Late Phase Of Response Research Articles

Distinct dynamic behavioural response to social exclusion in male patients with a history of alcohol dependence.

Social exclusion contributes to alcohol consumption, whereas the development of alcohol dependence (AD) can in turn lead to the social exclusion of people with AD. Previous research observed altered neural responses to experimentally induced social exclusion (i.e., Cyberball game) in patients with AD. In addition, inflammation has been associated with both social behaviours and AD. Our study aimed to investigate the dynamic behavioural response and the inflammatory effects of social exclusion in male patients with a history of AD. To this end, we analysed dynamic changes in ball tossing during a partial exclusion Cyberball game and the cytokine interleukin (IL)-1b in saliva in 31 male patients who had a history of AD and 29 gender-matched healthy controls without AD. Participants were included in the first 2 min of the Cyberball game and then excluded by one of the two co-players in the proceeding 5 min. Saliva was collected three times: one before and two after the Cyberball game. Across groups, participants passed the ball more often to the excluder during the partial exclusion period. Analysis using piece-wise linear mixed models showed that patients rapidly increased ball tosses to the excluder upon exclusion, which lasted to the late response phase, whereas the early behavioural response to exclusion took longer for controls. There was no significant change of salivary IL-1b level to exclusion in either patients or controls. The results indicate a distinct dynamic behavioural response to social exclusion in male patients with a history of AD.

Translational Aspects of Nuclear Factor-Kappa B and Its Modulation by Thalidomide on Early and Late Radiation Sequelae in Urinary Bladder Dysfunction

This preclinical study aimed to investigate the role of nuclear factor (NF)-κB in early and late radiogenic sequelae of urinary bladder dysfunction in mice. Thalidomide was applied either during the early or late response phase to determine potential effects of NF-κB inhibition on functional bladder impairment. After pelvic irradiation on day 0, female C3H/Neu mice were observed over a period of 360 days and radiation response was evaluated for alterations in bladder functionality and NF-κB activation. Functionality was determined in graded dose experiments (14-24 Gy) and assessed by micturition frequency analysis and transurethral cystotonometry to reveal alterations in voiding and volume. The induction of the NF-κB proteins p50 and p65 was evaluated by immunohistochemistry in response to a single dose of 23 Gy (ED90). Thalidomide (100 mg/kg/d) was applied intraperitoneally in 3 treatment groups: daily from day 1 to 15, daily from day 16 to 30, and in 2-day-intervals from day 150 to180. Immunohistochemical analysis showed a biphasic activation of p50 and p65 during the early radiation cystitis phase (day 1-30). After a transient decrease, p50, but not p65, was reactivated permanently leading to increased levels, which suggests an occurrence of chronic inflammation correlated with functional impairment. Both early thalidomide treatments reduced NF-κB activation and shifted the ED50 value for early radiation cystitis and late radiation sequelae to higher doses. These data clearly demonstrate the involvement of NF-κB signaling in the pathogenesis of radiation-induced urinary bladder dysfunction. Additionally, this study emphasizes that biological targeting of early radiogenic processes has enormous effect on chronic symptoms. The late administration of thalidomide showed no significant effect on functionality.

Polyubiquitin Chains Linked by Lysine Residue 48 (K48) Selectively Target Oxidized Proteins In Vivo.

Aims: Ubiquitin is a highly conserved protein modifier that heavily accumulates during the oxidative stress response. Here, we investigated the role of the ubiquitination system, particularly at the linkage level, in the degradation of oxidized proteins. The function of ubiquitin in the removal of oxidized proteins remains elusive because of the wide range of potential targets and different roles that polyubiquitin chains play. Therefore, we describe in detail the dynamics of the K48 ubiquitin response as the canonical signal for protein degradation. We identified ubiquitin targets and defined the relationship between protein ubiquitination and oxidation during the stress response. Results: Combining oxidized protein isolation, linkage-specific ubiquitination screens, and quantitative proteomics, we found that K48 ubiquitin accumulated at both the early and late phases of the stress response. We further showed that a fraction of oxidized proteins are conjugated with K48 ubiquitin. We identified ∼750 ubiquitinated proteins and ∼400 oxidized proteins that were modified during oxidative stress, and around half of which contain both modifications. These proteins were highly abundant and function in translation and energy metabolism. Innovation and Conclusion: Our work showed for the first time that K48 ubiquitin modifies a large fraction of oxidized proteins, demonstrating that oxidized proteins can be targeted by the ubiquitin/proteasome system. We suggest that oxidized proteins that rapidly accumulate during stress are subsequently ubiquitinated and degraded during the late phase of the response. This delay between oxidation and ubiquitination may be necessary for reprogramming protein dynamics, restoring proteostasis, and resuming cell growth.

Genes, pathways and transcription factors involved in seedling stage chilling stress tolerance in indica rice through RNA-Seq analysis

BackgroundRice plants show yellowing, stunting, withering, reduced tillering and utimately low productivity in susceptible varieties under low temperature stress. Comparative transcriptome analysis was performed to identify novel transcripts, gain new insights into different gene expression and pathways involved in cold tolerance in rice.ResultsComparative transcriptome analyses of 5 treatments based on chilling stress exposure revealed more down regulated genes in susceptible and higher up regulated genes in tolerant genotypes. A total of 13930 and 10599 differentially expressed genes (DEGs) were detected in cold susceptible variety (CSV) and cold tolerant variety (CTV), respectively. A continuous increase in DEGs at 6, 12, 24 and 48 h exposure of cold stress was detected in both the genotypes. Gene ontology (GO) analysis revealed 18 CSV and 28 CTV term significantly involved in molecular function, cellular component and biological process. GO classification showed a significant role of transcription regulation, oxygen, lipid binding, catalytic and hydrolase activity for tolerance response. Absence of photosynthesis related genes, storage products like starch and synthesis of other classes of molecules like fatty acids and terpenes during the stress were noticed in susceptible genotype. However, biological regulations, generation of precursor metabolites, signal transduction, photosynthesis, regulation of cellular process, energy and carbohydrate metabolism were seen in tolerant genotype during the stress. KEGG pathway annotation revealed more number of genes regulating different pathways resulting in more tolerant. During early response phase, 24 and 11 DEGs were enriched in CTV and CSV, respectively in energy metabolism pathways. Among the 1583 DEG transcription factors (TF) genes, 69 WRKY, 46 bZIP, 41 NAC, 40 ERF, 31/14 MYB/MYB-related, 22 bHLH, 17 Nin-like 7 HSF and 4C3H were involved during early response phase. Late response phase showed 30 bHLH, 65 NAC, 30 ERF, 26/20 MYB/MYB-related, 11 C3H, 12 HSF, 86 Nin-like, 41 AP2/ERF, 55 bZIP and 98 WRKY members TF genes. The recovery phase included 18 bHLH, 50 NAC, 31 ERF, 24/13 MYB/MYB-related, 4 C3H, 4 HSF, 14 Nin-like, 31 bZIP and 114 WRKY TF genes.ConclusionsTranscriptome analysis of contrasting genotypes for cold tolerance detected the genes, pathways and transcription factors involved in the stress tolerance.

Auditory brainstem stimulation with a conformable microfabricated array elicits responses with tonotopically organized components

Auditory brainstem implants (ABIs) restore hearing to deaf individuals not eligible for cochlear implants. Speech comprehension in ABI users is generally poor compared to that of cochlear implant users, and side effects are common. The poor performance may result from activating broad areas and multiple neuronal populations of the cochlear nucleus, however detailed studies of the responses to surface stimulation of the cochlear nucleus are lacking. A conformable electrode array was microfabricated to fit on the rat's dorsal cochlear nucleus (DCN). It hosts 20 small electrodes (each 100 μm diam.). The array was tested by recording evoked potentials and neural activity along the tonotopic axis of the inferior colliculus (IC). Almost all bipolar electrode pairs elicited responses, in some cases with an even, or relatively constant, pattern of thresholds and supra-threshold measures along the long axis of the array. This pattern suggests that conformable arrays can provide relatively constant excitation along the surface of the DCN and thus might decrease the ABI side effects caused by spread of high current to adjacent structures. We also examined tonotopic patterns of the IC responses. Compared to sound-evoked responses, electrically-evoked response mappings had less tonotopic organization and were broader in width. They became more tonotopic when the evoked activity common to all electrodes and the late phase of response were subtracted out, perhaps because the remaining activity is from tonotopically organized principal cells of the DCN. Responses became less tonotopic when inter-electrode distance was increased from 400 μm to 800 μm but were relatively unaffected by changing to monopolar stimulation. The results illustrate the challenges of using a surface array to present tonotopic cues and improve speech comprehension in humans who use the ABI.

Linking Transcriptional Changes over Time in Stimulated Dendritic Cells to Identify Gene Networks Activated during the Innate Immune Response

The innate immune response is primarily mediated by the Toll-like receptors functioning through the MyD88-dependent and TRIF-dependent pathways. Despite being widely studied, it is not yet completely understood and systems-level analyses have been lacking. In this study, we identified a high-probability network of genes activated during the innate immune response using a novel approach to analyze time-course gene expression profiles of activated immune cells in combination with a large gene regulatory and protein-protein interaction network. We classified the immune response into three consecutive time-dependent stages and identified the most probable paths between genes showing a significant change in expression at each stage. The resultant network contained several novel and known regulators of the innate immune response, many of which did not show any observable change in expression at the sampled time points. The response network shows the dominance of genes from specific functional classes during different stages of the immune response. It also suggests a role for the protein phosphatase 2a catalytic subunit α in the regulation of the immunoproteasome during the late phase of the response. In order to clarify the differences between the MyD88-dependent and TRIF-dependent pathways in the innate immune response, time-course gene expression profiles from MyD88-knockout and TRIF-knockout dendritic cells were analyzed. Their response networks suggest the dominance of the MyD88-dependent pathway in the innate immune response, and an association of the circadian regulators and immunoproteasomal degradation with the TRIF-dependent pathway. The response network presented here provides the most probable associations between genes expressed in the early and the late phases of the innate immune response, while taking into account the intermediate regulators. We propose that the method described here can also be used in the identification of time-dependent gene sub-networks in other biological systems.

Cardiorespiratory fitness predicts insulin action and secretion in healthy individuals

Long-term cardiorespiratory fitness (CRF) and the development of type 2 diabetes mellitus are inversely correlated. Here, we examined the relationships between peak oxygen uptake (VO 2peak), on the one hand, and glucose infusion rate at rest (GIR rest) and during exercise (GIR exercise), as well as insulin secretion (both the early and late phases of response [area under the curve {AUC} insulin]), on the other. Eight male and 4 female healthy, lean, nonsmoking volunteers were recruited. The VO 2peak was measured during graded exercise on a cycle ergometer until exhaustion was reached. The GIR rest and GIR exercise were determined using a euglycemic-hyperinsulinemic clamp, and insulin secretion at rest was evaluated with an intravenous glucose tolerance test. The VO 2peak correlated positively to GIR rest ( r = 0.81, P = .001) and GIR exercise ( r = 0.87, P < .001) and negatively to AUC insulin ( r = −0.64, P = .03). The respiratory exchange ratio (RER) during insulin infusion was positively correlated to GIR rest ( r = 0.83, P < .001) and GIR exercise ( r = 0.86, P < .01) and negatively correlated to both the early insulin response ( r = −0.86, P < .0001) and AUC insulin ( r = −0.87, P = .001). The VO 2peak accounted for 45% of the variability in RER ( R 2 = 0.45, P = .035). In this healthy population, CRF and RER were highly correlated to insulin sensitivity and secretion, as well as to the ability to alter the substrate being oxidized during exercise. These findings highlight the importance of good CRF to maintaining normal insulin action.

Alteration of carotid body chemoreflexes after neonatal intermittent hypoxia and caffeine treatment in rat pups

In human neonates, caffeine therapy for apnoea of prematurity, especially when associated with hypoxemia, is maintained for several weeks after birth. In the present study, we used newborn rats and whole-body plethysmography to test whether chronic exposure to neonatal caffeine treatment (NCT), alone or combined with neonatal intermittent hypoxia (n-IH) alters: (1) baseline ventilation and response to hypoxia (12% O(2), 20 min); and (2) response to acute i.p. injection of caffeine citrate (20 mg/kg) or domperidone, a peripheral dopamine D2 receptor antagonist (1 mg/kg). Four groups of rats were studied as follows: raised under normal conditions with daily gavage with water (NWT) or NCT, or exposed to n-IH (n-IH+NWT and n-IH+NCT) from postnatal days 3 to 12. In n-IH+NCT rats, baseline ventilation was higher than in the other groups. Caffeine or domperidone enhanced baseline ventilation only in NWT and n-IH+NWT rats, but neither caffeine nor domperidone affected the hypoxic ventilatory response in these groups. In n-IH+NWT rats, the response during the early phase of hypoxia (<10 min) was higher than in other groups. During the late response phase to hypoxia (20 min), ventilation was lower in n-IH+NWT and n-IH+NCT rats compared to NWT or NCT, and were not affected by caffeine or domperidone injection. NCT or caffeine injection decreased baseline apnoea frequency in all groups. These data suggest that chronic exposure to NCT alters both carotid body dopaminergic and adenosinergic systems and central regulation of breathing under baseline conditions and in response to hypoxia.

Altered expression of adenosine A 1 and A 2A receptors in the carotid body and nucleus tractus solitarius of adult male and female rats following neonatal caffeine treatment

Neonatal caffeine treatment (adenosine receptor antagonist, 15 mg/kg/day, between postnatal days 3 and 12) affects respiratory patterns in adult male but not female rats as shown by an increase in the respiratory frequency in the early phase of response to hypoxia and an increase in the tidal volume in the late phase of response. Here, we tested the hypothesis that these changes are correlated with modified expression of adenosine receptors in the chemoreflex pathway. Carotid bodies, nucleus tractus solitarii, and superior cervical ganglia were collected from 3-month-old male and female rats that were either naive (not manipulated during the neonatal period) or treated with caffeine (NCT) or water (NWT) between postnatal days 3 and 12 by gavage. Western blot analysis was used to assess the expression of adenosine A 1 and A 2A receptors and tyrosine hydroxylase, the rate-limiting enzyme for dopamine synthesis. In male rats, there was a 37% increase in the level of A 2A receptor and a 17% decrease in tyrosine hydroxylase in the carotid body of NCT ( p < 0.001) as compared to NWT rats. In the nucleus tractus solitarius, we found a 13% and 19% decrease in A 1 receptor expression in NWT and NCT rats ( p < 0.01), respectively, compared to naive rats. In the superior cervical ganglion, there was no change in A 1 receptor, A 2A receptor, and tyrosine hydroxylase expression. In female rats, the only changes observed were decreases of 12% and 15% in A 1 receptor levels in the nucleus tractus solitarius of NWT and NCT rats ( p < 0.01), respectively, compared to naive rats. We conclude that NCT induces long-term changes in the adenosine receptor system. These changes may partially explain the modifications of the respiratory pattern induced by NCT in adults. The increased expression of the adenosine A 2A receptor (specific to male rats), combined with the decreased tyrosine hydroxylase expression in the carotid body, suggests that NCT affects adenosine–dopamine interactions regulating chemosensory activity.

Radiation-Induced Hyposuppression of the Hypothalamic-Pituitary-Adrenal Axis is Associated with Alterations of Hippocampal Corticosteroid Receptor Expression

Therapeutic brain irradiation in children can cause a progressive decline in cognitive functions through a diminished capability to learn and memorize. Because of the known involvement of the hippocampus in memory consolidation, this study was aimed at examining the late effects of gamma radiation on hypothalamic-pituitary-adrenal (HPA) axis activity and hippocampal corticosteroid receptor expression in an animal model of cranial radiotherapy. In the late-response phase, the basal and stress-induced corticosterone levels were not affected by radiation, but the suppression of glucocorticoid negative feedback by dexamethasone was attenuated in irradiated rats. Western blot analyses showed that exposure to radiation led to a decrease of cytosolic glucocorticoid receptor (GR) levels and a concomitant elevation of mineralocorticoid receptor (MR). The results obtained were complemented by those of RT-PCR, since the ratio of GR/MR mRNA was also decreased after radiation exposure. Dexamethasone appeared to be much less effective in shifting GR to the nuclear compartment in irradiated rats than in sham-irradiated animals. However, the expression of chaperones that aid GR intracellular trafficking, Hsp90 and Hsp70, remained unaffected. In conclusion, our data suggest that the hallmark of the late response to gamma radiation is a hyposuppressive state of the HPA axis that is associated with a decrease in both the GR/MR ratio and the nuclear accumulation of dexamethasone-activated GR in the hippocampus.

Radiation-induced Variations in Urothelial Expression of Uroplakin-III and Tight Junction Protein Occludin in Mouse Bladder

Radiotherapy of pelvic tumours results often in unavoidable side effects. One of these–radiation-induced urinary bladder dysfunction–occurs in three phases: an early, reversible reaction, a dose-dependent, symptom-free latent time, and a progressive and irreversible late response phase. Since the cellular mechanisms underlying these early and late effects are not fully understood, studies in experimental animals are needed. The present investigation addressed the question whether impairment of the urothelial barrier contributes to radiation effects in the mouse urinary bladder.

Transcriptomic and proteomic analyses of the pMOL30-encoded copper resistance in Cupriavidus metallidurans strain CH34

The four replicons of Cupriavidus metallidurans CH34 (the genome sequence was provided by the US Department of Energy-University of California Joint Genome Institute) contain two gene clusters putatively encoding periplasmic resistance to copper, with an arrangement of genes resembling that of the copSRABCD locus on the 2.1 Mb megaplasmid (MPL) of Ralstonia solanacearum, a closely related plant pathogen. One of the copSRABCD clusters was located on the 2.6 Mb MPL, while the second was found on the pMOL30 (234 kb) plasmid as part of a larger group of genes involved in copper resistance, spanning 17 857 bp in total. In this region, 19 ORFs (copVTMKNSRABCDIJGFLQHE) were identified based on the sequencing of a fragment cloned in an IncW vector, on the preliminary annotation by the Joint Genome Institute, and by using transcriptomic and proteomic data. When introduced into plasmid-cured derivatives of C. metallidurans CH34, the cop locus was able to restore the wild-type MIC, albeit with a biphasic survival curve, with respect to applied Cu(II) concentration. Quantitative-PCR data showed that the 19 ORFs were induced from 2- to 1159-fold when cells were challenged with elevated Cu(II) concentrations. Microarray data showed that the genes that were most induced after a Cu(II) challenge of 0.1 mM belonged to the pMOL30 cop cluster. Megaplasmidic cop genes were also induced, but at a much lower level, with the exception of the highly expressed MPL copD. Proteomic data allowed direct observation on two-dimensional gel electrophoresis, and via mass spectrometry, of pMOL30 CopK, CopR, CopS, CopA, CopB and CopC proteins. Individual cop gene expression depended on both the Cu(II) concentration and the exposure time, suggesting a sequential scheme in the resistance process, involving genes such as copK and copT in an initial phase, while other genes, such as copH, seem to be involved in a late response phase. A concentration of 0.4 mM Cu(II) was the highest to induce maximal expression of most cop genes.

CopH from Cupriavidus metallidurans CH34. A Novel Periplasmic Copper-Binding Protein

The copH gene is one of the 19 open reading frames (ORFs) found in the cop cluster borne by the large plasmid pMol30 in Cupriavidus metallidurans CH34. The entire cluster is involved in detoxification of copper from the cytoplasm as well as from the periplasm. The function of the corresponding protein, CopH, is not yet clear, but it seems to be involved in the late response phase. We have cloned copH and overproduced and purified the corresponding protein. CopH is rather unique as only one paralog can be found in the databases. It is a dimeric protein with a molecular mass of 13 200 Da per subunit and located in the periplasm. The metal binding properties of CopH were examined by using a series of techniques such as UV-visible spectroscopy, circular dichroism (CD), electron paramagnetic resonance (EPR), surface plasmon resonance (SPR), mass spectrometry, and nuclear magnetic resonance (NMR). All together, the corresponding data are consistent with a dimeric protein containing one metal-binding site per subunit. These sites have a high affinity for Cu(II) but can also bind zinc or nickel. CopH does not contain any cysteines or methionines but contains two histidines. EPR and UV-visible features are consistent with the presence of Cu(II) type 2 centers in a nitrogen ligand field. SPR data confirm the involvement of the histidine residues in copper binding. CD and NMR data reveal that CopH is partially unfolded.

Effect of Recombinant Human Keratinocyte Growth Factor (rHuKGF, Palifermin) on Radiation-Induced Mouse Urinary Bladder Dysfunction

Purpose/Objective: Radiation-induced changes in urinary bladder storage capacity are a frequent side effect of pelvic radiotherapy. In mice, early functional changes in bladder occur within the first month after irradiation in two phases, with peaks around day 7 (acute phase 1) and day 23 (acute phase 2). Acute changes are followed by a dose-dependent latent time period and by a subsequent and irreversible late response phase. Recently, administration of growth factors, such as keratinocyte growth factor (KGF), has been shown to modify radiation effects. Therefore, the present study was initiated to identify the effect of Palifermin (rHuKGF) on acute and late radiation effects in the mouse urinary bladder Materials/Methods: For this, graded radiation doses were applied to generate full dose-effect curves. Changes in bladder function, measured by transurethral cystometry, were assessed. Conclusions: In conclusion, early steps of the radiation-induced acute changes in the mouse urinary bladder can be modified with a single administration of Palifermin (rHuKGF) before irradiation. However, the optimum dosage and also the influence of the repeated injections have to be identified in further experiments. Moreover, studies into KGF-effects during fractionated irradiation must be performed.

Estradiol-induced vascular endothelial growth factor-A expression in breast tumor cells is biphasic and regulated by estrogen receptor-alpha dependent pathway.

Estrogens have been shown to regulate vascular endothelial growth factor-A (VEGF-A) for physiological and patho-physiological functions. However, estrogen action on VEGF-A mRNA expression has not been completely elucidated. We have identified two phases of activation of VEGF-A mRNA transcription, one early and one late response, induced by 17beta-estradiol (17beta-E2) in ER+ MCF-7 breast tumor cells, depending upon the length of exposure. VEGF-A mRNA level was significantly higher than control in tumor cells after 2 h of 17beta-E2 exposure. Furthermore this induction was not inhibited by cycloheximide, indicating that it was a direct effect of estrogen. In contrast VEGF-A mRNA expression was back at basal level in MCF-7 cells exposed to 17beta-E2 for 6 h. However, expression levels were again significantly augmented after 24 h of exposure, and this induction was unaltered by cycloheximide indicating that de novo protein synthesis was not required and like early response, it was a direct effect of estrogen. The antiestrogen ICI 182,780 was a pure antagonist for the early response phase of VEGF-A mRNA induction, but it had partial but significant effect on the late response phase, further suggesting that both early and late phases were ER dependent. In human mammary epithelial cells (HMEC) lacking estrogen receptor (ER-alpha) the early and late response phase of VEGF-A mRNA induction in response to 17beta-E2 was not found, but significant inductions were seen in the early and late phases when ER-alpha transfected HMEC were exposed to 17beta-E2 for 2 or 24 h. Taken together, these studies suggest that VEGF-A is an estrogen responsive gene and modulation of this gene expression by estrogen is biphasic and can be mediated through ER-alpha dependent pathway.

Central involvement of kinin B1 and B2 receptors in the febrile response induced by endotoxin in rats.

1. The effect of central injection of selective kinin B1 and B2 receptor antagonists on the febrile response induced by endotoxin (E. coli lipopolysaccharide, LPS) in rats was investigated. 2. Intracerebroventricular (i.c.v.) injection of a selective B2 receptor antagonist (Hoe-140, 8 nmol) reduced the early (0-2 h), but increased the late phase (4-6 h) of the febrile response induced by intravenous (i.v.) injection of LPS (0.5 microgram kg-1). 3. Co-administration of Hoe-140 (8 nmol, i.c.v.) with LPS (0.5 microgram kg-1, i.v.), followed 2.5 h later by the i.c.v. injection of a selective B1 receptor antagonist [des-Arg9-Leu8]-bradykinin (BK, 8 nmol), significantly reduced the febrile response induced by LPS throughout the whole experimental period. 4. Intravenous injection of Hoe-140 (1 mg kg-1) significantly reduced the febrile response induced by LPS (0.5 microgram kg-1, i.p.). 5. Pretreatment (24 h) with LPS (0.5 microgram kg-1, i.v.) reduced the febrile response induced by BK or [Tyr8]-BK (both, 5 nmol, i.c.v.), but markedly increased the febrile response induced by [des-Arg9]-BK (5 nmol, i.c.v.). The response induced by [des-Arg9]-BK in LPS-pretreated rats was significantly inhibited by co-injection of [des-Arg9-Leu8]-BK (15 nmol, i.c.v.). 6. The results suggest that kinins are involved in the induction of LPS-induced fever and that central B2 and B1 receptors are activated during the initial and late phase of this response, respectively. The results also suggest that downregulation and/or desensitization of B2 receptors and induction and/or upregulation of B1 receptors in LPS-pretreated animals may have a significant pathophysiological role in the induction and maintenance of fever. These observations may be specifically important in the case of chronic inflammatory conditions, because the BK metabolite [des-Arg9]-BK, so far considered an inactive metabolite, acquires an active and relevant role with the progressive expression of B1 receptors that occurs in such states.

Transcriptional control of sodium transport in tight epithelial by adrenal steroids.

The model for the adrenal steroid action on Na transport in tight epithelia as depicted in Fig. 3A and B dissociates two phases: an early phase during which the pre-existing Na transport machinery is activated and a late phase during which the transport capacity of the machinery is increased. These two sequential phases have been distinguished based on differences in functional aspects of the induced transport, on selective effects of agents interfering with transcriptional regulation and on a correlation of the late response phase with an increase in transport protein synthesis and expression [26, 45, 46, 98, 99, 124]. These observations suggest that a bimodal stimulation of Na transport could involve two different gene networks which are directly (in the physiological meaning) and independently stimulated by the action of the hormone-receptor complex and the following “molecular” cascades (see section Molecular and Physiological Cascades). The relatively clear temporal dissociation of the responses found in experimental situations is probably the consequence of inherent properties of the two networks. Indeed, to generate rapid functional changes, the genes involved in the early response must encode products which have relatively short half-lifes at the mRNA and protein levels. In contrast, the constitutive elements of the Na transport machinery that are increased during the late phase of adrenal steroid action have, as shown for the Na,K-ATPase [82], relatively long half-lifes. Consequently, even though changes in transcription may take place early in the course of the hormonal treatment, they impact on protein synthesis and pools only slowly and after a substantial lag period.