Serotonin metabolism in the arthus reaction.
To better characterize the role of serotonin in the Arthus reaction, we examined the concentration of the amine and the activities of serotonin-metabolizing enzymes, monoamine oxidase (MAO) and serotonin-N-acetyltransferase (NAT), in reaction sites induced in guinea pig skin. The specific activity of total MAO in the intact skin was 108.0 +/- 15.9 pmol/min/mg protein, and consisted of about 92% of type A activity and 8% of type B. The activity of total MAO was about 10 times greater than that of NAT. Total MAO activity increased to 130%-150% of control levels at 2 h after initiation of the reaction and approximated the control level at 3 to 6 h. Subsequently, the activity decreased linearly to 50% at 12 h and to 20% at 24 h. Although the time-dependent changes of MAO type A activity were similar to those of total MAO activity, MAO type B activity increased to 42% at 30 min, remained at 30%-40% until 6 h, and then decreased to 20% at 12 h and to 5% at 24 h. NAT activity in the reaction sites decreased with time to 50% of the control at 30 min and to 35% at 4 h and was stationary until 24 h. The serotonin concentration decreased linearly with time to 16% of the control level at 1 h, increased sharply to 240% at 6 h, and remained at more than 200% until 24 h. This biphasic change in serotonin concentration seems to be related to the dynamic changes in the activities of serotonin-degrading enzymes. In addition, the accumulation of platelets in the reaction sites may increase serotonin concentration and MAO activity subsequent to 1 h after the initiation.
Tachibana
T
T
Department of Dermatology, Faculty of Medicine, Kyoto University, Japan.
Taniguchi
S
S
Furukawa
F
F
Miwa
S
S
Imamura
S
S
D000818:Animals; D001183:Arthus Reaction / Q000201:enzymology / Q000378:metabolism*; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D001665:Binding Sites / Q000187:drug effects; D006168:Guinea Pigs; D008995:Monoamine Oxidase / Q000378:metabolism; D009994:Osmolar Concentration; D010293:Pargyline / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D012867:Skin / Q000201:enzymology / Q000378:metabolism
D012701:Serotonin; D010293:Pargyline; D008995:Monoamine Oxidase; D001191:Arylamine N-Acetyltransferase