Serum progesterone levels correlate with decreased cerebral edema after traumatic brain injury in male rats

Previous animal research suggests that progesterone may have powerful neuro protective effects in traumatic brain injury (TBI). This experiment tested the hypothesis that progesterone levels correlate with decreased cerebral e dema in male rats with bilateral medial frontal cortex injuries. Three grou ps of male Sprague-Dawley rats were used: injured given progesterone (4 mg/ kg), injured given vehicle (oil), and uninjured controls given vehicle. Pro gesterone or vehicle was administered intraperitoneally at 1, 6, and 24 h p ostinjury. At 48 h postinjury, the rats were killed, brains extracted, and assayed for edema. Percent difference in water content of the area surround ing the lesion was compared to posterior cortex. A strong inverse relations hip was found between serum progesterone levels and percent cerebral edema; the higher the progesterone levels, the lower the percent edema. Both prog esterone and oil-treated animals had some edema compared to sham-operated c ontrols. The brains of the injured animals given control solution were high er in water content than either the uninjured group or injured progesterone -treated rats 48 h postinjury. These findings confirm that progesterone sig nificantly decreases cerebral edema after TBI in adult male subjects.