The inhibition by indoleamines (tryptamine and serotonin) of ocular serotonin-N-acetyltransferase from Rana perezi is temperature-dependent.
Temperature effects on ocular serotonin N-acetyltransferase (NAT) kinetics characteristics from Rana perezi have been studied with respect to tryptamine and serotonin as substrates. Monoamine oxidase (MAO) activity does not interfere in NAT assay at acceptoramine concentrations used in NAT kinetics characterization from R. perezi retina. NAT shows an inhibition by high substrate (serotonin) concentration, which is temperature-dependent. NAT follows the Michaelis-Menten equation at low temperature, whereas at high temperatures (> 10 degrees C) an inhibition by serotonin is observed. This inhibition of NAT activity by serotonin could act as an amplification mechanism to increase daily melatonin rhythm amplitude in the retina of ectotherms.
Alonso-Gómez
A L
AL
Departamento de Biología Animal II, Fisiología Animal, Facultad de Bioloía, Universidad Complutense, Madrid, Spain.
Alonso-Bedate
M
M
Delgado
M J
MJ
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D005123:Eye / Q000201:enzymology*; D007700:Kinetics; D008954:Models, Biological; D011898:Ranidae / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology*; D013696:Temperature; D014363:Tryptamines / Q000494:pharmacology*
D014363:Tryptamines; D012701:Serotonin; C030820:tryptamine; D001191:Arylamine N-Acetyltransferase