Chronic mild stress-induced dysregulation of MAPK and PI3K/AKT signaling in the hippocampus and medial prefrontal cortex of WKY female rats.

Wistar-Kyoto (WKY) rats subjected to chronic mild stress (CMS) represent a valid model of treatment-resistant depression (TRD). Considering that depression is more prevalent in women than in men, in the present study, female rats were used. We investigated the effect of CMS on behavior and different factors involved in neuroinflammatory processes and neuroplasticity in the hippocampus and medial prefrontal cortex (mPFC) of WKY female rats. The results show that unstressed WKY females exhibited hypolocomotion, decreased exploratory behavior, and an increase in the total grooming time. After exposure to CMS, WKY females displayed intensified grooming. To investigate potential neural mechanisms underlying these behavioral changes, we analyzed signaling and inflammatory pathways in the hippocampus and mPFC. The findings indicate reduced BDNF and elevated levels levels of IL-1ß in both brain structures and NLRP3 in the mPFC of unstressed WKY female rats. WKY rats subjected to CMS showed a further decrease in BDNF levels and increased IL-1ß and NLRP3 in these brain structures. WKY showed reduced pERK1/2 and increased pp38 levels in both brain structures, while CMS revealed a further increase of pp38 in WKY in these brain structures. Expressions of p110ß and pAKT were decreased in the hippocampus and mPFC of WKY rats. The CMS further suppressed p110 and the downstream AKT phosphorylation in the hippocampus, but did not affect the p110 and pAKT in the mPFC. Our findings indicate behavioral and molecular differences in genetically vulnerable WKY female rats and in their response to CMS that may be involved in TRD.

Sex-Related and Brain Regional Differences of URB597 Effects on Modulation of MAPK/PI3K Signaling in Chronically Stressed Rats.

Gender differences exist in depression incidence and antidepressant efficacy. In addition to the neurotransmission theory of depression, inflammation and disrupted signaling pathways play crucial roles in the pathophysiology of depression. Endocannabinoids offer a novel approach to treat inflammatory and emotional disorders like depression. URB597, a FAAH inhibitor, reduces endocannabinoids breakdown. In this study, URB597 effects were investigated on the pro-inflammatory cytokine interleukin-1ß (IL-1ß), nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3(NLRP3), and mitogen-activated protein kinase (MAPK)/ phosphatidylinositol 3-hydroxy kinase/ protein kinase B (PI3K) signaling in the hippocampus and the medial prefrontal cortex (mPFC) of male and female rats subjected to chronic unpredictable stress (CUS). The results show that CUS induces depression-like behaviors, and the URB597 exhibited antidepressant-like effects inboth sexes. URB597 reduced the CUS-induced NLRP3 and IL-1ß increase in the hippocampus and mPFC of both sexes. URB597 increased the reduced pERK1/2 levels in the mPFC of both sexes and hippocampus of CUS males. URB597 also prevented the increase in p38 phosphorylation after chronic stress in the mPFC of both sexes and in the hippocampus of the females. The CUS suppressed the downstream Akt phosphorylation in the mPFC and hippocampi of both sexes. URB597 produced an up-regulation of the pAkt in the hippocampus of the CUS animals but did not affect the pAkt in the mPFC. These data demonstrated a sexual dimorphism in the neural cell signaling, and in the effects of endocannabinoids, and indicated these dimorphisms are region-specific.

URB597 attenuates stress-induced ventricular structural remodeling by modulating cytokines, NF-κB, and JAK2/STAT3 pathways in female and male rats.

Endocannabinoids act as a stress response system; simultaneously, the modulation of this system has emerged a novel approach for the therapy of cardiovascular disorders. We investigated the protective effects of the chronic administration of the fatty acid amide hydrolase inhibitor URB597 on morphology, pro-inflammatory and anti-inflammatory cytokine, the cytoplasm-nuclear distribution of JAK2/STAT3, and NF-κB and Nrf2/HO-1 signaling in the left ventricle of female and male rats exposed to chronic unpredictable stress. Our results show that URB597 treatment exhibits an antidepressant-like effect, decreases the heart/body weight ratio, prevents the hypertrophy of cardiomyocytes, and reduces the increased level of IL-6 in the wall of the left ventricle of stressed female and male rats. The phosphorylation levels of JAK2 and STAT3 in the ventricle of male rats treated with URB597 were declined, whereas in female rats the decrease of STAT3 was observed. In addition, URB597 reduced increased NF-κB in both females and males and increased the expression of Nrf2 and HO-1 protein in the cytosol of male rats, whereas did not affect their levels in females. Cardioprotective effects of URB597 could be linked to the ability to inhibit the JAK2 in males and the STAT3 inflammatory signaling pathways in both females and males.

Effects of Fatty Acid Amide Hydroxylase Inhibitor URB597 on the Catecholaminergic Activity of the Adrenal Medulla in Stressed Male and Female Rats.

INTRODUCTION: The present study examined the effects of fatty acid amide hydrolase inhibitor URB597 on the level of plasma catecholamine and their content, synthesis, and degradation in the adrenal medulla of male and female rats subjected to chronic unpredictable stress (CUS). MATERIAL AND METHODS: Male and female Wistar rats were exposed to the 6 weeks of CUS and treated intraperitoneally with either 0.3 mg/kg/day of URB597 or vehicle in the last 2 weeks of stress protocol. Catecholamines' plasma levels and catecholamines' levels in adrenal medulla were examined using Elabscience ELISA kits. Western blot analysis was used to detect the protein in the medulla. RESULTS: The results of our experiment showed that adrenal weights and catecholamine of unstressed control were higher in females and that CUS induced further enlargement of adrenal glands and catecholamine content and its synthesis compared to male rats. CUS caused an increase of plasma norepinephrine and depletion of norepinephrine content as well as unchanged synthesis and degradation of catecholamine in the adrenal medulla of male rats. URB597 reduced enlarged adrenals and catecholamine content and its synthesis in stressed female rats. URB597 reduces increased plasma norepinephrine and restores its content in the adrenal medulla, unchanging the expression of enzyme synthesis, while reduced protein levels of monoamine oxidase A in male rats are exposed to CUS. DISCUSSION: Our results support the role of endocannabinoids as an antistress mechanism that inhibits elevated adrenomedullary activation and promotes its recovery to baseline in both male and female stressed rats.

Sex specific effects of the fatty acid amide hydrolase inhibitor URB597 on memory and brain ß2-adrenergic and D1-dopamine receptors.

An increasing body of evidence shows significant sex differences in the mammalian brain in multiple behaviours and psychiatric and neurological diseases and as well as that the endocannabinoid system may differ between males and females. In this study we investigated sex differences in working, short-term and long-term memory and the expression of ß2-adrenergic and D1- and D2-receptors in the mPFC and hippocampus, brain regions that are involved in stress response and memory modulation in rats exposed to the chronic unpredictable stress (CUS) and the potential beneficial effects of the chronic fatty acid amide hydrolase inhibitor URB597 treatment. Chronically stressed male rats had an improvement of working memory, while stressed females showed very low object-recognition abilities. On the other hand, animals of both sexes exhibited long-term memory impairment. Our results showed that CUS decreased the expression of ß2-adrenoceptors in the mPFC and D1 receptors in the mPFC and hippocampus of male rats and decreased ß2-adrenoceptors and D1- receptors in the hippocampus of female. URB597 treatment had a positive effect on the short-term memory of stressed animals of both sexes whereas failed to restore long-term memory and did not affect the protein levels ß2-adrenoceptors and D1 receptors in the hippocampus of CUS female rats. The present results support that endocannabinoids induced long-term memory and neurochemical alternations which are sex dependent, suggesting sex specific treatment strategies of mental disorders.

Inhibition of the fatty acid amide hydrolase changes behaviors and brain catecholamines in a sex-specific manner in rats exposed to chronic unpredictable stress.

Sex differences in the susceptibility to chronic unpredictable stress (CUS) and the effects of fatty acid amide hydrolase (FAAH) inhibitor URB597 in rats have been investigated in this study. In this context, we investigated the effects of prolonged treatment with URB597 on behavior, pro-inflammatory interleukin-6 (IL-6) and anti-inflammatory interleukin-10 (IL-10), catecholamine content and the expression of its biosynthetic and degrading enzymes in the hippocampus, hypothalamus and medial prefrontal cortex (mPFC) of rats subjected to CUS. The results show that CUS increases anxiety-like and depression-like behaviors but it was more pronounced in females. The data suggests sex differences in brain cytokines, catecholamines and their enzymes of synthesis and degradation expression in response to CUS. Our findings indicate that the FAAH inhibitor URB597 differently regulated catecholamine levels and its enzymes of synthesis and degradation in the examined brain areas of male and female rats. URB treatment failed to reduce anxiety or restore reduced norepinephrine and did not affect enzymes of catecholamine degradation in the mPFC, hippocampus and hypothalamus of CUS female rats. These studies are important because they investigate the neurochemical consequences of stress related mood disorders that might lead to the development of sex specific treatments.

The fatty acid amide hydrolase inhibitor URB597 modulates splenic catecholamines in chronically stressed female and male rats.

The changes in sympathetic innervations in lymphoid organs could be a key factor in immune dysregulation. The endocannabinoid system has been shown to exhibit potent immunomodulatory effects that may differ between males and females, representing a potential therapeutic target for peripheral and central inflammatory disorders. Thus, in the present study, an examination was made of the effect of fatty acid amide hydrolase inhibitor URB597 treatment on splenic catecholamine content, synthesis, uptake and degradation in chronically unpredictably stressed (CUS) female and male rats. The results show that CUS increases anxiety-like behaviors and that URB597 had an anxiolytic effect on chronically stressed animals of both sexes. CUS induced the expression of plasma interleukin - 6 (IL-6), interleukin - 10 (IL-10) and IL-6 in the spleen, whereas the expression of IL-10 was reduced in the spleen of both sexes. URB597 treatment did not cause changes in IL-6 in plasma or the spleen, whereas it increased IL-10 in the spleen in CUS animals of both sexes. CUS caused a significant depletion of noradrenaline content in the spleen of female rats and a reduction in noradrenaline uptake in the spleen of female rats, while stressed males had a small but insignificant decrease of splenic noradrenaline levels and an enhanced uptake. The FAAH inhibitor URB597 enhances reduced noradrenaline content, affecting its uptake directly at the level of the spleen. It gives rise to the possibility that endocannabinoids exert a neurorestorative effect on the sympathetic nerve system and cell-mediated immune responses in the spleen of chronically stressed rats.

Melatonin treatment affects changes in adrenal gene expression of catecholamine biosynthesizing enzymes and norepinephrine transporter in the rat model of chronic-stress-induced depression.

This study investigated the effects of melatonin treatment on adrenal catecholamine content, synthesis, uptake, and vesicular transport induced by the chronic unpredictable mild stress (CUMS) model of depression in rats. This entailed quantifying the norepinephrine, epinephrine, mRNA, and protein levels of tyrosine hydroxylase (TH), dopamine-ß-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), norepinephrine transporter (NET), and vesicular monoamine transporter 2 (VMAT2) in the adrenal medulla. CUMS caused a significant depletion of norepinephrine stores and protein levels of TH, DBH, and NET, whereas the gene expression of PNMT was increased. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in norepinephrine content and the protein expression of TH, DBH, and NET in the adrenal medulla of chronically stressed rats. The present study demonstrates the stimulatory effect of melatonin on adrenomedullary synthesis, the uptake and content of catecholamine in the rat model of chronic stress-induced depression.

Oxytocin modulates the expression of norepinephrine transporter, ß3-adrenoceptors and muscarinic M2 receptors in the hearts of socially isolated rats.

Social stress produces behavioral alterations, and autonomic and cardiac dysfunction in animals. In addition to the well-known roles of oxytocin on birth and maternal bonding, recent evidence shows that this neuropeptide possesses cardio-protective properties. However less is known about its role in the regulation of the autonomic nervous system. The direct influence of oxytocin on the cardiac catecholamine synthesizing enzyme, transport beta-adrenoceptors and muscarinic receptors in animals exposed to chronic social isolation stress has not yet been studied. In this study, we examined the influence of peripheral chronic oxytocin treatment on anxiety-related behavior, the morphology and content of epinephrine and norepinephrine, mRNA and protein levels of tyrosine hydroxylase (TH), norepinephrine transporter (NET) and receptors  3 (ß3-AR) and muscarinic 2 (M2 MR) in the right and left cardiac atrium and ventricle of chronically socially isolated male rats. Our results show that oxytocin treatment exhibits an anxiolytic effect, decreases the heart/body weight ratio and prevents the hypertrophy of cardiomyocytes in the wall of the left ventricle of stressed rats. Epinephrine and TH protein levels were unchanged after prolonged oxytocin treatment. Peripheral oxytocin administration led to the enhancement of gene expression of ß3-AR in both atria, NET protein in the left ventricle and gene expression of M2 MR in the right atrium and the left ventricle of chronically socially isolated rats. The study provides evidence that oxytocin treatment in chronically socially isolated animals enhances norepinephrine uptake and expression of cardio-inhibitory receptors in cardiac tissues, which could have a beneficial effect on the cardiovascular system under the increased activity of the sympathoneural system.

Altered cardiac gene expression of noradrenaline enzymes, transporter and ß-adrenoceptors in rat model of rheumatoid arthritis.

Baseline sympathetic activity was found to be elevated in rheumatoid arthritis (RA) patients and it is related to increased cardiovascular risk in these patients. Although many studies have highlighted the association between RA and increased cardiac sympathetic activity, the underlying mechanistic links remain unclear. The aim of the present study was to understand how diseases-triggered changes in gene expression may result in maladaptive physiological changes. Our results suggest that the equilibrium between noradrenaline synthesis, release and reuptake was disrupted in the ventricles of arthritic rats. In the acute phase of the arthritic process, decreased gene expression of MAO-A might lead to accumulation of noradrenaline in myocardial interstitial space, whereas increased gene expression of NET protected cardiomyocytes from the deleterious effects of enhanced noradrenaline. During the chronic phase, reduced expression of ß1-adrenoceptor and decreased efficiency of noradrenaline reuptake contribute to progressive damage of the myocardium and limits heart efficiency.

Melatonin mediated antidepressant-like effect in the hippocampus of chronic stress-induced depression rats: Regulating vesicular monoamine transporter 2 and monoamine oxidase A levels.

The hippocampus is sensitive to stress which activates norepinephrine terminals deriving from the locus coeruleus. Melatonin exerts positive effects on the hippocampal neurogenic process and on depressive-like behaviour. Thus, in the present study, an examination was made of the effect of chronic melatonin treatment on norepinephrine content, synthesis, uptake, vesicular transport and degradation in the hippocampus of rats exposed to CUMS. This entailed quantifying the norephinephrine, mRNA and protein levels of DBH, NET, VMAT 2, MAO-A and COMT. The results show that CUMS evoked prolonged immobility. Melatonin treatment decreased immobility in comparison with the placebo group, reflecting an antidepressant-like effect. Compared with the placebo group, a dramatic decrease in norepinephrine content, decreased VMAT2 mRNA and protein and increased MAO-A protein levels in the hippocampus of the CUMS rats were observed. However, no significant differences in the levels of DBH, NET, COMT mRNA and protein and MAO-A mRNA levels between the placebo and the stressed groups were found. The results showed the restorative effects of melatonin on the stress-induced decline in the norepinephrine content of the hippocampus. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in VMAT2 mRNA and protein levels, whereas it reduced the increase of the mRNA of COMT and protein levels of MAO-A. Chronic treatment with melatonin failed to alter the gene expression of DBH or NET in the hippocampus of the CUMS rats. Additionally, the results show that melatonin enhances VMAT2 expression and norepinephrine storage, whilst it reduces norepinephrine degrading enzymes.

Effects of oxytocin on adreno-medullary catecholamine synthesis, uptake and storage in rats exposed to chronic isolation stress.

PURPOSE/AIM: The adreno-medullar system represents one of the main systems involved in the response to stressful events. The neuropeptide oxytocin, is highly sensitive to the social environment, and regulates autonomic function. Adreno-medullary activity is dependent on the synthesis of catecholamine, its reuptake, release, degradation and vesicular transport. A direct influence of oxytocin on catecholamine synthesizing enzyme and transports in animals exposed to chronic social isolation stress has not been studied yet. MATERIALS AND METHODS: In the present study, we examined the effect of chronic oxytocin treatment on the level of plasma catecholamine and its content, mRNA and protein levels of tyrosine hydroxylase (TH), noradrenaline transporter (NET) as well as vesicular monoamine transporter 2 (VMAT2) in the adrenal medulla of socially isolated rats. RESULTS: Our results show that, by the end of 12 weeks, social isolation did not produce any significant changes in catecholamine content but increased plasma catecholamine level and synthesis in the adrenal medulla. Oxytocin treatment had no further effect either on catecholamine synthesis or content in socially stressed animals whereas a significant elevation of plasma norepinephrine and epinephrine were reduced. On the other hand, chronic isolation caused a significant increase in VMAT2 and decrease in NET protein levels. Oxytocin treatment brought about an increase in protein levels of NET and its return to the levels of control group. Besides, it further increases VMAT2 protein levels in the adrenal medulla of individually housed rats. CONCLUSION: The present results show that peripheral oxytocin treatment enhances catecholamine uptake and storage in the adrenal medulla of chronically isolated animals.

Differential regulation of catecholamine synthesis and transport in rat adrenal medulla by fluoxetine treatment.

We have recently shown that chronic fluoxetine treatment acted significantly increasing plasma norepinephrine and epinephrine concentrations both in control and chronically stressed adult male rats. However, possible effects of fluoxetine on catecholamine synthesis and re-uptake in adrenal medulla have been largely unknown. In the present study the effects of chronic fluoxetine treatment on tyrosine hydroxylase, a rate-limiting enzyme in catecholamine synthesis, as well as a norepinephrine transporter and vesicular monoamine transporter 2 gene expressions in adrenal medulla of animals exposed to chronic unpredictable mild stress (CUMS) for 4 weeks, were investigated. Gene expression analyses were performed using a real-time quantitative reverse transcription-PCR. Chronically stressed animals had increased tyrosine hydroxylase mRNA levels and decreased expression of both transporters. Fluoxetine increased tyrosine hydroxylase and decreased norepinephrine transporter gene expression in both unstressed and CUMS rats. These findings suggest that chronic fluoxetine treatment increased plasma catecholamine levels by affecting opposing changes in catecholamine synthesis and uptake.

Hippocampal asymmetry in expression of catecholamine synthesizing enzyme and transporters in socially isolated rats.

OBJECTIVES: Right-left asymmetry of human brain function has been known for a century. Brain asymmetry and lateralization has been observed at the neurochemical level. At the neurochemical level, it is important to further correlate changes in monoaminergic activity with the synthesis and reuptake of these monoamines. The aim of the present study was to analyze the effect of social isolation on catecholamine stores as well as on the regulation of catecholamine synthesis and uptake in the right and left hippocampus. METHODS: We examined changes in protein levels of dopamine-ß-hydroxylase (DBH), norepinephrine transporter (NET) and vesicular monoamine transporter 2 (VMAT 2) in the right and left hippocampus of socially isolated adult male rats during 12 weeks by Western blot analysis. RESULTS: Chronic isolation stress reduced norepinephrine content in the right hippocampus. No changes were observed in protein levels of DBH and NET in the right hippocampus, whereas expression of this norepinephrine synthetizing enzyme and transporter were elevated in the left hippocampus. On the other hand, chronic isolation stress caused reduction of VMAT2 protein in the right hippocampus. CONCLUSION: Our results reveale not only the lateralization of stress regulatory system but they also show that long-term isolation stress produces right-left asymmetry of the hippocampus norepinephrine, different regulation of the catecholamines synthesis and reuptake.

Modulation of catecholamine-synthesizing enzymes in adrenal medulla and stellate ganglia by treadmill exercise of stressed rats.

The sympatho-adrenal system represents one of the main systems involved in the response to stressful events because its stress-induced activation results in an increased release of catecholamines. Exercise training acts as an important modulator of sympatho-adrenal system, adrenal medulla and stellate ganglia being two components of this system. This study aimed at investigating physical exercise-related changes in gene expression of catecholamine biosynthetic enzymes tyrosine hydroxylase (TH), dopamine-ß-hydroxylase (DBH) and phenylethanolamine N-methyltransferase in the adrenal medulla and stellate ganglia of chronically psychosocially stressed adult rats exposed daily to 20-min treadmill exercise for 12 weeks, using TaqMan RT-PCR assay. Chronic psychosocial stress decreased gene expression of the examined enzymes in the adrenal medulla and treadmill exercise did not lead to further modulation of the corresponding gene expression. On the other hand, chronic psychosocial stress produced a significant increase of TH (about 51%) and DBH (about 103%) gene expression in stellate ganglia, while treadmill exercise decreased gene expression of these enzymes to control levels in psychosocially stressed rats. Our data indicate that treadmill exercise leads to a decreased gene transcription of catecholamine biosynthetic enzymes in stellate ganglia and attenuation of cardiac noradrenaline production in stressful situations. Reduction of catecholamine synthesis in stellate ganglia may be linked to the beneficial effects of treadmill exercise on cardiovascular system in stressed animals.

Chronic fluoxetine treatment affects gene expression of catecholamine enzymes in the heart of depression model rats.

Depression is associated with increased risk of coronary heart diseases. Selective serotonin reuptake inhibitors (SSRIs) have been proved to be very effective in normalizing symptoms of depression, but the data on possible influence of these drugs on cardiovascular function is controversial. Applying Taqman RT-PCR assay, the effect of chronic treatment with a SSRI antidepressant fluoxetine has been investigated on gene expression of catecholamine biosynthetic enzymes in all four heart chambers of rats with signs of depression. Depression was induced by exposing the animals to chronic unpredictable mild stress (CUMS). Tyrosine-hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) mRNA levels were decreased both in right and left atria, while phenylethanolamine N-methyltransferase (PNMT) mRNAs were increased in left atria and both ventricles of depression model rats. Fluoxetine elevated gene expression of TH and DBH in atria, but did not influence this process in the ventricles. Also, this antidepressant did not express a significant effect on the level of PNMT mRNA both in atria and ventricles. These results indicate that fluoxetine acted stimulating noradrenaline synthesis in the heart, which could lead to increased risk of heart disease.

Maprotiline treatment differentially influences cardiac β -adrenoreceptors expression under normal and stress conditions

Alterations in cardiac function were observed in antidepressants treated patients and published in several clinical reports. These detected changes could be either a consequence of the treatment or of depression itself, which has already been proved to be a risk factor in heart diseases. In order to determine a possible influence of chronic treatment with norepinephrinergic reuptake inhibitor, maprotiline, on the heart, we investigated gene expression of cardiac β-adrenoceptors both in controls and in animals with signs of depression. The rats were divided into two groups, unstressed controls and those exposed to chronic unpredictable mild stress (CUMS). The groups were further divided into two subgroups, one receiving daily intraperitoneal injections of vehicle (sterile water) and another one maprotiline (10 mg/kg) for four weeks. Tissue samples were collected after the last application. Gene expression of cardiac β1- and β2-adrenoceptor was determined using Real-time RT-PCR analysis. Our results show that in control animals expression of both adrenoreceptors was decreased in the right atria after 4 weeks of maprotiline application. Contrary, the same treatment led to a significant increase in expression of cardiac β1-adrenoceptor in the stressed rats, with no change in the characteristics of β2-adrenoceptor. Our findings might reflect the that molecular mechanisms are underlying factors involved in the development of cardiovascular diseases linked with antidepressant treatment.

Vários relatórios clínicos observaram alterações de funcionamento cardíaco de pacientes depressivos que foram tratados com os antidepressivos. As alterações detectadas podem ser consequência do tratamento ou, por outro lado, da depressão que, como se tem provado, é um fator de risco no caso de doenças cardíacas. De modo a determinar a possível influência de tratamento crônico com o inibidor da recaptação de norepinefrina, maprotilina, no coração, foi investigada a expressão do gene aos receptores β-adrenérgicos cardíacos dos animais em grupos de controle e em grupos com sinais de depressão. Os ratos foram divididos em grupos de controle não estressados e os grupos de ratos submetidos ao estresse crônico moderado imprevisível (CUMS). Os grupos foram, ainda, divididos em dois subgrupos, que, durante quatro semanas, diariamente receberam injeções intraperitoneais de placebo (água estéril) ou de maprotilina (10 mg/kg). As amostras de tecido foram coletadas após a última aplicação. A expressão do gene aos receptores adrenérgicos β1 e β2 foi determinada utilizando a análise PCR quantitativa em tempo real (RT-PCR). Os nossos resultados demonstram a diminuição de expressão dos ambos os receptores adrenérgicos no átrio direito dos animais do grupo de controle depois de quatro semanas de aplicação de maprotilina. Em contraste, o mesmo tratamento conduziu ao aumento significativo na expressão do receptor β1-adrenérgico no coração dos ratos estressados, sem qualquer alteração nas características do receptor β2-adrenérgico. Estes resultados podem refletir os mecanismos moleculares envolvidos no desenvolvimento de doenças cardiovasculares associadas ao tratamento com os antidepressivos.

Subsequent stress increases gene expression of catecholamine synthetic enzymes in cardiac ventricles of chronic-stressed rats.

Since previous experience of stressful situation profoundly affects response to a subsequent novel stressor, we examined changes in gene expression and protein levels of catecholamine biosynthetic enzymes in cardiac ventricles after exposure of chronic psychosocially isolated adult Wistar male rats to short-term immobilization stress. Chronic social isolation did not affect gene expression of tyrosine hydroxylase (TH) in either right or left ventricle. Subsequent immobilization of these animals produced an elevation of TH mRNA level in right and left ventricles. The levels of dopamine-ß-hydroxylase (DBH) mRNA were detectable only after immobilization both in right and left ventricles of control and chronically isolated rats. Chronic isolation stress increased phenylethanolamine N-methyltransferase (PNMT) mRNA levels in the right ventricle. Immobilization led to an elevated PNMT mRNA level in right and left ventricles of both control and chronically stressed animals. Protein levels of TH, DBH, and PNMT in right and left ventricles of socially isolated rats were increased after subsequent immobilization. Taking into consideration the role of cardiac catecholamines in physiological and pathophysiological processes, it could be hypothesized that increased catecholamine synthesis in the ventricles after novel immobilization stress could point to the susceptibility of the heart to subsequent stress.

Chronic individual housing-induced stress decreased expression of catecholamine biosynthetic enzyme genes and proteins in spleen of adult rats.

OBJECTIVE: Social isolation is regarded as one of the most relevant causes of diseases in mammalian species. The activation of the sympathoneural system represents one of the key components of the stress response. The sympathetic nervous system is one of the major pathways involved in immune-neuroendocrine interactions. The aim of the present study was to determine plasma epinephrine and norepinephrine in individually housed rats, as well as to find out whether splenic gene expression of catecholamine synthesizing enzymes and their protein levels are affected by chronic psychosocial stress. METHODS: Tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) mRNA levels were quantified by quantitative real-time RT-PCR. The TH, DBH and PNMT immunoproteins were assayed by Western blot. RESULTS: Chronic social isolation of adult male rats produced a significant increase in plasma catecholamine levels and a decrease in splenic TH mRNA, DBH mRNA and PNMT mRNA. Protein levels of TH, DBH and PNMT were also reduced. CONCLUSION: These results suggest that increased plasma catecholamines and decreased gene expression and protein levels of catecholamine biosynthetic enzymes in the spleen of chronically individually housed animals might reduce catecholamine synthesis, thus leaving the immunocompetent tissues depleted of catecholamines and consequently leading to an impairment of immune response.

Psychosocial stress-related changes in gene expression of norepinephrine biosynthetic enzymes in stellate ganglia of adult rats.

In this study we investigated the changes in norepinephrine biosynthetic enzymes tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) gene expression in the stellate ganglia of naive controls and long-term socially isolated (12 weeks) adult rats and the response of these animals to additional immobilization stress. Psychosocial stress produced a significant increase of both TH mRNA and DBH mRNA levels in stellate ganglia. Additional immobilization of long-term psychosocially stressed rats expressed no effect on gene expression of these enzymes. The results presented here suggest that psychosocial stress-induced increase in gene expression of norepinephrine biosynthetic enzymes in stellate ganglia may be connected to the increased risk of cardiovascular disease.