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. will double the uterine cAMP activity within 15 s (Proc Natl Acad Sci USA 1967;58:1711-8), and also that estrogens will bind to the outer surfaces of endometrial cells (Nature 1977;265:69-72), suggesting that these steroids can both engage and direct intracellular events. Unfortunately, studies of such rapid membrane effects of steroids have languished due to the accumulation of compelling data for the more slowly manifest actions of these compounds at the level of nuclear DNA. We report a number of observations in women, in experimental animals, and in isolated organ or cell systems using 17beta-estradiol, progesterone or glucocorticoids which provide ample evidence for rapid intracellular metabolic responses to these steroids, mediated by their actions at the cellular plasma membrane. Such rapid responses have been shown in various classic targets or not, such as the B cell of the endocrine pancreas and the fat cell. They involve plasma membrane binding, changes in membrane electrical activity, Ca2+ handling, G and Ras proteins, cAMP, cGMP, IP(3), DAG, phosphodiesterases, protein kinases, tyrosine kinases, ER kinases, and mitogen activated protein kinases (MAPks) and nitric oxide synthase. These recent findings are discussed in detail and should lead to a fuller understanding of the cellular effects of the steroid hormones.     

The effects of sex steroids and vasotocin on behavioral responses to visual and olfactory sexual stimuli in ovariectomized female roughskin newts

Previous studies have found that vasotocin (AVT) administration to male roughskin newts (Taricha granulosa) enhances courtship clasping as well as appetitive responses to specific sexual stimuli and that treating female newts with androgens plus AVT induces the expression of male-typical courtship clasping (the selective clasping of females). However, the unique and/or interactive effects of sex steroids and AVT on appetitive responses to specific sexual stimuli have not yet been determined. To first identify male-typical, sexually dimorphic appetitive responses to female sexual stimuli, we tested intact newts during the breeding season and found that males, but not females, are attracted to female visual and pheromonal sexual stimuli. We then used ovariectomized (ovx) females implanted with empty silastic capsules (Blk) or with capsules containing testosterone (T), dihydrotestosterone (DHT), or estradiol (E2) and then injected with either saline or AVT to determine the effects of steroids and AVT, alone or in combination with each other, on male-typical behavioral responses to those stimuli. E2 treatment depressed responses toward female visual stimuli independently of AVT. On the other hand, only T-implanted, AVT-injected females displayed male-typical behavioral responses toward female olfactory stimuli, preferring to spend more time in proximity to female-scented than unscented newt models and selectively clasping the female-scented models. Together, these results support the conclusion that sex steroids and AVT influence behavioral responses to sexual stimuli via sensory-specific mechanisms. Furthermore, they suggest that T and AVT interact within the brain to influence sensorimotor processing in the pathways that integrate olfactory sexual stimuli into male-typical courtship behaviors.     

Sexually dimorphic effects of morphine and MK-801: sex steroid-dependent and -independent mechanisms.

Rats show gender differences in responses to morphine and the N-methyl-D-aspartate receptor antagonist dizocilpine (MK-801); the role of sex steroids in mediating these differences is unclear. We tested the overall hypothesis that circulating gonadal steroids determine the gender differences in morphine- and MK-801-induced behavior and c-Fos expression. Morphine caused a greater expression of c-Fos in the striatum of intact males than of that females, which was independent of sex steroids. MK-801 completely inhibited morphine-induced c-Fos in intact females but only caused partial inhibition in intact males; castrated males showed complete inhibition, which was reversed by testosterone, but gonadal steroids had no effect on this response in females. In thalamus, there was a large sex difference in the response to MK-801 that was independent of gonadal steroids. Behavioral responses to morphine were greater in males, but responses to MK-801 were greater in females; both were sex steroid independent. These findings show significant sex differences in response to morphine and MK-801 that are mediated by sex steroid-dependent and -independent mechanisms, which may be important in treatment outcomes of drug addiction.     

Slow infusions of vinblastine in the treatment of adult idiopathic thrombocytopenic purpura: a report on 43 cases

Forty-three adult patients with idiopathic thrombocytopenic purpura (ITP) were treated by slow intravenous infusions of vinblastine. Nineteen had ITP of recent onset (i.e. of less than 6 months duration) and had contraindication to steroids (3 patients), refractoriness to steroids (6 patients) or to steroids and high dose intravenous immunoglobulins (IVIg, 10 patients). Of the 19 patients, 10 achieved complete response (CR), 2 achieved partial response (PR), 2 had minor response (MR) and the remaining 5 patients had no response (NR). Six of the complete responders remained in CR after 12 to 48 months, whereas all other responders relapsed within 3 months, in spite of maintenance therapy. Twenty-four patients had chronic ITP (i.e. of 6 months duration or more) and had showed no or only transient response to steroids and/or splenectomy, and in many of them, to other therapeutic approaches. Four achieved CR, 4 PR, 6 MR and 10 NR. All but 3 responses were shorter than 3 months, in spite of maintenance therapy. Most responses to slow infusions of vinblastine began after the first infusion. Main side effects included leukopenia in 9 patients (but with absolute neutropenia in only one) and peripheral neuropathy in 2 patients. Interval from diagnosis was the only prognostic factor of response to treatment. We conclude that slow infusions of vinblastine may be a useful approach in ITP of recent onset, when contraindication or refractoriness to steroids and/or IVIg exists. In our experience, this treatment has limited benefit in chronic ITP. In addition, it remains to be demonstrated that slow infusions of vinca alkaloids have any superiority over intravenous bolus injections of the same drugs.     

Neuroactive steroids.

Neuroactive steroids are natural or synthetic steroids that rapidly alter the excitability of neurons by binding to membrane-bound receptors such as those for inhibitory and (or) excitatory neurotransmitters. The best-studied neuroactive steroids are a series of sedative-hypnotic 3 alpha-hydroxy ring A-reduced pregnane steroids that include the major metabolites of progesterone and deoxycorticosterone, 3 alpha-hydroxy-5 alpha-pregnan-20-one (allopregnanolone) and 3 alpha,21-dihydroxy-5 alpha-pregnan-20-one (allotetrahydroDOC), respectively. These 3 alpha-hydroxysteroids do not interact with classical intracellular steroid receptors but bind stereoselectively and with high affinity to receptors for the major inhibitory neurotransmitter in brain, gamma-amino-butyric acid (GABA). Biochemical and electrophysiological studies have shown that these steroids markedly augment GABA-activated chloride ion currents in a manner similar (but not identical) to that of anesthetic barbiturates. Several steroids have also been observed to have convulsant or proconvulsant properties, including the synthetic amidine 3 alpha-hydroxy-16-imino-5 beta-17-azaandrostan-11-one (RU5135) and the natural sulfate esters of pregnenolone and dehydroepiandrosterone. Several of these have been shown to be bicuculline or picrotoxin-like GABAA receptor antagonists. Examples of steroids that alter neuronal excitability rapidly by augmenting or inhibiting excitatory amino acid receptor-mediated responses have also been reported. Recently, allopregnanolone and allotetrahydroDOC have also been measured in brain and plasma where their levels have been shown to fluctuate in response to stress and during the estrous and menstrual cycles of rats and humans, respectively. Although the major fraction of allopregnanolone in tissue, including brain, is of adrenal and/or ovarian origin, appreciable levels of allopregnanolone can still be measured in the brains of adrenalectomized and/or oophorectomized animals. Receptor-active neurosteroids may represent an important class of neuromodulators that can rapidly alter central nervous system excitability via novel nongenomic mechanisms.     

Anabolic-androgenic steroid interaction with rat androgen receptor in vivo and in vitro: a comparative study

Anabolic steroids are synthetic derivatives of testosterone and are characterized by their ability to cause nitrogen retention and positive protein metabolism, thereby leading to increased protein synthesis and muscle mass. There are disagreements in the literature in regards to the interaction of anabolic steroids with the androgen receptor (AR) as revealed by competitive ligand binding assays in vitro using cytosolic preparations from prostate and skeletal muscle. By use of tissue extracts, it has been shown that some anabolic steroids have binding affinities for the AR that are higher than that of the natural androgen testosterone, while others such as stanozolol and methanedienone have significantly lower affinities as compared with testosterone. In this study we show that stanozolol and methanedienone are low affinity ligands of the rat recombinant AR as revealed by a ligand binding assay in vitro, however, based on a cell-based AR-dependent transactivation assay, they are potent activators of the AR. We also show that a single injection of stanozolol and methanedienone causes a rapid cytosolic depletion of AR in rat skeletal muscle. Based on these results, we conclude that anabolic steroids with low affinity to AR in vitro, can in fact in vivo act on the AR to cause biological responses.     

Low sodium intake enhances sensitivity of 11-deoxycortisol and deoxycorticosterone to ACTH in ACTH-suppressed normal subjects.

Continued administration of ACTH to patients with hypopituitarism produced normal increases in steroids dependent on microsomal cytochrome P450(21) and P450(17 alpha) but reduced responses of steroids dependent on mitochondrial cytochrome P450(11 beta-18). To explore possible mechanisms and to determine whether this dissociation occurs with short-term ACTH suppression, we have examined the steroid responses to ACTH after 1 h in 12 normal subjects after equilibration on sodium intakes of 124 mmol/d [normal sodium diet (NSD)], 22 mmol/d [low sodium diet (LSD)], and 240 mmol/d [high sodium diet (HSD)] before and during continued ACTH suppression with dexamethasone (DEX). Two distinct patterns of steroid responses were observed. Deoxycorticosterone (DOC) responses were initially reduced during LSD-DEX but eventually returned to the NSD-control (NSD-CONT) values; in contrast 18-hydroxydeoxycorticosterone and corticosterone remained suppressed. 11-Deoxycortisol and 21-deoxycortisol showed patterns similar to DOC, with a return to normal ACTH responses on LSD-DEX. Basal cortisol levels were reduced and the ACTH response was unchanged by LSD. HSD-DEX reduced basal levels of all steroids as well as their ACTH responses. LSD and/or increased activity of the renin-angiotensin system have a significant impact on 17 alpha- and 21-hydroxylation functions in the zona fasciculata to maintain a normal ACTH response of microsomally dependent steroids under these conditions. In contrast, on HSD-DEX with the renin-angiotensin system suppressed, there is generalized impairment of steroid responses to ACTH.     

Sex differences in Seoul virus infection are not related to adult sex steroid concentrations in Norway rats

Field studies of hantavirus infection in rodents report that a higher percentage of infected individuals are males than females. To determine whether males were more susceptible to hantavirus infection than females, adult male and female Long Evans rats (Rattus norvegicus) were inoculated with doses of Seoul virus ranging from 10(-4) to 10(6) PFU. The 50% infective doses (ID(50)) were not significantly different for male and female rats (10(0.05) and 10(0.8) PFU, respectively). To determine whether sex differences in response to infection were related to circulating sex steroid hormones, sex steroid concentrations were manipulated and antibody responses and virus shedding were assessed following inoculation with the ID(90). Regardless of hormone treatment, males had higher anti-Seoul virus immunoglobulin G (IgG) and IgG2a (i.e., Th1) responses than females and IgG1 (i.e., Th2) responses similar to those of females. Males also shed virus in saliva and feces longer than females. Manipulation of sex steroids in adulthood did not alter immune responses or virus shedding, suggesting that sex steroids may organize adult responses to hantavirus earlier during ontogeny.     

The influence of the adrenal glands upon acute spinal cord injury

The contribution of the adrenal glands to the pressor and nerve tissue necrotic responses that follow acute paralyzing spinal cord injury was determined in cats by total adrenal gland removal. The study suggests that either epinephrine or endogenous steroids may exert posttraumatic protective influences on the cord since after adrenalectomy, both the systematic pressor response and local hemorrhagic necrosis are significantly increased.     

Neuroactive steroids alter the circadian system of the Syrian hamster in a phase-dependent manner

Several steroid compounds affect neuronal function, primarily by modulating the GABAA receptor complex. A circadian variation in the brain concentration of neurosteroids has been reported in rats and humans. We have previously reported that natural occurring or synthetic neuroactive steroids such as androsterone and alphaxalone also have a rhythmic effect on behavior (anesthetic and anticonvulsant activity) and GABAergic activity. In the present work, we have tested the ability of neuroactive steroids to phase shift circadian rhythms in hamsters. The GABA(A) negative modulator dehydroepiandrosterone sulphate (DHEAS) elicited phase advances when administered at CT 6, while the positive modulator androsterone lacked any effect at this time. A complete phase response curve for DHEAS revealed a nonphotic-like effect. DHEAS also blocked the circadian effects of light, while androsterone induced photic-like responses. There is also evidence that neurosteroids may be present and even synthesized in the SCN. Collectively, the results so far indicate that some neuroactive steroids might modulate the activity of the circadian clock.     

THE OUTWARD TRANSPORT OF CORTISOL BY MAMMALIAN CELLS IN VITRO

It has been determined that cortisol and a few other steroids are transported outward from certain mammalian cells growing in vitro. The extrusion process is temperature dependent, glucose dependent, saturable, and operates for only a few selected steroids. Many, but not all, steroids are able to block the extrusion process but are not themselves transported. The outward transport process for steroids has been found in mouse fibroblasts, mouse lymphoma cells, and functional mouse adrenal gland tumor cells growing in vitro. The transport process is not present in two varieties of cells cultured from human sources—HeLa or diploid fibroblasts, WI-38.     

Effects of steroids on the regulation of the levels of cyclic AMP in human lymphocytes

Glucorticosteroids, and estradiol increase the cyclic AMP response of lymphocytes to isoproterenol and PGE. This response, unlike the usual steroid responses initiated by specific cytoplasmic steroid receptors, does not require the biosynthesis of macromolecules for its activity. The effect may depend partially on the inhibitory effect of steroids on cyclic nucleotide phosphodiesterase. The potentiating effect of steroids however, is greater than that can be achieved with theophylline, a more potent inhibitor of phosphodiesterase prepared from lymphocytes.     

Gonadal steroids and astroglial plasticity

Summary 1. Recent evidence indicates that astroglia participate in the metabolism of gonadal hormones, in the synthesis of neurosteroids, and in the plastic responses of neurons to gonadal steroids. The role of astroglia on plastic responses of neural tissue to gonadal hormones and neurosteroids is examined in this review.2. Gonadal steroids and neurosteroids promote astroglia plasticity in several areas of the central nervous system, including the hypothalamus, the striatum, and the hippocampus.3. Gonadal steroids and neurosteroids modulate astroglia proliferation and the formation of reactive astroglia after brain injury.4. Astroglia is a source of trophic factors that may mediate effects of gonadal steroids on neural tissue.5. Astroglia is involved in the promotion of synaptic plastic changes by gonadal hormones.6. The effect of gonadal hormones on astroglial plasticity is dependent on specific membrane interactions with neurons and on the expression of the embryonic highly polysialylated isoform of the neural cell adhesion molecule on neuronal membranes.7. In conclusion, coordinated responses of neurons and astroglia appear to be involved in the modulation of neural function and response to injury by gonadal hormones and neurosteroids.     

Independent influences of sex steroids of systemic and central origin in a rat model of Parkinson's disease: A contribution to sex-specific neuroprotection by estrogens

This review considers evidence which reveals considerable complexity and sex differences in the response of the nigrostriatal dopaminergic (NSDA) system to hormonal influences. This pathway degenerates in Parkinson's disease (PD) and sex hormones contribute to sex differences in PD, where men fare worse than women. Here we discuss evidence from animal studies which allows us to hypothesize that, contrary to expectations, the acclaimed neuroprotective property of physiological concentrations of estradiol arises not by promoting NSDA neuron survival, but by targeting powerful adaptive responses in the surviving neurons, which restore striatal DA functionality until over 60% of neurons are lost. Estrogen generated locally in the NSDA region appears to promote these adaptive mechanisms in females and males to preserve striatal DA levels in the partially injured NSDA pathway. However, responses to systemic steroids differ between the sexes. In females there is general agreement that gonadal steroids and exogenous estradiol promote striatal adaptation in the partially injured NSDA pathway to protect against striatal DA loss. In contrast, the balance of evidence suggests that in males gonadal factors and exogenous estradiol have negligible or even harmful effects. Sex differences in the organization of NSDA-related circuitry may well account for these differences. Compensatory mechanisms and sexually dimorphic hard-wiring are therefore likely to represent important biological substrates for sex dimorphisms. As these processes may be targeted differentially by systemic steroids in males and females, further understanding of the underlying processes would provide valuable insights into the potential for hormone-based therapies in PD, which would need to be sex-specific. Alternatively, evidence that estrogen generated locally is protective in the injured male NSDA pathway indicates the great therapeutic potential of harnessing central steroid synthesis to ameliorate neurodegenerative disorders. A clearer understanding of the relative contributions and inter-relationships of central and systemic steroids within the NSDA system is an important goal for future studies.     

Behavioural and electrophysiological responses by reproductive female Neogobius melanostomus to odours released by conspecific males

Behavioural and electrophysiological responses of reproductive and non‐reproductive female round gobies Neogobius melanostomus to water previously occupied by male round gobies (reproductive male water) were compared. Reproductive females spent more time than non‐reproductive females in a tank near the input of water conditioned from reproductive males. Also, reproductive females swam significantly faster than non‐reproductive females, suggesting that reproductive male odour may have activated spawning behaviour. Olfactory epithelial field potential measurement (electro‐olfactogram, EOG) showed that reproductive male water was a potent olfactory stimulus to reproductive females, but not to non‐reproductive females. Reproductive females responded significantly more than non‐reproductive females to solid‐phase (octadecylsilane) extracts of reproductive male water. Also, when these extracts were separated on reverse phase high performance liquid chromatography (HPLC), reproductive females showed noticeably greater responses than non‐reproductive females to the fractions that eluted between 30 and 40 min. The behavioural data support the hypothesis that reproductive male round gobies release compounds into the water that attract potential mates. The EOG data indicate that these compounds can be quantitatively extracted from the water and be partially purified by HPLC. The evidence is not sufficient to indicate whether or not the compounds are steroids. The relatively early elution time on HPLC, however, suggests that if these compounds are steroids, then it is more likely that they will be conjugated rather than free steroids.     

Role of cyclic AMP in steroid action in rat intestine

We have investigated the effect of mineralocorticoids on intestinal fluid and electrogenic glucose-linked Na+ transport across isolated sections of the rat small intestine. A rapid in vitro response is observed that contrast with the delay normally associated with steroid hormone responses. Cyclic AMP is known to affect intestinal glucose, water and Na+ transport and the effects of the steroids may be understood in terms of an inhibitory effect on intestinal cyclic AMP production. An inhibitory effect of the steroids on membrane-bound adenylate cyclase has been demonstrated and dose-response effects suggest the presence of specific membrane-bound glucocorticoid receptors.     

Assessment of adrenal function by measurement of salivary steroids in response to corticotrophin in patients infected with human immunodeficiency virus

OBJECTIVE: Adrenal insufficiency has been reported among critically ill HIV-infected patients. This is the first study that attempts to detect subclinical hypoadrenal states in non-critical HIV patients through salivary steroids in response to intramuscular low-dose ACTH injection. PATIENTS AND METHODS: We studied 21 ambulatory adult HIV-infected patients without specific clinical signs or symptoms of adrenal insufficiency. Normal salivary flow-rate and salivary alpha-amylase activity confirmed adequate salivary gland function. Salivary cortisol (SAF) and salivary aldosterone (SAL) were obtained at baseline and 30 min after the injection of 25 microg of ACTH in the deltoid muscle (LDT(s)). Assessment of salivary steroids after stimulation with 250 microg of intramuscular ACTH (HDT(s)) was performed on those who hyporesponded to LDT(s). Basal blood samples were drawn for steroids, renin and ACTH measurements. RESULTS: At baseline SAF and SAL correlated significantly (p=0.0001) with basal serum cortisol and aldosterone (r=0.70 and 0.91, respectively). Plasma ACTH and renin concentrations were within the normal range in all patients. Eight of the twenty-one HIV(+) patients were LDT(s) hyporesponders in either SAF (n:1) or SAL (n:7). LDT(s) repeated in six cases after a year reconfirmed the impairment of aldosterone secretion. LDT(s) hyporesponders had normal steroid responses to HDT(s). CONCLUSIONS: LDT(s) is a simple, safe, well-accepted and non-invasive approach to assess adrenal function in HIV-infected ambulatory patients. It revealed subnormal cortisol (5%) and aldosterone responses (33%) when HDT(s) results were normal.