Rapid non-genomic and genomic responses to progestogens, estrogens, and glucocorticoids in the endocrine pancreatic B cell, the adipocyte and other cell types.

Rapid biologic responses to injected steroids were described as early as 60 years ago. More recently, evidence has been presented that 17beta-estradiol given i.v.

Acute effects of progesterone on glucose metabolism in rat adipocytes: are they modulated by endogenous adenosine?

Progesterone rapidly inhibits glucose oxidation of isolated rat adipocytes. Because this inhibition is triggered by endogenous adenosine, the present study was designed to examine the effect of the steroid on cyclic adenosine monophosphate (cAMP) accumulation, its relation to lipolysis, and the possible participation of adenosine. The results strongly indicate that physiological concentrations of progesterone increase the release of adenosine by isolated adipocytes, with maximal release at the end of a 20-minute incubation.

The isolation of glucose tolerance factors from brewer's yeast and their relation to chromium.

A new dietary factor, the glucose tolerance factor (GTF), was reported in 1957 that improved impaired glucose tolerance in rats. Most studies on GTF have used brewer's yeast as the starting material, and it has been postulated that the active material is a low-mol wt organic complex containing Cr3+. It seemed thus important to isolate an active GTF from chromium-rich yeast (228 ppm Cr) obtained by incubation with chromium and to compare each fraction with corresponding ones from untreated yeast (0.

Inhibition of glucose metabolism by progesterone in adipocytes: role of protein synthesis.

Progesterone decreases [I-14C]glucose oxidation in isolated female rat adipocytes within 20 min of incubation. Because steroids regulate transcription mechanisms, the relationship between protein synthesis and glucose metabolism was studied in the presence of progesterone. Actinomycin D does not affect basal glucose oxidation or the progesterone effects on it; cycloheximide and puromycin decrease basal glucose oxidation, but only puromycin decreases the inhibitory progesterone effect.

Effects of placental lactogen and progesterone on insulin stimulated glucose metabolism in rat muscles in vitro.

The short term effects of ovine placental lactogen and progesterone have been studied on skeletal muscle glucose metabolism in order to determine their respective roles in pregnancy-induced insulin resistance. The rates of hexose transport, glycogen synthesis, and glycolysis were measured in vitro by incubating stretched soleus, extensor digitorum longus (EDL) and epitrochlearis from virgin rats. When incubated in plasma from late pregnant rats, EDL glucose metabolism was reduced by 30% when compared to EDL incubated in plasma from virgin rats despite similar glucose (8 mM) and insulin (200 microU/ml) concentrations.