Changes in MAO activities in several organs of rats after administration of l-thyroxine.

Egashira, Toru; Yamanaka, Yasumitsu

doi:10.1254/jjp.45.135

Cited by 6 publications

(1 citation statement)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The possible existence of MAO activity modulators has, for example, been reported in several rat organs after administration of l-thyroxine. 10 Interestingly, kinetic analysis of MAO B activity showed an a. nicotra et al…”

Section: Discussionmentioning

confidence: 99%

Monoamine oxidase A and B activities in embryonic chick hepatocytes: differential regulation by retinoic acid

Nicotra¹,

Falasca²,

Senatori³

et al. 2001

Cell Biochemistry & Function

View full text Add to dashboard Cite

Monoamine oxidases (MAOs) A and B are two isoenzymes involved in the degradation of many biological amines in the nervous system and in peripheral organs. In the present work hepatocytes isolated from 14-day-old chick embryos were used as a model system to determine whether retinoic acid (RA) is capable of modulating the activity of the two MAO forms. RA is a retinoid that, by binding with nuclear receptors, interferes with the expression of specific genes in many differentiation processes. Enzymic activity was measured with a radiochemical method using serotonin and beta-phenylethylamine as preferential substrates for MAO A and MAO B, respectively. The specific activity of the two forms was measured in hepatocytes cultured for 24, 48 and 72 h in the presence and the absence of serum. RA stimulated MAO B but not MAO A activity, in a dose- and time-dependent way, and only in the presence of serum. Maximum stimulation (about 3.5-fold) was obtained after treatment with 5 microM RA for 72 h. Kinetic analysis of MAO B activity showed an increase in V(max) in treated hepatocytes (5 microM RA for 72 h) with no change in K(m). In conclusion, the present work shows that RA selectively elicits MAO B activity in cultured chick embryonic hepatocytes, this stimulation requires the presence of some factors present in the serum and is probably due to an increase in the number of enzyme molecules.

show abstract

Section: Discussionmentioning

confidence: 99%