Alireza Azizzadeh Delshad; Marjan Heshmati; Taki Tiraihi
Volume 3, Issue 2 , March 2008, , Pages 67-74
Abstract
Background and Objective: As apoptotic cell death is extremely involved in physiological development and many pathological situations such as cancer and neurodegenerative diseases, the understanding of its molecular machinery can be useful in designing new therapeutic strategies. The present ...
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Background and Objective: As apoptotic cell death is extremely involved in physiological development and many pathological situations such as cancer and neurodegenerative diseases, the understanding of its molecular machinery can be useful in designing new therapeutic strategies. The present study investigated the temporal expression of the proapoptotic protein Bax in adult spinal motoneurons. Materials and Methods: Following unilateral mid-thigh sciatic transection in adult rats, the incidence and nature of spinal motoneuron loss were evaluated by means of light microscopic cell count and electron microscopy 1 day, 1 week, 1 month and 3 months post-operatively. In all groups the temporal expression of Bax was immunohistochemically determined and the findings were compared with the results of the cell count. Results: Following axotomy the related motoneurons underwent chromatolytic changes which increased up to one month and diminished in the 3-month group. One day following axotomy the number of motoneurons did not show any significant reduction, but thereafter a progressive cell loss occurred, which was most prominent after three months. Electron microscopic study confirmed the ultrastructural apoptotic nature of cell death. Bax immunohistochemistry indicated an increasing immunoreactivity up to one month post-axotomy, but in 3-month group it was clearly diminished. Conclusion: Following transection of a peripheral nerve in adult animals, related motoneurons undergo chromatolytic changes which in some neurons may proceed to apoptotic cell death. Although the proapoptotic protein Bax has long been believed as the main apoptotic factor, other Bax-independent pathways may also participate in the axotomy-induced neuronal apoptosis which must not be ignored.
Marjan Heshmati; Hesam Amini
Volume 2, Issue 2 , April 2007, , Pages 45-48
Abstract
Background and Objective: Deprenyl is a drug for the treatment of Parkinson’s disease, where the dopaminergic neurons are the target of this drug. Several reports also documented that deprenyl has an effect on the sensory and motor neurons. There are some reports about the mode of action of deprenyl ...
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Background and Objective: Deprenyl is a drug for the treatment of Parkinson’s disease, where the dopaminergic neurons are the target of this drug. Several reports also documented that deprenyl has an effect on the sensory and motor neurons. There are some reports about the mode of action of deprenyl on motoneurons as a neuroprotective agent, while others believe that deprenyl acts as a neurorescuer. Materials and Methods: In this experimental study, the axotomized spinal motoneurons in rat neonates were used to investigate the mode of action of deprenyl on motoneurons. Six groups of newborn rats (5 each) were used in this study. The first group was treated with 2.5 mg/kg of drug (for 21 days) one hour before surgical transection of the left sciatic side, the second treated at the time of surgery, and the third one treated one hour after surgery. The fourth, fifth, and sixth groups were given normal saline 1 hour before the surgery, at the time of surgery, and 1 hr after the surgery respectively. The animals were perfused and spinal cords were removed. The tissues were processed in paraffin and then sectioned. Tissues were stained with Cresyl violet. Total motoneuron count was done and the percentage of motoneuron reduction as well as motoneuron survival index was calculated. Results: The obtained data revealed that deprenyl in pre-treated group was more effective than in the other two modes of treatment. Conclusion: Taken together, deprenyl is more neuroprotective than neurorescuer of spinal motoneurons in rats.
Marjan Heshmati; Taki Tiraihi
Volume 1, Issue 4 , September 2006, , Pages 161-168
Abstract
Background and Objective: Sciatic nerve transection is characterized by a rapid wave of motoneuron death associated with progressive synaptic lesions. The purpose of this study was to evaluate the long term synaptic changes. Materials and Methods: This basic study was carried out on paraffin- or resin-embedded ...
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Background and Objective: Sciatic nerve transection is characterized by a rapid wave of motoneuron death associated with progressive synaptic lesions. The purpose of this study was to evaluate the long term synaptic changes. Materials and Methods: This basic study was carried out on paraffin- or resin-embedded tissue blocks for evaluation of synaptophysin and choline acetyl transaferase (CHAT) immunoreactivities and the ultrastructural changes in the synapses of spinal motoneurons following sciatic nerve axotomy in the newborn rats. Results: The results showed that there was a progressive decrease in the percentage of survived motoneurons and high percentage of chromatolytic motoneurons. There was also a high percentage of degenerated motoneurons with dotted pattern synaptophysin immunoreactivity, low percentage of intact motoneurons with complete synaptophysin labeling, and high percentage of motoneurons with low CHAT labeling. The ultrastructural study showed that there were many motoneurons with synaptic pathological changes including irregularity of the synaptic membrane and displacement of synaptic vesicles. Conclusion: The findings of this study indicate that there is a delayed synaptic lesion in axotomized motoneurons of newborn rats.
