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  Background and Objective: Ovarian and steroid hormones have long and short-term effects on brain. Progesterone has functional and structural effect on Hippocampus neurons. In epilepsy probably the number of brain neurons can reduce due to cell mortality. Therefore, in this study effect of progesterone were evaluated on the number of CA3 Hippocampus neurons.

  Material and Methods: In this experimental study, 45 Male wistar rats were divided into 5 groups. 5 rats selected as an intact group. Group1 (control) were received, 50-mg/kg- pentylenetetrazd (PTZ) i.p. for kindling. Group 2 received PTZ sesom oil (i.p) (vehicle), 30 min before, groups 3 and 4 received 25 and 50 mg/kg progesterone (i.p) 30 min before receiving PTZ. PTZ injected every 48 h and the rate of mortality, seizure stage and duration of V phase were calculated during in min after PTZ injection. If animal reach to phase 5, for three times they were considered as kindled rats and anesthetized by ether for histological study. Their brain were perfuse for fixation by formaldehyde (10%). and after passage and blocking, 10 micron slices prepared and stained with H & E and Cresyl violet methods. Then CA3 neurons were counted with morphometric lens per mm².

  Results: The results were shown that injection of 25 and 50mg/kg progesterone reduced duration of phase V from 175.2 S in sham to 123.1 S and 113.1 S respectively, (p<0.05 and p<0.01). PTZ reduced the number of CA3 neurons form 178.3±8 in intact animals to 123.2±14.2 in control (p<0.05). The mean number of neurons in 25 and 50 mg/kg progesterone were 137.3±10.5 and 145±8.5 respectively. The number of CA3 neuron in 50mg/kg progesterone group had significant difference compared to control group (p<0.05).

  Conclusion: The results of this study showed that, neuron mortality due to PTZ, reduced in progesterone receiving group compared to control. It seem that there is correlation between neuron mortality and phase 5 duration in progesterone receiving group.

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  Key words: Progesterone, CA3 Hippocampus Neurons, Chemical Kindling, Morphometric

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  [1] - ( Corresponding author ) Academic Member, Dept. of Anatomy, University of Medical Sciences, Rafsanjan
Tel: (0391)5234003, Fax:(0391)5225209, E-mail: shariatik@yahoo.com

  [2] - Assistant Professor, Dept. of Physiology, University of Medical Sciences, Rafsanjan

  [3] - Academic Member, Dept. of Microbiology, University of Medical Sciences, Rafsanjan