The Effect of Thyrotropin Releasing Hormone on somatosensory Evoked Potentials in Cats with Spinal Cord Injury

ABSTRACT

The therapeutic goal for the spinal injury has been focused on preventing the secondary ischemic changes because of the poor regeneration of human spinal cord. Naloxone, an antagonist of endogenous opiates, has been clinically used for the purpose of preventing ischemic change and improving the recovery of neurological function after spinal injury. Recently, thyrotropin releasing hormone(TRH), a hypothalamic hormone inducing the thyrotropin secretion in anterior pituitary gland, has been known as a potent stimulator of cardiovascular functions in shock and the neurologic recovery in injuries of central nervous system, however, its underlying mechanism is still obscure. The present study was designed to determine whether TRH was also effective to improve the experimentally induced spinal injury as naloxone did, Somatosensory evoked potentials(SEPs) have used as an index for recovery of neurological function after the spinal injury which was induced by the 400gm.cm contusion of the T-7 spinal level in cats. The results are summarized as follows 1. SEPs abolished soon after spinal contusion were reappeared 3 hours after injury when either of naloxone(10mg/kg) or TRH(4mg/kg) was administrated intravenously. Its recovery was completed after 24 hours. 2. The recovery rates of SEPs after treatments of naloxone and TRH were 62.5% and 64.7% of experimental animals, respectively. In conclusion, the present studies confirm the therapeutic benefit of TRH in experimental spinal injury and demonstrate that it is superior to treatment with naloxone. Further studies would be needed to explain the underlying mechanism of TRH effects.