[Comparison of the effects of progesterone, allopregnanolone and gender on suppressing edema formation after traumatic brain injury in rats]

ABSTRACT

Brain edema is one of the most important causes of death within the first few days following head trauma. In this study we investigated the role of gender as well as the effects of progesterone and allopregnanolone one hour after diffuse traumatic brain injury on edema formation in rats. This interventional-experimental study was performed on 12 groups of female and male rats. They were divided into 12 groups as follows 1 and 2 intact female and male rats, 3 and 4 trauma male and female rats, 5 vehicle of progesterone [benzyl alcohol with sesame oil], 6 sham [ovariectomized female rats ovx], 7 sham [no ovx], 8 sham[male], 9 and 10 low dose [4mg/kg] and high dose [8mg/kg] of progesterone, 11 allopregnanolone and 12 vehicle of allopregnanolone [water]. Hormones were injected i. p one hour after diffuse traumatic brain injury through Marmarou model. The results showed a significant increase of 5.32 times in Evans blue and 2.42% in water content in trauma male group comparing to control groups, while in female rats the difference was significant just for Evans blue [4.68 times]. Evans blue and water content were also significantly greater in traumatic males than female rats [1.57 times and 2.04% respectively]. After injection of low and high doses of progesterone, there was a significant decrease in water content [2.21% and 2.30%] and Evans blue content [2.55 and 2.98 times]. Allopregnanolone significantly decreased these parameters [2.36% and 1.82 times respectively]. Moreover, the injection of progesterone in both low and high doses increased the serum progesterone of female ovarectomized rats as compared to vehicle group. Based on these results, it can be concluded that the rate of edema formation in traumatic male rats is higher compared to traumatic female rats. Moreover, both progesterone and allopregnanolone decrease edema formation in ovariectomized female rats