Cytochemical localization of adenylate cyclase and 3',5'-nucleotide phosphodiesterase in Dictyostelium.

Estradiol was found to stimulate the activity of adenylate cyclase in the cervicovaginal epithelium of neonatal mice, demonstrated with adenylyl-imidodiphosphate and also with adenosine triphosphate (ATP) as substrate. Measures were taken to exclude interference by other ATP-degrading enzymes. The deposits of the reaction product, indicating enzyme activity, were localized on the plasma membrane of all sides of the epithelial cells. A similar distribution of enzyme activity was recorded in both controls and estradiol-stimulated animals with either of the two substrates; however, the deposits appeared most prominent after estradiol-treatment. In view of a previous report on increased activity of the cyclic AMP-degrading enzyme phosphodiesterase after estradiol-treatment, it was concluded that the parallel elevation in activity of both adenylate cyclase and cyclic AMP-phosphodiesterase indicates a role of cyclic AMP in the action mechanism of estradiol.

Adenylate cyclase in an estradiol sensitive tissue: A cytochemical study

Publisher Summary This chapter discusses the pharmacological control of the synthesis and metabolism of cyclic nucleotides. A cyclic nucleotide mediates the epinephrine-induced activation of liver phosphorylase. Adenosine 3'3'-monophosphate (cyclic AMP) and other cyclic nucleotides have been demonstrated not only to mediate the effects of most hormones and neurotransmitters but also to be involved in scores of biochemical and physiological events. The evidence that cyclic nucleotides influence the function of normal cells suggests that any abnormal alteration in the concentration of these compounds may be responsible for abnormal cell function that is, a diseased state. Indeed, several lines of investigation indicate that cyclic nucleotides may be involved in a variety of clinical conditions ranging from cancer to cardiovascular disease to mental illness. Cyclic AMP and the enzymes responsible for its biosynthesis and degradation are present in all tissues at all stages of their development. However, the rate at which these enzymes develop varies with the tissue and species. Moreover, the rate at which the hormone-sensitive adenylate cyclase system develops does not necessarily coincide with the development of the basal or fluoride-stimulatable enzyme.

Pharmacological control of the synthesis and metabolism of cyclic nucleotides.

The responses of the developing endocrine system to hormones and drugs

The enzyme 3′,5′-nucleotide phosphodiesterase was localized in certain tissues of the planarian Dugesia lugubris (O. Schmidt) by means of ultracytochemical methods. This enzyme was found to be active in epithelium, muscles, nerve tissue and in rhabdite-forming cells. The active enzyme was present at the outer or inner side of the membrane, and even in the cytoplasm. Problems of the ultracytochemical localization of PDE are discused.

Ultracytochemistry of cyclic 3',5'-nucleotide phosphodiesterase activity in the planarian Dugesia lugubris (O. Schmidt).

Cyclic-35-adenosine monophosphate phosphodiesterase (cAMP-PD) and 5-nucleotidase were demonstrated histochemically in the cervicovaginal epithelium of 3-day-old mice and enhanced in mice treated with estradiol. The incubation medium for cAMP-PD was .05 M tris-maleate buffer pH 7.6-7.7 with .01 M MgC12 2 mM lead acetate .1-1 mg per ml snake venom (source of 5-nucleotidase) 1.53 mM cAMP and .1 M theophylline. The 5nucleotidase medium was .2 M tris-maleate buffer pH 7.2 .1 M MgS04 1.8 mM lead nitrate 3.8 mM 5AMP. In 3-day-old control mice cAMP-PD was seen in the apical or luminal plasma membrane of the epithelial cells. 5 mcg estradiol-17beta daily for 2 days broadened the lead deposit; 5 injections of estradiol further increased cAMP-PD activity. Theophylline decreased the activity. Almost no 5 nucleotidase was present in newborns and in 3-day-old mice but nucleotidase was increased by estradiol in the superficial part of the epithelial cells. The authors considered these enzymes active in estrogens mechanism of action.

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OESTRADIOL-17β: ITS INFLUENCE ON CYCLIC 3′5′-ADENOSINE MONOPHOSPHATE PHOSPHODIESTERASE AND 5′-NUCLEOTIDASE IN THE CERVICOVAGINAL EPITHELIUM OF NEONATAL MICE

M. G. Higazi

Papers

OESTRADIOL-17β: ITS INFLUENCE ON CYCLIC 3′5′-ADENOSINE MONOPHOSPHATE PHOSPHODIESTERASE AND 5′-NUCLEOTIDASE IN THE CERVICOVAGINAL EPITHELIUM OF NEONATAL MICE