Physical injury to the spinal cord gives rise to a variety of environmental changes including ischemia, free radical formation, massive ion shifts, and changes in osmotic equilibria. Many believe that in terms of neuronal death, spread of necrosis and neurological deficits these """"""""secondary"""""""" insults do far more damage than the physical trauma. Some of the therapies developed to address these conditions include low temperature, hyperbaric oxygen, corticosteroids, free radical scavengers, hyperosmotic agents, and dimethyl sulfoxide (DMSO). However, the efficacies of many of these treatments are still a matter of controversy and the isolated effects of such therapies have not been investigated quantitatively in terms of neuronal survival. The previous grant period established baseline data on reactions of single neurons in culture to physical trauma (dendrite amputation and shock wave trauma) by defining the probability of cell survival under normal culture conditions as a function of lesion parameters. The observed response categories (rapid cell death within 1 to 2 hours, or survival with slow recovery over more than 24 hrs) elucidated, on the cellular level, two major clinical problems: (1) there is little time for intervention to save acutely traumatized neurons, and (2) those neurons which are recovering from physical trauma may be especially vulnerable to secondary insults for at least one and possibly several days. We propose to address directly these vital problems in the highly simplified and well controlled environment of neuronal monolayer cell culture. Using unique laser cell surgery techniques, routine biochemical methods, and novel multielectrode analyses of network spike activity, this research will focus on four areas of investigation: (1) identification of those factors of the secondary insult which pose the greatest threat to injured neurons during the recovery period. (2) Assessment of the effects of various commonly applied therapies on the continued survival of recovering neurons under normal culture conditions and in conjunction with secondary insults. (3) Investigation of early (15 min to 1 h) physical, chemical, or pharmacological interventions that may slow down the rapid cell deterioration or death and """"""""buy time"""""""" until established therapies may be attempted. In addition (4), we plan to investigate the ionic basis of the damage gradients that we have shown to develop in transected processes. Our observation that neurons continue to die in calcium-free medium has focused attention on endogenous Ca++ and has led to the formation of the sodium/endogenous calcium hypothesis of cell death. We wish to be given the opportunity to test this hypothesis thoroughly.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS023686-05
Application #
3407456
Study Section
Neurology A Study Section (NEUA)
Project Start
1985-09-01
Project End
1991-03-31
Budget Start
1989-04-01
Budget End
1991-03-31
Support Year
5
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of North Texas
Department
Type
Schools of Arts and Sciences
DUNS #
City
Denton
State
TX
Country
United States
Zip Code
76203
Emery, D G; Lucas, J H; Gross, G W (1991) Contributions of sodium and chloride to ultrastructural damage after dendrotomy. Exp Brain Res 86:60-72
Lucas, J H; Wang, G F; Gross, G W (1990) NMDA antagonists prevent hypothermic injury and death of mammalian spinal neurons. J Neurotrauma 7:229-36
Lucas, J H; Emery, D G; Higgins, M L et al. (1990) Neuronal survival and dynamics of ultrastructural damage after dendrotomy in low calcium. J Neurotrauma 7:169-92
Lucas, J H; Wang, G F; Gross, G W (1990) Paradoxical effect of hypothermia on survival of lesioned and uninjured mammalian spinal neurons. Brain Res 517:354-7
Shi, R Y; Lucas, J H; Wolf, A et al. (1989) Calcium antagonists fail to protect mammalian spinal neurons after physical injury. J Neurotrauma 6:261-76;discussion 277-8
Emery, D G; Lucas, J H; Gross, G W (1987) The sequence of ultrastructural changes in cultured neurons after dendrite transection. Exp Brain Res 67:41-51
Lucas, J H (1987) Proximal segment retraction increases the probability of nerve cell survival after dendrite transection. Brain Res 425:384-7