Marijuana: interaction with the estrogen receptor.

Crude marijuana extract competed with estradiol for binding to the estrogen receptor of rat uterine cytosol. Condensed marijuana smoke also competed with estradiol for its receptor. Pure delta 9-tetrahydrocannabinol, however, did not interact with the estrogen receptor. Ten delta 9-tetrahydrocannabinol metabolites also failed to compete with estradiol for its receptor. Of several other common cannabinoids tested, only cannabidiol showed any estrogen receptor binding. This was evident only at very high concentrations of cannabidiol. Apigenin, the aglycone of a flavinoid phytoestrogen found in cannabis, displayed high affinity for the estrogen receptor. To assess the biological significance of these receptor data, estrogen activity was measured in vivo with the uterine growth bioassay, using immature rats. Cannabis extract in large doses exhibited neither estrogenic nor antiestrogenic effects. Thus, although estrogen receptor binding activity was observed in crude marijuana extract, marijuana smoke condensate and several known components of cannabis, direct estrogenic activity of cannabis extract could not be demonstrated in vivo.

delta 1-11-oxa-11-deoxycortisol: a new antiglucocorticoid with activity in vivo.

A new steroid-like compound, delta 1-11-oxa-11-deoxycortisol, was tested in a one-week growth suppression, thymus suppression and adrenal weight suppression bioassay for possible glucocorticoid antagonist activity in vivo. We hypothesized that this compound would have antiglucocorticoid activity based on previous studies of 11-deoxycortisol and delta 1,9(11)-11-deoxycortisol, which were optimal glucocorticoid antagonists in vivo in adrenalectomized rats, but which lost antiglucocorticoid activity in intact animals, apparently due to adrenal 11 beta-hydroxylation. Thus, delta 1-11-oxa-11-deoxycortisol, a compound which cannot undergo 11 beta-hydroxylation, was synthesized and tested as an antiglucocorticoid. This analog had an affinity for the rat thymus glucocorticoid receptor similar to that of its parent compounds (Ki 0.9-3.1 x 10(-7) M). A dose of 1 mg/rat antagonized the effect of 15 microgram of dexamethasone in the growth suppression assay (p less than 0.05) and in the thymus suppression assay (p less than 0.06), but did not antagonize dexamethasone-induced adrenal weight suppression. delta 1-11-Oxa-11-deoxycortisol did not exhibit glucocorticoid activity in any of the three assays. These data suggest that delta 1-11-oxa-11-deoxycortisol may be a pure competitive antagonist of dexamethasone.

SC 25152: a potent mineralocorticoid antagonist with decreased antiandrogenic activity relative to spironolactone.

The widely used mineralocorticoid antagonist spironolactone has antiandrogenic activity that may contribute to its side effects of decreased libido, impotence and gynecomastia. We have therefore sought a less antiandrogenic analog of spironolactone that may exhibit reduced endocrine side effects. The analog SC 25152 was chosen for pharmacological testing because of the previous observation that it has considerably reduced affinity for the androgen receptor of both man and rat but exhibits an affinity for the mineralocorticoid receptor similar to that of spironolactone. Bioassays in the rat show that SC 25152 has a 60% decrease in antiandrogenicity, and a 4-fold increase in antimineralocorticoid activity compared to spironolactone, resulting in an overall reduction of antiandrogenic activity to one-tenth that of spironolactone at doses giving equal antimineralocorticoid activity. These studies demonstrate that the antiandrogenic and antimineralocorticoid activities of spironolactone analogs can be dissociated and illustrates the utility of measurements of drug-receptor interaction to identify a compound with desired pharmacological properties.

Rat adrenal androgen receptor: a possible mediator of androgen-induced decreased in rat adrenal weight.

Many previous studies have demonstrated effects of gonadal steroids on adrenal weight in the rat. Most of these effects are indirect, depending upon alterations in the pituitary-adrenal axis for their expression. In this study we have attempted to examine the direct effects of gonadal steroids on adrenal weight in the rat. This was done using hypophysectomized, castrated male rats receiving ACTH replacement, a model which excludes pituitary-adrenal feedback effects. Estradiol-treated rats did not differ from controls, whereas testosterone-treated rats exhibited a small but statistically significant decrease in adrenal weight. As a first step in exploring the mechanism of this androgen effect, we have identified a specific dihydrotestosterone-binding protein in the rat adrenal gland. A single class of high affinity (Kd = 0.6-2.0 x 10(-8) M), saturable (28 fmol/mg cytosol protein), cytoplasmic binding sites was found using both protamine sulfate precipitation and dextran-coated charcoal assays. The specificity, sedimentation coefficient on sucrose gradient, and sensitivity to sulfhydryl reagents and heat of this dihydrotestosterone-binding protein are typical of the cytoplasmic androgen receptor from other androgen target tissues such as prostrate. We conclude that testosterone can decrease rat adrenal weight directly, and that the mechanism may involve a high affinity binding protein, as has been shown in other androgen-responsive systems.

SC 25152: A potent mineralocorticoid antagonist with reduced affinity for the 5 alpha-dihydrotestosterone receptor of human and rat prostate.

It has previously been shown that spironolactone possesses antiandrogenic activity in the rat and interacts with rat prostate 5 alpha-dihydrotestosterone cytoplasmic receptors to block the nuclear uptake of this hormone. Current evidence suggests that this androgen receptor interaction may be an important mechanism through which spironolactone causes endocrine side effects in rat and man. We have analyzed the interactions of several spirolactone analogs with the androgen receptor of human and rat prostate and the mineralocorticoid receptor of human and rat kidney. One analog, SC 25152, was found to have considerably reduced affinity for the prostate 5 alpha-dihydrotestosterone receptor [Ka = 24 +/- 1% and 19 +/- 6% (mean +/- SE) in the human and rat, respectively, of the Ka for spironolactone] while maintaining similar affinity for the mineralocorticoid receptors of human and rat kidney [Ka = 113 +/- 37% and 86 +/- 7% (mean +/- SE), respectively, of the Ka for spironolactone]. These findings would predict this analog to have reduced antiandrogenicity at equivalent therapeutic doses.