Improved spatial memory, neurobehavioral outcomes, and neuroprotective effect after progesterone administration in ovariectomized rats with traumatic brain injury: Role of RU486 progesterone receptor antagonist

The contribution of classic progesterone receptors (PR) in interceding the neuroprotective efficacy of progesterone (P4) on the prevention of brain edema and long-time behavioral disturbances was assessed in traumatic brain injury (TBI).

Female Wistar rats were ovariectomized and apportioned into 6 groups: sham, TBI, oil, P4, vehicle, and RU486. P4 or oil was injected following TBI. The antagonist of PR (RU486) or DMSO was administered before TBI. The brain edema and destruction of the blood-brain barrier (BBB) were determined. Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and beam walk (BW) task were evaluated previously and at various times post-trauma. Long-time locomotor and cognitive consequences were measured one day before and on days 3, 7, 14, and 21 after the trauma.

RU486 eliminated the inhibitory effects of P4 on brain edema and BBB leakage (p <0.05, p <0.001, respectively). RU486 inhibited the decremental effect of P4 on ICP as well as the increasing effect of P4 on CPP (p <0.001) after TBI. Also, RU486 inhibited the effect of P4 on the increase in traversal time and reduction in vestibulomotor score in the BW task (p <0.001). TBI induced motor, cognitive, and anxiety-like disorders, which lasted for 3 weeks after TBI; but, P4 prevented these cognitive and behavioral abnormalities (p <0.05), and RU486 opposed this P4 effect (p <0.001).

The classic progesterone receptors have neuroprotective effects and prevent long-time behavioral and memory deficiency after brain trauma.