Hormonal modulation of reproduction–specific thiamin carrier protein in the rat.
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Date
1985-03
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Abstract
The hormonal modulation of thiamin carrier protein in the plasma and uterine
luminal secretion during the normal reproductive phases of the animal (estrous cycle and
pregnancy) as well as during experimental estrogenisation was investigated in the rat using a
specific and sensitive homologous radioimmunoassay procedure developed for this purpose.
Following a single injection of estrogen to immature male rats, thiamin carrier protein rapidly
accumulated in plasma attaining peak concentration at 48 h and declining thereafter. A 1·5-
fold amplification of the inductive response was observed on secondary stimulation with the
hormone. The magnitude of the response exhibited a clear dependency on the dose of the
steroid hormone, whereas the time at which peak levels of thiamin carrier protein production
was remained unaltered in the concentration range of the steroid tested. The inductive effect of
estrogen was severely curtailed by the antiestrogens, viz., En- and Zu-clomiphene citrates,
while progesterone was incapable of either modulating the estrogen-induced response or
eliciting an induction by itself. Cycloheximide drastically blocked the response to estrogen.
Evidence for the ability of uterus to serve as yet another independent site of thiamin carrier
protein synthesis was obtained by in vitro incorporation of radioactive amino acids into
immunoprecipitable thiamin carrier protein in the tissue explants of estrogenised female rats.
The levels of thiamin carrier protein in uterine luminal fluid measured during estrous cycle,
pregnancy and experimental estrogenisation exhibited remarkable similarity to the plasma
thiamin carrier protein profiles.
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Keywords
Thiamin carrier protein, radioimmunoassay, estrogen induction, specificity, antiestrogens, secondary stimulation, physiological modulation, uterine synthesis
Citation
Malathy P V, Adiga P R. Hormonal modulation of reproduction–specific thiamin carrier protein in the rat. Journal of Biosciences. 1985 Mar; 7(2): 77-94.