Induction of riboflavin-carrier protein in the immature male rat by estrogen: Kinetic and hormonal specificity
- 22 Downloads
The kinetics of estrogen-induced accumulation of riboflavin-carrier protein in the plasma was investigated in immature male rats using a specific and sensitive homologous radio-immunoassay procedure developed for this purpose. Following a single injection of the steroid hormone, plasma riboflavin-carrier protein levels increased markedly after an initial lag period of approximately 24 h, reaching peak levels around 96 h and declining thereafter. A 1.5 fold amplification of the inductive response was evident on secondary stimulation with the hormone. The magnitude of the response was dependent on hormonal dose, whereas the initial lag phase and the time of peak riboflavin-carrier protein induction were unaltered within the range of the steroid doses (0.1–10 mg/ kg body wt.) tested. Simultaneous administration of progesterone did not affect either the kinetics or the maximum level of the protein induced. The hormonal specificity of this induction was further adduced by the effect of administration of antiestrogens viz., En and Zu chlomiphene citrates, which effectively curtailed hormonal induction of the protein. That the induction involvedde novo-protein synthesis was evident from the complete inhibition obtained upon administration of cycloheximide. Passive immunoneutralization of endogenous riboflavin-carrier protein with antiserum to the homologous protein terminated pregnancy in rats confirming the earlier results with antiserum to chicken riboflavin-carrier protein.
KeywordsRiboflavin carrier protein radioimmunoassay estrogen induction specificity kinetics amplification antiestrogens secondary stimulation immunoneutralization pregnancy termination
thiamine carrier protein
biotin carrier protein
Unable to display preview. Download preview PDF.
- Eakin, R. E. Shell. E. E. and Williams, R. J. (1940)J. Biol. Chem.,136, 801.Google Scholar
- Hayward, M. A., Mitchell, T. A. and Shapiro, D. J. (1981)J. Biol. Sci.,255, 11308.Google Scholar
- Maw, A. J. G. (1954)Poult. Sci.,33, 216.Google Scholar
- Mohla, S. and Prasad, M. R. N. (1969)Acta Endocrinol (Copenhagen),62, 489.Google Scholar
- Moudgal, N. R. and Madhwaraj, H. G. (1974) inMethods in Hormone Radioimmunoassay, eds. B. M. Jaffe and H. R. Behrman (New York: Academic Press) pp. 57–85.Google Scholar
- Mulholland, H. and Jones, C. R. (1968)Fundamentals of Statistics, (London: The English Language Book Society and Butter-Worths) pp. 139–156.Google Scholar
- Murty, C. V. R. and Adiga, P. R. and Adiga, P. R. (1980)Indian J. Biochem. Biophys.,17, 102.Google Scholar
- Seal, U. S. and Doe, R. P. (1969) inMetabolic Effects of Gonadal Hormones and Contraceptive Steroids, eds. H. A. Salhanick, D. M. Kipsis and R. L. Vande (New York: Wiele-Plenum Press) pp. 277–318.Google Scholar