Effect of L-tyrosine on 3beta-HSD activity of rat luteal cells in vitro / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To study the effects of L-tyrosine on 3beta-HSD activity of rat luteal cells in vitro.</p><p><b>METHODS</b>Luteal cells were isolated from ovary tissues of female rats pretreated with PMSG and hCG. Luteal cells were cultured with 95% oxygen and 5% carbon dioxide in 37 degrees C. 3beta-HSD activity was measured by radioimmunoassay (RIA).</p><p><b>RESULTS</b>(1) 0.2 mmol x L(-1) and 2.0 mmol x L(-1) L-tyrosine significantly inhibited 3beta-HSD activity. (2) 0.2 mmol x L(-1) L-tyrosine exerted different effects on 3beta-HSD activity at different concentrations of pregnenolone (Ph). It increased 3beta-HSD activity at 0.1 micromol x L(-1) and 1 micromol x L(-1) of Pn concentration. With further increase in the concentration of Pn to 100 micromol x L(-1), the stimulating effect of L-tyrosine was switched to suppression effect. (3) L-tyrosine and L-tyrosine hydrazide both inhibited 3beta-HSD activity induced by hCG.</p><p><b>CONCLUSION</b>L-tyrosine affects 3beta-HSD activity of rat luteal cells in vitro. L-tyrosine and tyrosine hydrazide inhibits hCG induced 3beta-HSD activity.</p>