bluuebunny/crossref_metadata_2025 huggingface dataset:
From Brain to Blood: Alternative Splicing Evidence for the Cholinergic Basis of Mammalian Stress Responses
Authors: PICK MARJORIE , FLORES‐FLORES CESAR , SOREQ HERMONA
Published: July 2004

Abstract: Three principal features of mammalian stress responses are that they span peripheral and CNS changes, modify blood cell composition and activities, and cover inter‐related alterations in a large number of gene products. The finely tuned spatiotemporal regulation of these multiple events suggests the hierarchic involvement of modulatory neurotransmitters and modified process(es) in the pathway of gene expression that together would enable widely diverse stress responses. We report evidence supporting the notion that acetylcholine (ACh) acts as a stress‐response‐regulating transmitter and that altered ACh levels are variously associated with changes in the alternative splicing of pre‐mRNA transcripts in brain neurons and peripheral blood cells. We used acetylcholinesterase (AChE) gene expression as a case study and developed distinct probes for its alternative splice variants at the mRNA and protein levels. In laboratory animals and human‐derived cells, we found stress‐induced changes in the alternative splicing patterns of AChE pre‐mRNA, which attributes to this gene and its different protein products diverse stress responsive functions that are associated with the enzymatic and noncatalytic properties of AChE. Together, these approaches provide a conceptually unified view of the studied pathways for controlling stress responses in brain and blood.
Life‐Long Serotonin Reuptake Deficiency Results in Complex Alterations in Adrenomedullary Responses to Stress
Authors: TJURMINA OLGA A. , ARMANDO INES , SAAVEDRA JUAN M. , LI QIAN , MURPHY DENNIS L.
Published: July 2004

Abstract: This study examined whether serotonin transporter (SERT) deficiency influences adrenal serotonin (5‐HT), catecholamine and Angiotensin II (Ang II) systems, and the hormonal response to acute restraint stress. Control SERT mice (+/+) expressed high numbers of SERT binding sites in adrenal medulla. Fifteen minutes of restraint stress increased adrenal 5‐HT, adrenomedullary tyrosine hydroxylase (TH) mRNA expression and plasma epinephrine (EPI), and norepinephrine levels without alterations in adrenal catecholamine content. In SERT+/+, these responses coincided with a significant increase in adrenomedullary Ang II AT2 receptor expression. SERT‐deficient mice did not express SERT binding sites; their adrenal 5‐HT was significantly depleted and further reduced after stress. They had exaggerated stress‐induced EPI release into plasma, the increase in TH transcription did not occur, adrenal catecholamine content was decreased compared with SERT+/+, and stress induced a reduction rather than increase in the number of adrenomedullary AT2 receptors. SERT−/− mice also possessed decreased pituitary 5‐HT. Their pituitary ACTH was reduced after stress, but stress‐induced increases in plasma ACTH and corticosterone were not different from those of SERT+/+ mice. Our results indicate that SERT function not only restrains stress‐induced EPI release but also is required for the increase in adrenal catecholamine synthesis and AT2 receptor expression.
Different Effects of Novel Stressors on Sympathoadrenal System Activation in Rats Exposed to Long‐Term Immobilization
Authors: DRONJAK SLADJANA , JEZOVA DANIELA , KVETNANSKY RICHARD
Published: July 2004

Abstract: Activation of the sympathoadrenal system, evaluated by plasma levels of epinephrine (E) and norepinephrine (NE) after exposure of rats to various stressors, is well documented. However, response of rats exposed long‐term to a homotypic stressor and then exposed once to a heterotypic novel stressor is poorly understood. In the present study, we examined changes in plasma levels of catecholamines (CA) and corticosterone (COR) of rats after a single (2‐h) or long‐term repeated immobilization (41 times, 2 h daily) and in rats adapted to long‐term immobilization exposed once to the novel stress of cold exposure or insulin or 2‐deoxy‐D‐glucose (2DG) administration. Long‐term immobilization produced a significant elevation of basal plasma COR but not NE and E levels. Long‐term immobilized rats exposed to insulin or 2DG showed significant elevation of plasma CA and COR levels in comparison to the administration to control rats. Exposure of long‐term immobilized and control rats to cold stress increased plasma NE and COR, whereas plasma E was not significantly changed. The exposure of long‐term immobilized rats to a further single immobilization (2 h) increased plasma CA levels, but, in naive control rats, the single immobilization produced more pronounced increases. These data suggest that rats exposed to homotypic long‐term immobilization are able to respond to heterotypic stressors by higher activation of the sympathoadrenal system as compared with the control, previously unstressed rats. Reduced plasma CA levels in long‐term immobilized rats exposed to homotypic stressor are most probably due to an adaptation at the level of brain regulatory centers.
Angiotensin II AT1 Receptor Blockade Prolongs the Lifespan of Spontaneously Hypertensive Rats and Reduces Stress‐Induced Release of Catecholamines, Glucocorticoids, and Vasopressin
Authors: BAIARDI GUSTAVO , BREGONZIO CLAUDIA , JEZOVA MIROSLAVA , ARMANDO INES , SAAVEDRA JUAN M.
Published: July 2004

Abstract: A 2‐week pretreatment with an Angiotensin II AT1 antagonist prevented the adrenomedullary and hormonal response to isolation stress. We studied the effect of life‐long treatment with the AT1 receptor antagonist candesartan, 10 mg/kg/day, or vehicle administered orally in the drinking water from 8 weeks of age on the response to stress of stress‐sensitive spontaneously hypertensive rats (SHRs) and their normotensive controls, the Wistar Kyoto (WKY). Rats were submitted to 24‐h isolation stress at different times during the treatment. Treatment with candesartan extended the lifespan of SHRs. AT1 receptor blockade retained its capacity to blunt the response to isolation stress over a long period of treatment. The AT1 antagonist inhibited epinephrine release in SHR but not in WKY rats during the first 3 months, corticosterone release in SHR and WKY rats during 10 months, and vasopressin release in SHR rats during 18 months of treatment when rats were submitted to isolation stress. There were no changes in vasopressin release in WKY rats during stress or after AT1 receptor blockade. We conclude that the blockade of the stress response by the AT1 receptor antagonist is long lasting and differs between stress‐prone SHR and WKY rats and that the specific components of the stress response (sympathoadrenal activity, hypothalamic‐pituitary‐adrenal axis activation, and vasopressin release) react differently to AT1 receptor blockade. The long‐term protective effects of AT1 receptor blockade can be important in animals vulnerable to stress and, in conjunction with the normalization of blood pressure, can prolong lifespan through end‐organ protection.
Fight or Flight, Forbearance and Fortitude: The Spectrum of Actions of the Catecholamines and Their Cousins
Authors: ARUN C P
Published: July 2004

Abstract: Catecholamines are recognized to play an important part in the fight‐or‐flight response to impending stress. Catecholamine and other phase‐reactant levels are raised in the first 24 h following acute stress, but the bigger picture of their action on the organism is unavailable. In this article, we examine their actions in light of the theory of phase transitions borrowed from the numerate sciences. Phase transitions involve changes in the state of matter or an organism with a common example of what is termed a first‐order phase transition (sudden change) being provided by the popular expression “the straw that broke the camel's back.” We propose that the response to catecholamines follows a triphasic response: a Phase I response is the fight‐or‐flight response to impending stress that protects the animal. With mild to intermediate stress, the Phase II or forbearance response allows it to tolerate the physiological upset. With severe stress, however, severe vital organ vasoconstriction leads to a quick death. The present theory has value in understanding the clinical picture in acute stress. Phase II or Forbearance Phase corresponds to Classes I, II, and III of hemorrhagic shock, and Phase III or Fortitude Phase to Class IV. Thus, a Phase III or fortitude response is to the animal what apoptosis is to the individual cell and has social implications. The present framework provides a fresh perspective on the action of the catecholamines and their cousins.
Chronic Stress‐Induced Effects of Corticosterone on Brain: Direct and Indirect
Authors: DALLMAN M F. , AKANA S F , STRACK A M , SCRIBNER K S , PECORARO N , LA FLEUR S E , HOUSHYAR H , GOMEZ F
Published: July 2004

Abstract: Acutely, glucocorticoids act to inhibit stress‐induced corticotrophin‐releasing factor (CRF) and adrenocorticotrophic hormone (ACTH) secretion through their actions in brain and anterior pituitary (canonical feedback). With chronic stress, glucocorticoid feedback inhibition of ACTH secretion changes markedly. Chronically stressed rats characteristically exhibit facilitated ACTH responses to acute, novel stressors. Moreover, in adrenalectomized rats in which corticosterone was replaced, steroid concentrations in the higher range are required for facilitation of ACTH responses to occur after chronic stress or diabetes. Infusion of corticosterone intracerebroventricularly into adrenalectomized rats increases basal ACTH, tends to increase CRF, and allows facilitation of ACTH responses to repeated restraint. Therefore, with chronic stressors, corticosterone seems to act in brain in an excitatory rather than an inhibitory fashion. We believe, under conditions of chronic stress, that there is an indirect glucocorticoid feedback that is mediated through the effects of the steroid ± insulin on metabolism. Increased energy stores feedback on brain to inhibit hypothalamic CRF and decrease the expression of dopamine‐β‐hydroxylase in the locus coeruleus. These changes would be expected to decrease the level of discomfort and anxiety induced by chronic stress. Moreover, central neural actions of glucocorticoids abet the peripheral effects of the steroids by increasing the salience and ingestion of pleasurable foods.
Alcohol Alters Rat Adrenomedullary Function and Stress Response
Authors: PATTERSON‐BUCKENDAHL PATRICIA , BLAKLEY GREGORY , KUBOVCAKOVA LUCIA , KRIZANOVA OLGA , POHORECKY LARISSA A. , KVETNANSKY RICHARD
Published: July 2004

Abstract: Most alcohol researchers do not address the effects of intoxication on the sympatho‐adrenomedullary system response to stressful situations. We previously determined that rats consuming nearly 9 g ethanol (EtOH) per kg body weight per day in liquid diet form for 1 week increased adrenal gene expression of enzymes for catecholamine synthesis that was further elevated by acute IMMO. We hypothesized that the response to chronic mild stressors would also be altered after consumption of lower concentrations of EtOH in drinking water. Two experiments were conducted: 10% w/v for 4 weeks or 6% w/v for 7 weeks ± wire mesh restraint (WMR). These were compared with ad libitum (adlib) and pair‐fed control rats. Adrenal gene expression of catecholamine synthesizing enzymes was assayed. Tyrosine hydroxylase gene expression was elevated 80% to 90% by alcohol consumption in both experiments (P < 0.001) compared with adlib control rats. Dopamine βb‐hydroxylase and phenylethanolamine‐N‐methyl transferase gene expressions were unaffected by 10% alcohol (P > 0.05) but were increased by 6% alcohol (P < 0.01). WMR decreased already elevated gene expression of all three enzymes. Pair feeding to 6% EtOH drinkers also increased gene expression for the three enzymes but was decreased by WMR, although not to levels of adlib rats. Increased gene expression for adrenal synthesis of catecholamines in response to repeated alcohol consumption increases the likelihood that the subject can respond physiologically to acute or chronic stress. This may have life‐saving consequences in humans and in animals known to consume fermented materials and may contribute to increased aggressive behavior.
Pivotal Role of an Endogenous Tetrahydroisoquinoline, Salsolinol, in Stress‐ and Suckling‐Induced Release of Prolactin
Authors: RADNAI B , MRAVEC B , BODNÁR I , KUBOVCAKOVA L , FÜLÖP F , FEKETE M I K , NAGY G M , KVETNANSKY R
Published: July 2004

Abstract: In mammals, the role of a prolactin‐releasing factor (PRF) in the acute changes of prolactin (PRL) secretion that usually occur after challenges (e.g., suckling stimulus or stress) of homeostasis has been suspected for a long time. We have recently observed that 1‐methyl‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline, salsolinol (SAL), produced by the hypothalamus and the neuro‐intermediate lobe (NIL) of the pituitary gland, can selectively release PRL from the anterior lobe (AL). Moreover, binding sites for SAL have been detected in areas like median eminence, NIL, and AL. It has been proposed that SAL is a putative endogenous PRF. We have also found that a structural analogue of SAL, 1‐methyl‐3,4‐dihydroisoquinoline (1MeDIQ), is able to block dose‐dependently SAL‐, suckling‐, and immobilization (IMO) stress‐induced release of PRL without having any influence on α‐methyl‐p‐tyrosine (αMpT)‐induced PRL responses. Neither SAL nor 1MeDIQ has any effect on α‐melanocyte‐stimulating hormone (αMSH), adrenocorticotrophic hormone (ACTH), β‐endorphin (β‐END) and arginine‐vasopressin (AVP) secretion. Moreover, SAL‐induced PRL response was attenuated in male rats pretreated with dexamethasone (DEX). These results strongly suggest that SAL has an important role in the regulation of PRL release induced by physiologic and environmental stimuli; therefore, it can be considered as the strongest candidate for being the PRF in the hypothalamo‐hypophysial system. Our findings also indicate that the adrenal steroids may play an inhibitory feedback role in SAL‐mediated PRL response.
Effect of Chronic Emotional Stress on Habituation Processes in Open Field in Adult Rats
Authors: DUBOVICKY MICHAL , JEZOVA DANIELA
Published: July 2004

Abstract: In our previous study, repeated stress in the neonatal period was found to slow habituation in the open field in adult rats. The objective of the present study was to investigate how chronic stress can affect habituation processes in the open field when occurring in adulthood. Animals were exposed to 1 week of immobilization on metal boards followed by 1 week of hypokinesis. After the stress procedure, rats were tested in the open field (once daily in 6‐min sessions for four consecutive days). Immediately after the last open‐field test, animals were decapitated. The rapidity of between‐ and within‐session habituation was lower than in control rats. However, this lowering failed to be statistically significant compared with control rats. On the other hand, time latency to step down from an elevated platform was significantly increased in stress‐exposed animals. Four days after the last stressful event, corticotropin‐releasing hormone mRNA levels in the paraventricular nucleus were significantly increased, indicating a long‐term activation of the hypothalamic‐pituitary‐adrenocortical axis. The results suggest that, in contrast to neonatal stress exposure, chronic emotional stress in adult rats does not represent a risk factor for the alteration of habituation processes.
Effect of Immobilization onIn VitroThyrotropin‐Releasing Hormone Release from Brain Septum in Wild‐Type and Corticotropin‐Releasing Hormone Knock‐Out Mice
Authors: KISS A , ADAMEOVÁ A , KUBOVČÁKOVÁ L , JAMAL B , BAČOVÁ Z , ZÓRAD Š , TYBITANCLOVÁ K , KVETŇANSKÝ R , ŠTRBÁK V
Published: July 2004

Abstract:There is considerable evidence linking alcohol consumption, sedation, and thyrotropin‐releasing hormone (TRH) in the brain septum. We have shown that ethanol in clinically relevant concentrations canin vitroinduce TRH release from the septum by a mechanism involving neuronal swelling. Corticotropin‐releasing hormone‐deficient (CRH‐KO) mice serve as an interesting model to help us understand the role of CRH in the regulation of different neuroendocrine systems. The aim of this study was to compare TRH release activity in the brain septum at basal and stress conditions in CRH‐KO mice and their wild‐type (WT) littermates. Experimental mice were decapitated immediately or 3 h after single (2 h) or repeated (seven times for 2 h daily) immobilization stress. The brain septum was immediately cut out and incubated to measure basal‐, ethanol‐, and hyposmosis‐stimulated TRH releasein vitro. Ethanol in isosmotic medium or hyposmotic medium stimulated TRH release from mice septal explants from WT and CRH‐KO mice. The response was disturbed immediately after immobilization and recovered 3 h later. Our results show that immobilization stress transiently affects the TRH system in brain septum. Inborn absence of CRH does not affect septal TRH and its response to ethanol before and 3 h after immobilization.
Stress Is Associated with Inhibition of Type I Iodothyronine 5′‐Deiodinase Activity in Rat Liver
Authors: BRTKO JÚLIUS , MACEJOVÁ DANA , KNOPP JÁN , KVETŇANSKÝ RICHARD
Published: July 2004

Abstract: Type I iodothyronine deiodinase (5′‐DI) generates the thyromimetically active hormone 3,5,3′‐triiodothyronine (T3) by reductive monodeiodination of the phenolic ring of L‐thyroxine (T4). The present study was undertaken to compare the effects of cold stress (4°C) alone or in combination with immobilization stress (IMO), insulin treatment (5 IU/kg, i.p.) or 2‐deoxy‐D‐glucose (2DG)‐induced intracellular glucopenia on the activity of 5′‐DI in rat liver. Cold stress either for 24 h or 28 days when compared to that in the nonstressed group of rats significantly reduced (P < 0.001) the activity of 5′‐DI in liver. In comparison with cold stressed rats for 28 days, an additional decrease in 5′‐DI activity was observed when those rats underwent 1 × IMO in cold for 2 h (P < 0.001) or insulin treatment (P < 0.05). A significant decrease in 5′‐DI activity was found also in rats maintained at room temperature that underwent a single 1 × IMO for 2 h (P < 0.001) or insulin treatment (P < 0.01) when compared to nonstressed animals. In comparison with nonstressed rats, no significant change of the 5′‐DI activity was observed after 2DG application (500 mg/kg, i.p.) at room temperature. In conclusion, cold stress and/or 1 × IMO, insulin treatment, or 1 × IMO at room temperature markedly affects reductive monodeiodination of T4, and thus reduces the concentration of biologically active T3 in liver.
Leaky Catecholamine Stores: Undue Waste or a Stress Response Coping Mechanism?
Authors: EISENHOFER GRAEME , KOPIN IRWIN J. , GOLDSTEIN DAVID S.
Published: July 2004

Abstract: Turnover of catecholamines, representing the constant loss and replenishment of neurotransmitter by synthesis, is usually considered to be driven exclusively by catecholamine release. This is incorrect. An important contribution of intraneuronal metabolism of norepinephrine to turnover, and dependence of this on leakage of norepinephrine from vesicular stores, was originally proposed by Kopin in 1964. Several years later, Maas and colleagues concluded that at least 75% of norepinephrine turnover is due to intraneuronal metabolism without prior release at sympathetic nerve endings. More recently it was shown in the resting human heart that about 12% of norepinephrine turnover is due to extraneuronal uptake and metabolism or loss of the transmitter to the circulation, 15% is due to intraneuronal metabolism after reuptake, and 73% is due to intraneuronal metabolism of norepinephrine leaking from storage vesicles. Thus, contrary to usual depictions, vesicular stores of catecholamines do not exist in a static state simply waiting for exocytotic release. Rather, these stores exist in a highly dynamic equilibrium with the surrounding cytoplasm, with passive outward leakage of amines counterbalanced by inward active transport under the control of vesicular monoamine transporters. The large contribution of leakage to catecholamine turnover may seem inconsistent with cellular economy. In fact, this contribution provides an important mechanism for “gearing down” the requirement for increases in catecholamine synthesis to match increases in catecholamine release, and thereby provides sympathetic nerves with a capacity for a more extended range of sustainable release rates in response to stress than would otherwise be possible.
Functional Neuroimaging of Sympathetic Innervation of the Heart
Authors: GOLDSTEIN DAVID S.
Published: July 2004

Abstract: Many concepts about acute and chronic effects of stress depend on alterations in sympathetic nerves supplying the heart. Physiologic, pharmacologic, and neurochemical approaches have been used to evaluate cardiac sympathetic function. This article describes a fourth approach that is based on nuclear scanning to visualize cardiac sympathetic innervation and function and relationships between the neuroimaging findings and those from other approaches. Multiple‐system atrophy with orthostatic hypotension (formerly the Shy‐Drager syndrome) features normal cardiac sympathetic innervation and normal entry of norepinephrine into the coronary sinus (cardiac norepinephrine spillover), in contrast to Parkinson disease with orthostatic hypotension, which features neuroimaging and neurochemical evidence for loss of cardiac sympathetic nerves. This difference may have important implications not only for diagnosis but also for understanding the etiology of Parkinson disease. By analysis of curves relating myocardial radioactivity with time (time‐activity curves) after injection of a sympathoneural imaging agent, it is possible to obtain information about cardiac sympathetic function. Abnormal time‐activity curves are seen in common disorders such as heart failure and diabetic neuropathy and provide an independent, adverse prognostic index. Analogous abnormalities might help explain increased cardiovascular risk in psychiatric disorders such as melancholic depression.
Basal and Stress‐Induced Differences in HPA Axis, 5‐HT Responsiveness, and Hippocampal Cell Proliferation in Two Mouse Lines
Authors: VEENEMA ALEXA H. , KOOLHAAS JAAP M. , DE KLOET E RONALD
Published: July 2004

Abstract: To characterize individual differences in neuroendocrine and neurochemical correlates of stress coping, two lines of wild house mice were studied. These mice are genetically selected for high and low aggression and show distinctly different behavioral strategies toward environmental stimuli. Long attack latency (LAL), low aggressive mice display a passive coping style, whereas short attack latency (SAL), high aggressive mice show an active coping style. It was hypothesized that this difference in behavioral coping style is associated with differences in stress system reactivity. This was tested by investigating the regulation of the hypothalamus‐pituitary‐adrenal (HPA) axis and the serotonin (5‐HT) system and hippocampal cell proliferation rate in these mice under baseline and stress conditions. Baseline corticosterone output in LAL mice was found to be more sensitive to adrenocorticotropic hormone, but showed less day/night variation than in SAL mice. Furthermore, LAL mice showed lower hippocampal 5‐HT1A receptor gene expression and function. Basal hippocampal cell proliferation rate was slightly lower in LAL than in SAL mice. Exposure to acute stress (forced swimming for 5 min) resulted in a hyper‐reactive HPA response, a reduced increase in brain 5‐HT metabolism, and an almost 50% reduction in hippocampal cell proliferation rate in LAL compared with SAL mice. Chronic psychosocial stress (sensory contact stress) induced long‐lasting changes in the HPA axis in LAL, but not in SAL mice. In conclusion, these studies show that a genetic trait in behavioral coping style in wild house mice is associated with differences in HPA regulation, 5‐HT neurotransmission, and hippocampal cell proliferation rate. The results further indicate that LAL mice have a higher stress responsivity than SAL mice. These results may have implications for a differential susceptibility for stress‐related mood disorders.
Repeated Stress‐Induced Stimulation of Catecholamine Response Is Not Followed by Altered Immune Cell Redistribution
Authors: IMRICH RICHARD , TIBENSKA ELENA , KOSKA JURAJ , KSINANTOVA LUCIA , KVETNANSKY RICHARD , BERGENDIOVA‐SEDLACKOVA KATARINA , BLAZICEK PAVOL , VIGAS MILAN
Published: July 2004

Abstract: Stress response is considered an important factor in the modulation of immune function. Neuroendocrine hormones, including catecholamines, affect the process of immune cell redistribution, important for cell‐mediated immunity. This longitudinal investigation was aimed at evaluating the effect of repeated stress‐induced elevation of catecholamines on immune cell redistribution and expression of adhesive molecules. We assessed the responses of epinephrine (EPI), norepinephrine (NE), cortisol, changes in lymphocytes subpopulations, and percentages of CD11a+, CD11b+, and CD62L+ lymphocytes to a 20‐min treadmill exercise of an intensity equal to 80% of the individual's Vo2max. The exercise was performed before and after 6 weeks of endurance training consisting of a 1‐h run 4 times a week (ET) and after 5 days of bed rest (HDBR) in 10 healthy males. We did not observe any significant changes in the basal levels of EPI, NE, and cortisol in the plasma, nor in the immune parameters after ET and HDBR. The exercise test led to a significant (P < .001) elevation of EPI and NE levels after both ET and HDBR, a significant elevation (P < .01) of cortisol after HDBR, an increase in the absolute numbers of leukocytes, granulocytes, monocytes, CD3+, CD4+, CD8+, CD16+, CD19+ lymphocytes, percentage of CD11a+ and CD11b+ lymphocytes, and to a decrease of CD62L1 before, after ET, and after HDBR. We found comparable changes in all measured immune parameters after ET and HDBR. In conclusion, repeated stress‐induced elevation of EPI and NE was not associated with an alteration in immune cell redistribution found in response to the single bout of exercise.
Enriched Environment Influences Adrenocortical Response to Immune Challenge and Glutamate Receptor Gene Expression in Rat Hippocampus
Authors: MLYNARIK MARTIN , JOHANSSON BARBRO B. , JEZOVA DANIELA
Published: July 2004

Abstract: Housing of animals in an enriched environment (EE) has many positive effects on brain structure and function and can facilitate recovery from various brain injuries. The purpose of this study was to evaluate whether enriched rearing could alter the stress response induced by repeated immune challenge and to investigate the influence of EE and immune challenge on glutamate receptor gene expression in the hippocampus. Male 2‐mo‐old Wistar rats were kept under standard conditions (SC) or in an EE for 5 weeks. Immune challenge was performed by Escherichia coli lipopolysaccharide (LPS) injected repeatedly (ip) in increasing doses (10, 20, and 40 μg/kg/mL) once daily for five consecutive days. The animals were decapitated 2 h after the last injection. Blood samples, adrenals, and hippocampi were collected. LPS induced an increase in plasma and adrenal levels of corticosterone and a transient decrease in body weight of animals kept under SC, but not in an EE. Enriched housing resulted in an increase in adrenal weights and enhanced gene expression of hippocampal AMPA GluR1 receptor subunit. Concerning the LPS treatment, no effects on adrenal and thymus weights and glutamate receptor mRNA levels in the hippocampus were noticed. Thus, vulnerability to some negative effects of repeated immune challenge may be modified by environmental conditions associated with changes in brain plasticity. The fact that differences in housing conditions change stress response has to be considered in biomedical research.
Prenatal Immune Challenge Affects Growth, Behavior, and Brain Dopamine in Offspring
Authors: BAKOS JAN , DUNCKO ROMAN , MAKATSORI AIKATERINI , PIRNIK ZDENO , KISS ALEXANDER , JEZOVA DANIELA
Published: July 2004

Abstract: It is known that the development and plasticity of the neuroendocrine system can be affected by many factors, and that adverse events during the prenatal period can result in long‐lasting changes in adulthood. This study was aimed at evaluating the possible consequences for offspring from chronic inflammation during pregnancy. Chronic inflammation was simulated by treatment with increasing doses of lipopolysaccharide (LPS) to dams on days 15 through 19 of pregnancy. Attempts were made to prevent possible negative alterations by keeping animals in an enriched environment (EE). Maternal exposure to LPS resulted in a significant reduction of body weight of male offspring during the weaning period. This difference remained until the age of 63 days in controls (C), but not in animals reared in EE. The content of dopamine in the nucleus accumbens was found to be lower in prenatally stressed (PS) adult males. Furthermore, prenatal exposure to maternal immune challenge was associated with lower locomotor activity in elevated plus maze and increased number of skips in the beam‐walking test, as observed in female offspring. No differences in ACTH and corticosterone concentrations with regard to prenatal treatment were found; however, both groups kept in EE showed increased levels of corticosterone as well as enlarged adrenal glands. Thus, immune activation during pregnancy may induce long‐term changes in brain catecholamines and behavior, but it is not harmful to basal hormone secretion in the offspring.
Regulation of Vasopressin V1b Receptors and Stress Adaptation
Authors: VOLPI SIMONA , RABADÁN‐DIEHL CRISTINA , AGUILERA GRETI
Published: July 2004

Abstract: Vasopressin (VP) regulates pituitary corticotroph function by acting upon plasma membrane G‐protein receptors of the V1b subtype (V1bR), coupled to calcium‐phospholipid signaling. The number of these receptors in the anterior pituitary varies during stress in direct correlation with corticotroph responsiveness, suggesting that the V1bR plays an important role during adaptation of the hypothalamic‐pituitary‐adrenal (HPA) axis to stress. The molecular regulation of pituitary V1bR involves transcriptional and translational mechanisms. V1bR gene transcription, which is necessary to maintain V1bR mRNA levels, depends on a number of responsive elements in the promoter region, of which the stretch of GA repeats near the transcription start point (GAGA box) is essential. Although transcriptional activation is necessary to maintain V1bR mRNA levels, the lack of correlation between VP binding and V1bR mRNA suggests that V1bR content is mainly regulated at the translational level. Two potential mechanisms by which the 5′ untranslated region (5′UTR) of the V1bR mediates negative and positive regulation of V1bR translation were identified. This includes the repressor effect of small open reading frames (ORF) present upstream of the main V1bR ORF, and an internal ribosome entry site (IRES), which activates V1bR translation. The existence of multiple loci of regulation for the V1bR at transcriptional and translational levels provides a mechanism to facilitate plasticity of regulation of the number of pituitary vasopressin receptors according to physiological demand.
Angiotensin II AT1 and AT2 Receptor Types Regulate Basal and Stress‐Induced Adrenomedullary Catecholamine Production through Transcriptional Regulation of Tyrosine Hydroxylase
Authors: ARMANDO I , JEZOVA M , BREGONZIO C , BAIARDI G , SAAVEDRA J M.
Published: July 2004

Abstract: The sympathoadrenal response to stress includes a profound increase in adrenomedullary catecholamine synthesis driven by stimulation of tyrosine hydroxylase (TH) transcription. We studied the role of Angiotensin II type 1 and 2 (AT1 and AT2) receptors during isolation stress, and under basal conditions. Pretreatment of rats with the AT1 receptor antagonist candesartan for 14 days prior to isolation completely prevented the stress‐induced stimulation of catecholamine synthesis, decreasing tyrosine hydroxylase transcription by preventing the expression of the transcriptional factor, Fos‐related antigen 2 (Fra‐2). In addition, AT1 receptor antagonism prevented the stress‐induced increase in adrenomedullary AT2 receptor binding and protein. Treatment of non‐stressed, grouped animals under basal conditions with the AT1 receptor or with PD 123319, an AT2 receptor antagonist, decreased the adrenomedullary norepinephrine (NE) content and TH transcription. While AT1 receptor antagonism decreased the levels of Fra‐2 and the phosphorylated forms of cAMP responsive element binding protein (pCREB) and EKR2 (p‐ERK2, phosphor‐p42 MAP kinase), the AT2 antagonist decreased Fra‐2 with no change in the phosphorylation of CREB or EKR2. Our results demonstrate that both adrenomedullary AT1 and AT2 receptor types maintain and promote the adrenomedullary catecholamine synthesis and the transcriptional regulation of TH. Instead of opposing effects, however, our results indicate a complex synergistic regulation between the AT1 and AT2 receptor types.
The Effects of Short‐Term Immobilization Stress on Muscarinic Receptors, β‐Adrenoceptors, and Adenylyl Cyclase in Different Heart Regions
Authors: MYSLIVEČEK JAROMÍR , ŘÍČNÝ JAN , PALKOVITS MIKLÓS , KVETŇANSKÝ RICHARD
Published: July 2004

Abstract:Heart muscarinic receptors (MR) and β‐adrenoceptors (BAR) belong to a large family of G‐protein‐coupled receptors. Although the role of catecholamines in the stress has been under keen investigation for many years, the effects of immobilization on this pair of receptors, considering their almost completely opposite actions in the heart, are not yet known. We have studied the effects of short‐term immobilization (for 120 min) with different times of decapitation after the end of the immobilization period (0, 3, and 24 h) on MR, BAR (β1‐AR and β2‐AR using radioligand binding studies), and adenylyl cyclase (AC; using high‐pressure liquid chromatography detection of cAMP) in different heart regions (left and right atria with or without cardiac ganglion cells [auriculae], septum, and left and right ventricles). The effects of one immobilization period were first apparent after 24 h. Stress brought about a downregulation of MR and BAR with decrease in AC activity. These effects were regionally specific and were predominantly expressed in the right atria, which is rich in ganglia cells, and in the right ventricles. Our results indicate that stressful stimuli can influence not only BAR, but MR, and that AC activity can also be affected. This finding is in good agreement with our previous hypothesis that parallel changes are possible in the number of this pair of receptors on cell membranes.
Spatial Performance and Corticosteroid Receptor Status in the 21‐Day Restraint Stress Paradigm
Authors: KITRAKI EFTHIMIA , KREMMYDA OLYMPIA , YOULATOS DIONYSSIOS , ALEXIS MICHALIS , KITTAS CHRISTOS
Published: July 2004

Abstract: Twenty‐one days of restraint stress has been shown to affect hippocampal plasticity, neurogenesis, and spatial memory. Hippocampal glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) are the main mediators of stress response and learning/memory processes. We studied the performance of male and female rats on a hippocampal‐dependent spatial task after 21 days of restraint in relation to the stress‐induced changes of GR and MR status in their hippocampi. Reduced GR immunostaining was detected in the dentate gyrus and CA1 area of stressed male rats. Stressed male rats performed worse than the male control rats on the Morris water maze. In contrast, unaltered (in the dentate gyrus) or increased (in CA1) GR immunoreactivity was seen in the hippocampus of stressed female rats. Stressed female rats had an improved memory score in the task compared with the female control rats. In addition, stressed female rats showed increased MR immunostaining in the CA3 area, which is known to be severely affected by stress. The observed sexually dimorphic effects of 21‐day restraint in spatial learning and memory may be associated with the sex‐dependent changes in hippocampal corticosteroid receptor status after stress.
Glucocorticoid Receptor and Beta‐Adrenoceptor Expression in Epididymal Adipose Tissue from Stressed Rats
Authors: FARIAS‐SILVA ELISÂNGELA , DOS SANTOS IRAÍDES NUNES , DO AMARAL MARIA ESMÉRIA COREZOLA , GRASSI‐KASSISSE DORA MARIA , SPADARI‐BRATFISCH REGINA CELIA
Published: July 2004

Abstract: Adipocytes isolated from epididymal adipose tissue of foot‐shock stressed rats are supersensitive to isoprenaline and subsensitive to norepinephrine. These alterations are probably mediated by a stress‐induced increase in plasma corticosterone levels. We investigated whether foot‐shock stress modifies the expression of glucocorticoid receptors (GRs) and β‐adrenergic protein receptors (β‐ARs) in epididymal adipose tissue from rats submitted to one daily foot‐shock session on three consecutive days. This stress protocol caused decreases in GR, β1‐AR, and β3‐AR protein levels, but caused an increase in β2‐AR. These results confirm and support previous functional studies. The alterations in protein expression may be modulated by the high corticosterone levels that downregulate the glucocorticoid receptor.
Angiotensin II AT1 Receptor Blockade Decreases Brain Artery Inflammation in a Stress‐Prone Rat Strain
Authors: ANDO HIROMICHI , JEZOVA MIROSLAVA , ZHOU JIN , SAAVEDRA JUAN M.
Published: July 2004

Abstract: The spontaneously hypertensive rats (SHR) are a genetically hypertensive strain with vulnerability to brain ischemia and stress. In SHR, the brain Angiotensin II (Ang II) system is chronically stimulated, resulting in brain artery remodeling and inflammation. Pretreatment with Ang II AT1 receptor antagonists protects from brain ischemia and prevents the hormonal and sympathoadrenal response to stress. In addition, the anti‐inflammatory effects of AT1 receptor antagonists are partially responsible for preventing the development of stress‐induced gastric ulcers. We asked whether AT1 receptor antagonists could exert anti‐inflammatory effects in the brain vasculature as a mechanism for their protective effects against ischemia. As determined by immunohistochemistry, long‐term inhibition of brain AT1 receptors by peripheral administration of the AT1 receptor antagonist candesartan (0.3 mg/kg/day for 28 days) normalized the pathologic remodeling, decreased expression of the intercellular adhesion molecule‐1 and the number of associated macrophages, and normalized the endothelial nitric oxide synthase expression in cerebral vessels of SHR. The anti‐inflammatory effects of AT1 receptor antagonists may be an important mechanism for protection against ischemia and could participate in the anti‐stress properties of this class of compounds.
Angiotensin II AT1 Receptor Blockade Prevents Gastric Ulcers during Cold‐Restraint Stress
Authors: BREGONZIO C , ARMANDO I , ANDO H , JEZOVA M , BAIARDI G , SAAVEDRA J M
Published: July 2004

Abstract: Cold‐restraint stress reduces gastric blood flow and produces acute gastric ulcers. We studied the role of Angiotensin II (Ang II) on gastric blood flow and gastric ulceration during stress. Spontaneously hypertensive rats, a stress‐sensitive strain, were pretreated for 14 days with the AT1 receptor antagonist candesartan before cold‐restraint stress. AT1 blockade increased gastric blood flow 40% to 50%; prevented gastric ulcer formation by 70% to 80%; reduced the increase in adrenomedullary epinephrine and TH mRNA without preventing the stress‐induced increase in adrenal corticosterone; decreased the stress‐induced expression of tumor necrosis factor α (TNF‐α) and adhesion protein ICAM‐1 in arterial endothelium, and neutrophil infiltration in the gastric mucosa; and decreased PGE2 content. AT1 receptor blockers prevent stress‐induced ulcerations by a combination of gastric blood flow protection, decreased sympathoadrenal activation, anti‐inflammatory effects with reduction in TNF‐α, and ICAM‐1 expression, leading to reduced neutrophil infiltration while maintaining the protective glucocorticoid effects and PGE2 release. Ang II has a crucial role, through stimulation of AT1 receptors, in the production and progression of stress‐induced gastric injury, and AT1 receptor antagonists could be of therapeutic benefit.
Genetic Mechanisms for Adrenergic Control during Stress
Authors: WONG DONA L , TAI T C , WONG‐FAULL DAVID C , CLAYCOMB ROBERT , KVETNANSKY RICHARD
Published: July 2004

Abstract: Cortisol and epinephrine released in response to stress are replenished via activation of the hypothalamic‐pituitary‐adrenal (HPA or stress) axis. Immobilization (IMMO) stress in rats stimulates epinephrine production in part via the gene encoding the epinephrine‐synthesizing enzyme phenylethanolamine N‐methyltransferase (PNMT). PNMT mRNA rose up to 7.0‐fold with acute or chronic stress. Two transcription factors mediating stress induction of the PNMT gene are the glucocorticoid receptor (GR) and Egr‐1, which interact with −533, −759, and −773 bp, and −165 bp binding sites in the rat PNMT promoter, respectively. To identify molecular mechanisms involved, effects of hypoxic stress on PNMT promoter activity were examined in PC12 cells transfected with the PNMT promoter‐luciferase reporter gene construct pGL3RP893. Oxygen reduction to 5% increased PNMT promoter‐driven luciferase expression, with maximum activity at 6 h. Pretreatment of the cells with protein kinase A (PKA) and protein kinase C (PKC) inhibitors, H‐89 and GF109203X, respectively, attenuated the rise in luciferase. Similarly, PKA‐deficient PC12 cells transfected with pGL3RP893 and exposed to hypoxia also showed attenuated PNMT promoter‐driven luciferase expression. Mutation of the Egr‐1 binding site completely prevented PNMT promoter activation, indicating that Egr‐1 is essential to the stress response. Consistent with this result, hypoxia increased Egr‐1 protein. Hypoxia also increased endogenous PNMT mRNA. However, a shift to intron‐retaining mRNA from which truncated, nonfunctional protein is produced, occurred, suggesting that posttranscriptional regulation may be an important genetic mechanism controlling adrenergic expression and hence, epinephrine, during stress.
Hypertonic Saline and Immobilization Induce Fos Expression in Mouse Brain Catecholaminergic Cell Groups: Colocalization with Tyrosine Hydroxylase and Neuropeptide Y
Authors: PIRNIK ZDENO , MRAVEC BORIS , KUBOVCAKOVA LUCIA , MIKKELSEN JENS D. , KISS ALEXANDER
Published: July 2004

Abstract: The aim of the present study was to reveal stress‐type dependent differences in hindbrain catecholaminergic (CA) cells and parabrachial nuclei (PBN) in the wild‐type mouse. Neuronal activities were evaluated based on the incidence of Fos‐labeling analyzed 60 min after injection of hypertonic saline (HS; 400 μL, 1.5 M, i.p.) or 120 min of immobilization (IMO) stress. The phenotypic nature of neurons was identified by costaining of Fos with either tyrosine hydroxylase (TH) or the neuropeptide Y (NPY) antibody. Generally, HS elicited broader Fos‐staining than IMO. In comparison with IMO, HS induced more extensive Fos activation in the nucleus tractus solitarii‐area postrema complex, and in TH‐ and NPY‐positive cells in the A1 and C1 areas. Locus coeruleus (LC) cells displayed similar Fos activation after HS and IMO, and both stimuli also evoked evident TH‐Fos colocalizations. Both stimuli also induced TH‐Fos costainings in the A5 area. In contrast, IMO failed to activate PBN cells. The data indicate that the activity of TH and NPY hindbrain neurons responds differently to HS and IMO stress, supporting the notion that different stressors have different effects on the activity of autonomic centers.
Modulation of Catecholamine‐Synthesizing Enzymes in the Rat Heart by Repeated Immobilization Stress
Authors: MICUTKOVA LUCIA , KREPSOVA KATARINA , SABBAN ESTHER , KRIZANOVA OLGA , KVETNANSKY RICHARD
Published: July 2004

Abstract: Stress is one of the major risk factors responsible for the increased incidence of a number of common life‐threatening disorders, predominantly of cardiovascular origin. The aim of the present study was to establish the effect of repeated immobilization stress on gene expression and protein levels of aromatic L‐amino acid decarboxylase (AADC) and phenylethanolamine N‐methyltransferase (PNMT) in cardiac left and right atria. In the process of repeated immobilization, rats were immobilized 2 h daily for 7 days and killed 3 h after the last immobilization. Gene expression was determined by regular and real‐time reverse transcription with subsequent polymerase chain reaction, and protein levels were determined by Western blot analysis. In cardiac atria, we identified mRNA for AADC and PNMT. Repeated immobilization stress did not affect AADC mRNA levels. However, repeated immobilization significantly increased PNMT mRNA levels compared with unstressed control animals. No further increase was observed compared with adapted control rats (rats immobilized six times for 2 h daily and decapitated 24 h after the sixth immobilization). AADC protein levels corresponded with mRNA levels of this enzyme. However, we were not able to detect PNMT immunoreactive protein. The observed elevation in the gene expression of PNMT mRNA levels in the heart may be involved in the increased risk of cardiovascular diseases with stress.
Changes in Gene Expression of Phenylethanolamine N‐Methyltransferase in the Transplanted Human Heart
Authors: GONCALVESOVA EVA , MICUTKOVA LUCIA , MRAVEC BORIS , KSINANTOVA LUCIA , KRIZANOVA OLGA , FABIAN JURAJ , KVETNANSKY RICHARD
Published: July 2004

Abstract: Heart transplantation (HTx) is an accepted treatment for precisely defined patients with chronic congestive heart failure; however, as a result of the procedure, the graft is completely denervated. Our study focused on the catecholamine biosynthetic pathway, that is, the production of epinephrine, which is known to have positive chronotropic and inotropic effects on the heart. mRNA levels of the phenylethanolamine N‐methyltransferase (PNMT), the enzyme catalyzing epinephrine synthesis in myocardial tissue, were determined in 18 patients (0 to 10 yr after HTx). Samples of myocardium were obtained from the right ventricle at the time of a routine endomyocardial biopsy performed for the diagnosis of graft rejection. Results were correlated with the following clinical parameters: heart rate, heart rate variability, blood pressure, graft systolic function, and the presence of the rejection. We observed that heart PNMT mRNA levels were significantly higher during the first 3 yr as compared to longer periods after HTx. Also, a decrease in the average heart rate and an increase in the heart rate variability were documented. Levels of the PNMT mRNA do not correlate with blood pressure, left ventricular systolic function at rest, and rejection. Thus, a gradual decrease of the heart rate and an increase in the heart rate variability after HTx is considered to be a sign of cardiac graft reinervation. We speculate that the increased PNMT transcription in human myocardium in early intervals after HTx reflects “autonomous sympathicotrophy.” A decrease in the PNMT gene expression with the number of years after HTx could be a consequence of the reinnervation process.