scholarly journals Phosphodiesterase Activities in the Eye of Old and Young Rats in Normoxic, Hypoxic and Hyperoxic Atmospheres

2003 ◽  
Vol 1 (1) ◽  
pp. 25-32 ◽  
Author(s):  
G. Spoto ◽  
A. Contento ◽  
M. Di Nicola ◽  
G. Bianchi ◽  
C. Di Giulio ◽  
...  
Keyword(s):  
Cyclic Nucleotides ◽  
Biological Effects ◽  
Atmospheric Oxygen ◽  
Second Messengers ◽  
Camp Phosphodiesterase ◽  
Young Rats ◽  
Physiological Processes ◽  
Adaptive Processes ◽  
Old Rats

Phosphodiesterase activity was tested on homogenized eyes of young and old rats kept in hypoxic and hyperoxic conditions, with the aim of correlating any difference in PDE activity with aging and variations in atmospheric oxygen contents. The activities of the two enzymes, cAMP phosphodiesterase (cAMP-PDE) and cGMP phosphodiesterase (cGMP-PDE), were tested. Phosphodiesterases seem to be particularly susceptible to variations in oxygen tension, suggesting an important role of cyclic nucleotides in cellular adaptive processes. Particularly, cAMP-PDE activity increases lightly both in hypoxic and hyperoxic conditions in young and old rats. For cGMP-PDE activity of young rats, a similar behaviour to cAMP-PDE activity is observed with a similar increase in hypoxic and hyperoxic conditions respect to the control rats. Instead old rats seem to be quite insensible to hypoxia, while they show a fair increase in cGMP-PDE activity in the case of hyperoxia. The second messengers cAMP and cGMP play important roles in mediating the biological effects of a wide variety of first messengers. The intracellular levels of cyclic nucleotides depend upon rates of synthesis and degradation, actuated, respectively, by cyclases and phosphodiesterases (PDEs). Therefore, PDEs seem to play an important role in a wide variety of physiological processes.

The Hypothalamo–Pituitary–Adrenocortical Axis—An Overview of the Role of Glucocorticoids in the Pathophysiology of Endocrine Disorders and Perspectives for the Future

2011 ◽  
Vol 07 (01) ◽  
pp. 65
Author(s):  
Christopher D John ◽  
Julia C Buckingham ◽  
◽  
Keyword(s):  
Acute Stress ◽  
Subsequent Development ◽  
Endocrine Disorders ◽  
Adaptive Responses ◽  
Inhibitory Effects ◽  
Cellular Processes ◽  
Physiological Processes ◽  
Wear And Tear ◽  
Adaptive Processes

Glucocorticoids (GCs) are the end products of the hypothalamo–pituitary–adrenocortical axis (HPA) and, via activation of the ubiquitously expressed GC receptor, influence numerous physiological processes. GCs are also involved in the regulation of basal homeostasis as well as mediating adaptive responses to stress that act to restore homeostasis. This article discusses the various factors that are important in regulating plasma and intracellular GC concentrations and describes the genomic and non-genomic mechanisms used by GCs to influence cellular processes. We describe the concept of allostatic overload associated with chronic HPA activation and the subsequent development of tissue dysfunction and disease. While allostasis is associated with acute stress and a restoration of homeostasis, chronic stress is likely to induce allostatic overload owing to the sustained activation of adaptive processes. Increased wear and tear in GC-sensitive tissues can eventually lead to tissue dysfunction and disease. Chronic elevations in GCs can also induce dysfunction or disease associated with decreased tissue function owing to the prolonged inhibitory effects of GCs or the redistribution of metabolic resource away from physiological systems not involved in restoring homeostasis. Numerous endocrine-related disorders are associated with aberrant GC levels and in terms of pathophysiology may be linked with chronic tissue-specific alterations in GC actions.

scholarly journals A Survey of Nucleotide Cyclases in Actinobacteria: Unique Domain Organization and Expansion of the Class III Cyclase Family inMycobacterium tuberculosis

2004 ◽  
Vol 5 (1) ◽  
pp. 17-38 ◽  
Author(s):  
Avinash R. Shenoy ◽  
K. Sivakumar ◽  
A. Krupa ◽  
N. Srinivasan ◽  
Sandhya S. Visweswariah
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cyclic Nucleotides ◽  
Metabolic Pathways ◽  
Second Messengers ◽  
Class Iii ◽  
Genome Sequences ◽  
Important Group ◽  
Unique Domain ◽  
First Time

Cyclic nucleotides are well-known second messengers involved in the regulation of important metabolic pathways or virulence factors. There are six different classes of nucleotide cyclases that can accomplish the task of generating cAMP, and four of these are restricted to the prokaryotes. The role of cAMP has been implicated in the virulence and regulation of secondary metabolites in the phylum Actinobacteria, which contains important pathogens, such asMycobacterium tuberculosis, M. leprae, M. bovisandCorynebacterium, and industrial organisms from the genusStreptomyces. We have analysed the actinobacterial genome sequences found in current databases for the presence of different classes of nucleotide cyclases, and find that only class III cyclases are present in these organisms. Importantly, prominent members such asM. tuberculosisandM. lepraehave 17 and 4 class III cyclases, respectively, encoded in their genomes, some of which display interesting domain fusions seen for the first time. In addition, a pseudogene corresponding to a cyclase fromM. aviumhas been identified as the only cyclase pseudogene inM. tuberculosisandM. bovis. TheCorynebacteriumandStreptomycesgenomes encode only a single adenylyl cyclase each, both of which have corresponding orthologues inM. tuberculosis. A clustering of the cyclase domains in Actinobacteria reveals the presence of typical eukaryote-like, fungi-like and other bacteria-like class III cyclase sequences within this phylum, suggesting that these proteins may have significant roles to play in this important group of organisms.

scholarly journals Deciphering the function of the CNGB1b subunit in olfactory CNG channels

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Vasilica Nache ◽  
Nisa Wongsamitkul ◽  
Jana Kusch ◽  
Thomas Zimmer ◽  
Frank Schwede ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Cyclic Nucleotides ◽  
Second Messengers ◽  
Receptor Potential ◽  
Similar Extent ◽  
Exact Role ◽  
Channel Activation ◽  
Signal Transduction Cascade ◽  
Camp And Cgmp

Abstract Olfactory cyclic nucleotide-gated (CNG) ion channels are key players in the signal transduction cascade of olfactory sensory neurons. The second messengers cAMP and cGMP directly activate these channels, generating a depolarizing receptor potential. Olfactory CNG channels are composed of two CNGA2 subunits and two modulatory subunits, CNGA4, and CNGB1b. So far the exact role of the modulatory subunits for channel activation is not fully understood. By measuring ligand binding and channel activation simultaneously, we show that in functional heterotetrameric channels not only the CNGA2 subunits and the CNGA4 subunit but also the CNGB1b subunit binds cyclic nucleotides and, moreover, also alone translates this signal to open the pore. In addition, we show that the CNGB1b subunit is the most sensitive subunit in a heterotetrameric channel to cyclic nucleotides and that it accelerates deactivation to a similar extent as does the CNGA4 subunit. In conclusion, the CNGB1b subunit participates in ligand-gated activation of olfactory CNG channels and, particularly, contributes to rapid termination of odorant signal in an olfactory sensory neuron.

scholarly journals Role of Cannabinoid Receptors in Psychological Disorder

2020 ◽  
Vol 3 (4) ◽  
pp. 199-208
Author(s):  
Ambika Nand Jha ◽  
Dhaval M Patel
Keyword(s):  
Cannabinoid Receptors ◽  
Biological Effects ◽  
Endocannabinoid System ◽  
Brain Regions ◽  
The Body ◽  
Psychological Disorder ◽  
Physiological Processes ◽  
Neurochemical Changes ◽  
G Protein Coupled

Cannabinoid receptors, located throughout the body, are part of the endocannabinoid system. Cannabinoid CB1 and CB2 receptors are G protein-coupled receptors present from the early stages of gestation, which is involved in various physiological processes, including appetite, pain-sensation, mood, and memory. Due to the lipophilic nature of cannabinoids, it was initially thought that these compounds exert several biological effects by disrupting the cell membrane nonspecifically. Recent biochemical and behavioral findings have demonstrated that blockade of CB1 receptors engenders antidepressant-like neurochemical changes (increases in extracellular levels of monoamines in cortical but not subcortical brain regions) and behavioral effects consistent with antidepressant/antistress activity. We aim to define various roles of cannabinoid receptors in modulating signaling pathways and association with several pathophysiological conditions.

scholarly journals Selenium, Selenoproteins, and Immunity

Nutrients ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1203 ◽  
Author(s):  
Joseph Avery ◽  
Peter Hoffmann
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
High Throughput ◽  
Molecular Mechanisms ◽  
Immune Cell ◽  
Biological Effects ◽  
Cell Functions ◽  
Experimental Systems ◽  
Physiological Processes

Selenium is an essential micronutrient that plays a crucial role in development and a wide variety of physiological processes including effect immune responses. The immune system relies on adequate dietary selenium intake and this nutrient exerts its biological effects mostly through its incorporation into selenoproteins. The selenoproteome contains 25 members in humans that exhibit a wide variety of functions. The development of high-throughput omic approaches and novel bioinformatics tools has led to new insights regarding the effects of selenium and selenoproteins in human immuno-biology. Equally important are the innovative experimental systems that have emerged to interrogate molecular mechanisms underlying those effects. This review presents a summary of the current understanding of the role of selenium and selenoproteins in regulating immune cell functions and how dysregulation of these processes may lead to inflammation or immune-related diseases.

scholarly journals Epididymal antimicrobial peptides: the role in sperm function (review)

2021 ◽  
pp. 4-12
Author(s):  
П.А. Шабанов ◽  
О.В. Шамова ◽  
Д.С. Орлов ◽  
А.Ю. Грязнов ◽  
Н.О. Янчук
Keyword(s):  
Antimicrobial Peptides ◽  
Germ Cells ◽  
Plasma Membranes ◽  
Reproductive Tract ◽  
Biological Effects ◽  
Physiological Activity ◽  
Female Reproductive Tract ◽  
Physiological Processes ◽  
Molecular Regulatory Mechanisms

Значительное снижение показателей мужской фертильности, наблюдаемое в последнее время во всем мире, ведёт к необходимости более глубокого изучения механизмов молекулярной регуляции гаметогенеза и посттестикулярной трансформации сперматозоидов. Совершенствование способов влияния на эти процессы, а также поиск веществ, повышающих устойчивость гамет к действию различных повреждающих факторов, открывают перспективы разработки новых подходов в лечении мужского бесплодия. В связи с этим актуальным направлением является исследование роли эндогенных антимикробных пептидов и их физиологической активности при созревании и функционировании мужских половых клеток. Антимикробные пептиды - это уникальные компоненты системы врожденного иммунитета. Они не только обеспечивают противоинфекционную защиту организма от бактерий, вирусов и грибов, но и проявляют достаточно разнообразные биологические эффекты, которые связаны, в том числе и со способностью этих молекул принимать непосредственное участие в физиологических процессах посттестикулярного созревания половых клеток, модификации цитоплазматических мембран сперматозоидов в эпидидимисе, а также капацитации в женском репродуктивном тракте. В настоящем обзоре рассмотрены современные представления о роли антимикробных пептидов придатков яичек с позиций их участия в функционировании сперматозоидов в норме и при патологии. The significant worldwide decline in male fertility requires a comprehensive study of molecular regulatory mechanisms of gametogenesis and post-testicular sperm maturation. Improving ways to influence these processes as well as searching for substances that increase the resistance of gametes to the action of various damaging factors open up prospects for development of new approaches to treat male infertility. In this regard, current emphasis is on the study of a role of endogenous antimicrobial peptides (AMPs) and their physiological activity during the maturation and functioning of male germ cells. AMPs are unique components of the innate immune system. They not only provide protection against bacteria, viruses, and fungi, but also have relatively diverse biological effects. These effects are closely related to the ability of AMPs to be directly involved in the physiological processes of post-testicular maturation of germ cells, in modification of the plasma membranes of sperms in the epididymis, and their capacitation in the female reproductive tract. This review focuses on the current understanding of the role of epididymal AMPs with regard to the functioning of sperm in normal and pathological conditions.

The Hypothalamo–Pituitary–Adrenocortical Axis – An Overview of the Role of Glucocorticoids in the Pathophysiology of Endocrine Disorders and Perspectives for the Future

2010 ◽  
Vol 7 (1) ◽  
pp. 47
Author(s):  
Christopher D John ◽  
Julia C Buckingham ◽  
◽  
Keyword(s):  
Acute Stress ◽  
Subsequent Development ◽  
Endocrine Disorders ◽  
Adaptive Responses ◽  
Inhibitory Effects ◽  
Cellular Processes ◽  
Physiological Processes ◽  
Wear And Tear ◽  
Adaptive Processes

Glucocorticoids (GCs) are the end products of the hypothalamo–pituitary–adrenocortical axis (HPA) and, via activation of the ubiquitously expressed GC receptor, influence numerous physiological processes. GCs are also involved in the regulation of basal homeostasis as well as mediating adaptive responses to stress that act to restore homeostasis. This article discusses the various factors that are important in regulating plasma and intracellular GC concentrations and describes the genomic and non-genomic mechanisms used by GCs to influence cellular processes. We describe the concept of allostatic overload associated with chronic HPA activation and the subsequent development of tissue dysfunction and disease. While allostasis is associated with acute stress and a restoration of homeostasis, chronic stress is likely to induce allostatic overload owing to the sustained activation of adaptive processes. Increased wear and tear in GC-sensitive tissues can eventually lead to tissue dysfunction and disease. Chronic elevations in GCs can also induce dysfunction or disease associated with decreased tissue function owing to the prolonged inhibitory effects of GCs or the redistribution of metabolic resource away from physiological systems not involved in restoring homeostasis. Numerous endocrine-related disorders are associated with aberrant GC levels and in terms of pathophysiology may be linked with chronic tissue-specific alterations in GC actions.

Follicle-stimulating hormone-dependent estrogen secretion by rat Sertoli cells in vitro: Modulation by calcium

1991 ◽  
Vol 125 (3) ◽  
pp. 280-285 ◽  
Author(s):  
J. Alan Talbot ◽  
Ann Lambert ◽  
Robert Mitchell ◽  
Marek Grabinski ◽  
David C. Anderson ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Culture Medium ◽  
Follicle Stimulating Hormone ◽  
Dibutyryl Camp ◽  
Immature Rat ◽  
Estradiol Secretion ◽  
Old Rats ◽  
Stimulating Hormone

Abstract We have investigated the role of Ca2+ in the control of FSH-induced estradiol secretion by Sertoli cells isolated from 8-10 days old rats. Exogenous Ca2+ (4-8 mmol/1) inhibited FSH-stimulated E2 secretion such that, with 8 mmol/l Ca2+ and FSH (8 IU/l) E2 secretion decreased from 2091±322 to 1480±84 pmol/l (p<0.002), whilst chelation of Ca2+ in the culture medium with EGTA (3 mmol/l) increased E2 secretion from 360±45 to 1242±133 pmol/l) in the absence of FSH. Further, EGTA (3 mmol/l) markedly potentiated FSH (8 IU/l), forskolin (1 μmol/l) and dibutyryl cAMP (1 mmol/l)-stimulated E2 secretion. Addition of the Ca2+ ionophores, ionomycin (2-5 μmol/l) and A23187 (2 μmol/l), inhibited FSH (8 IU/l)-stimulated E2 secretion by >80%. The effect of ionomycin was totally reversible, whereas that of A23187 was irreversible. Ionomycin (5 μmol/l) had no effect on EGTA-induced E2 secretion in the absence of FSH, but reduced EGTA-provoked E2 secretion by 59% in the presence of FSH (8 IU/l). Similarly, forskolin- and dibutyryl cAMP-provoked E2 production was inhibited 46-50% by ionomycin (5 μmol/l). We conclude that FSH-induced E2 secretion from immature rat Sertoli cells is modulated by intra- and extracellular Ca2+.

Stimulation of Ca(2+)-dependent exocytosis of the sperm acrosome by cAMP acting downstream of phospholipase A2

Reproduction ◽  
2000 ◽  
pp. 57-68 ◽  
Author(s):  
J Garde ◽  
ER Roldan
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Phospholipase C ◽  
Phosphodiesterase Inhibitors ◽  
Dibutyryl Camp ◽  
Camp Phosphodiesterase ◽  
Ram Sperm ◽  
Camp Formation ◽  
Stimulation Of

Spermatozoa undergo exocytosis in response to agonists that induce Ca2+ influx and, in turn, activation of phosphoinositidase C, phospholipase C, phospholipase A2, and cAMP formation. Since the role of cAMP downstream of Ca2+ influx is unknown, this study investigated whether cAMP modulates phospholipase C or phospholipase A2 using a ram sperm model stimulated with A23187 and Ca2+. Exposure to dibutyryl-cAMP, phosphodiesterase inhibitors or forskolin resulted in enhancement of exocytosis. However, the effect was not due to stimulation of phospholipase C or phospholipase A2: in spermatozoa prelabelled with [3H]palmitic acid or [14C]arachidonic acid, these reagents did not enhance [3H]diacylglycerol formation or [14C]arachidonic acid release. Spermatozoa were treated with the phospholipase A2 inhibitor aristolochic acid, and dibutyryl-cAMP to test whether cAMP acts downstream of phospholipase A2. Under these conditions, exocytosis did not occur in response to A23187 and Ca2+. However, inclusion of dibutyryl-cAMP and the phospholipase A2 metabolite lysophosphatidylcholine did result in exocytosis (at an extent similar to that seen when cells were treated with A23187/Ca2+ and without the inhibitor). Inclusion of lysophosphatidylcholine alone, without dibutyryl-cAMP, enhanced exocytosis to a lesser extent, demonstrating that cAMP requires a phospholipase A2 metabolite to stimulate the final stages of exocytosis. These results indicate that cAMP may act downstream of phospholipase A2, exerting a regulatory role in the exocytosis triggered by physiological agonists.

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