Ali-Mohammad Kamali - Department of Neuroscience, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
Fatemeh Karimi - Histomorphometry and Stereology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
Mohammad-Taghi Sharafi - Cellular and Molecular Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
Mohammad Nami - Department of Neuroscience, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran

Progesterone, as a reproductive hormone in the brain tissue, has been shown to have different effects on memory. Taking the important role of the hippocampus in learning and memory into account, the effects of intrahippocampal injection of different doses of progesterone on the volume and cell number of the hippocampus in a rat model were investigated in this study. A total of 49 adult male rats were divided into 7 groups: control (saline), control– cannula (saline), almond oil-cannula and progesterone- cannula (0.5, 1, 1.5 and 2 mg). In order to investigate the effects of injection after two weeks, stereological methods were applied to evaluate the rats’ brain. Our results indicated an increase in the volume of CA1 in progesterone at a dose of 2mg compared to the control group (p =0.028). Moreover, the numerical density of the pyramidal cells of CA1 increased in progesterone at a dose of 2 mg in comparison to the control group (p= 0.004). The result revealed no statistically significant changes in the volume and numerical density of CA2 and CA3 in the other experimental groups in comparison to the control groups. Based on our findings, intrahippocampal injection of progesterone at a dose of 2mg may lead to beneficial effects in terms of volumetric correlation and neuronal numerical density of the hippocampal CA1.

Progesterone, Hippocampus, Stereology, Rat