The circadian biology of the marbled crayfish

The parthenogenetic marbled crayfish (Procambarus spec.) has recently been introduced as a new preparation for neuroethological studies. Since isogeneity apparently limits inter-individual variation, this otherwise typical decapod species may be especially valuable for circadian studies. Locomotor activity of isolated marbled crayfish and agonistic activity of small social groups maintain circadian rhythmicity in constant darkness. As potential signals of circadian time information, levels of 5HT, N-acetylserotonin and melatonin were determined in brains of marbled crayfish at different daytimes. However, location and structural organization of crustacean circadian pacemakers are still elusive. Immunocytochemical and backfill studies in the marbled crayfish revealed neural structures that may correspond to portions of circadian pacemaker systems in the insect optic lobe. Position and additional chemical contents in two pigment-dispersing hormone-expressing neuron groups resembled insect pigment-dispersing factor-expressing cells in the lamina and the accessory medulla, a neuropil discussed as center for integration of timing information. Here, we discuss new findings about the possible organization of the circadian system of the marbled crayfish in the light of current knowledge about circadian clocks in crustacea.

Co-ordination of osmotic stress responses through osmosensing and signal transduction events in fishes

This review centres upon the molecular regulation of osmotic stress responses in fishes, focusing on how osmosensing and signal transduction events co-ordinate changes in the activity and abundance of effector proteins during osmotic stress and how these events integrate into osmotic stress responses of varying magnitude. The concluding sections discuss the relevance of osmosensory signal transduction to the evolution of euryhalinity and present experimental approaches that may best stimulate future research. Iterating the importance of osmosensing and signal transduction during fish osmoregulation may be pertinent amidst the increased use of genomic technologies that typically focus solely on changes in the abundances of gene products, and may limit insight into critical upstream events that occur mainly through post-translational mechanisms.

Seasonal changes in the behavior and plasma titers of various hormones in barheaded geese, Anser indicus

A number of behavioral and physiological parameters including the circulating levels of 7 hormones were investigated in a free ranging population of barheaded geese in Seewiesen, W. Germany. Behavioral data were collected on the entire flock from which seasonal changes in the frequencies were determined. In addition, data on the behavior of individuals were obtained to aid in the comparison of seasonal changes in behavior and hormones. The resulting curves were used to examine whether the annual changes in the frequencies of various behaviors were related to changes in circulating hormonal concentrations. Lastly, the physiological data were discussed with regard to reproductive biology in birds.

Altered gene synchrony suggests a combined hormone-mediated dysregulated state in major depression

Coordinated gene transcript levels across tissues (denoted “gene synchrony”) reflect converging influences of genetic, biochemical and environmental factors; hence they are informative of the biological state of an individual. So could brain gene synchrony also integrate the multiple factors engaged in neuropsychiatric disorders and reveal underlying pathologies? Using bootstrapped Pearson correlation for transcript levels for the same genes across distinct brain areas, we report robust gene transcript synchrony between the amygdala and cingulate cortex in the human postmortem brain of normal control subjects (n = 14; Control/Permutated data, p<0.000001). Coordinated expression was confirmed across distinct prefrontal cortex areas in a separate cohort (n = 19 subjects) and affected different gene sets, potentially reflecting regional network- and function-dependent transcriptional programs. Genewise regional transcript coordination was independent of age-related changes and array technical parameters. Robust shifts in amygdala-cingulate gene synchrony were observed in subjects with major depressive disorder (MDD, denoted here “depression”) (n = 14; MDD/Permutated data, p<0.000001), significantly affecting between 100 and 250 individual genes (10–30% false discovery rate). Biological networks and signal transduction pathways corresponding to the identified gene set suggested putative dysregulated functions for several hormone-type factors previously implicated in depression (insulin, interleukin-1, thyroid hormone, estradiol and glucocorticoids; p<0.01 for association with depression-related networks). In summary, we showed that coordinated gene expression across brain areas may represent a novel molecular probe for brain structure/function that is sensitive to disease condition, suggesting the presence of a distinct and integrated hormone-mediated corticolimbic homeostatic, although maladaptive and pathological, state in major depression.

Spermatogenesis in fish

Spermatogenesis is a developmental process during which a small number of diploid spermatogonial stem cells produce a large number of highly differentiated spermatozoa carrying a haploid, recombined genome. We characterise morphologically the different germ cell stages with particular attention for the spermatogonial generations, including the stem cells and their specific capacity to colonise a recipient's testis after transplantation. We propose a nomenclature for fish germ cells to improve the comparability among different teleost fish but also to higher vertebrates. Survival and development of germ cells depends on their continuous and close contact to Sertoli cells, and we review their multiple roles in the cystic mode of spermatogenesis seen in fish. We then discuss gene expression patterns associated with testis maturation. The endocrine system of vertebrates has evolved as master control system over spermatogenesis. In fish, both pituitary gonadotropins LH and FSH stimulate gonadal sex steroid hormone production directly by activating Leydig cells. Information is reviewed on the effects of progestin, androgens, and estrogens on global testicular gene expression patterns (microarray analysis), and on the molecular mechanisms by which steroids regulate specific candidate genes (identified by subtractive hybridization approaches) during early stages of testis maturation. Moreover, progestin and androgen effects on spermiation and milt hydration are discussed. Sex steroids mainly act via receptors expressed by Sertoli cells. One type of response is that Sertoli cells change growth factor expression, which subsequently modulates germ cell proliferation/differentiation via mechanisms yet to be characterised. Finally, we review data on germ cell autonomous processes, mainly derived from loss-of-function mutant fish lines, before identifying a number of focus areas for future research activities.

A tiny touch: activation of cell signaling pathways with magnetic nanoparticles

Magnetic nanoparticles can be coated with specific ligands that enable them to bind to receptors on a cell's surface. When a magnetic field is applied, it pulls on the particles so that they deliver nanoscale forces at the ligand-receptor bond. It has been observed that mechanical stimulation in this manner can activate cellular signaling pathways that are known as mechanotransduction pathways. Integrin receptors, stretch-activated ion channels, focal adhesions, and the cytoskeleton are key players in activating these pathways, but there is still much we do not know about how these mechanosensors work. Current evidence indicates that applied forces at these structures can activate Ca(2+) signaling, Src family protein kinase, MAPK, and RhoGTPase pathways. The techniques of magnetic twisting and magnetic tweezers, which use magnetic particles to apply forces to cells, afford a fine degree of control over how cells are stimulated and hold much promise in elucidating the fundamentals of mechanotransduction. The particles are generally not harmful to cellular health, and their nanoscale dimensions make them advantageous for probing a cell's molecular-scale sensory structures. This review highlights the basic aspects of magnetic nanoparticles, magnetic particle techniques and the structures and pathways that are involved in mechanotransduction.

Oogenesis in teleosts: how eggs are formed

One of the major objectives of the aquaculture industry is the production of a large number of viable eggs with high survival. Major achievements have been made in recent years in improving protocols for higher efficiency of egg production and viability of progeny. Main gaps remain, however, in understanding the dynamic processes associated with oogenesis, the formation of an egg, from the time that germ cells turn into oogonia, until the release of ova during spawning in teleosts. Recent studies on primordial germ-cells, yolk protein precursors and their processing within the developing oocyte, the deposition of vitamins in eggs, structure and function of egg envelopes and oocyte maturation processes, further reveal the complexity of oogenesis. Moreover, numerous circulating endocrine and locally-acting paracrine and autocrine factors regulate the various stages of oocyte development and maturation. Though it is clear that the major regulators during vitellogenesis and oocyte maturation are the pituitary gonadotropins (LH and FSH) and sex steroids, the picture emerging from recent studies is of complex hormonal cross-talk at all stages between the developing oocyte and its surrounding follicle layers to ensure coordination of the various processes that are involved in the production of a fertilizable egg. In this review we aim at highlighting recent advances on teleost fish oocyte differentiation, maturation and ovulation, including those involved in the degeneration and reabsorption of ovarian follicles (atresia). The role of blood-borne and local ovarian factors in the regulation of the key steps of development reveal new aspects associated with egg formation.

Stress and fish reproduction: the roles of allostasis and hormesis

This paper is a review of the effects of stress on reproduction in fishes. I hope to further the development of the concepts of allostasis and hormesis as relevant to understanding reproduction in general and in fish in particular. The main contentions I derive in this review are the following: Stressors affect fish reproduction in a variety of ways depending on the nature and severity of the stressor. The effects are transduced through a hormonal cascade initiated by perception of the stressor and involving the hypothalamus-pituitary-interrenal axis, the catecholamines, and also cytokines. Mounting a stress response and resisting a stressor is an energetically costly process, including costs associated with allostasis, attempting to reset homeostatic norms. Responses in emergency situations (e.g., being chased by a predator or a net) can be different from those where fish can cope (e.g., being in a more crowded environment) with a stressor, but both situations involve energy re-budgeting. Emergency responses happen in concert with the onset of energy limitations (e.g., the fish may not eat), while coping with allostatic overload can happen in a more energy-rich environment (e.g., the fish can continue to eat). Low levels of stress may have a positive effect on reproductive processes while greater stress has negative effects on fish reproduction. The concept of hormesis is a useful way to think about the effect of stressors on fish reproduction since responses can be nonmonotonal, often biphasic.

Cell-specific precursor processing

The singular gene for a peptide hormone is expressed not only in a specific endocrine cell type but also in other endocrine cells as well as in entirely different cells such as neurons, adipocytes, myocytes, immune cells, and cells of the sex-glands. The cellular expression pattern for each gene varies with development, time and species. Endocrine regulation is, however, based on the release of a given hormone from an endocrine cell to the general circulation from whose cappilaries the hormone reaches the specific target cell elsewhere in the body. The widespread expression of hormone genes in different cells and tissues therefore requires control of biogenesis and secretion in order to avoid interference with the function of a specific hormonal peptide from a particular endocrine cell. Several mechanisms are involved in such control, one of them being cell-specific processing of prohormones. The following pages present four examples of such cell-specific processing and the implications of the phenomenon for the use of peptide hormones as markers of diseases. Notably, sick cells - not least the neoplastic cells - often process prohormones in a manner different from that of the normal endocrine cells.

Regulation of nutrient metabolism and inflammation

Metabolic and immune-related pathways intersect at numerous levels. Their common regulation is effectuated by several hormonal signaling routes that involve specific nuclear hormone receptors and adipokines. Glucocorticoids and leptin are hormones that play a key role in coordinating energy metabolism and food-seeking behavior during energy deficiency as does the nuclear hormone receptor Peroxisome Proliferator Activated Receptor α (PPARalpha). Importantly, the glucocorticoid, leptin, and PPARalpha signaling routes share a profound role in governing inflammation and other immune-related processes. Using specific examples, this chapter aims at illustrating the interplay between metabolism and immunity/inflammation by discussing common endocrine and transcriptional regulators of metabolism and inflammation and by highlighting the interaction between macrophages and metabolically active cells in liver and adipose tissue. Convergence of metabolic and immune signaling is likely at least partially driven by the evolutionary need during times of food insufficiency to minimize loss of energy to processes that are temporarily nonessential to the survival of the species.

Suprachiasmatic nucleus: cell autonomy and network properties

The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals. Individual SCN neurons in dispersed culture can generate independent circadian oscillations of clock gene expression and neuronal firing. However, SCN rhythmicity depends on sufficient membrane depolarization and levels of intracellular calcium and cAMP. In the intact SCN, cellular oscillations are synchronized and reinforced by rhythmic synaptic input from other cells, resulting in a reproducible topographic pattern of distinct phases and amplitudes specified by SCN circuit organization. The SCN network synchronizes its component cellular oscillators, reinforces their oscillations, responds to light input by altering their phase distribution, increases their robustness to genetic perturbations, and enhances their precision. Thus, even though individual SCN neurons can be cell-autonomous circadian oscillators, neuronal network properties are integral to normal function of the SCN.

Roles of hormones in taste signaling

Proper nutrition, avoidance of ingesting substances that are harmful to the whole organism, and maintenance of energy homeostasis are crucial for living organisms. Additionally, mammals possess a sophisticated system to control the types and content of food that we swallow. Gustation is a vital sensory skill for determining which food stuffs to ingest and which to avoid, and for maintaining metabolic homeostasis. It is becoming apparent that there is a strong link between metabolic control and flavor perception. Although the gustatory system critically influences food preference, food intake, and metabolic homeostasis, the mechanisms for modulating taste sensitivity by metabolic hormones are just now being explored. It is likely that hormones produced in the tongue influence the amounts and types of food that we eat: the hormones that we associate with appetite control, glucose homeostasis and satiety, such as glucagon-like peptide-1, cholecystokinin, and neuropeptide Y are also produced locally in taste buds. In this report, we will provide an overview of the peptidergic endocrine hormone factors that are present or are known to have effects within the gustatory system, and we will discuss their roles, where known, in taste signaling.

Adipose tissue and the reproductive axis: biological aspects

The discovery of leptin has clearly demonstrated a relationship between body fat and the neuroendocrine axis since leptin influences appetite and the reproductive axis. Since adipose tissue is a primary source of leptin, adipose tissue is no longer considered as simply a depot to store fat. Recent findings demonstrate that numerous other genes, i.e. neuropeptides, interleukins and other cytokines and biologically active substances such as leptin and insulin-like growth factors I and II, are also produced by adipose tissue, which could influence appetite and the reproductive axis. Targets of leptin in the hypothalamus include neuropeptide Y, proopiomelanocortin and kisspeptin. Transsynaptic connection of hypothalamic neurons to porcine adipose tissue may result in a direct influence of the hypothalamus on adipose tissue function. Nutritional signals such as leptin are detected by the central nervous system and translated by the neuroendocrine system into signals which ultimately regulates luteinizing hormone secretion. Furthermore, leptin directly affects gonadotropin-releasing hormone release from the hypothalamus, luteinizing hormone from the pituitary gland and ovarian follicular steroidogenesis. Although leptin is identified as a putative signal that links metabolic status and neuroendocrine control of reproduction, other adipocyte protein products may play key roles in regulating the reproductive axisin the pig.

[Endocannabinoid system I--the role in regulation of physiology functions]

Endocannabinoid system has a wide scale of actions on CNS and on peripheral tissues. The system consists of cannabinoid receptors CB1 and CB2, endocannabinoids and their biosynthetic and degrading enzymes. CB1 receptors in high density occur on presynaptic neuronal terminals in brain influencing neurotransmission thereby number of functions--pain perception, inhibition of stress reaction, regulation of motor functions, cognition, emotional reactions, regulation of food intake, psychical homeostasis and motivation. CB1 receptors are present in GIT cells, hepatocytes, adipocytes, pancreatic isles cells. Energy homeostasis is the main function in peripheral issues. CB2 receptors are present mainly in cells of immune system, in the cilliary body of eye, in testes, vasal cells, and intestinal smooth muscle cells.

Hypothalamic obesity

Following extensive suprasellar operations for excision of hypothalamic tumors, some patients develop morbid obesity, the so-called hypothalamic obesity (HyOb). HyOb complicates disorders related to the hypothalamus, including those that cause structural damage to the hypothalamus, pituitary macroadenoma with suprasellar extension, glioma, meningioma, teratoma, germ cell tumors, radiotherapy, Prader-Willi syndrome, and mutations in leptin, leptin receptor, POMC, MC4R and CART genes. It is conceivable that a subgroup of patients with 'simple obesity' also have HyOb. The hypothalamus regulates body weight by precisely balancing the intake of food, energy expenditure and body fat tissue. Orexigenic and anorexigenic hypothalamic centers (hyperphagia when impaired) play a central role, connecting to adipose tissue by means of an intricate efferent and afferent signals circuit. Other mechanisms by which the brain regulates adipose tissue and beta cells of the pancreas include the sympathetic nervous system, vagally mediated hyperinsulinemia and the endocrine system, namely growth hormone, thyroid-stimulating hormone and the hypothalamo-pituitary-adrenal axis. Corticotropin-releasing hormone, adrenocorticotropic hormone glucocorticoids and the 11beta-HSD-1 shuttle regulate lipolysis both directly and indirectly. All the above mechanisms may be impaired in HyOb. Management of HyOb targets the major manifestations: hyperphagia, autonomic dysfunction, hyperinsulinemia and impaired energy expenditure. Individual variation is considerable. Satisfactory therapy is currently unavailable.

Neuroendocrine consequences of anorexia nervosa in adolescents

Anorexia nervosa (AN) is a condition of severe undernutrition characterized by alterations in multiple neuroendocrine axes and peptides that signal or regulate energy intake. These alterations include a state of hypogonadotropic hypogonadism, a nutritionally acquired resistance to growth hormone (GH) with low IGF-1 levels, relative hypercortisolemia, low total T3 despite normal TSH, low levels of leptin and insulin, and elevated levels of ghrelin, peptide YY (PYY) and possibly adiponectin. Although many of these changes are adaptive to low weight, they can impact bone metabolism, body composition, reproductive function and statural growth. Low bone mass is characteristic of AN in both adolescent boys and girls. In girls, sites of trabecular bone are more likely to be affected than sites of cortical bone, whereas in boys with AN, sites of cortical bone are more commonly affected. Bone microarchitecture is also affected in adolescent girls with AN, with a decrease in trabecular thickness and bone trabecular volume, and an increase in trabecular separation. Important predictors of low bone density include nutritional factors, body composition, hypogonadism, low IGF-1, elevated cortisol and PYY levels, with possible contributions of low insulin. Weight gain is associated with a stabilization of bone density, although residual deficits persist in the short term, and in some cases, long term.

Factors contributing to peritoneal tissue remodeling in peritoneal dialysis

Peritoneal dialysis (PD) is associated with functional and structural changes of the peritoneal membrane. In this review we describe factors contributing to peritoneal tissue remodeling, including uremia, peritonitis, volume loading, the presence of a catheter, and the PD fluid itself. These factors initiate recruitment and activation of peritoneal cells such as macrophages and mast cells, as well as activation of peritoneal cells, including mesothelial cells, fibroblasts, and endothelial cells. We provide an overview of cytokines, growth factors, and other mediators involved in PD-associated changes. Activation of downstream pathways of cellular modulators can induce peritoneal tissue remodeling, leading to ultrafiltration loss. Identification of molecular pathways, cells, and cytokines involved in the development of angiogenesis, fibrosis, and membrane failure may lead to innovative therapeutic strategies that can protect the peritoneal membrane from the consequences of long-term PD.

Vascular endothelial growth factor during hypoglycemia in patients with type 1 diabetes mellitus: relation to cognitive function and renin-angiotensin system activity

In healthy adults, levels of vascular endothelial growth factor (VEGF) increase in response to mild hypoglycemia. VEGF is implicated in glucose transport over the blood-brain barrier, and the increase during hypoglycemia has been positively correlated with preservation of cognitive function during hypoglycemia. High activity in the renin-angiotensin system (RAS) is associated with an increased risk of severe hypoglycemia in patients with type 1 diabetes mellitus. Renin-angiotensin system possibly exerts its mechanism in hypoglycemia via VEGF. We studied the impact of mild hypoglycemia on plasma VEGF in patients with type 1 diabetes mellitus and high or low RAS activity and analyzed associations between VEGF levels and cognitive function during hypoglycemia. Eighteen patients with type 1 diabetes mellitus-9 with high and 9 with low RAS activity-underwent a single-blinded, placebo-controlled, crossover study with either mild hypoglycemia or stable glycemia. Cognitive function was assessed by the California Cognitive Assessment Package and the Alzheimer Quick Test. Nadir plasma glucose was 2.2 (0.3) mmol/L. During the control study, plasma VEGF did not change. During hypoglycemia, plasma VEGF increased from 39 to 58 pg/L in the high-RAS group (P = .004) and from 76 to 109 pg/L in the low-RAS group (P = .01), with no difference between RAS groups (P = .9). A weak association between reduced preservation of cognitive function during hypoglycemia and low VEGF response was observed. Plasma VEGF levels increase during mild, short-term hypoglycemia in patients with type 1 diabetes mellitus. The VEGF response is not dependent on RAS activity and only weakly associated with preservation of cognitive function during hypoglycemia. Thus, the previously described association between low RAS activity and better cognitive performance during hypoglycemia does not seem to be mediated by VEGF.

Hormones, hormonal agents, and neuropeptides involved in the neuroendocrine regulation of sleep in humans

Sleep is an essential ubiquitous biological process, a periodical state of quiescence in which there is minimal processing of sensory information and no interaction with conspecifics or the environment. Despite relevant research on sleep structure and testing of numerous endogenous sleep-affecting chemicals, questions as to the precise mechanisms and functions of sleep remain without satisfactory responses. The purpose of this review is to report on current evidence as regards the effect of several endogenous and exogenous hormones, hormonal agents, and neuropeptides on sleep onset or wake process, when administered in humans in specific doses and via different routes. The actions of several peptides are presented in detail. Some of them (growth hormone releasing hormone, ghrelin, galanin, neuropeptide Y) seem to promote sleep, whereas others (corticotropin, somatostatin) impair its continuity.

Lipoprotein lipase: from gene to obesity

Lipoprotein lipase (LPL) is a multifunctional enzyme produced by many tissues, including adipose tissue, cardiac and skeletal muscle, islets, and macrophages. LPL is the rate-limiting enzyme for the hydrolysis of the triglyceride (TG) core of circulating TG-rich lipoproteins, chylomicrons, and very low-density lipoproteins (VLDL). LPL-catalyzed reaction products, fatty acids, and monoacylglycerol are in part taken up by the tissues locally and processed differentially; e.g., they are stored as neutral lipids in adipose tissue, oxidized, or stored in skeletal and cardiac muscle or as cholesteryl ester and TG in macrophages. LPL is regulated at transcriptional, posttranscriptional, and posttranslational levels in a tissue-specific manner. Nutrient states and hormonal levels all have divergent effects on the regulation of LPL, and a variety of proteins that interact with LPL to regulate its tissue-specific activity have also been identified. To examine this divergent regulation further, transgenic and knockout murine models of tissue-specific LPL expression have been developed. Mice with overexpression of LPL in skeletal muscle accumulate TG in muscle, develop insulin resistance, are protected from excessive weight gain, and increase their metabolic rate in the cold. Mice with LPL deletion in skeletal muscle have reduced TG accumulation and increased insulin action on glucose transport in muscle. Ultimately, this leads to increased lipid partitioning to other tissues, insulin resistance, and obesity. Mice with LPL deletion in the heart develop hypertriglyceridemia and cardiac dysfunction. The fact that the heart depends increasingly on glucose implies that free fatty acids are not a sufficient fuel for optimal cardiac function. Overall, LPL is a fascinating enzyme that contributes in a pronounced way to normal lipoprotein metabolism, tissue-specific substrate delivery and utilization, and the many aspects of obesity and other metabolic disorders that relate to energy balance, insulin action, and body weight regulation.

Aspects of placental estrogen synthesis in the pig

Conceptus estrogen synthesis in the pig begins with the d 11 blastocyst and continues throughout pregnancy. Estrogens have been implicated as regulators of numerous in utero events related to conceptus survival and development. Studies conducted in our laboratory indicate that progesterone (P4) production by the porcine placenta increases steadily throughout gestation. Estrone (E1) production is triphasic with peaks between d 14-18, around d 30, and a sustained increase from d 70 until parturition. Addition of pregnenolone (P5) augments in vitro P4 and E1 production by both the placenta and the endometrium. Both estrogen concentrations and the ratio between conjugated and free estrogens change drastically during gestation. Evidence from our laboratory suggests that enhanced and prolonged sulfatase activity by d 90 of gestation, coupled with an increase in sulfatase activity-not a change in aromatase activity-contributes to the rise in free estrogens as parturition approaches. We assessed the relative importance of ovarian versus placental production of P4 as a mediator of prenatal survival, conceptus development, and steroidogenesis by the placenta and endometrium. Among other findings, exogenous administration of the non-aromatizable progestagen medroxyprogesterone acetate (MPA) to ovariectomized (OVX) gilts between either d 20-30 or d 60-70 of gestation did not adversely affect concepts survival or development, in vivo estrogen measurements, or in vitro placental steroidogenesis. We also demonstrated that pregnancy may also be maintained during d 20-30 and d 60-70 in OVX gilts administered large quantities of P5 exogenously, presumably due to placental P4 production. Recent studies have examined variables of region of the placenta and intrauterine position on conceptus development, and placental and endometrial steroidogenesis under normal and crowded intrauterine conditions. Results indicated 1) a differential release of P4 and E1 by different regions of the placenta at certain days of gestation, 2) no compensatory increase in steroidogenic activity of the pig placenta when total placental mass was reduced, and 3) a less pronounced effect of intrauterine position on steroidogenic activity in the pig compared with other litter-bearing species.

Paracrine and autocrine functions of the placenta: a key to the success of viviparity?

The evolution of specific nuclear transcriptional regulators has endowed tissues of the reproductive system with responsiveness to small hydrophobic compounds such as steroids. Steroids are widely distributed in Nature and their distribution in prokaryotes and eukaryotes has given rise to the concept that their hormonal role came about by target organ specialization and not by the evolution of steroids themselves. Specific nuclear receptors for progesterone in the uterus are prominent during the establishment and maintenance of pregnancy. Anti-progesterone antagonists which interfere with receptor-mediated DNA activation abrogate pregnancy and thus emphasize the functional importance of the pathways by which the effects of progesterone as an extracellular signal are transduced. Comparative studies show that progesterone itself can be ovarian or placental in origin. This seems to reflect the evolution of different mechanisms of endocrine function rather than any obvious selective advantage being associated with the source of hormone secretion. For this reason, the question of whether the endocrine function of the placenta is obligatory for the adoption of viviparity in mammals is far from certain, and should be considered as an evolutionary option rather than a sine qua non. Of growing importance is the idea that the interaction between trophoblast and endometrial cells controls the degree of invasiveness at implantation and immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Placental progesterone, prostaglandins and mechanisms leading to initiation of parturition in the human

Present knowledge allows the identification of some features of the initiation of human parturition. Progesterone reduces myometrial sensitivity to labour-inducing agents. It suppresses gap junction formation and facilitates beta-adrenergic receptor expression by the myometrium which, in turn, exerts a positive feedback by enhancing beta-adrenergic-induced increases in placental progesterone production. Inhibition of gestagen action does not result in immediate initiation of labor but sensitises myometrial cells to contraction-inducing agents. Estrogens, in contrast, enable the myometrium to prepare for parturition by inducing oxytocin receptors and this seems to be the first step towards parturition. Coordinated myometrial contractions are facilitated by the increased gap junctions due to the estrogen drive. Absence of estrogen will result in failed parturition. The myometrium seems to be sensitised to oxytocin by placental CRF. Myometrial CRF receptors increase their avidity for CRF with ongoing pregnancy. Oxytocin evokes a variety of auto- and paracrine events which culminate in increased free intracellular calcium and the consequent contractions. In this cascade, prostaglandins can be identified as positive feedback agents, as they further enhance estrogen-induced expression of oxytocin receptors. Another second messenger of oxytocin action are the inositol phosphates which can further increase free intracellular calcium concentrations. Finally, endothelin-1, derived from endometrium and decidua, under oxytocin control, may serve as a myometrial contractor following delivery when oxytocin concentrations decline but when a strong myometrial contraction is needed to prevent large blood loss during and after placenta expulsion.

Developmental aspects of bladder function

A review was conducted of the current knowledge of fetal and postnatal development of autonomic bladder function in animals. Studies of fetal and neonatal bladder development have been done in many animal species. Development of normal bladder function requires coordination of a number of different systems and processes, and continues after birth during the early neonatal period. In many neonatal animals, micturition occurs only after stimulation of a perineal-to-bladder reflex triggered when the mother licks the perineal region, and bladder distension fails to stimulate micturition. Voiding resulting from the normal bladder-to-bladder spinobulbospinal reflex activated by bladder distension develops only slowly over the first few weeks of life as synaptic connections in the sacral parasympathetic nucleus mature. The neurogenic response of bladder strips from young neonates is more sensitive to inhibition by atropine than that of strips from older animals, suggesting that there are developmental changes in the contribution of non-adrenergic, non-cholinergic transmitters to the response of the bladder smooth muscle to intramural nerve stimulation. Release of acetylcholine from cholinergic nerves and the mechanisms required to transform muscarinic receptor stimulation into efficient bladder contraction and emptying are fully developed at birth, but contractile and relaxant responses to many other agonists, such as adenosine triphosphate and noradrenaline, are developmentally regulated. Changes in calcium influx and storage may be responsible for many of these changes. Fetal detrusor is exquisitely sensitive to nitric oxide. Electrical stimulation of precontracted fetal bladder strips causes relaxation, an effect that is not seen in adult tissues, and is decreased by inhibitors of the actions of nitric oxide. Development of bladder function occurs before the onset of puberty and therefore is not normally dependent on sex hormones. However, neonatal treatment with or depletion of sex hormones can modulate bladder function. In particular, alpha-adrenergic receptor-mediated contractile responses of bladder detrusor are increased by prepubertal castration, an effect that may result from increases in the density of alpha-adrenergic receptors and/or changes in alpha-adrenergic receptor subtype expression.

Immunosteroid as a regulator for Th1/Th2 balance: Its possible role in autoimmune diseases

Immune balance controlled by Th1 and Th2 cells is critical for the protection of host from pathogenic invasion while its imbalance becomes the cause of various immune disorders including autoimmune diseases. Cytokines, such as IL-12 and IL-4, are critical factor to drive the differentiation of naïve CD4(+) T cells to Th1 or Th2 cells. In addition to cytokines, steroid hormones have been demonstrated to affect on the control of Th1/Th2 balance and the onset of autoimmune diseases. Here, we will propose a new concept that immunosteroid, which is designated as a steroid produced by immunoregulatory cells, also play a critical role for regulation of Th1/Th2 balance. First example of immunosteroid is Th2-dependently produced progesterone. Th2 cells, but not Th1 cells expressed P450scc and 20alpha-HSD and produced progesterone from 22R-hydroxycholesterol in cooperation with 3beta-HSD-expressing mouse fibroblasts. Th2-dependently produced progesterone induced apoptotic cell death of Th1 cells and inhibited the differentiation of Th1 cells. While Th2 cells were escaped from toxic effect of progesterone by metabolizing it to non-toxic 20alpha-hydroxyprogesterone with 20alpha-HSD. Second example of immunosteroid is dendritic cell (DC)-dependently produced 1alpha,25-dihydroxyvitamin D3 [1,25(OH)(2)D] secosteroid hormone, which has been demonstrated to inhibit autoimmune diseases. We found that 25-hydroxyvitamin D3 1alpha-hydroxylase, which metabolize 25-hydroxyvitamin D3 (inactive form) to 1,25(OH)(2)D was expressed in Th2-cytokine induced bone marrow-derived DC2 but not Th1-cytokine induced DC1. Moreover, 1,25(OH)(2)D was significantly inhibited DC1-induced type1 immunity. Thus, we initially demonstrated the critical role of immunosteroids in the control of Th1/Th2 balance influencing on the onset of autoimmune diseases. Therefore, it will be an important issue to investigate the possible role of immunosteroids for the regulation of autoimmune diseases.

Sex, gender, and pain: a review of recent clinical and experimental findings

Sex-related influences on pain and analgesia have become a topic of tremendous scientific and clinical interest, especially in the last 10 to 15 years. Members of our research group published reviews of this literature more than a decade ago, and the intervening time period has witnessed robust growth in research regarding sex, gender, and pain. Therefore, it seems timely to revisit this literature. Abundant evidence from recent epidemiologic studies clearly demonstrates that women are at substantially greater risk for many clinical pain conditions, and there is some suggestion that postoperative and procedural pain may be more severe among women than men. Consistent with our previous reviews, current human findings regarding sex differences in experimental pain indicate greater pain sensitivity among females compared with males for most pain modalities, including more recently implemented clinically relevant pain models such as temporal summation of pain and intramuscular injection of algesic substances. The evidence regarding sex differences in laboratory measures of endogenous pain modulation is mixed, as are findings from studies using functional brain imaging to ascertain sex differences in pain-related cerebral activation. Also inconsistent are findings regarding sex differences in responses to pharmacologic and non-pharmacologic pain treatments. The article concludes with a discussion of potential biopsychosocial mechanisms that may underlie sex differences in pain, and considerations for future research are discussed.

PERSPECTIVE

This article reviews the recent literature regarding sex, gender, and pain. The growing body of evidence that has accumulated in the past 10 to 15 years continues to indicate substantial sex differences in clinical and experimental pain responses, and some evidence suggests that pain treatment responses may differ for women versus men.

Hormones in the naso-oropharynx: endocrine modulation of taste and smell

Olfaction and gustation are important sensory modalities for locating food and for determining which foodstuffs to ingest. It is becoming apparent that there is a strong link between olfaction, gustation and metabolic control. Because endocrine signaling in the naso-oropharynx is likely to influence food intake, satiety and general metabolic control, it is important to examine some of the major hormones that play an integral part in energy homeostasis. Here, we provide an overview of the main endocrine factors known to be present in the naso-oropharynx and discuss their functional roles in maintaining metabolic function. Gaining a greater appreciation of how flavor perception is linked to peripheral metabolism could lead to novel therapeutic strategies for obesity and lifestyle-related diseases.

Steroid hormones and distribution of adipose tissue

Several descriptive studies, performed in women before and after menopause, in young and older men and in women with Cushing's disease, have suggested that steroid hormones have a role in the regulation of regional fat metabolism. Femoral lipoprotein lipase (LPL) activity seems to be increased by progesterone, while it might be inhibited by testosterone. Estradiol and testosterone might be lipolytic in the abdominal region. Long-term exposure to corticosteroid might increase femoral LPL activity and decrease abdominal lipolysis. These conclusions, however, are only tentative. Corticosteroid hormones bind to the cytosolic fraction of human adipose tissue, while no binding was observed with estradiol or progesterone. The relationship between steroid hormone receptors and biological effects in unknown. Further work should be performed to investigate the mechanisms by which steroid hormones might influence human adipose tissue metabolism and distribution.

Short-term calorie restriction in male mice feminizes gene expression and alters key regulators of conserved aging regulatory pathways

Background

Calorie restriction (CR) is the only intervention known to extend lifespan in a wide range of organisms, including mammals. However, the mechanisms by which it regulates mammalian aging remain largely unknown, and the involvement of the TOR and sirtuin pathways (which regulate aging in simpler organisms) remain controversial. Additionally, females of most mammals appear to live longer than males within species; and, although it remains unclear whether this holds true for mice, the relationship between sex-biased and CR-induced gene expression remains largely unexplored.

Methodology/Principal Findings

We generated microarray gene expression data from livers of male mice fed high calorie or CR diets, and we find that CR significantly changes the expression of over 3,000 genes, many between 10- and 50-fold. We compare our data to the GenAge database of known aging-related genes and to prior microarray expression data of genes expressed differently between male and female mice. CR generally feminizes gene expression and many of the most significantly changed individual genes are involved in aging, hormone signaling, and p53-associated regulation of the cell cycle and apoptosis. Among the genes showing the largest and most statistically significant CR-induced expression differences are Ddit4, a key regulator of the TOR pathway, and Nnmt, a regulator of lifespan linked to the sirtuin pathway. Using western analysis we confirmed post-translational inhibition of the TOR pathway.

Conclusions

Our data show that CR induces widespread gene expression changes and acts through highly evolutionarily conserved pathways, from microorganisms to mammals, and that its life-extension effects might arise partly from a shift toward a gene expression profile more typical of females.

Putative sex differences in verbal abilities and language cortex: a critical review

This review brings together evidence from a diverse field of methods for investigating sex differences in language processing. Differences are found in certain language-related deficits, such as stuttering, dyslexia, autism and schizophrenia. Common to these is that language problems may follow from, rather than cause the deficit. Large studies have been conducted on sex differences in verbal abilities within the normal population, and a careful reading of the results suggests that differences in language proficiency do not exist. Early differences in language acquisition show a slight advantage for girls, but this gradually disappears. A difference in language lateralization of brain structure and function in adults has also been suggested, perhaps following size differences in the corpus callosum. Neither of these claims is substantiated by evidence. In addition, overall results from studies on regional grey matter distribution using voxel-based morphometry, indicate no consistent differences between males and females in language-related cortical regions. Language function in Wada tests, aphasia, and in normal ageing also fails to show sex differentiation.

Hormonal control of aging in rodents: the somatotropic axis

There is a growing body of literature focusing on the somatotropic axis and regulation of aging and longevity. Many of these reports derive data from multiple endocrine mutants, those that exhibit both elevated growth hormone (GH) and insulin-like growth factor I (IGF-1) or deficiencies in one or both of these hormones. In general, both spontaneous and genetically engineered GH and IGF-1 deficiencies have lead to small body size, delayed development of sexual maturation and age-related pathology, and life span extension. In contrast, characteristics of high circulating GH included larger body sizes, early puberty and reproductive senescence, increased cancer incidence and reduced life span when compared to wild-type animals with normal plasma hormone concentrations. This information, along with that found in multiple other species, implicates this anabolic pathway as the major regulator of longevity in animals.

The influence of endocrine disruptors on pubertal timing

PURPOSE OF REVIEW

Overview of the effects of endocrine disruptors on pubertal timing.

RECENT FINDINGS

Epidemiologic studies in humans support animal data demonstrating that exposures to endocrine-disrupting compounds have pronounced effects on pubertal timing and that the timing of endocrine-disrupting compound exposure and the specific agent causes different outcomes. Recent studies confirm subtle effects of lead, dioxins, and phytoestrogens on delaying onset of puberty and demonstrate an association of phthalates and polychlorinated biphenyls with earlier breast development and menarche, respectively. These studies, however, are complicated by mixed exposures of compounds which individually may have opposing actions on the reproductive axis.

SUMMARY

Animal and human data confirm perturbations in pubertal onset with exposures to endocrine-disrupting compounds.

Hormone signaling through protein destruction: a lesson from plants

Ubiquitin-dependent protein degradation has emerged as a major pathway regulating eukaryotic biology. By employing a variety of ubiquitin ligases to target specific cellular proteins, the ubiquitin-proteasome system controls physiological processes in a highly regulated fashion. Recent studies on a plant hormone auxin have unveiled a novel paradigm of signal transduction in which ubiquitin ligases function as hormone receptors. Perceived by the F-box protein subunit of the SCF(TIR1) ubiquitin ligase, auxin directly promotes the recruitment of a family of transcriptional repressors for ubiquitination, thereby activating extensive transcriptional programs. Structural studies have revealed that auxin functions through a "molecular glue" mechanism to enhance protein-protein interactions with the assistance of another small molecule cofactor, inositol hexakisphosphate. Given the extensive repertoire of similar ubiquitin ligases in eukaryotic cells, this novel and widely adopted hormone-signaling mechanism in plants may also exist in other organisms.

Peptide processing and biology in human disease

PURPOSE OF REVIEW

To describe recent advances in the processing of gastrointestinal hormones, and the consequences for human disease of mutations in the enzymes involved.

RECENT FINDINGS

Although gastrointestinal prohormones were long regarded as devoid of biological activity, recent data indicate that the prohormones for both gastrin and gastrin-releasing peptide are bioactive, through different receptors from the mature hormones. Mutations in the family of prohormone convertases responsible for the initial steps in the processing of gastrointestinal hormones are associated with several different pathophysiological conditions in humans.

SUMMARY

Human mutational studies, when taken together with the phenotypes observed in mice deficient in the prohormone convertases, emphasize the crucial importance of the processing enzymes in mammalian biology. Although the phenotypes may often be ascribed to defective production of a mature hormone or growth factor, the recognition that the precursors are independently bioactive suggests that the increased precursor concentrations may also contribute to the symptoms. The observation that the precursors often act through different receptors from the mature hormones may permit the development of precursor-selective antagonists for therapeutic use.

Immunoendocrine mechanisms associated with resistance or susceptibility to parasitic diseases during pregnancy

During pregnancy, the mammalian endocrine system plays a leading role in maintaining the fetus, characterized by an increase in the level of hormones such as progesterone, oestradiol and some gonadotropic hormones. The immune system participates during pregnancy by self-regulating to prevent fetus rejection. The distinctive type of immunity during gestation is characterized by an increase in levels of Th2 type cytokines IL-4, IL-6 and IL-10, concomitant with a decrease in IL-2, INF-gamma and TNF-alpha levels. Along pregnancy, sex steroids and factors associated with them regulate the immune response. In this way, endocrine and immunologic factors have an impact on the pregnant female's susceptibility or resistance to parasitic diseases. There are three main mechanisms proposed to explain this susceptibility or resistance: (1) sex steroids influence the host's immune system; (2) hormones acting directly on the parasites inhibit or promote their reproduction, or (3) the two effects can occur simultaneously within a network of immuno-endocrine host-parasite interactions, mediated by hormones, cytokines, antibodies and other factors interacting directly and bidirectionally. The present work reviews recent literature concerning the most frequent parasitic infections during pregnancy and discusses the mechanisms implied in the establishment, growth, reproduction or elimination of the parasite.

Signal-response modeling of partial hormone feedback networks

BACKGROUND

Endocrine feedback control networks are typically complex and contain multiple hormones, pools, and compartments. The hormones themselves commonly interact via multiple pathways and targets within the networks, and a complete description of such relationships may involve hundreds of parameters. In addition, it is often difficult, if not impossible, to collect experimental data pertaining to every component within the network. Therefore, the complete simultaneous analysis of such networks is challenging. Nevertheless, an understanding of these networks is critical for furthering our knowledge of hormonal regulation in both physiologic and pathophysiologic conditions.

METHODS

We propose a novel approach for the analysis of dose-response relationships of subsets of hormonal feedback networks. The algorithm and signal-response quantification (SRQuant) software is based on convolution integrals, and tests whether several discretely measured input signals can be individually delayed, spread in time, transformed, combined, and discretely convolved with an elimination function to predict the time course of the concentration of an output hormone. Signal-response quantification is applied to examples from the endocrine literature to demonstrate its applicability to the analysis of the different endocrine networks.

RESULTS

In one example, SRQuant determines the dose-response relationship by which one hormone regulates another, highlighting its advantages over other traditional methods. In a second example, for the first time (to the best of our knowledge), we show that the secretion of glucagon may be jointly controlled by the β and the δ cells.

CONCLUSION

We have developed a novel convolution integral-based approach, algorithm, and software (SRQuant) for the analysis of dose-response relationships within subsets of complex endocrine feedback control networks.

Neuroimmunomodulation during infectious diseases: mechanisms, causes and consequences for the host

In this special issue of Neuroimmunomodulation, the reader will find reviewed some of the hottest topics in the field of neuroendocrine-immune interactions, with emphasis on infectious diseases. For instance, the role that immunoendocrine alterations have during human tuberculosis, a chronic infectious disease, is discussed, and it is concluded that these immunoendocrine interactions may play a detrimental role during the disease, in terms of the development of protective immune responses, control of tissue damage and metabolic disorders. Also, the role that neuroimmunomodulation plays in parasitic diseases is presented, and emphasizes the importance of the host-parasite neuroimmunoendocrine network during helminth infection. Moreover, the influence of beta-androstenes on resistance to viral and bacterial infections is discussed, as well as the impact of infectious diseases upon neuroendocrine circuits. Also, the reader will find contributions to the study of sex hormones and modulation of immunity against leishmaniasis, as well as recent work on the immune mechanisms associated with resistance or susceptibility to parasitic diseases during pregnancy. We hope that our readers will find the first ever special issue devoted to neuroimmunomodulation and infectious diseases fascinating and enticing.

[Pathophysiological implications of the chemical messengers]

To maintain a physical organization and a different composition of its surroundings environment, living beings use a great part of the energy that they produce. Vital processes require an elevated number of reactions which are regulated and integrated by chemical messengers. They use autocrine, paracrine, endocrine and synaptic signals through receptors of cell surface, nuclear or associated with ionic chanels, enzymes, trimeric G proteins and to intracellular kinases. Through these mechanisms pheromones play an important role in the relationships between different individuals, and hormones are able to regulate the integrative functions of our organism. In the nervous system, neurotransmitters, neuromodulators, sensors and receptors between other messengers, play functions of great relevance, while growth factors stimulate cell proliferation and cytokines have many effects but the most important is the ones related with the control of the immflamatory process. Alterations of these messengers permit us a better understanding of the diseases and possibly of its treatments in a near future. Modifications of the expression of genes from the nuclear and mitochondrial genomas are responsible of monogenic, polygenic and mitochondrial diseases, while alterations in the activities of dopamine and serotonin neurotransmitters are related with schizophrenia, Parkinson disease and depression, respectively. Other example is the hyperthyroidism of the Graves-Bassedow disease due to the competitive interference of the LATS immunoglobulin with TSH at the level of the folicular cells producing thyroid hormones Twenty five years ago in the reviews on the mechanisms of insulin action, there was presentations in which the insulin receptor was located in the plasma membrane of the target cells while in the cytoplasm only a big interrogative was observed, that at present is replaced by chemical mediators cascades responsible of the multiple effects of insulin. This finding is similar to many other processes, and all together constitute a new approach for a better knowledge of the biological processes and as a consequence of the diseases.

The impact of infectious diseases upon neuroendocrine circuits

During infectious diseases, neuroendocrine and immune networks act in concert, facilitating host response. It is known that infections cause profound immune changes, but the impact upon immunoendocrine circuits has been less studied. Disorders in the hypothalamic-pituitary-adrenal (HPA) axis were frequently observed associated with infections, and these changes often occur in parallel to alterations in the systemic cytokine network. Explanations for the infection-associated immunoendocrine disturbances include several and not mutually exclusive possibilities. Changes in cytokine levels can enhance or suppress the HPA axis, by acting at the hypothalamus-pituitary unit and/or at the adrenal glands. In situ inflammatory reactions or structural changes like vascular alterations or an enhanced extracellular matrix deposition in the endocrine microenvironment may also lead to a transient HPA dysfunction. Lastly, a microbe-related effect by means of pathogen infiltration or exploitation of the host's hormonal microenvironment may be involved as well. A better understanding of the relevance of immunoendocrine communication during infectious diseases, and how disturbances in the flux of information lead to neuroendocrine immune-related disorders will provide important insights into mechanisms underlying the disease pathology.

Voyages of discovery

The metabolism of calcium and bone is controlled by five principal hormones: parathyroid hormone, 1,25-dihydroxyvitamin D, calcitonin, parathyroid hormone-related peptide and fibroblast growth factor 23, some of which have been known for several decades and some of which have only recently been identified. The stories of discovery of these hormones have constituted a series of complex journeys which have been undertaken over the past century or so and none of which has yet been completed. The complexities of bone and calcium metabolism have been and remain, to many people, somewhat mysterious and a daunting task to understand. This book is designed to try to unravel those mysteries and present them in an interesting and comprehensible manner.

Arabidopsis Hormone Database: a comprehensive genetic and phenotypic information database for plant hormone research in Arabidopsis

Plant hormones are small organic molecules that influence almost every aspect of plant growth and development. Genetic and molecular studies have revealed a large number of genes that are involved in responses to numerous plant hormones, including auxin, gibberellin, cytokinin, abscisic acid, ethylene, jasmonic acid, salicylic acid, and brassinosteroid. Here, we develop an Arabidopsis hormone database, which aims to provide a systematic and comprehensive view of genes participating in plant hormonal regulation, as well as morphological phenotypes controlled by plant hormones. Based on data from mutant studies, transgenic analysis and gene ontology (GO) annotation, we have identified a total of 1026 genes in the Arabidopsis genome that participate in plant hormone functions. Meanwhile, a phenotype ontology is developed to precisely describe myriad hormone-regulated morphological processes with standardized vocabularies. A web interface (http://ahd.cbi.pku.edu.cn) would allow users to quickly get access to information about these hormone-related genes, including sequences, functional category, mutant information, phenotypic description, microarray data and linked publications. Several applications of this database in studying plant hormonal regulation and hormone cross-talk will be presented and discussed.

Disease expression in women with hereditary angioedema

OBJECTIVE

Fluctuations in sex hormones can trigger angioedema attacks in women with hereditary angioedema. Combined oral contraceptive therapies, as well as pregnancy, can induce severe attacks. The course of angioedema may be very variable in different women.

STUDY DESIGN

Within the PREHAEAT project launched by the European Union, data on 150 postpubertal women with hereditary angioedema were collected in 8 countries, using a patient-based questionnaire.

RESULTS

Puberty worsened the disease for 62%. Combined oral contraceptives worsened the disease for 79%, whereas progestogen-only pills improved it for 64%. During pregnancies, 38% of women had more attacks, but 30% had fewer attacks. Vaginal delivery was usually uncomplicated. Attacks occurred within 48 hours in only 6% of cases. Those more severely affected during menses had more symptoms during pregnancies, suggesting a hormone-sensitive phenotype for some patients.

CONCLUSION

The course of angioedema in women with C1 inhibitor deficiency is affected by physiologic hormonal changes; consequently, physicians should take these into account when advising on management.