Objective        To determine the effects of ghrelin on combined radiation and burn injury in rats and investigate the possible mechanism involved in its therapeutic effects.       Methods        A total of 120 male SD rats were randomly divided into 4 groups

control group (Con)

ghrlein treatment group (GHR

receiving intraperitoneal injection of ghrelin)

combined radiation and burn injury group (CRBI

recei

ving total body 5 Gy

60

Co irradiation and full-thickness burn injury on 15% TBSA)

combined injury with ghrelin treatment group (CRBI+GHR). Ghrelin was given to the corresponding rats through intraperitoneal injection at a dose of 3.37×10

-2

mg/kg for 5 consecutive days. Survival rate for 30 d

hematopoietic function

peripheral hemogram of the 7th

14th

and 21st days

spleen nodes forming experiment

spleen index and bone marrow nucleated cell counts (BMNC) at the 10th day

serum levels of TNF-α

IL-6

acetylcholine (ACH)

epinephrine (E) and cortisol (Cor) at the 2nd

4th

and 6th hours after the final injection of ghrelin were measured.       Results        Ghrelin significantly improved the survival rate of combined radiation and burn injury rats (about 25% compared with CRBI group). As to the hematopoietic function

the WBC count at the 7th day and BMNC at the 10th day were significantly elevated (

P

0.05). However

the spleen node counts and spleen index don’t indicate a significant difference (

P

0.05). Compared with CRBI group

ghrelin treatment significantly reduced the content of proinflammatory mediator TNF-α and IL-6

neurotransmitter Ach and E

and endocrine hormone Cor (

P

0.05) in the serum at the 4th day after last ghrelin injection.       Conclusion        Ghrelin has therapeutic effect on combined radiation and burn injury rats

which might be due to its alleviating the inhibition of hematopoietic function

down-regulating the pro-inflammatory mediators and regulating the excitability of autonomic nervous system.