The behavioral and molecular effects of estradiol and progesterone on a rat model of spinothalamic tract lesion

Introduction:The spinal cord injury is temporary or permanent damage in the spinal cord that disturbs the motor and sensory functions.The neuroprotective effects of steroids has been reported previously.Therefore, we designed a study to investigate the effects of different doses of estradiol (Est) and progesterone (Prog) on unilateral lesion of the spinothalamic tract (STT).Methods: The 77 male adult Wistar rats were under the anesthesia for dorsal laminectomy at the spinal segments T8-T9.A tungsten-electrode was targeted to the right STT and unilateral lesion was made by a brief current pulse (300µA, 90s).Rats were divided into 11 groups and Est or Prog (2, 4, 8 and 16mg/kg) were administered 30min post-injury.Mechanical allodynia and open field as assessed before, 14 and 28 days after the injection then the animals were sacrificed.The western blotting was performed on T8-9 spinal segments to evaluate protein expression of ERK, p-P38, JNK, Iba1 and GFAP at the lesion site.Results: Est but not Prog significantly increased the pain threshold and motor activity at the dose of 8mg/kg on post-surgery days 14 and 28.Est but not Prog significantly increased the protein expression of ERK while decreased JNK protein.Both Est and Prog significantly decreased protein expression of p-P38, Iba1 and GFAP.Conclusion: These results show Est (8mg/kg) is able to decrease mechanical allodynia and improve motor activity 14 and 28 days after spinothalamic tract lesion.It seems ERK, p-P38, JNK, Iba1 and GFAP are involved. www.phypha.ir/ppj