Temperature can alter the functional outcome of spinal cord regeneration in larval lampreys

Now that spinal cord regeneration has been demonstrated in mammals [Bregman B. S. et al. (1995) Nature 378, 498-501; Cheng H. et al. (1996) Science 27 3, 510-51.3], we must examine the consequences and look for means of avoidi ng negative outcomes. The larval lamprey, which readily regenerates cut spi nal axons, offers a model for this important next step. In the present stud y, one group of larval lampreys with spinal lesions was kept at room temper ature during recovery. Another group was returned to their usual cold room temperature. A majority of animals kept at room temperature recovered full locomotor behavioral function, while a majority of those that recovered at a colder temperature exhibited dysfunctional locomotor behavior. The dysfun ction most often consisted of segments rostral and caudal to the lesion sit e lacking the usual coordination and apparently interfering with each. In b oth groups, there was a close association between the presence of dysfuncti on and the quality of the intersegmental coordination as assessed in the is olated spinal cord preparation. These results suggest that a relatively minor difference in conditions unde r which an animal recovers may drastically alter the likelihood of a favora ble functional outcome. (C) 1999 IBRO. Published by Elsevier Science Ltd.