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فهرست مطالب نویسنده:

abdoreza sabahi

  • Mohammad Hosseini-Sharifabad, Abdoreza Sabahi
    In spite of the existing reports on behavioural and biochemical changes related to the cerebellum due to noise stress, not much is known about the effect of noise stress on the neuronal changes in the cerebellum. The present study aims at investigating the effects from one week noise exposure on granule cell number and Purkinje cell volume within the neonate rat cerebellum.15-day-old male Wistar rats were randomly divided into noise exposed (NE) and control groups (n=8 in each group). NE rats exposed to loud noise (100 dB/30 min/3 times per day) during the third postnatal week. One cerebellar half was selected at random for estimating the volume of the cerebellar layers and neuronal quantifications and the other was used for estimating individual somal volume of Purkinje cells. Cavalieri’s principle, physical disector and nucleator methods were employed respectively for unbiased estimation of the volumes of the cerebellar layers, the numerical density of neurons and the individual volume of Purkinje cells.Results of this study show that noise stress significantly decreases the volume of granule layer together with decreased numerical density and total number of granule cells in the cerebellum. Furthermore, a decrease in somal volume of Purkinje cells was found in NE rats. These results, for the first time, demonstrate an effect of noise stress on the granule cell number and individual volume of Purkinje cells in rat cerebellum.
  • محمد حسینی شریف آبا*د، عبدالرضا صباحی
    مقدمه
    در ادامه مطالعه بر روی اثرات استرس صوتی، این مطالعه با هدف تعیین اثر استرس صوتی بر روی اضطراب و حجم هسته های آمیگدال بعنوان بخش کلیدی مغز که در اضطراب نقش دارد، انجام شد.
    روش بررسی
    در این مطالعه تجربی، رتهای نر دو ماهه ی ویستار بطور تصادفی به دو گروه استرس صوتی و شاهد تقسیم شدند(در هر گروه 10 سر رت). رتهای شاهد در شرایط استاندارد آزمایشگاه نگهداری و رتهای گروه استرس در معرض صدایی به شدت 75 دسی بل(فرکانس 1100 هرتز) بمدت 20 دقیقه، 3 بار در روز و برای 90 روز قرار گرفتند. سپس رفتار اضطرابی حیوانات بوسیله Elevated plus maze وTerritory Discrimination test سنجیده شد. برشهای متوالی کرونال از آمیگدال به ضخامت 25 میکرون تهیه و از هر دو برش یکی انتخاب و حجم هسته های آمیگدال با استفاده از اصل کاوالیه تعیین گردید.
    یافته ها
    نتایج نشان داد که رتهایی که در معرض استرس صوتی بودند ورودهای کمتری به بازوهای باز ماز بعلاوه مرتفع داشته و مدت زمان کمتری را در این بازو گذراندند.همچنین در آزمون تشخیص قلمرو گروه استرس صوتی تاخیر بیشتری در ورود به بخش بیگانه داشتند. حجم هسته جانبی آمیگدال حیوانات گروه استرس صوتی نسبت به حیوانات شاهد بطور معنی داری بیشتر بود.
    نتیجه گیری
    نتایج این مطالعه نشان داد که مواجهه مزمن با سر و صدا باعث افزایش اضطراب و نیز حجم هسته مرکزی آمیگدال رت می شود. این تحقیق تجربی، نگرش مفیدی در درک برخی از جنبه های پاتوفیزیولوژی اختلالات اضطرابی ناشی از استرس صوتی ارائه می کند.
    کلید واژگان: استرس صوتی, استریولوژی, اضطراب, آمیگدال
    Mohammad Hosseini, Sharifabad*, Abdoreza Sabahi
    Background
    In continuing our work on effects of noise stress, this study aimed to determine the effect of noise stress on the anxiety and the volume of the amygdale nuclei as a key brain component plays role in the anxiety.
    Methods
    In this experimental study, two-months old Wistar male rats were randomly divided into noise stress and control groups (n=10 in each group). Control rats were maintained under standard laboratory conditions and noise-stressed rats were exposed to 75 dB noise (1100Hz), 20 min/3 times/day for 90 days. The anxiety behaviors were assessed applying elevated plus maze and Territory discrimination test. Coronal serial sections of 25 µm thickness through rat amygdale were made. Every 2th section was selected and the volume of amygdale nuclei was determined by using Cavalieri's principle.
    Results
    Results indicated that the noise-exposed rats had fewer entrances to open arm of elevated plus maze and spend less time in this arm. In territory discrimination test, noise stressed group had more latency to enter in unknown compartment. The volume of lateral nucleus of amygdale was significantly higher in noise stressed group compared to control animal.
    Conclusion
    Result of this study indicated that the chronic exposure to noise induces anxiety behavior and caused increase in central nucleus of amygdale volume. In this view, our experimental research may present a useful approach in understanding some aspects of the pathophysioloy of anxiety disorders due to noise stress.
    Keywords: Amygdale, Anxiety, noise stress, stereology
  • Mohammad Hosseini-Sharifabad, Abdoreza Sabahi
    Objective(s)
    The hippocampus has been implicated in pathophysiology of schizophrenia. Prenatal stress is a contributing risk factor for a wide variety of neuropsychiatric diseases including schizophrenia. This study examined long-term effects of prenatal restraint stress on the stereological parameters in the Cornu Ammonis (CA) of adult male rats as an animal model of schizophrenia.
    Materials And Methods
    Wistar pregnant dams in experimental group were stressed in a cylindrical Plexiglas restrainer daily for 1 hr during last week of gestation. Controls remained in the animal room and were exposed only to normal animal room conditions. At 2 months of age, the volume of the pyramidal cell layer of the CA, the numerical density and the somal volume of the respective neurons were assessed in the male offspring generated from stressed and control pregnancies. Cavalieri''s principle, physical disector and nucleator were applied for stereological analyses.
    Results
    This study showed that prenatal stress significantly decreased the volume of CA3 pyramidal cell layer and the individual somal volume of CA3 pyramidal neurons. However, there were no markedly differences in the numerical density, total number of CA3 pyramidal neurons and stereological parameters in CA1 of prenatally stressed and control animals.
    Conclusion
    These data indicate that prenatal stress exposure induced neuronal changes in the CA3 subfield of hippocampus which are similar to what is observed in schizophrenia.
    Keywords: Cornu ammonis, Hippocampus, Prenatal stress, Stereology
  • Mohammad Khaksari Hadad, Zahra Soltani, Ali Reza Sarkaki, Gholamreza Sepehri, Sohrab Hajizadeh, Abdoreza Sabahi
    Introduction
    Following a traumatic brain injury (TBI), the excessive release of proinflammatory cytokines is major cause of cerebral edema that can cause permanent neuronal loss. This study examined the changes in brain concentrations of proinflammatory cytokines IL-1, IL-6, TNF-α and TGF- after different doses of estrogen or progesterone treatment in brain-injured rats at 6 and 24 h post-injury.
    Methods
    Adult female rats were divided into 14 groups, and underwent either bilateral ovariectomy (12 groups) or sham surgery (2 groups). The hormones or vehicle were given intraperitoneally 0.5 h after TBI. Moderate TBI was induced by Marmarou method in TBI or treatment groups and brain levels of proinflammatory cytokines were measured 6 and 24 h post-injury.
    Results
    The results indicated that high dose of estrogen (E2) and low dose of progesterone (P1) increase brain levels of IL-1 6 h post-injury by 52.8% and 79.2%, respectively compared to the vehicle. By the 24th h post-injury brain IL-1 level was reduced 27.5% and 27%, respectively compared to vehicle, when estrogen low dose (E1) and E2 were administered. Progesterone high dose treatment reduced brain level of IL-6 by 45.9% at 6 h post-injury and P1 treatment reduced IL-6 level by 20.5% at 24 h post-injury when compared to the vehicle. The brain TNF-α level was reduced by 72.5% by P2 at 6 h and 48.5% by E2 at 24 h post-injury, when compared to the vehicle. In addition, TGF- level seem to be increased by E1 up to 3.37 times at 24 h post-injury compared to the vehicle. Both doses of hormones showed increased levels of TGF- at 6 h post-injury, when compared to the vehicle.
    Conclusion
    We conclude that progesterone and estrogen may change the levels of proinflammatory cytokines in the acute or delayed phases after TBI and this may be one of the mechanisms by which hormones reduce cerebral edema.
  • Mohammad Hosseini, Sharifabad, Abdoreza Sabahi
    ObjectiveThe hippocampal circuit integrity is crucial for learning and memory. Despite the existing reports on hippocampal–dependent memory impairment due to noise stress, there are only a few studies on the effect of noise stress on anatomical structure of hippocampus. The present study is aimed to investigate the likely effects of chronic noise exposure on the volume of rat hippocampus.Materials and MethodsTwo-month male Wistar rats were randomly divided into three groups (n=10 in each group). In the control group rats were maintained under standard laboratory conditions (150 days). In the noise-exposed group: Rats were exposed to 40 dB unmodulated sinosoidal noise with a frequency of 1100 Hz for 20 mins, three times per day for 90 days. The recovery group rats were exposed to noise for 90 days and allowed to survive without further treatment until the day of sacrifice (180th day). The right hemispheres were selected for stereological study. Twenty five μm thick sections were cut along the entire extent of the hippocampus. Using systematic uniformly random sampling, one section from every twenty sections was analyzed. Volume estimation was performed using Cavalieri principle.ResultsStatistical analysis revealed that noise stress induces a significant reduction in volume of all layers of hippocampal subdivisions, except CA1 hippocampal field. In addition, we found that rats which were allowed to recover from noise displayed larger volume of dentate gyrus and CA3 hippocampal field in comparison to noise-exposed rats.ConclusionReduced volume of hippocampal layers most probably reflects structural alterations in the neurites of related neurons. These results provide a neuroanatomical basis that may be relevant to the reported memory disturbances in human and animals following noise stress
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