Steroid Function Research Articles

Solubilization and pharmacological characterization of a glucocorticoid membrane receptor from an amphibian brain

Physiological functions of steroid hormones involve activation of intracellular receptors as well as poorly understood membrane receptors. We report the pharmacological characterization of a solubilized corticosterone receptor from neuronal membranes. This receptor previously was shown to localize with plasma membrane subcellular fractions and to be involved in the modulation of courtship behaviors in the roughskin newt ( Taricha granulosa). We describe procedures with non-ionic detergents that solubilize the receptor and maintain high affinity [ 3H]corticosterone binding. The pharmacology of the solubilized corticosterone receptor resembles that of the membrane receptor with high affinity for [ 3H]corticosterone and an identical rank-order potency for other steroid ligands (corticosterone>cortisol>aldosterone>dexamethasone). Unlike binding in membrane preparations, [ 3H]corticosterone binding to the solubilized receptor is insensitive to negative modulation by guanyl nucleotides and only modestly sensitive to the presence of Mg 2+. We also identified two ligands that exhibit high affinity binding to the solubilized receptor and have the potential to be used in an affinity purification scheme. They are corticosterone-3-carboxymethyloxime (CORT-3-CMO), which may be covalently attached to a Sepharose resin, and a derivitized azide form of CORT-3-CMO which can be covalently coupled to the solubilized receptor itself. The stability of the solubilized [ 3H]corticosterone receptor in the detergent system will facilitate further purification and molecular characterization.

Effects ofin Uteroand Lactational Exposure of the Laboratory Rat to 2,4,2′,4′- and 3,4,3′,4′-Tetrachlorobiphenyl on Dopamine Function

Offspring of Sprague–Dawley derived dams were exposed to either 2,4,2′,4′-tetrachlorobiphenyl (TCB) (1, 10, or 20 mg/(kg·day)) or 3,4,3′,4′-TCB (0.1 or 1 mg/(kg·day)) from gestational Day 6 through weaning by providing the dams with cookies adulterated with the appropriate amount and type of PCB. Male and female offspring were sacrificed on postnatal Days 35, 60, and 90, and brain concentrations of dopamine and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, were determined in the frontal cortex, caudate nucleus and substantia nigra by high-performance liquid chromatography with electrochemical detection.In uteroand lactational exposure to 3,4,3′,4′-TCB resulted in significant elevations in concentrations of dopamine in the frontal cortex, and of dopamine and its metabolites in the substantia nigra that persisted into adulthood. In contrast,in uteroand lactational exposure to 2,4,2′,4′-TCB resulted in significant decreases in concentrations of dopamine in the frontal cortex and caudate nucleus that also persisted into adulthood. We suggest that the reductions in brain dopamine concentrations are a consequence ofortho-substituted PCB congener-induced inhibition of the synthesis of dopamine during critical periods of development acting, perhaps, in concert with PCB-induced changes in cholinergic receptor function. On the other hand, the persistent elevations in brain dopamine and metabolite concentrations following perinatal exposure to 3,4,3′,4′-TCB may be mediated by alterations in steroid hormone function during key developmental periods.

Stability of EEG inter-and intrahemispheric correlation in women

EEG correlation and coherence analyses have been used to study functional relationships between cortical regions, and found to vary as a function of physiological conditions, sex hormones and cognitive processes. However, the utility of serial EEG studies is dependent upon the within-subject reliability of repeated EEG recordings. The present study was undertaken to assess the within-subject and within-group stability of EEG correlations in a group of young women (n = 9). EEG was recorded during relaxed wakefulness at F3, F4, C3, C4, P3, P4, O1 and O2 for 11 sessions, during 1 month. Ten artifact-free 2-s epochs of EEG from each session were digitally filtered by means of a fast Fourier transform into 6 broad bands, and correlation coefficients between the EEG activity of every pair of derivations and bands were calculated in the time domain. All EEG features were submitted to principal component analysis and the first 5 components did not show significant differences between sessions (ANOVAs) for any band or pair of derivations. Alpha and beta showed higher variability whereas slow bands showed very little variability. The within-subject stability was assessed calculating multiple correlation coefficients between all EEG features of the eleven sessions of each subject: R-values ranged from 0.85 to 0.97. Present results indicate that the pattern of functional relationships between cortical regions during resting wakefulness is a stable characteristic for each woman at least over a 1 month period and that there are no significant group differences over sessions when menstrual phases are randomly distributed between women.

Inhibition of human and rabbit liver steroid and xenobiotic UDP-glucuronosyltransferases by tertiary amine drugs--implications for adverse drug reactions.

1. To investigate the hypothesis that disruption of glucuronidation of endogenous compounds by drugs represents a potential mechanism for pathogenesis of adverse drug reactions, the effects of a range of tertiary amine and amide drugs (many with effects on sex hormone function) on steroid hormone and xenobiotic UDP-glucuronosyltransferase activities in human and rabbit liver microsomes were studied in vitro. 2. Chlorpromazine, amitriptyline, imipramine, promethazine and cyproheptadine were consistently the most potent inhibitors of the glucuronidation of testosterone, androsterone, oestriol and 1-naphthol, the steroid activities being more susceptible to inhibition (up to 90%). 3. Carbamazepine, diphenhydramine, sulphadimethoxine, dimenhydrinate and (+/-)-chlorpheniramine had little effect on the UDPGT activities measured. 4. The structural features within this group of compounds required for inhibitory potency were the presence of a rigid tricyclic ring (e.g. phenothiazine) and either a dimethylaminopropyl or a methylpiperidine side-chain. 5. The implications of these data for involvement of disruption of the normal cellular function of glucuronidation in the pathogenesis of frequently observed adverse side-effects associated with these compounds are discussed.

Stereochemical complementarity of progesterone and cavities between base pairs in partially unwound double stranded DNA using computer modeling and energy calculations to determine degree of fit

Computer modeling was applied for the first time to investigate previously reported complementarity of progesterone and cavities formed between base pairs in partially unwound double stranded DNA. Computer graphics enabled a more objective assessment of complementarity; energy calculations provided a rigorous method to evaluate degree of fit. Graphics confirmed that the complementarity was virtually “lock and key”, i.e. close contacts were formed between van der Waals surfaces in the progesterone/DNA complexes and hydrogen bonds were formed between the two carbonyl groups on opposite ends of the steroid and phosphate groups on adjacent strands of DNA. Molecular mechanics calculations revealed that insertion of the steroid resulted in a relatively stable complex i.e. both van der Waals and electrostatic energies were lowered due to favorable steric interactions and stereospecific hydrogen bonds, respectively. Three published X-ray crystal structures of progesterone exhibited similar complementarity. Ent-progesterone which does not occur naturally possessed very poor complementarity. These findings confirm that the structure of progesterone is directly reflected in the stereochemistry of DNA. While no mechanistic explanation for these results is proffered, we hypothesize that such complementarity must have played a decisive role in the evolution of steroid hormone structure and function.

Dualism in biology: The case of sex hormones

In the last decades the subject of sex hormones has intruded into the lives of many women, not only by the introduction of hormonal contraceptives but also by creating the image of the hormonal woman. Biology tells us that our preference for dolls or cars, our sexual orientation, and even our career choice is “all in our hormones.” In the early decades of this century biologists introduced male and female sex hormones as the chemical messengers of femininity and masculinity. Since the introduction in the 1920s the concept of male and female sex hormones has been translated into innumerable theories on masculinity and femininity. This paper presents an analysis of two episodes of the history of sex hormones: the birth of sex hormones (1920–1940) and more recently the introduction of the theory on prenatal function of sex hormones (1959–1985). We discuss how the development of research on sex hormones in both episodes was structured by the cultural assumption of sexual duality, and how in the 1970s more liberating views on sex differences emerged from endocrinology.

CUTANEOUS ABNORMALITIES IN ANOREXIA NERVOSA

Anorexia Nervosa (A.N.) is a relatively common eating disorder with well recognised psychological and physiological features. A study of 14 female patients with A.N. revealed a number of dermatological disorders, including lanugo hair, xeroderma and hyperpigmentation. Laboratory investigations revealed various abnormalities including elevated Beta-carotene levels, abnormal sex hormone and thyroid function. An unusual finding was the development of acne in a small subset of patients at the time of weight gain, during recovery from A.N. Anorexia Nervosa represents a useful model for the interaction between eating disorders, endocrine function and the skin.

Endocrinologists and the conceptualization of sex, 1920-1940.

The study of sex differences in modern biomedical sciences has a tradition that dates only from the eighteenth century. Earlier scientists were not very interested in differences between the sexes. They assumed that there existed one basic structure for the human body; men and women were thought to differ only in the anatomy of their genitalia. It was in the course of the eighteenth century that the study of sex became a priority in scientific research. After 1750, publications appeared suggesting that the description of the female body had been ignored by leading physiologists, and scientists were encouraged to study sex differences. Following these suggestions, scientists took up the study of skeletons, blood, and other anatomical and physiological features, comparing male and female organisms.' In the twentieth century new ways of studying sex were introduced through the emergence of new fields of science, including the important field of endocrinology. Endocrinologists defined sex on the basis of a new concept: sex hormones. The early development of sex endocrinology was directed by the underlying assumption of a dualistic concept of sex, according to which female sex hormones could be found only in the female organism, and male sex hormones were believed to be present only in males. However, starting in the 1 920s the idea of maleness and femaleness as clearly defined endocrinal states became a topic of debate in the scientific community. Observations on the origin and function of sex hormones contradicted the original concept of sexual specificity, and by 1940 it had been transformed into a concept of relative sexual specificity. Maleness and femaleness were

A concept of physiological time: rhythms in behavior and reproductive physiology.

Biological clocks are self-sustained and endogenous. Animals have biological clocks in a variety of frequencies. Biological clocks provide temporal coordination among physiological, behavioral, and environmental events. One important function of steroid hormones may be to alter the temporal coordination among those events. Biological clocks provide a referent mechanism for the timing of both current and future endogenous and exogenous events. Physiological time is a unifying principle in biology.

Personality and sexuality in relation to an index of gonadal steroid hormone balance in a 70-year old population.

Relationships between an index of gonadal steroid hormone function and personality as well as sexual activity were studied in a sample representative for 70-year-olds in Gotenburg, Sweden. Personality was described by means of inventories, sexual activity through a systematic interview and the balance between androgen and oestrogen activity by the quotient between lecithin and lysolecithin in plasma. Men with a relative dominance of oestrogen activity reported a lower frequency of sexual intercourse than other men. Women with a relative dominance of oestrogen activity described themselves as more resourceful, active, confident, unconcerned with the opinion of others, and able to take care of themselves than other women. There were no associations in women between the hormonal balance and the frequency of sexual intercourse.

Ionic transport through model membranes. II. Function of cholesterol and steroid hormones

1. 1. The kinetics of transfer of a water-soluble azo dye, Orange IV, from an aqueous into phospholipid micelles in an adjacent organic phase have been investigated as a method of evaluating the possible effects of various hydrocarbons on the structure of the lipid micelles and interfacial films. The transport of this dyestuff probe apparently requires the presence of unsaturated alkyl chains in the lipid, provided by egg phosphatidylcholine or by synthetic lecithin (1-oleyl-2-hexadecyl ether). 2. 2. The kinetics had previously been shown to be retarded by those n- alkanes that are promoters of carcinogenesis. On the basis of this correlation it had been predicted n- C 18H 38 and n- C 20H 42 should be the most active biologically of the n- alkanes . This has been confirmed in detail by biological tests for promoting activity. 3. 3. Inclusion of cholesterol and various steroid metabolites, including androgens and progestogens, had profound effects on the rate of dye transport by egg phosphatidylcholine (very little transfer to the bulk organic phase was achieved by the steroids without the phospholipid). Cholesterol had the maximum retarding effect, but increased somewhat the ultimate equilibrium transfer of dye to the micelles in the organic phase. 4. 4. The C 19 steroids, dihydrotestosterone, testosterone, androsterone, and epiandrosterone enhanced the rate of transport by lecithin-cholesterol micelles in different critical ranges of concentration. The four steroids were thus ranked in the same order of effective concentration in the model transport system as they are in assays of their biological activities as androgens. The metabolic intermediate, pregnenolone, affected the transport kinetics similarly to testosterone. In contrast, the C 21 hormone, progesterone, and the estrogen analog, diethylstilbestrol, retarded ionic transport in this model.

An experimental basis for carcinogenic effects of ultraviolet radiation.

Several hypotheses to explain ultraviolet carcinogenesis have been advanced. One such theory contended that cholesterol was directly involved in actinic carcinogenesis. Although the hypothesis, in its original form, was generally abandoned by the scientific community, it has been revived and modified from time to time as structures and functions of steroid hormones become more clearly understood. In essence it suggests that carcinogenic substances, structurally related to steroid hormones might result from photochemical conversion of cholesterol. Although some compounds with such properties have been isolated under controlled chemical conditions, until recently the failure to find such compounds in biological systems had cast serious doubt upon the validity of this hypothesis. It has now been demonstrated that cholesterol-derived oxidation products are formed in human skin upon exposure to ultraviolet light. One of the products formed is known to possess carcinogenic properties when administered to experimental animals.

Independent variation of glucagon and epinephrine responsive components of hepatic adenyl cyclase as a function of age, sex and steroid hormones.

This study presents data which indicate that the activities of the glucagon and epinephrine responsive components of hepatic adenyl cyclase vary separately as a function of age, sex and steroid hormone levels in the rat. These observations lend support to the hypothesis that the 2 hormonally sensitive adenyl cyclase systems in liver are independent. (Endocrinology86: 154, 1970)

Pharmacologic alteration of steroid hormone functions.

A large number of compounds can modify the function, synthesis, or metabolism of steroid hormones. These are not necessarily otherwise related chemically or pharmacologically. The drugs used as examples in this review were selected to show the wide variety of potential sites and modes of action. While many compounds have been shown to interfere with one or another step in the biosynthesis of corticosteroids, the number of known substances having any profound effect on gonadal steroidogenesis is surprisingly few. On the other hand, many more compounds are known either to mimic or modify the end‐organ response to gonadal than to adrenal steroids. The field of endocrine pharmacology is being rapidly widened as systematic searches are now being made for drugs which affect endocrine function either as a primary or incidental action.

Experimental Studies on essential cause for the sexual difference of the thyroid function

It has been clincically known that thyroid diseases are seen more frequently in the female than in the male. However, the sexual differences are not as yet fully explained. For this purpose, effects of castration on the thyroid function and effects of gonadal steroid hormones on the thyroid function of the castrate mature rats of both sexes were investigated. For determination of the thyroid function, radioactive iodine I131 was used and remarkable findings were obtained.The results are summarized as follows : 1) Effects of castration on the thyroid function were manifested by hypofunction, usually, 14 days in the female and 42 days in the male, after castration, and greater changes were found in females than in males, and the effects were persisted even 2 months after the castration. It may be concluded that those greater changes in females without distinction to post-operative period had apparently indicated the fact that there are substantial differences of the thyroid function between male and females.2) It is the matter of course that sexual differences should be looked for in the gonads. But, for the explanation of this mechanism, 3 kinds of steroid hormones ; estradiol benzoate, progesterone, and testosterone propionate were administered to the castrated mature rats and these effects on the thyroid function were examined. Marked differences have been found to exist between two sexes.(1) Estrogen has an accelerating effects on the thyroid uptake of I131 for the female, and on the release of thyroid hormone in the blood of male rats. This diverse response against estrogen is considered to be attributable to the difference in the affinity of the thyroid to estrogen.(2) When progesterone is injected to the castrated female rats, no changes were found, and in the male, decreased thyroid uptake of I131 was found 14 days, and no obvious changes occurred 2 months after castration.(3) Androgen has no constant effects on the thyroid of the castrated both sexes.(4) By the fact that estrogen has coherent effects on the thyroid while androgen causes no change, it can be assumed that the sexual differences are chiefly attributable to estrogen.(5) The results of steroid hormones injection indicated that in the female thyroid is closely related with the gonad, while the thyroid in the male is not under this control.(6) Estrogen has an accelerating effects on the female thyroid uptake of I132 irrespective of post-operative periods, suggests the reason for the more frequent occurrence of thyroid diseases in the female.3) In order to explain the mechanism in which estrogen is the primary fractor on the sexual differences of the thyroid, estrogen was administered to the hypophysectomized female rats and its effect was investigated. Thyroid uptake of I131 showed remarkable increase in comparison with the control groups. By this fact, it can be noted that the estrogen has a direct effects on the thyroid.