowly, the animal had 120 seconds to go from light box to dark box; and dark box entry delayed time was recorded. The animal having entered into the dark box, the door was closed and after 5 seconds, 1.5mA shock was applied for 2 seconds. 20 seconds after applying shock, the animal was removed from the apparatus and transferred into the cage. At this stage, if the animal did not go into the dark box after 120 seconds, it was removed from the study. After 48 hours from the training stage, retrieval experiment was done. At this stage, the intermediate guillotine door of two boxes was closed. The animal was slowly put into the light box. After 30 seconds, the guillotine door having been opened, the animal had 300 seconds to go into the dark box. The animal having gone into the dark box, time was recorded, as well as staying time within the dark box. This is the time interval, beginning from the entrance into the dark box and terminating at time of returning to the light box. After entering the light box, the animal was removed from the apparatus [19]. 10 minutes after glucose injection and in order to ensure of increase in blood glucose, blood sugar of the animals was measured, using glucometer and blood sugar measuring strip (Bayonim; Germany) [17, 18]. SPSS 16 software was used to statistical analysis. One-way ANOVA and LSD test were used to compare the groups.

There was no significant difference in darkness entry delayed time before experiment between control, saline, and glucose receiving groups. After intravenous injection of glucose, there was a significant increase in dark box entry delayed time in retrieval time in glucose receiving group than control and saline groups did. Nevertheless, there was no significant difference between control and saline groups. There was a significant difference in staying time within the dark box between glucose receiving group and other groups at retrieval stage. However, in this respect, there was no significant difference between control and saline groups. 10 minutes after injection of glucose, there was a significant difference in blood glucose concentration between glucose receiving group and control and saline groups. However, there was no significant difference in blood glucose concentration between control and saline groups (Table 1).

… [20, 21] The results show that glucose intravenous injection increases learning, which is inconsistent with results of another study revealing learning impairment caused by local injection of glucose [22].

Effects of central injection of glucose on memory and learning ought to be investigated in different learning-assessing apparatuses.

Lack of measurement of other blood factors affected by blood glucose was one of the limitations for the study.

Before training stage, intravenous injection of glucose increases passive avoidance learning in adult male rats in shuttle box apparatus.

The researchers feel grateful to the university teachers and Research Deputy of Shahid Chamran University, Ahvaz, Iran.

Non-declared

All procedures were done according to ethical protocols of the International Neuroscience Society and implemented protocols at Shahid Chamran University.

Research Deputy of Shahid Chamran University funded the research.

TABLES and CHARTS

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