Effects of pineal body and melatonin on lymphocyte proliferation and dinoprostone production in rat spleen.

AIM: To determine the effects of pineal body and melatonin (Mel) on lymphocyte proliferation and dinoprostone production in rat spleen.

METHODS

Pinealectomy (PE), lymphocyte proliferation assay and dinoprostone radioimmunoassay were used.

RESULTS

A circadian rhythm of splenic lymphocyte proliferation which peaked at 22:00 was obliterated by PE in rats. PE led to an impairment of lymphocyte proliferation and an increase of dinoprostone production, which were restored by ip Mel 10 micrograms.kg-1.d-1 at 16:00 for 7 d. Mel promoted lymphocyte proliferation and inhibited dinoprostone production in intact rats. A negative correlation between the change in lymphocyte proliferation and dinoprostone production was seen.

CONCLUSION

The pineal body and its main hormone Mel play a regulatory role in circadian lymphocyte proliferation which is related to dinoprostone production in rat spleen.