Objective   To investigate the effects of corticotrophin-releasing hormone (CRH) on production of interleukin-10 (IL-10) from macrophages and to further elucidate its signal transduction mechanism.    Methods   Rat peritoneal macrophages cultured were divided into 6 groups: control group

CRH group

CP+CRH group

HL+CRH group

H89+CRH group and PKAi+CRH group. The control group was cultured with 2 ml RPMI1640 medium. The CHR group was stimulated with 2 ml CRH at a final concentration of 10

9

mol/L.The other four groups were respectively pretreated with CRHR1 antagonist CP154526 at 5×10

-4

mol/L

CRHR1/2 nonselective antagonist α-helical CRH9-41 at 10

-6

mol/L

AC inhibitor H89 compound at 10

-6

mol/L or PKA inhibitor PKAi (6-22) amide (10

-4

mol/L) for 2 h before stimulation with CRH. The concentration of IL-10 in the supernatant after stimulation for 0.5

1

2

4 and 8 h were measured by ELISA method.    Results   In the normal control group

the average concentration of IL-10 kept at  (29.41±3.10)μg/g. As macrophages exposed to CRH

the content of IL-10 increased quickly and reached its first peak at 1 h compared with that in CRH group at 0.5 h (P0.01)

nearly two folds of that in normal control group (P0.01)

then its level decreased by degrees. There existed a second peak of IL-10 expression at 4 h

which was significantly higher than that in CRH group at 0.5 h (P0.01) and that in control group (P0.01). The concentration of IL-10 in CP+CRH group and HL+CRH group at 1 and 4 h were significantly lower than that in CRH group (P0.01)

and were similar to that in control group (P0.05). At 8 h

the concentration of IL-10 in the 2 groups were significantly higher than that in normal control group (P0.01) or CRH group (P0.01). There was no statistical difference of IL-10 concentration between CP+CRH group and HL+CRH group (P0.05) at 0.5 to 4 h

however  that in HL+CRH group was significantly lower than that in CP+CRH group at 8 h (P0.01). Furthe

rmore

pretreatment of macrophages with AC inhibitors H89 in H89+CRH group induced a significant inhibition of the content of IL-10 cytokines at 1

4 and 8 h

while the content of IL-10 cytokines at 4 and 8 h was lower than that in normal control group (P0.05). After pretreated with PKAi (6-22) amide

the content of IL-10 was significantly inhibited during 0.5 to 8 h compared with that in CRH group or control group(P0.01).    Conclusion   CRH increases IL-10 production by rat peritoneal macrophages through activating CRHR1

which involves in the intracellular cAMP/PKA signal pathway.