The Effects of Sustained Release Growth Hormone in the Repair of Neurological Deficits in Rats with the Spinal Cord Injury

Kim, Min Su; Heo, Jung; Kwon, Yong Seok; Lee, Keun Cheol; Kim, Seok Kwun

Abstract

PURPOSE: Due to increasing interest in the treatment of spinal cord injuries, many histopathological studies have been conducted to prove that many neurotrophic factors including growth hormone are important for regeneration of the injured spinal cord. Growth hormone has to be given everyday, however, and this negatively affects compliance in clinical trials. Recently, the invention of sustained release growth hormone (SRGH) that can be given just once a week may both help the regeneration of injured spinal cord and, at the same time, be more compliant and convenient for clinical patients.
METHODS
In this study, thirty 7-week-old female Spraque-Dawley rats were subjected to a weight-driven impact spinal cord injury. They were divided into 3 groups and Group I and II were injected with SRGH once a week for 4 weeks; Group I were injected into the injured spinal cord area, while Group II were injected into the peritoneal cavity. Meanwhile, Group III were injected with normal saline solution. The functional outcome was evaluated using the Basso-Beattie-Bresnahan motor rating score and the inclined plane test was done 4 weeks after the first injection. Histopathological examination was performed at the same time and the amount of residual white matter was measured in all groups.
RESULTS
After 4 weeks, Groups I and II showed greater improvement than Group III(the control group) in the functional test. In the control group, invasion of atypical phagocytes, axonal degeneration, edema and cavity formation in the posterior site of spinal cord gray matter was observed in histopatholgical examination. The rate of residual white matter in Group III was less than in the other groups.
CONCLUSION
Data showed significant functional and histopathological improvement in the groups treated with SRGH into the spinal and peritoneal cavity compared with the control group. SRGH is therefore beneficial because it helps with regeneration of the injured spinal cord and improves the compliance and convenience of patients.