@2024 Afarand., IRAN

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ISSN: 2252-0805    The Horizon of Medical Sciences 2014;20(1):53-57

Background
During pregnancy, stress is a potential cause of neurological diseases for the mother and fetus [1]. It may result in shift in hypothalamic-pituitary-adrenal axis activity during fetal period and after that [2]. Having impact on brain’s structure and function, this disorder disturbs after birth processes of nervous system.
Previous Studies
According to some studies, gender and time-dependent fetal stress among rats intensifies induced seizures by pilocarpine, and raises corticosterone level in blood [3]. In addition, stress during pregnancy may results in changes in brain evolution, and disturbs stable performance of brain via creating unusual neuronal communication [4]. Results of a conducted study show that during pregnancy, some stressors affect brain evolution, head circumference, and fetal weight at birth [5]. According to conducted researches, facing with types of physical-environmental stresses in fetal period affects behavioral responds to different environmental stimuli. Intensity of pain sensation may change by stress [8]. However, impact of stress in fetal period on pain threshold may be different or contradictory, depending on its time, severity, and kind [9].
Aim(s)
The aim of the study was to investigate the effect of three types of common stresses in modern living environment, i.e. electromagnetic waves, immobilization, and disturbance, individually and combined on pain threshold in infant male rats.
Research type
This study is an experimental one.
Research society, place and time
The research society was the population of pregnant female rats of Sprague Race (Razi Vaccine and Serum Research Center; Iran) and all their own male infants. All the rats were kept under proper light and temperature at Animal House of the University with unlimited available food and water.
Sampling method and number
40 female rats and all their own male infants were studied.‏
Used devices&materials
After confirmation of pregnancy with vaginal plug, the female rats were divided into 5 “control”, ”electromagnetic stress”, “immobilization stress”, “disturbance stress”, and “combined stress” groups. These groups, in the order they have been listed, show “normal pregnancy without stress”, “4 hours a day exposure of 1.2 t and 50 Hz electromagnetic waves”, “2 times a day 30 minutes immobilization stress”, “keeping all the group rats in a small cage”, and “combination of three stresses similar to each individual group’s stress”, respectively. From eighth day of gestation, pregnant rats of stress groups were exposed to stress for 10 consecutive days. To produce electromagnetic field, 2 solenoids with same dimensions and nearly 1780 rounds were used, being in serial connection to form a long solenoid of 3560 rounds. Animals’ placement point was in the middle of the solenoid. 75 days after childbirth (after maturity), the male infants were subjected to formalin pain test. Measuring the pain intensity was done via "zero" (putting the feet on the ground completely), "1" (putting the paw on the ground), "2" (raising the feet), and "3" (biting or licking the feet) scales, with every minute recording [10]. Data were analyzed by the use of SPSS 18 software, One-way Variance Analysis test (to general comparison), and Tukey's Post Hoc test (to compare the results between groups).
Findings by Text
By subcutaneous injection of formalin into the plantar, acute and chronic pain stages were observed in the rats of all groups, which had no significant statistical difference. Average pain severity at the acute phase of the formalin test between each stress group and the control group was not significant. Average pain severity of the interphase stage of the formalin test was significant only between the electromagnetic stress and the control groups. Average pain severity at the chronic stage of formalin test, especially during 15 to 40 minutes, was significant between each of the combined stress and immobility stress groups on the one hand, and the control group on the other hand (Diagram 1).
Main comparison to the similar studies
Non-declared
Suggestions
Non-declared
Limitations
Non-declared
Conclusions
Stress during pregnancy affects the pain behavior of the rats after maturity. In addition, it is probable that the impact of some combined stresses on chronic pain feeling and understanding system is more than that of stress alone does.
Acknowledgments
Researchers feel grateful to Research Deputy of Qazvin University of Medical Sciences, and Faculty of Paramedical Sciences.
Conflict of interest
Non-declared
Ethical Permissions
Care of the rats was done according to the international ethical instructions on working with animals.
Funding Sources
Research Deputy of Qazvin University of Medical Sciences and Faculty of Paramedical Sciences funded the research.

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