Steroid Pharmacology Research Articles

Analysis of Modulation of the ρ1 GABAA Receptor by Combinations of Inhibitory and Potentiating Neurosteroids Reveals Shared and Distinct Binding Sites

The ρ1 GABAA receptor is prominently expressed in the retina and is present at lower levels in several brain regions and other tissues. Although the ρ1 receptor is insensitive to many anesthetic drugs that modulate the heteromeric GABAA receptor, it maintains a rich and multifaceted steroid pharmacology. The receptor is negatively modulated by 5β-reduced steroids, sulfated or carboxylated steroids, and β-estradiol, whereas many 5α-reduced steroids potentiate the receptor. In this study, we analyzed modulation of the human ρ1 GABAA receptor by several neurosteroids, individually and in combination, in the framework of the coagonist concerted transition model. Experiments involving coapplication of two or more steroids revealed that the receptor contains at least three classes of distinct, nonoverlapping sites for steroids, one each for the inhibitory steroids pregnanolone (3α5βP), 3α5βP sulfate, and β-estradiol. The site for 3α5βP can accommodate the potentiating steroid 5αTHDOC. The findings are discussed with respect to receptor modulation by combinations of endogenous neurosteroids. SIGNIFICANCE STATEMENT: The study describes modulation of the ρ1 GABAA receptor by neurosteroids. The coagonist concerted transition model was used to determine overlap of binding sites for several inhibitory and potentiating steroids.

Current use and abuse of anabolic steroids

Common abuse of anabolic androgenic steroids (AASs) is no longer confined to high performance athletes, as it has spread among the general population. Epidemiological data about the abuse of these substances show that it is a common practice in young populations. Its use is based on the desire to increase muscle mass and strength, as well as improving physical performance. The ease of acquisition of this type of substances has developed a “sophisticated” knowledge of steroid pharmacology based on subjective and anecdotal analysis with no adverse event information, which translates into a public health crisis. Unfortunately, athletes seem to be more influenced by these experiences than by their physician's advice.The abuse of AAS by the athlete and non-athlete population and its adverse events ought to be evaluated in order to improve routine clinical practice on this regard.

Uso y abuso de agentes anabolizantes en la actualidad

Common abuse of anabolic androgenic steroids (AAS) is no longer confined to high performance athletes, as it has spread among the general population. Epidemiological data about the abuse of these substances show that it is a common practice in young populations. Its use is based on the desire to increase muscle mass and strength, as well as improving physical performance. The ease of acquisition of this type of substances has developed a “sophisticated” knowledge of steroid pharmacology based on subjective and anecdotal analysis with no adverse event information, which translates into a public health crisis. Unfortunately, athletes seem to be more influenced by these experiences than by their physician's advice.The abuse of AAS by the athlete and non-athlete population and its adverse events ought to be evaluated in order to improve routine clinical practice on this regard.

Pharmacology of steroids in the musculoskeletal system

Steroids, of both plant and animal origin, are a large group of fat-soluble organic compounds. The majority have important physiological actions. In the musculoskeletal system, they regulate bone growth and muscle development. The structural modification of naturally occurring steroids has generated thousands of derivatives; many of which are used in medicine. The synthetic analogs of glucocorticoids (e.g. prednisone, cortisone, hydrocortisone), often called corticosteroids, are used clinically across many diverse therapeutic domains (e.g. rheumatology, gastroenterology, oncology and dermatology). The terms glucocorticoid and corticosteroid are used interchangeably in the published literature. This article utilizes glucocorticoids (GCs) as a general descriptor encompassing both synthetic and naturally occurring analogues. It explains the rationale behind the use of GCs in the management of rheumatic diseases and provides a balanced view of the beneficial and detrimental effects of systemic GC treatment, using rheumatoid arthritis as the predominant disease example.

Neurosteroid Influences on Sensitivity to Ethanol

This review will highlight a variety of mechanisms by which neurosteroids affect sensitivity to ethanol, including physiological states associated with activity of the hypothalamic–pituitary–adrenal (HPA) and hypothalamic–pituitary–gonadal (HPG) axes, and the effects of chronic exposure to ethanol, in addition to behavioral implications. To date, γ-aminobutyric acid (GABAA) receptor mechanisms are a major focus of the modulation of ethanol effects by neuroactive steroids. While NMDA receptor mechanisms are gaining prominence in the literature, these complex data would be best discussed separately. Accordingly, GABAA receptor mechanisms are emphasized in this review with brief mention of some NMDA receptor mechanisms to point out contrasting neuroactive steroid pharmacology. Overall, the data suggest that neurosteroids are virtually ubiquitous modulators of inhibitory neurotransmission. Neurosteroids appear to affect sensitivity to ethanol in specific brain regions and, consequently, specific behavioral tests, possibly related to the efficacy and potency of ethanol to potentiate the release of GABA and increase neurosteroid concentrations. Although direct interaction of ethanol and neuroactive steroids at common receptor binding sites has been suggested in some studies, this proposition is still controversial. It is currently difficult to assign a specific mechanism by which neuroactive steroids could modulate the effects of ethanol in particular behavioral tasks.

Commentary: Androgens and “Anabolic Steroids”: The One-Headed Janus

Steroid nomenclature has the difficult task of bridging the gap between the approved but arcane systematic nomenclature (1) and the generic names needed to provide the clear functional descriptions as essential shorthand for scientific discourse. The gap between the strictly correct and the necessarily practical creates the possibility of misleading terminology. When this gap grows sufficiently large, it can become a chasm of misunderstanding, and cleaning up becomes a thankless task over which lingers a disagreeable whiff of pedantry. Ultimately, however, lucid scientific thinking requires accurate terminology. For estrogens, endocrinology gained a valuable service by an editorial (2), hopefully to be cited more among trainees than in bibliometric indices. Now the spotlight turns to an analogous task for androgens; notably, the meaningless term “anabolic steroid” when used alone or in the oxymoron “androgenic-anabolic steroid.” An androgen is classically defined as a substance capable of developing and maintaining masculine reproductive characteristics and contributing to the anabolic status of somatic tissues (3). This physiological definition is complemented by a biochemical definition that an androgen is a chemical that binds to and activates the androgen receptor (AR) (4). Following its characterization as the mammalian male sex hormone in the mid-1930s, testosterone was quickly evaluated in numerous clinical and experimental applications before the hiatus of the war. The early postwar decades, the golden age of steroid pharmacology, saw the pharmaceutical industry successfully commercialize synthetic estrogens, progestins, and glucocorticoids in an epoch that witnessed the development of the oral contraceptives and synthetic glucocorticoids that remain among the most widely used medicines. These monumental achievements encouraged industry research in a parallel quest for wide application of synthetic androgens. The goal was to identify an anabolic steroid, an androgen without virilising properties, making it suitable for use in women and children, not just men. Unlike the other challenges, this systematic search was abandoned by the 1970s, having failed comprehensively (5). The reasons for the failure are now understood to include both flaws in the whole animal androgen (Hershberger) bioassay guiding the search as well as the singularity of the AR, which directs essentially similar receptormediated effects in reproductive tissue and muscle. The original prewar whole animal androgen bioassay used to characterize testosterone involved measuring prostate and seminal vesicle responses of castrated mature rats (6). The postwar search for an anabolic steroid required a measure of myotrophic activity and ultimately the levator ani muscle was selected (7) in what became standardized as the Hershberger bioassay (8) whereby myotropic (anabolic) could be separated from androgenic activity of synthetic androgens. However, even the original description noted the choice of the levator ani as being because “this muscle is more responsive to castration and testosterone than other striated muscles” (7), a choice of convenience probably reflecting the unusual androgen responsiveness characteristic of autonomically innervated pelvic organs (9) rather than intrinsic to that muscle (as implied by a musclespecific endpoint). This undermines the goal of reflecting all striated muscles, as implied by searching for an anabolic steroid. Recent studies (re)discover other limitations of the Hershberger-type bioassays whereby the relative (anabolic:androgenic) potency of a test chemical depends markedly on bioassay design features rather than being a relatively fixed characteristic of that chemical (10). Although the choice of muscle endpoint seemed adroitly practical, especially compared with the cumbersome alternatives (like nitrogen retention, or its modern succes-

Pharmacology of steroids used during epidural steroid injections

Steroids are well recognized for their excellent anti-inflammatory actions. After first steroid was used to treat painful arthritis, it became apparent that epidural steroid administration may be effective for management of sciatica pain and low back pain. Later on, other types of neural blockade techniques, such as facet joint injections, were described as the treatment option for low back pain. The most commonly used steroid preparations for the neuraxial blockade are methylprednisolone acetate (Depo-Medrol, Pfizer, New York, NY), triamcinolone acetonide and diacetate (Kenalog, Bristol-Myers Squibb, Princeton, NJ), betamethasone acetate (Celestone, Schering-Plough Corporation, Kenilworth, NJ), and dexamethasone (Decadron, Merch & Company Inc, West Point, PA). Glucocorticoids are postulated to improve immunologic activity and wound healing. They are also required to maintain normal carbohydrate, lipid, and protein metabolism. The formulations available for injectable steroids contain various chemicals, which include buffers, polyethylene glycol, benzyl alcohol, and benzalkonium chloride. Toxicities that are associated with epidural steroid injections (ESIs) are often delayed. There have been several cases that reported injury to the central nervous system following transforaminal ESIs. The most accepted explanation for this is an occlusion of the segmental artery by the steroid particulate matter or embolization through the vertebral artery.

Unraveling Androgen Action in Muscle: Genetic Tools Probing Cellular Mechanisms

For the largest tissue in the body and with functions relevant to virtually every medical discipline (although central to none), muscle physiology is surprisingly neglected in medical research. Despite profound discoveries in subcellular muscle structure and function winning Nobel prize recognition, understanding the physiological regulation of muscle as a tissue remains a mostly unexplored territory with few reliable landmarks. Perhaps in a world in which research remains most strongly propelled by discipline-based quests for knowledge, muscle as an orphan lacking a disciplinary home with the necessity and priority to drive deeper discovery has, accordingly, been relatively overlooked. Among the most salient biological clues to regulation of muscle function is the gender dimorphism in muscle mass and strength appearing after puberty and attributable to dramatic differences in endogenous androgen exposure. Considering the nearly 30-fold increase in testosterone production experienced across male puberty, men’s larger and stronger muscles testify to marked androgen dependence, providing an opportunity for pharmaceutical exploitation over the 7 decades since testosterone started being used clinically. Yet exploitation for therapeutic benefit has progressed slowly, due in part to the pharmaceutical industry’s failed, and then abandoned, quest for a pure anabolic (i.e. nonandrogenic) steroid in the postwar decades, the golden age of steroid pharmacology. By contrast, unscrupulous illicit androgen abuse has flourished on the fact of increased muscle mass and strength, which sufficed without requiring explanation (1). Only since decades of denial that exogenous androgens enhanced muscular mass and strength in eugonadal men (2) was overturned by the studies of Bhasin et al. (3) in the mid-1990s have androgens been clearly acknowledged as having the most potent known anabolic and ergogenic effects on skeletal muscle, a fact reflected by androgens continuing to be the most widely abused class of drugs used in sports doping as well as the wider community for nonmedical purposes (4). Rigorous, placebocontrolled studies show testosterone has dose-response effects on muscle mass (fiber hypertrophy) and strength from below to well above the physiological range in both young (5) and older (6) men. Furthermore, high-quality clinical studies show androgens increase muscle mass in various chronic diseases such as HIV wasting (7), chronic obstructive pulmonary disease (8), chronic renal disease (9), and burns (10) and possibly the frailty, falls, and fractures that diminish quality of life during ageing (11). Yet despite proven increases in muscle mass in a few small studies, androgens are not in routine clinical use for these indications because of both limited evidence of sufficient functional benefits and risks of adverse off-target effects on cardiovascular disease and the liver (for 17-alkylated androgens) as well as prostate disease in men and virilization or hormone-dependent cancers in women. Further pharmaceutical development coupled with well-controlled clinical studies still appears to have great, untapped potential for androgens as adjunctive therapy for ageing and chronic disease states. By modern biochemical definition, androgens act by binding to the androgen receptor (AR), a ligand-dependent nuclear transcription factor (12). Yet androgen action is complex, involving prereceptor enzymatic activation and postreceptor coregulator mechanisms (13) as well as cell and tissue specificity within target organs. Although androgens are classically considered reproductive hormones, AR is expressed almost ubiquitously (14) including in nonreproductive target tissues like skeletal muscle. Prereceptor activation of androgen action involves either amplification of testosterone to the more potent androgen dihydrotestosterone (15) or diversification by aromatization to estradiol with effects mediated via the estrogen receptor (ER)and (16). An additional mechanism of androgen action, involving nongenomic actions without apparently requiring DNA binding, remains ill defined and of unknown physiological importance (17). The pharmaceutical goal of separating androgenic (reproductive system, somatic virilization) from the anabolic (enhancing muscle and bone growth and function) actions of androgens has been revived after invention of the first nonsteroidal andro-

A fully dissociated compound of plant origin for inflammatory gene repression

The identification of selective glucocorticoid receptor (GR) modifiers, which separate transactivation and transrepression properties, represents an important research goal for steroid pharmacology. Although the gene-activating properties of GR are mainly associated with undesirable side effects, its negative interference with the activity of transcription factors, such as NF-kappaB, greatly contributes to its antiinflammatory and immune-suppressive capacities. In the present study, we found that Compound A (CpdA), a plant-derived phenyl aziridine precursor, although not belonging to the steroidal class of GR-binding ligands, does mediate gene-inhibitory effects by activating GR. We demonstrate that CpdA exerts an antiinflammatory potential by down-modulating TNF-induced proinflammatory gene expression, such as IL-6 and E-selectin, but, interestingly, does not at all enhance glucocorticoid response element-driven genes or induce GR binding to glucocorticoid response element-dependent genes in vivo. We further show that the specific gene-repressive effect of CpdA depends on the presence of functional GR, displaying a differential phosphorylation status with CpdA as compared with dexamethasone treatment. The antiinflammatory mechanism involves both a reduction of the in vivo DNA-binding activity of p65 as well as an interference with the transactivation potential of NF-kappaB. Finally, we present evidence that CpdA is as effective as dexamethasone in counteracting acute inflammation in vivo and does not cause a hyperglycemic side effect. Taken together, this compound may be a lead compound of a class of antiinflammatory agents with fully dissociated properties and might thus hold great potential for therapeutic use.

Use of filter paper for sample collection and transport in steroid pharmacology

Field studies of androgen pharmacology are complicated by the necessity to collect, process, and store blood samples in a central facility. We have assessed the feasibility of using capillary blood spots collected by fingerprick and dried on filter paper for pharmacokinetics and pharmacodynamic measurements with nandrolone and testosterone RIAs modified for extracts from capillary blood spots. Assays on punched spots of 7.9-mm diameter (14.9 microL of dried blood) permitted accurate quantification of testosterone down to 0.4 nmol/L from a single spot and nandrolone down to 0.9 nmol/L from two spots. Stability of the steroids in dried blood spots to adverse environmental conditions, notably increased temperatures, was investigated both in the laboratory and in field studies of dried spots sent through the postal system. Storage or postal transport under moderate conditions appeared to have no deleterious effects on apparent androgen concentrations. However, under extreme conditions of storage at 50 degrees C for a week or more, or transport to a very hot tropical location, a rise in the final concentration of nandrolone, and, to a lesser extent, testosterone when corrected for tracer recovery, was noticed. These effects were largely due to apparent susceptibility of tritiated tracer, but not unlabeled androgen, to thermal degradation. In a pilot pharmacological study involving intramuscular injection of 100 mg of nandrolone decanoate in 1 mL of arachis oil, nandrolone concentrations in concurrently collected plasma as well as venous and capillary blood spots showed good agreement. Testosterone concentrations in contemporaneously collected plasma and venous blood spots also showed very good agreement. We propose that these methods may allow patients and experimental subjects to self-collect samples at remote or field locations for convenient mailing to a central laboratory for androgen assay. Applications of this methodology are now under way.

Recent Progress in Hormone Research, Volume XIV.

The Proceedings of the Laurentian Conference of 1957 covers five primary topics. The first topic, Hormone Structure and Function, comprises ( a ) a general review of structure-activity relations of newer steroids; ( b ) the chemistry and biological activities of 16-hydroxylated steroids; ( c ) studies on the mechanism of action of estrogens, and ( d ) relations between the molecular structure of steroids and phenanthrene derivatives and growth of mammary tumors. Under ( a ) an almost complete pharmacopeia of new drugs is described. The pharmacology of steroids is a joint contribution by the synthetic chemist and the biologist in producing compounds with diuretic, ganglionic blocking, antihypertensive, lipoidiatic (antiatherogenic), antiovulatory, and many other properties. Under ( b ) the discussion of 16α-hydroxylation centers around the negation of sodium-retaining properties of corticosteroids without seriously compromising therapeutic properties. In ( c ) the effect of estrogen treatment on serine and protein synthesis in the uterus could be accounted for by increases in the

Antifibromatogenic potency of 9alpha-fluoro derivatives of progesterone.

THE use of halogenated pregnene derivatives, especially of 9α-fluoro-hydrocortisone, has been undoubtedly the greatest recent advance in the experimental pharmacology of steroids, as evidenced by the outstanding work of Fried and his colleagues1 on the various potencies of this corticoid. In the present communication we discuss results obtained in guinea pigs, in which we tried to prevent the abdominal fibromatogenic action of œstrogen; other antiœstrogenic potencies also have been studied.