Journal of North Khorasan

Introduction:       prenatal  stress   have  different effects  on biological processes  and  different sections of emberyonic structures  and make  disorders in hypothalamo-pitutary-adrenal  (HPA). In  this  research the

effects of prenatal stress on morphological properties of hippocampus in newborn and adult rats and their

havior in Open Field (OF) and Elevated Plus Maze (EPM) in maturity period was studied.

.Iaterial  and Methods: Female pregnant Wistar rat were devided into control and experimental groups.Control pregnant  females were left undisturbed in their horne cages without any stressfull conditions. In the Experimental groups, pregnant females restrained for 3 hours per day (from the 2nd weak of pregnancy until delivery). Behavioral studies were performed using Open Field (OF) and Elevated Plus Maze (EPM). Histological studies of hippocampus of new born and 2.5 month old litters were performed using Golgi and oluidin blue staining methods.

Results:  Behavioral stusdies of 2.5 month aged offsprings showed that there is significant differences in orne parameters of emotional reactivities and exploratory functions. So that, in the experimental groups

e tploratory  activity was diminished but emotional reactivity and anxiety were increased. Histologic studies of newborns hippocampus of adult offsprings showed significant decrease in the intensity of pyramidal and dentate gyrus fibers in experimental groups than control groups. Also the thickness of hippocampal layers were less in stress experienced newborns and adult.

Conclusion:  Considering  of  these  results  and  compaire with  the  developmental periods  and  structural

changes during embryonic period in rats we can have a hypothesis that following prenatal stress the normal de  elopment of hippocampal cells will be delayed. These abnormalities maybe due to changes in hormonal and neurotransmitters and growth factors involving in neural cells differentiation and less myelination and

changes in glucocorticoides amounts  that  is effected in regulation of cell proliferation and emotional and exploratory behavioral.