Fig. 2.

Tetracycline decreased HIOMT activity and melatonin production. T-Rex-HIOMT Jurkat cells were cultured in presence or absence of tetracycline (1 μg/ml) for 24 h. a After treatment, HIOMT activity of those cells was assayed. Data were first expressed in pmol and then averaged from five experiments performed in duplicate. Control value of HIOMT activity: 56.27 ± 17 pmol/mg protein/h. b Melatonin content in cells was measured by ELISA. Statistically significant differences were observed between cells treated with tetracycline and the group without the antibiotic. *P < 0.05, **P < 0.005, Student t test