A specific progesterone receptor of myometrial cytosol from the rhesus monkey

Assessment of the inhibitory potential of anabolic steroids towards human AKR1D1 by computational methods and in vitro evaluation

Exposure to xenobiotics can adversely affect biochemical reactions, including hepatic bile acid synthesis. Bile acids are essential for dissolving lipophilic compounds in the hydrophilic environment of the gastrointestinal tract. The critical micellar concentration of bile acids depends on the Δ4-reduction stereochemistry, with the 3-oxo-5β-steroid-Δ4-dehydrogenase (AKR1D1) introducing the cis ring A/B conformation. Loss-of-function mutations in AKR1D1 cause hepatic cholestasis, which, if left untreated can progress into steatosis and liver cirrhosis. Furthermore, AKR1D1 is involved in clearing steroids with an A-ring Δ4-double bond. Here, we tested whether anabolic-androgenic steroids (AAS), often taken off-label at high doses, might inhibit AKR1D1, thereby potentially causing hepatotoxicity. A computational molecular model was established and used for virtual screening of the DrugBank database consisting of 2740 molecules, yielding mainly steroidal hits. Fourteen AAS were selected for in vitro evaluation, as such compounds can reach high hepatic concentrations in an abuse situation. Nandrolone, clostebol, methasterone, drostanolone, and methenolone inhibited to various extent the AKR1D1-mediated reduction of testosterone. Molecular modeling suggests that 9 out of 14 investigated AAS are competitive inhibitors. Moreover quantum mechanical calculations show that nadrolone and clostebol are substrates of AKR1D1 with different activation energy barriers for the hydrogen transfer from cofactor to the C5 position affecting their turnover. In this multidisciplinary approach, we established a molecular model of AKR1D1, identified several AAS as inhibitors, and described their binding mode. This approach may be applied to study other classes of inhibitors including non-steroidal compounds.

A Structural Analysis of the FDA Green Book-Approved Veterinary Drugs and Roles in Human Medicine

The FDA Green Book is a list of all drug products that have been approved by the FDA for use in veterinary medicine. The Green Book, as published, lacks structural information corresponding to approved drugs. To address this gap, we have compiled the structural data for all FDA Green Book drugs approved through the end of 2019. Herein we discuss the relevance of this data set to human drugs in the context of structural classes and physicochemical properties. Analysis reveals that physicochemical properties are highly optimized and consistent with a high probability of favorable drug metabolism and pharmacokinetic properties, including good oral bioavailability for most compounds. We provide a detailed analysis of this data set organized on the basis of structure and function. Slightly over half (51%) of vet drugs are also approved in human medicine. Combination drugs are biologics are also discussed.

Selective Progesterone Receptor Modulators-Mechanisms and Therapeutic Utility

Selective progesterone receptor modulators (SPRMs) are a new class of compounds developed to target the progesterone receptor (PR) with a mix of agonist and antagonist properties. These compounds have been introduced for the treatment of several gynecological conditions based on the critical role of progesterone in reproduction and reproductive tissues. In patients with uterine fibroids, mifepristone and ulipristal acetate have consistently demonstrated efficacy, and vilaprisan is currently under investigation, while studies of asoprisnil and telapristone were halted for safety concerns. Mifepristone demonstrated utility for the management of endometriosis, while data are limited regarding the efficacy of asoprisnil, ulipristal acetate, telapristone, and vilaprisan for this condition. Currently, none of the SPRMs have shown therapeutic success in treating endometrial cancer. Multiple SPRMs have been assessed for efficacy in treating PR-positive recurrent breast cancer, with in vivo studies suggesting a benefit of mifepristone, and multiple in vitro models suggesting the efficacy of ulipristal acetate and telapristone. Mifepristone, ulipristal acetate, vilaprisan, and asoprisnil effectively treated heavy menstrual bleeding (HBM) in patients with uterine fibroids, but limited data exist regarding the efficacy of SPRMs for HMB outside this context. A notable class effect of SPRMs are benign, PR modulator-associated endometrial changes (PAECs) due to the actions of the compounds on the endometrium. Both mifepristone and ulipristal acetate are effective for emergency contraception, and mifepristone was approved by the US Food and Drug Administration (FDA) in 2012 for the treatment of Cushing's syndrome due to its additional antiglucocorticoid effect. Based on current evidence, SPRMs show considerable promise for treatment of several gynecologic conditions.

Progesterone: Therapeutic opportunities for neuroprotection and myelin repair

Progesterone and its metabolites promote the viability of neurons in the brain and spinal cord. Their neuroprotective effects have been documented in different lesion models, including traumatic brain injury (TBI), experimentally induced ischemia, spinal cord lesions and a genetic model of motoneuron disease. Progesterone plays an important role in developmental myelination and in myelin repair, and the aging nervous system appears to remain sensitive to some of progesterone's beneficial effects. Thus, the hormone may promote neuroregeneration by several different actions by reducing inflammation, swelling and apoptosis, thereby increasing the survival of neurons, and by promoting the formation of new myelin sheaths. Recognition of the important pleiotropic effects of progesterone opens novel perspectives for the treatment of brain lesions and diseases of the nervous system. Over the last decade, there have been a growing number of studies showing that exogenous administration of progesterone or some of its metabolites can be successfully used to treat traumatic brain and spinal cord injury, as well as ischemic stroke. Progesterone can also be synthesized by neurons and by glial cells within the nervous system. This finding opens the way for a promising therapeutic strategy, the use of pharmacological agents, such as ligands of the translocator protein (18 kDa) (TSPO; the former peripheral benzodiazepine receptor or PBR), to locally increase the synthesis of steroids with neuroprotective and neuroregenerative properties. A concept is emerging that progesterone may exert different actions and use different signaling mechanisms in normal and injured neural tissue.

Differential suppression of progesterone receptors by progesterone in the reproductive tract of female macaques

Ovariectomized cynomolgus macaques were treated with implants of estradiol (E2) for 14 days. Some animals then received an additional implant of progesterone (P) for 7-14 more days. After treatment with either E2 alone or with E2 plus P we removed the reproductive tracts and measured nuclear and cytosolic P receptors by exchange assay. In addition we used steroid radioimmunoassays(RIA) to measure levels of E2 and P in parallel aliquots of the nuclear and cytosolic fractions. P treatment reduced the concentrations of E2 in nuclear and cytosolic fractions in the cervix, endometrium, myometrium and oviduct compared to the amounts present after 14 days of E2; these data are consistent with many reports that P treatment significantly lowers the amount of nuclear and cytosolic estrogen receptors in all of these tissues. In the oviduct, myometrium and cervix both cytosolic and nuclear P receptor levels were lowered during P action. In the endometrium, however, P treatment reduced the amount of P receptor only in the cytosolic but not the nuclear fraction. RIA determinations of the amount of P retained in nuclear fractions of the P-treated animals indicate that P levels were significantly elevated only in the nuclei obtained from endometrium. This specific increase in the retention of P by endometrial nuclei during P action is consistent with the specific retention of P receptor by endometrial nuclei. These results lead to the unexpected conclusion that the stimulatory effects of P as expressed in the maintenance of the progestational state in the primate endometrium may require higher levels of occupied nuclear P receptor than do the suppressive effects of P as expressed in oviductal atrophy, diminished cervical secretion and myometrial quieting.

Estrogen and progesterone receptors in the uterus of the vervet monkey

Experimental conditions for the optimal measurement of estrogen (ER) and progesterone (PR) receptors in normal vervet monkey (Cercopithecus aethiops pygerythrus) uteri are described. The uteri of this primate were found to contain relatively high concentrations of both ER and PR. Levels of ER ranged from 151 to 822 femtomoles per mg protein (mean for group assayed is 327 +/- 165 femtomoles per mg protein). PR assays were performed on the same cytosols and the levels ranged from 444 to 2267 femtomoles per mg protein (mean of 1285 +/- 511 femtomoles per mg protein). Mean Kd values for the ER- and PR-ligand complexes were found to be 3.15 +/- 1.4 X 10(-10)M and 2.38 +/- 0.2 X 10(-9)M respectively, within the group analysed (n = 21). The ratio of PR to ER varied between 1.1 and 13.1 with a mean of 4.5 +/- 2.4. Ligand specificity studies revealed that [3H]-17 beta-estradiol binding to the ER could only be inhibited by estrogens or estrogen analogues. The PR however exhibited an affinity for a wider range of ligand types. In low ionic strength buffers both ER and PR sedimented as approximately 8S type molecules in the presence or absence of 10mM sodium molybdate. Both receptors dissociated into smaller components, following a short exposure to 0.4 M KCl and subsequent centrifugation in a gradient containing 0.4 M KCl.

Localization of a synthetic progestin in the reproductive organs of the female baboon

The uptake and retention of a radiolabeled synthetic progestin, ORG 2058, was studied in the female reproductive system of the baboon. Four estrogen-primed baboons were injected intravenously with 2.5 micrograms/kg body weight of 3H-ORG 2058. One animal, which served as a control, received an additional injection of 2.5 mg/kg body weight of unlabeled progesterone. One hour after the injections, the animals were killed and the uterus, cervix, oviduct, vagina, and labia were removed and processed for autoradiography. The cells in the germinative layers of the stratified squamous epithelium of the cervix, vagina, and labia demonstrated nuclear localization of the label. The columnar epithelium, both surface and glandular, of the uterus and cervix sequestered the synthetic steroid; however, the nuclei of the epithelium lining the oviduct were unlabeled. The nuclei of the fibroblasts and of the smooth muscle cells were labeled in all the organs studied. These preliminary observations suggest that there is a stage in the reproductive cycle in which progesterone receptors are contained in the stromal cells of the oviduct but are absent in the epithelium.

Analysis of progesterone receptor binding in the ovine uterus

The appropriate conditions for the measurement of ovine uterine cytoplasmic progesterone receptors (PR) have been determined to be 20 nM 3H-progesterone (3H-P4) with and without a 100-fold excess of non-radioactive progesterone (P4) 0-4 degrees C and 4 h of incubation. Under these conditions PR readily exchanged bound progesterone for progesterone added during the assay. This exchange occurred even when saturating concentrations of P4 were present. The progestins, R5020 and P4, effectively competed for the ovine uterine PR binding while non-progestin steroids and diethylstilbestrol failed to compete for the PR binding. The dissociation constant (Kd) measured for the 3H-P4 binding was 1.60 x 10-9 M indicating that the 3H-P4 binding was of high affinity. The levels of PR and the dissociation constant measured using 3H-R5020 in place of 3H-P4 were similar indicating a lack of corticosteroid binding globulin (CBG)-like binding in the ovine uterus.