DRUG AND ALCOHOL REVIEW, Issue 2 2009
An ESBRA Symposium report
Abstract There is growing evidence for a role of appetite-related peptides and volume-regulating hormones in alcoholism. In particular, recent evidence has suggested that hormones, such as ghrelin, insulin and leptin and volume-regulating hormones, could play a role in alcohol-seeking behaviour. The goal of this review is to discuss the results of recent preclinical and clinical investigations on this topic. The findings indicate that neuroendocrinological mechanisms are potentially involved in the neurobiology of alcohol craving. Accordingly, research on this topic could lead to possible development of new therapeutic approaches in the treatment of patients with alcohol problems. [Addolorato G, Leggio L, Hillemacher T, Kraus T, Jerlhag E, Bleich S. Hormones and drinking behaviour: New findings on ghrelin, insulin, leptin and volume-regulating hormones. An ESBRA Symposium report. Drug Alcohol Rev 2009] [source]

The Influence of Gonadal Hormones on Neuronal Excitability, Seizures, and Epilepsy in the Female

EPILEPSIA, Issue 9 2006
Helen E. Scharfman
Summary:, It is clear from both clinical observations of women, and research in laboratory animals, that gonadal hormones exert a profound influence on neuronal excitability, seizures, and epilepsy. These studies have led to a focus on two of the primary ovarian steroid hormones, estrogen and progesterone, to clarify how gonadal hormones influence seizures in women with epilepsy. The prevailing view is that estrogen is proconvulsant, whereas progesterone is anticonvulsant. However, estrogen and progesterone may not be the only reproductive hormones to consider in evaluating excitability, seizures, or epilepsy in the female. It seems unlikely that estrogen and progesterone would exert single, uniform actions given our current understanding of their complex pharmacological and physiological relationships. Their modulatory effects are likely to depend on endocrine state, relative concentration, metabolism, and many other factors. Despite the challenges these issues raise to future research, some recent advances have helped clarify past confusion in the literature. In addition, testable hypotheses have developed for complex clinical problems such as "catamenial epilepsy." Clinical and animal research, designed with the relevant endocrinological and neurobiological issues in mind, will help advance this field in the future. [source]

The skin as a mirror of the ageing process in the human organism , results of the ageing research in the German National Genome Research Network 2

EXPERIMENTAL DERMATOLOGY, Issue 8 2006
CH. C. Zouboulis
Intrinsic human skin ageing is influenced by the individual genetic predisposition and reflects degradation processes of the body. Hormones are decisively involved in intrinsic ageing with reduced secretion of pituitary, adrenal glands, and gonads, which leads to characteristic body and skin phenotypes. A number of advances were recently made in understanding skin ageing mechanisms and major molecular changes, especiallly of the extracellular matrix, were identified. Gene expression patterns compatible with mitotic misregulation and alterations in intracellular transport and metabolism were identified in fibroblasts of ageing humans and humans with progeria. Age-associated changes of extracellular matrix of the skin correlate well with changes been detected in the extracellular matrix of other organs of the human body. Within the National Genome Research Network 2 (NGFN-2) in Germany, the explorative project ,Genetic etiology of human longevity' targets the identification of age-related molecular pathways. For this purpose, skin models of ageing are used. Expression profiling employing cDNA microarrays from known and novel genes and RT-PCR are employed for gene detection and confirmation. Among the potential candidate genes several interesting target genes have been identified. The evaluation of ageing-associated genes in skin models will facilitate the understanding of global molecular ageing mechanisms in the future. [source]

Hormones as epigenetic signals in developmental programming

EXPERIMENTAL PHYSIOLOGY, Issue 6 2009
Abigail L. Fowden
In mammals, including man, epidemiological and experimental studies have shown that a range of environmental factors acting during critical periods of early development can alter adult phenotype. Hormones have an important role in these epigenetic modifications and can signal the type, severity and duration of the environmental cue to the developing feto-placental tissues. They affect development of these tissues both directly and indirectly by changes in placental phenotype. They act to alter gene expression, hence the protein abundance in a wide range of different tissues, which has functional consequences for many physiological systems both before and after birth. By producing an epigenome specific to the prevailing condition in utero, hormones act as epigenetic signals in developmental programming, with important implications for adult health and disease. This review examines the role of hormones as epigenetic signals by considering their responses to environmental cues, their effects on phenotypical development and the molecular mechanisms by which they programme feto-placental development, with particular emphasis on the glucocorticoids. [source]

The Effects of Steroid Hormones on the Transcription of Genes Encoding Enzymes of Oxidative Phosphorylation

EXPERIMENTAL PHYSIOLOGY, Issue 1 2003
Klaus Scheller
Regulation of energy metabolism is one of the major functions of steroid hormones. In this process, mitochondria, by way of oxidative phosphorylation, play a central role. Depending on the energy needs of the cell, on the tissue, on the developmental stage and on the intensity of the hormonal stimulus, the response can be an activation of pre-existing respiratory chain components, an increased transcription of nuclear-encoded and/or mitochondrial-encoded respiratory chain enzyme (OXPHOS) genes and of biosynthesis of the respective enzyme subunits or, in extreme cases of high energy needs, an increase in the number of mitochondria and mitochondrial DNA content per cell. Some of the hormonally regulated systems involving effects on nuclear and mitochondrial OXPHOS genes are reviewed in this paper. The possible molecular mechanisms of steroid hormone action on nuclear and mitochondrial gene transcription and possible ways of coordination of transcription in these two separate cell compartments involving direct interaction of steroid receptors with hormone response elements in nuclear OXPHOS genes and in mitochondria and induction/activation of nuclear-encoded regulatory factors affecting mitochondrial gene transcription are presented. [source]

Ovarian Sex Hormones and Headache

HEADACHE, Issue 2 2007
Article first published online: 13 FEB 200
No abstract is available for this article. [source]

Ovarian Hormones and Migraine Headache: Understanding Mechanisms and Pathogenesis,Part 2

HEADACHE, Issue 3 2006
Vincent T. Martin MD
Migraine headache is strongly influenced by reproductive events that occur throughout the lifespan of women. Each of these reproductive events has a different "hormonal milieu," which might modulate the clinical course of migraine headache. Estrogen and progesterone can be preventative or provocative for migraine headache under different circumstances depending on their absolute serum levels, constancy of exposure, and types of estrogen/progesterone derivatives. Attacks of migraine with and without aura respond differently to changes in ovarian hormones. Clearly a greater knowledge of ovarian hormones and their effect on migraine is essential to a greater understanding of the mechanisms and pathogenesis of migraine headache. [source]

Migraine and Sex Hormones: Epidemiological Data Stimulate Rethinking of Etiologic Role of Estrogen

HEADACHE, Issue 9 2004
Vinod Kumar Gupta MD Dr.
No abstract is available for this article. [source]

Hormones, gender and the aging brain,the endocrine basis of geriatric psychiatry.

INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 12 2001
Mary F. Morrison (ed).
No abstract is available for this article. [source]

Sex Hormones and Sexual Desire

JOURNAL FOR THE THEORY OF SOCIAL BEHAVIOUR, Issue 1 2008
JAMES GILES
ABSTRACT Some scholars attempt to explain sexual desire biologically by claiming that sex hormones play a necessary causal role in sexual desire. This can be claimed even if sexual desire is seen to be an experience. Yet the evidence for such biological essentialism is inadequate. With males the loss of sexual desire following hormonal changes can easily be explained in terms of social stigmas that are attached to the physiological situation. Concerning females, the relevance of sex hormones here is even more unclear. Although some women seem to have fluctuations in sexual desire during hormonal changes, other women do not. Even where there are such fluctuations these can be explained by responses to other physiological changes or the meanings that are attached to the situation. Research with non-human primates supports this view of the non-essential relation of sex hormones to sexual desire. A phenomenology of sex hormones is given that shows a possible non-essential relation between sex hormones and sexual desire. Here hormone induced excitations in the genitals may or may not lead to sexual desire depending on the meaning they are given within awareness. This suggests that sexual desire has its origin in the meanings we give our biology and not in our biology itself. [source]

Wintertime Vitamin D Supplementation Inhibits Seasonal Variation of Calcitropic Hormones and Maintains Bone Turnover in Healthy Men,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2009
Heli T Viljakainen
Abstract Vitamin D is suggested to have a role in the coupling of bone resorption and formation. Compared with women, men are believed to have more stable bone remodeling, and thus, are considered less susceptible to the seasonal variation of calcitropic hormones. We examined whether seasonal variation exists in calcitropic hormones, bone remodeling markers, and BMD in healthy men. Furthermore, we determined which vitamin D intake is required to prevent this variation. Subjects (N = 48) were healthy white men 21,49 yr of age from the Helsinki area with a mean habitual dietary intake of vitamin D of 6.6 ± 5.1 (SD) ,g/d. This was a 6-mo double-blinded vitamin D intervention study, in which subjects were allocated to three groups of 20 ,g (800 IU), 10 ,g (400 IU), or placebo. Fasting blood samplings were collected six times for analyses of serum (S-)25(OH)D, iPTH, bone-specific alkaline phosphatase (BALP), and TRACP. Radial volumetric BMD (vBMD) was measured at the beginning and end of the study with pQCT. Wintertime variation was noted in S-25(OH)D, S-PTH, and S-TRACP (p < 0.001, p = 0.012, and p < 0.05, respectively) but not in S-BALP or vBMD in the placebo group. Supplementation inhibited the winter elevation of PTH (p = 0.035), decreased the S-BALP concentration (p < 0.05), but benefited cortical BMD (p = 0.09) only slightly. Healthy men are exposed to wintertime decrease in vitamin D status that impacts PTH concentration. Vitamin D supplementation improved vitamin D status and inhibited the winter elevation of PTH and also decreased BALP concentration. The ratio of TRACP to BALP shows the coupling of bone remodeling in a robust way. A stable ratio was observed among those retaining a stable PTH throughout the study. A daily intake of vitamin D in the range of 17.5,20 ,g (700,800 IU) seems to be required to prevent winter seasonal increases in PTH and maintain stable bone turnover in young, healthy white men. [source]

Potential Role of Pancreatic and Enteric Hormones in Regulating Bone Turnover,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2005
Jackie A Clowes MB
First page of article [source]

Role of Gastrointestinal Hormones in Postprandial Reduction of Bone Resorption,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2003
Dennis B Henriksen
Abstract Collagen type I fragments, reflecting bone resorption, and release of gut hormones were investigated after a meal. Investigations led to a dose escalation study with glucagon like peptide-2 (GLP-2) in postmenopausal women. We found a dose-dependent effect of GLP-2 on the reduction of bone resorption. Introduction: The C-terminal telopeptide region of type I collagen as measured in serum (s-CTX) can be used to assess bone resorption. This marker of bone resorption has a significant circadian variation that is influenced by food intake. However, the mediator of this variation has not been identified. Materials and Methods: We studied the release of the gut hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2; a representative of the intestinal proglucagon-derived peptides) after ingestion of glucose, fat, protein, and fructose, as well as their effects after parenteral administration in relation to bone turnover processes in healthy volunteers. Furthermore, we studied the effect on bone turnover of a single subcutaneous injection of GLP-2 in four different dosages (100, 200, 400, or 800 ,g GLP-2) or placebo in 60 postmenopausal women (mean age, 61 ± 5 years). Results: All macronutrients significantly (p < 0.05) reduced bone resorption as assessed by s-CTX (39,52% from baseline), and only the glucagon-like peptides were secreted in parallel. Parenteral administration of GIP and GLP-1 did not result in a reduction of the s-CTX level, whereas GLP-2 caused a statistically significant and dose-dependent reduction in the s-CTX level from baseline compared with placebo (p < 0.05). Urine DPD/creatinine, a marker of bone resorption, was significantly reduced by 25% from baseline in the 800-,g GLP-2 group (p < 0.01). An area under the curve (AUC0,8h) analysis for s-CTX after GLP-2 injection confirmed the dose-dependent decrease (ANOVA, p = 0.05). The s-osteocalcin level was unaffected by the GLP-2 treatment. Conclusion: These studies exclude both GIP and GLP-1 as key mediators for the immediate reduction in bone resorption seen after a meal. The dose-dependent reduction of bone resorption markers found after subcutaneous injection of GLP-2 warrants further investigation into the mechanism and importance of GLP-2 for the bone turnover processes. [source]

Altered Thyroid Hormones and Behavioural Change in a Sub-Population of Rats Following Chronic Constriction Injury

JOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2010
E. Kilburn-Watt
Hypothyroidism is associated with a disturbance of behaviour and mood. There are also individuals, not classified as hypothyroid, with low to ,low normal' thyroid hormone levels and normal thyroid-stimulating hormone (TSH) levels who have mood and behavioural changes. As the peripheral thyroid hormones decrease, TSH is expected to increase. However, there are a number of physiological mechanisms known to suppress TSH. In the present study, we report on thyroid hormone regulation in a rat model of neuropathic pain and altered social behaviour that is usually transient, but is persistent in a sub-group of the population. Following ligation of the sciatic nerve, male Sprague-Dawley rats were assessed for social dominance towards an intruder: 20% showed persistently decreased social dominance. Plasma levels of thyroid hormones, TSH and corticosterone were measured before and on days 2, 3, 4, 5 and 6 after injury in 21 rats. The mean plasma thyroxine (T4), free thyroxine (fT4) and triiodothyronine (T3) levels decreased significantly post-injury in rats with persistently changed behaviour compared to rats with unchanged behaviour (P , 0.002). There was no significant difference between groups for mean change in free triiodothyronine (fT3) or TSH. There was a correlation between decreased dominance behaviour and decrease in both T4 (r = 0.62, P = 0.009) and fT4 (r = 0.71, P = 0.001), but no correlation with TSH. In a sub-population of rats, decreased thyroid hormones did not result in the expected increased levels of TSH to restore pre-injury levels, nor did they show increased hypothalamic thyrotrophin-releasing hormone mRNA expression, indicating altered hypothalamic-pituitary-thyroid axis regulation. Because T3 availability to the brain is dependent on both circulating T3 and T4, decreased peripheral thyroid hormones may result in changed neural function, as expressed in altered complex behaviours in this sub-population of rats. [source]

Differential Effects of Restricted Versus Unlimited High-Fat Feeding in Rats on Fat Mass, Plasma Hormones and Brain Appetite Regulators

JOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2009
T. Shiraev
The rapid rise in obesity has been linked to altered food consumption patterns. There is increasing evidence that, in addition to total energy intake, the macronutrient composition of the diet may influence the development of obesity. The present study aimed to examine the impact of high dietary fat content, under both isocaloric and hypercaloric conditions, compared with a low fat diet, on adiposity, glucose and lipid metabolism, and brain appetite regulators in rats. Male Sprague,Dawley rats were exposed to one of three diets: control (14% fat), ad lib high-fat palatable (HFD, 35% fat) or high-fat palatable restricted (HFD-R, matched to the energy intake of control) and were killed in the fasting state 11 weeks later. Body weight was increased by 28% in unrestricted HFD fed rats, with an almost tripling of caloric intake and fat mass (P < 0.001) and double the plasma triglycerides of controls. Glucose intolerance and increased insulin levels were observed. HFD-R animals calorie matched to control had double their fat mass, plasma insulin and triglycerides (P < 0.05). Only ad lib consumption of the HFD increased the hypothalamic mRNA expression of the appetite-regulating peptides, neuropeptide Y and pro-opiomelanocortin. Although restricted consumption of palatable HFD had no significant impact on hypothalamic appetite regulators or body weight, it increased adiposity and circulating triglycerides, suggesting that the proportion of dietary fat, independent of caloric intake, affects fat deposition and the metabolic profile. [source]

Sexual Differentiation of Behaviour in Monkeys: Role of Prenatal Hormones

JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2009
K. Wallen
The theoretical debate over the relative contributions of nature and nurture to the sexual differentiation of behaviour has increasingly moved towards an interactionist explanation that requires both influences. In practice, however, nature and nurture have often been seen as separable, influencing human clinical sex assignment decisions, sometimes with disastrous consequences. Decisions about the sex assignment of children born with intersex conditions have been based almost exclusively on the appearance of the genitals and how other's reactions to the gender role of the assigned sex affect individual gender socialisation. Effects of the social environment and gender expectations in human cultures are ubiquitous, overshadowing the potential underlying biological contributions in favour of the more observable social influences. Recent work in nonhuman primates showing behavioural sex differences paralleling human sex differences, including toy preferences, suggests that less easily observed biological factors also influence behavioural sexual differentiation in both monkeys and humans. We review research, including Robert W. Goy's pioneering work with rhesus monkeys, which manipulated prenatal hormones at different gestation times and demonstrated that genital anatomy and specific behaviours are independently sexually differentiated. Such studies demonstrate that, for a variety of behaviours, including juvenile mounting and rough play, individuals can have the genitals of one sex but show the behaviour more typical of the other sex. We describe another case, infant distress vocalisations, where maternal responsiveness is best accounted for by the mother's response to the genital appearance of her offspring. Taken together, these studies demonstrate that sexual differentiation arises from complex interactions where anatomical and behavioural biases, produced by hormonal and other biological processes, are shaped by social experience into the behavioural sex differences that distinguish males and females. [source]

Adipose Tissue Hormones and the Regulation of Food Intake

JOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2008
B. A. Henry
Over the past decade, adipose tissue has been shown to produce numerous factors that act as hormones. Many of these act on the brain to regulate energy balance via dual effects on food intake and energy expenditure. These include well-characterised hormones such as leptin, oestrogen and glucocorticoids and novel factors such as adiponectin and resistin. This review provides a perspective on the role of these factors as lipostats. [source]

Regulation of Soluble Guanylyl Cyclase Activity by Oestradiol and Progesterone in the Hypothalamus But Not Hippocampus of Female Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2007
A. Reyna-Neyra
Oestradiol and progesterone act in the hypothalamus to coordinate the timing of lordosis and ovulation in female rats in part through regulation of nitric oxide (NO) and cyclic guanosine monophosphate (cyclic GMP) signalling pathways. Soluble guanylyl cyclase is an enzyme that produces cyclic GMP when stimulated by NO and plays a crucial role in the display of lordosis behaviour. We examined the effects of oestradiol and progesterone on the stimulation of cyclic GMP synthesis by NO-dependent and independent activators of soluble guanylyl cyclase in preoptic-hypothalamic and hippocampal slices. Ovariectomised Sprague-Dawley rats were injected with oestradiol (2 µg oestradiol benzoate, s.c.) or vehicle for 2 days. Progesterone (500 µg, s.c.) or vehicle was injected 44 h after the first dose of oestradiol. Rats were killed 48 h after the first oestradiol or vehicle injection, and hypothalamus and hippocampus were obtained. NO-dependent activation of soluble guanylyl cyclase was induced by NO donors, sodium nitroprusside or diethylamine NONOate; NO-independent activation of soluble guanylyl cyclase was induced with 3-(5,-hydroxymethyl-2,-furyl)-1-benzyl indazole and 5,-cyclopropyl-2-[1,2fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyridine-4-ylamine. The NO-dependent activators of soluble guanylyl cyclase produced a concentration-dependent increase in cyclic GMP accumulation and induced significantly greater cyclic GMP accumulation in preoptic-hypothalamic slices from animals treated with oestradiol and progesterone than in slices from rats injected with vehicle, oestradiol or progesterone alone. Hormones did not modify soluble guanylyl cyclase activation by NO-independent stimulators or influence NO content in preoptic-hypothalamic slices. Oestradiol and progesterone did not affect activation of soluble guanylyl cyclase in hippocampal slices by any pharmacological agent, indicating a strong regional selectivity for the hormone effect. Thus, oestradiol and progesterone, administered in vivo, enhance the ability of NO to activate soluble guanylyl cyclase in brain areas modulating female reproductive function without an effect on production of NO itself. [source]

Single Chain Variants of the Glycoprotein Hormones and Their Receptors as Tools to Study Receptor Activation and for Analogue Design

JOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2004
D. Ben-Menahem
Abstract One of the crucial steps in the biosynthesis of multisubunit proteins is their assembly. The glycoprotein hormone, thyroid-stimulating hormone, and the gonadotropins, luteinizing hormone, follicle-stimulating hormone and chorionic gonadotropin, are noncovalent heterodimers. Their assembly is critical for bioactivity because the heterodimers, but not the monomeric subunits, efficiently bind to and activate the cognate heptahelical receptor. Occasionally, mutated subunits cannot combine into a functional hormone, or the bioactivity of the assembled, yet modified, heterodimer is suboptimal. [source]

Neuroendocrinology Briefings 16: Genomic Imprinting, Hormones and Behaviour

JOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2002
Article first published online: 9 OCT 200
First page of article [source]

Sex Hormones, Mood, Mental State and Memory

JOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2000
Article first published online: 24 DEC 200
[source]

Sex Hormones, Mood, Mental State and Memory

JOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2000
Article first published online: 24 DEC 200
[source]

Stress, Hormones and Your Brain

JOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2000
Article first published online: 24 DEC 200
[source]

Alcohol-Induced Disruption of Endocrine Signaling

ALCOHOLISM, Issue 8 2007
Martin J. J. Ronis
This article contains the proceedings of a symposium at the 2006 ISBRA Meeting in Sydney Australia, organized and cochaired by Martin J. Ronis and Thomas M. Badger. The presentations were (1) Effect of Long-Term Ethanol Consumption on Liver Injury and Repair, by Jack R. Wands; (2) Alcohol-Induced Insulin Resistance in Liver: Potential Roles in Regulation of ADH Expression, Ethanol Clearance, and Alcoholic Liver Disease, by Thomas M. Badger; (3) Chronic Gestational Exposure to Ethanol Causes Brain Insulin and Insulin-Like Growth Factor Resistance, by Suzanne M de la Monte; (4) Disruption of IGF-1 Signaling in Muscle: A Mechanism Underlying Alcoholic Myopathy, by Charles H. Lang; (5) The Role of Reduced Plasma Estradiol and Impaired Estrogen Signaling in Alcohol-Induced Bone Loss, by Martin J. Ronis; and (6) Short-Term Influence of Alcohol on Appetite-Regulating Hormones in Man, by Jan Calissendorff. [source]

Seasonal Variation in Serum Concentrations of Selected Metabolic Hormones in Horses

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2010
N.J. Place
Background: Determination of adrenocorticotropic hormone (ACTH) concentration is a commonly used test in the evaluation of endocrine causes of equine laminitis, but the concentration in healthy horses can be high at certain times of year, which alters the specificity of the ACTH test. Objective: To determine if circulating concentrations of ACTH, cortisol, glucose, insulin, and thyroxine vary month to month in healthy horses and in horses with equine metabolic syndrome (EMS). Animals: Nine healthy adult horses were studied on their farm/stable over the course of 1 year. After the diagnosis of EMS, 10 laminitic horses residing at the same farm/stable were also studied. Methods: Prospective study of healthy and laminitic horses. Plasma/serum samples were analyzed for concentrations of hormones and glucose. Results: ACTH was the only analyte to show a discrete seasonal pattern, with concentrations in healthy and EMS horses frequently outside of the reference range (9,35 pg/mL) in August through October. Insulin was elevated (>40 ,IU/mL) in EMS horses during most months and median serum glucose was generally higher in EMS horses (100 mg/dL, range, 76,163 mg/ dL) than in controls (94 mg/dL, range, 56,110 mg/dL), but no seasonal patterns for insulin or glucose were found. Conclusions and Clinical Importance: An increased ACTH concentration in horses in late summer or autumn should be interpreted with caution. In contrast, insulin concentration is maintained within the reference range throughout the year in healthy horses, thus an increased insulin concentration at any time of year should raise suspicions of EMS, ECD, or both. [source]

Ovarian Cancer Protection from Oral Contraceptives Is Greatest with the Lowest Doses of Hormones

PERSPECTIVES ON SEXUAL AND REPRODUCTIVE HEALTH, Issue 3 2007
D. Hollander
No abstract is available for this article. [source]

Sensitized Photooxidation of Thyroidal Hormones.

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005
Evidence for Heavy Atom Effect on Singlet Molecular Oxygen [O2(, g)]-mediated Photoreactions
ABSTRACT Thyronine derivatives are essential indicators of thyroid gland diseases in clinical diagnosis and are currently used as standards for developing ordinary biochemical assays. Photooxidation of gland hormones of the thyronine (TN) family and structurally related compounds (TN, 3,5-diiodo-thyronine,3,3,,5-triiodothyronine and 3,3,,5,5,-tetraiodothyronine or thyroxine) was studied using rose bengal, eosin and perinaphthenone (PN) as dye sensitizers. Tyrosine (Tyr) and two iodinated derivatives (3-iodotyrosine and 3,5-diiodotyrosine) were also included in the study for comparative purposes. Irradiation of aqueous solutions of substrates containing xanthene dyes with visible light triggers a complex series of competitive interactions, which include the triplet excited state of the dye (3Xdye*) and singlet molecular oxygen [O2(1,g)]-mediated and superoxide ion-mediated reactions. Rate constants for interaction with the 3Xdye*, attributed to an electron transfer process, are in the order of 108 -109M,1 s,1 depending on the dye and the particular substrate. The photosensitization using PN follows a pure Type-II (O2(1,g) mediated) mechanism. The presence of the phenolic group in Tyr, TN and iodinated derivatives dominates the kinetics of photooxidation of these compounds. The reactive rate constants, kr, and the quotient between reactive and overall rate constants (krlkt values, in the range of 0.7,0.06) behave in an opposite fashion compared with the overall rate constants and oxidation potentials. This apparent inconsistency was interpreted on the basis of an internal heavy atom effect, favoring the intersystem-crossing deactivation route within the encounter complex with the concomitant reduction of effective photooxidation. [source]

Book review: Vitamins and Hormones: Folic Acid and Folates, Volume 79, Vitamins, and Hormones Series

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010
Hanjo A. Hellmann
No abstract is available for this article. [source]