Does growth hormone augment brain edema caused by brain injury? A study with a freeze brain injury model in the rat.
OBJECTIVE
Because of the known sodium and water retention associated with growth hormone (GH) therapy, it is crucial to evaluate the safety of GH after brain injury. To clarify this issue, we investigated whether GH affects brain edema in a rat brain freeze-injury model.


METHODS
Male Wistar rats (n = 29) were divided into four groups according to the substance injected (GH vs. normal saline) and whether the brain was injured or not. The subcutaneous injections of GH (0.8 IU/kg) or saline were given 24 hours apart. In the injury groups, after the second injection, an aluminum rod (4-mm diameter) cooled to -50 degrees C was placed on the exposed dura mater in the right parietal region for 4 minutes, under anesthesia. At 4 hours after the insult, brain and skeletal muscle were excised and their water content was measured by drying.


RESULTS
Freeze injury of the brain caused an increase in water and sodium content in skeletal muscle. GH injection augmented this edema in skeletal muscle. Freeze injury of the brain also caused an increase in water and sodium content in the injured hemisphere of the brain. GH injection did not exacerbate this edema in injured brain tissue. Neither freeze injury nor GH injection caused brain edema in the noninjured hemisphere or in the cerebellum.


CONCLUSIONS
GH administration did not augment brain edema caused by brain injury in our model.
Yamamura
H
H
Department of Traumatology, Osaka University Medical School, Japan. hiraide@hp-gm.med.osaka-u.ac.jp
Hiraide
A
A
Matsuoka
T
T
Takaoka
M
M
Shimazu
T
T
Sugimoto
H
H
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001834:Body Water / Q000737:chemistry; D001923:Brain Chemistry; D001929:Brain Edema / Q000209:etiology*; D001930:Brain Injuries / Q000150:complications*; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D005615:Freezing; D019382:Human Growth Hormone / Q000009:adverse effects* / Q000097:blood; D007279:Injections, Subcutaneous; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry; D019289:Pyruvic Acid / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000032:analysis
D001786:Blood Glucose; D007328:Insulin; D019382:Human Growth Hormone; D019344:Lactic Acid; D019289:Pyruvic Acid; D012964:Sodium