Thyrotropin-Releasing Hormone Improves Neurologic Recovery after Spinal Trauma in Cats

Naloxone treatment improves neurologic outcome after experimentally induced spinal trauma, but this opiate-receptor antagonist may increase post-traumatic pain. In contrast, thyrotropin-releasing hormone appears to act in vivo as a partial physiologic opiate antagonist that spares analgesic systems; this activity prompted us to evaluate its effect in spinal injury. Cervical-spine trauma was produced in anesthetized cats by the Allen method. Six animals each received thyrotropin-releasing hormone, saline, or dexamethasone as an intravenous infusion over four hours, beginning one hour after injury. Neurologic recovery was significantly better after treatment with thyrotropin-releasing hormone than after saline or dexamethasone (P less than 0.01): at six weeks, the average animal given thyrotropin-releasing hormone was normal, whereas average control animals had marked spasticity. The beneficial effect of thyrotropin-releasing hormone in experimental spinal injury and its lack of effect on nociception indicate that it may have unique therapeutic potential in spinal trauma in human beings.