Pergamon ft. Steroid Biochem. Molec. Biol. Vol. 52, No. 6, pp. 587-594, 1995 Copyright © 1995 Elsevier Science Ltd 0960-0760(95)00010-0 Printed in Great Britain. All rights reserved 0960-0760/95 $9.50 + 0.00 31p NMR Study of Phosphorus Containing Metabolites in the Uterus of Hamster: Changes During the Estrous Cycle and the Effect of Hormonal Manipulation S. Shivaji,* L. G. Devi, M. B. Ahmad and C. S. Sundaram Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India Changes in the concelatrations of phosphorus containing metabolites were monitored by sip NMR in the uteri of hamsters during the estrous cycle. Concentrations of phosphocreatine (PCr) and ATP were significantly increased in estrus animals compared to diestrus animals. Concentrations of these metabolites were also increased in immature female hamsters and ovariectomized (OVX) adult hamsters treated with estradiol indicating that estradiol was responsible for this effect. However, the steroid hormones; progesterone and testosterone did not increase the concentrations of the phosphorus containing metabolites. Further, immature female hamsters also following treatment with estradiol showed an initial decline in phosphomonoester (PME), PCr, ATP and inorganic phosphate but by 24 h of treatment the concentrations returned to control levels. The NMR study also revealed that the intracellular pH of the hamster uterus was around 7.4 all through the estrous cycle. J. Steroid Biochem. Molec. Biol., Vol. 52, No. 6, pp. 587-594, 1995 INTRODUCTION In mammals, the uterus during the estrous cycle exhibits cyclic morphological, biochemical and physio- logical changes such as increase in tissue weight [1-3], accumulation of fluid [4-,6] and increase in biosynthetic activity [7]. Apart from an increase in the synthesis of DNA, RNA and proteins under the influence of estradiol, changes in the concentration of high energy metabolites such as phosphocreatine (PCr) and adenosine triphosphate (ATP) have also been observed in the uterus of rat following estradiol administration [8, 9]. But, all these earlier studies were performed using perchloric acid extracts of frozen uteri thus resulting in variations irt the reported results due to partial degradation of the, labile compounds. However, this difficulty could be overcome by the use of sip NMR. 31p NMR has been extensively used for the analysis of phosphate containing metabolites in excised tissues and whole animals [10-12] so as to avoid extraction and *Correspondence to S. Shivaji. Received 7 Oct. 1994; accepted 26 Dec. 1994. 587 homogenization methods which are not suitable for the analysis of labile compounds. Using this method, high- energy phosphate metabolites in the uterus of adult rats during pregnancy and parturition [13] and in the uteri of immature rats following estradiol administration [14] have been analyzed. However, as yet, very little is known about the changes in the concentration of high- energy phosphate metabolites during the functional state of the uterus such as during the various phases of the estrous cycle. Since steroid hormones play a direct role in modulating the estrous cycle it would also be important to evaluate the effect of steroid hormones on the concentration of the high-energy phosphate metabolites. Further, even less is known about the intracellular pH of the uterus during the estrous cycle. In an attempt to address the above questions the present paper reports data related to: (i) Changes in phosphate metabolites in adult hamster uteri during diestrus, proestrus and estrus phases of the estrous cycle. (ii) Changes in phosphate metabolites in the uteri of adult animals following ovariectomy and sub- sequent administration of estradiol, progester- one or testosterone.