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Endocrine Regulation (endocrine + regulation)
Selected AbstractsENDOCRINE REGULATION OF CALCIUM TRANSPORT IN EPITHELIACLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2008Ramesh C Khanal SUMMARY 1Calcium (re)absorption occurs in epithelia, including the intestine, kidney, mammary glands, placenta and gills (in the case of fish). 2Calcium is transported across epithelia by two transport mechanisms, paracellular and transcellular, and the movement is regulated by a complex array of transport processes that are mediated by hormonal, developmental and physiological factors involving the gastrointestinal tract, bone, kidney and the parathyroids. 3Clear understanding of the calcium transport pathways and their endocrine regulation is critical for minimizing various metabolic and health disorders at different physiological stages. Here, we first briefly review the calcium transport mechanisms before discussing in detail the endocrine factors that regulate calcium transport in the epithelia. [source] The Role of the Endometrium in Endocrine Regulation of the Animal Oestrous CycleREPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2008T Krzymowski Contents A critical analysis of the results of research in the function of the endometrium was carried out and a view point presented. The role of the endometrium in endocrine regulation of the oestrus cycle can be summarized as follows: 1. The transfer of prostaglandin F2, (PGF2,) from the uterus to an ovary, which causes luteolysis, occurs mainly via the lymphatic pathways. 2. The system of retrograde transfer of PGs enables PGF2, and PGE2 to reach the myometrium and endometrium with arterial blood at high concentration. In the luteal phase, PGF2,, together with the increasing concentration of progesterone, constricts the arterial vessels of the uterus; in the follicular phase and in early pregnancy, PGE2 together with oestrogen and embryonic signals, relaxes the arterial vessels. In addition, this system protects the corpus luteum from premature luteolysis during the cycle and luteolysis during early pregnancy. 3. In days 10,12 of the cycle, the blood flow in the uterus decreases by 60,70% in pigs and around 90% in sheep. This causes ischaemia and local hypoxia confirmed by the presence of hypoxia inducible factor and thus remodelling of the endometrium commences. 4. The pulsatile elevations in PGF2, concentration occurring in the blood flowing out of the uterus during the period of luteolysis and the next few days, do not result from increased PGF2, synthesis as suggested in numerous studies. They are the effect of excretion of PGF2, and its metabolites together with lymph and venous blood and tissue fluids in which prostaglandin accumulates. [source] Endocrine regulation of bone turnover in menCLINICAL ENDOCRINOLOGY, Issue 6 2005Christian Meier First page of article [source] Proliferation and differentiation of intestinal stem cells during metamorphosis of the red flour beetle, Tribolium castaneumDEVELOPMENTAL DYNAMICS, Issue 4 2008R. Parthasarathy Abstract The insect midgut epithelium is remodeled during larval-pupal metamorphosis when larval polyploid cells (LPCs) are replaced by the daughters of intestinal stem cells (ISCs). We characterized the proliferation of ISCs during midgut remodeling in the red flour beetle, Tribolium castaneum. Midgut remodeling is initiated at 96 hr after ecdysis into the final instar larval stage. Immunocytochemistry with bromodeoxyuridine and phospho-histone H3 antibodies showed that the ISCs are the progenitors of the pupal/adult midgut epithelium and they undergo proliferation and differentiation to form new midgut epithelium. In vitro midgut culture experiments revealed that 20-hydroxyecdysone (20E) in the absence of juvenile hormone induces proliferation of ISCs. RNA interference (RNAi) mediated silencing of ecdysone receptors (EcRA and EcRB) and ultraspiracle (USP) identified EcRA and USP but not EcRB as the proteins involved in 20E regulation of ISCs proliferation. These data show that the proliferation of ISCs is under both developmental and endocrine regulation. Developmental Dynamics 237:893,908, 2008. © 2008 Wiley-Liss, Inc. [source] Testosterone, growth and the evolution of sexual size dimorphismJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 8 2009R. M. COX Abstract The integration of macroevolutionary pattern with developmental mechanism presents an outstanding challenge for studies of phenotypic evolution. Here, we use a combination of experimental and comparative data to test whether evolutionary shifts in the direction of sexual size dimorphism (SSD) correspond to underlying changes in the endocrine regulation of growth. First, we combine captive breeding studies with mark-recapture data to show that male-biased SSD develops in the brown anole lizard (Anolis sagrei) because males grow significantly faster than females as juveniles and adults. We then use castration surgeries and testosterone implants to show that castration inhibits, and testosterone stimulates, male growth. We conclude by reviewing published testosterone manipulations in other squamate reptiles in the context of evolutionary patterns in SSD. Collectively, these studies reveal that the evolution of SSD has been accompanied by underlying changes in the effect of testosterone on male growth, potentially facilitating the rapid evolution of SSD. [source] The role of cell-specific circadian clocks in metabolism and diseaseOBESITY REVIEWS, Issue 2009M. S. Bray Summary Biological rhythms are an integral component of essentially all aspects of life. These rhythms are controlled in part by circadian clocks, transcriptionally based mechanisms that synchronize the organism to its changing environment. The central circadian clock is located within the suprachiasmatic nucleus of the brain, while peripheral clocks are located within virtually all cells outside of the suprachiasmatic nucleus. Although our understanding of central clock structure and function is well advanced, the role of peripheral clocks in whole body energy metabolism is just beginning to be elucidated. Both central and peripheral circadian clocks likely regulate many physiological functions, including insulin sensitivity, endocrine regulation, energy homeostasis, satiety signalling, cellular proliferation and cardiovascular function. Widely varying phenotypes have been reported following global genetic disruption of the clock mechanism in mice, with phenotype dependent on both the clock component targeted and genetic background. The inconsistency in phenotypes associated with clock disruption may be due, in part, to cell-specific effects of the circadian clocks. To address this question, many laboratories have begun generating animal models of cell type-specific clock disruption. In this review, we summarize the existing literature on tissue-specific models of circadian clock disruption and provide a focus for future research in this area. [source] The Role of the Endometrium in Endocrine Regulation of the Animal Oestrous CycleREPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2008T Krzymowski Contents A critical analysis of the results of research in the function of the endometrium was carried out and a view point presented. The role of the endometrium in endocrine regulation of the oestrus cycle can be summarized as follows: 1. The transfer of prostaglandin F2, (PGF2,) from the uterus to an ovary, which causes luteolysis, occurs mainly via the lymphatic pathways. 2. The system of retrograde transfer of PGs enables PGF2, and PGE2 to reach the myometrium and endometrium with arterial blood at high concentration. In the luteal phase, PGF2,, together with the increasing concentration of progesterone, constricts the arterial vessels of the uterus; in the follicular phase and in early pregnancy, PGE2 together with oestrogen and embryonic signals, relaxes the arterial vessels. In addition, this system protects the corpus luteum from premature luteolysis during the cycle and luteolysis during early pregnancy. 3. In days 10,12 of the cycle, the blood flow in the uterus decreases by 60,70% in pigs and around 90% in sheep. This causes ischaemia and local hypoxia confirmed by the presence of hypoxia inducible factor and thus remodelling of the endometrium commences. 4. The pulsatile elevations in PGF2, concentration occurring in the blood flowing out of the uterus during the period of luteolysis and the next few days, do not result from increased PGF2, synthesis as suggested in numerous studies. They are the effect of excretion of PGF2, and its metabolites together with lymph and venous blood and tissue fluids in which prostaglandin accumulates. [source] Ascorbic acid and reproduction in fish: endocrine regulation and gamete qualityAQUACULTURE RESEARCH, Issue 8 2001K Dabrowski Abstract High ascorbic acid concentrations have been associated with gonad and brain tissues in teleost fishes. Although a direct dietary effect on gamete quality has been given some attention recently, the mechanism of action of ascorbate along the cascade of reproductive events in the hypothalamus, pituitary and gonads has not been defined. Data relating to gamete production and quality, as well as a possible protective role for ascorbate against cumulative genetic defects during gametogenesis and congenital malformation during gestation (embryonic development) is reviewed. It is suggested that the gonad growth in response to gonadotropin stimulation involves direct interaction between catecholamines and steroid hormones and their receptor sites. This interaction acts as a regulatory mechanism of ascorbate absorption, transfer and metabolism (degradation and/or renewal) in the reproductive system. We conclude that ascorbic acid is a leading nutrient in reproductive tissue functions and further research is needed on: (1) its antioxidant effect on gametes' (sperm and ova) capacity to prevent DNA damage occurring prior to (endogenous) and after spawning (environmental insults); (2) its dietary requirement to optimize survival and physiological recovery in multiple spawners; (3) the integration mechanism of ascorbic acid action as part of the overall endocrine regulation of neurohormonal,hormonal pathway in fish reproduction; and (4) the possible role for ascorbate in regulating fish maturation and/or infertility in the presence of enhanced UV-radiation or conditions of intensive aquaculture (hypoxia, oxygen supersaturation, dietary pro,, and antioxidants). [source] ENDOCRINE REGULATION OF CALCIUM TRANSPORT IN EPITHELIACLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2008Ramesh C Khanal SUMMARY 1Calcium (re)absorption occurs in epithelia, including the intestine, kidney, mammary glands, placenta and gills (in the case of fish). 2Calcium is transported across epithelia by two transport mechanisms, paracellular and transcellular, and the movement is regulated by a complex array of transport processes that are mediated by hormonal, developmental and physiological factors involving the gastrointestinal tract, bone, kidney and the parathyroids. 3Clear understanding of the calcium transport pathways and their endocrine regulation is critical for minimizing various metabolic and health disorders at different physiological stages. Here, we first briefly review the calcium transport mechanisms before discussing in detail the endocrine factors that regulate calcium transport in the epithelia. [source] Effects of ecdysteroid agonist RH-2485 reveal interactions between ecdysteroids and juvenile hormones in the development of Sesamia nonagrioidesARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2007Matilde Eizaguirre Abstract Larvae of Sesamia nonagrioides developing under long day (LD) conditions pupate in the 5th or 6th instar, whereas under the short day (SD) conditions, they undergo several supernumerary larval molts and are regarded as diapausing. The development in early larval instars occurs in the LD larvae at a moderate and in the SD larvae at a high juvenile hormone (JH) titer; ecdysteroid titer cycles similarly under both conditions. The transformation to pupa is initiated by a burst of ecdysteroids at undetectable JH levels, whereas extra larval molts in the diapausing larvae are associated with moderate JH titer and irregular rises of ecdysteroids. Application of 0.2 ppm RH-2485 to the diet of the 6th instar larvae promotes hormonal changes supporting metamorphosis in the LD larvae and slightly accelerates larval molts in the diapausing SD larvae. The 0.5- and 1-ppm doses revert these patterns of endocrine regulations to a mode typical for early larval instars. Particularly dramatic is a JH titer increase provoked within 24 h in the LD larvae. After the treatment, both the LD and SD larvae undergo a series of larval molts, suggesting that hormonal programming of the larval development has been stabilized. A few insects receiving 1 ppm RH-2485, and a high proportion of those fed with 5 ppm RH-2485, deposit two cuticles within a single apolysis and die. Arch. Insect Biochem. Physiol. 65:74,84, 2007. © 2007 Wiley-Liss, Inc. [source] | |||||||||||||