Abstract
Methotrexate at 1 microM stimulated increase of serotonin N-acetyltransferase (NAT) activity in chick pineal glands cultured under each of three conditions of illumination. The peak of the circadian rhythm in NAT activity and the "spike" in content of cyclic GMP were both advanced in pineal glands cultured in the dark from midphotoperiod. In contrast, the time of peak NAT activity in glands cultured in the dark from late photoperiod was unaffected. In addition, methotrexate did not affect times of reaching maximum NAT activities in glands cultured from midphotoperiod in the light or under diurnal illumination. Doubling the concentration of methotrexate also eliminated the lag phase in increase of NAT activity in glands cultured in the dark. However, at a concentration of 5 microM methotrexate the curve depicting increase of NAT activity was biphasic, and neither time nor level of peak NAT activity differed from those of control glands. Results of attempts to demonstrate persistent effects of exposure to methotrexate were inconclusive.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call