Effect of pineal body and melatonin on chemiluminescence of peritoneal macrophages via hypothalamus in rats.

AIM: To study whether the hypothalamus was a major relay for the action of melatonin (Mel) on peritoneal macrophage (PM subliminal diameter of) function.

METHODS

Pinealectomy, luminol-dependent chemiluminescence (CL), hypothalamic dinoprostone radioimmunoassay, and intrahypothalamic injection of Mel were done in rats kept under light:dark 12h:12h.

RESULTS

CL value of PM subliminal diameter of was decreased and hypothalamic dinoprostone content was elevated after pinealectomy, which were restored by Mel (10 micrograms kg-1 d-1 ip at 16:00 for 7 d). The same treatment of Mel increased CL value of PM subliminal diameter of and depressed hypothalamic dinoprostone production in intact rats. CL value of PM subliminal diameter of showed negative relation to hypothalamic dinoprostone with r = -0.78 (P < 0.01). Intrahypothalamic injection of Mel (2 micrograms) enhanced CL value of PM subliminal diameter of in normal and pinealectomized rats.

CONCLUSION

The hypothalamus is a main site of pineal Mel action upon PM subliminal diameter of function.