Losartan may prevent the elevation of plasma glucose, corticosterone and catecholamine levels induced by chronic stress

Introduction

Stress is a stimulus that activates the hypothalamic pituitary adrenal (HPA) axis and sympathetic nervous system (SNS). Increased activity of the SNS causes to increment or impairment in blood pressure, heart rate, body temperature and plasma glucose and adrenocorticotrophic hormone (ACTH) levels. Angiotensin II (Ang II), which is a product of the renin-angiotensin system (RAS), is an important factor affecting the activity of the SNS and responses to stress. We suggest that the blockade of Ang II may be worthwhile in the prevention and treatment of diabetes mellitus and cardiovascular diseases affected by stress. Therefore, we investigated the effects of immobilisation stress on blood glucose, norepinephrine (NE), epinephrine (E) and corticosterone levels and the effects of an Ang II receptor antagonist, losartan, on these parameters.

Materials and methods

The rats were kept in small cylindrical cages for 60 min/day for 10 consecutive days to perform chronic immobilisation stress. Losartan (10 mg/kg) was given daily by gavage to Losartan (L) and Losartan + Chronic Stress (L+CS) groups. Control (C) and Chronic Stress (CS) P groups received an equal volume of saline daily by gavage for 10 days. After the last stress regimen, blood samples were collected for plasma glucose, NE, E and corticosteroid measurements.

Results

Plasma glucose, NE, E and corticosterone levels in the CS Group increased significantly compared with the C group. In Group L+CS, the plasma glucose, NE, E and corticosterone levels decreased significantly vs. Group CS. In Group L there was no significant difference vs. Group C.

Conclusion

It can be speculated that chronic blockade of RAS may decrease the excess sympathetic responses to stress in cardiovascular diseases and prevent the likely development of Type II diabetes mellitus.

Chromium picolinate, rather than biotin, alleviates performance and metabolic parameters in heat-stressed quail

1. The effects of chromium picolinate and biotin supplementation alone and in combination on performance, carcase characteristics, malondialdehyde (MDA), vitamin C, vitamin E, glucose and cholesterol levels were evaluated in Japanese quail exposed to high ambient temperature. 2. Two hundred and forty quails (10d old) were assigned randomly to 4 dietary treatments at room temperature (22 degrees C; thermoneutral, TN) or ambient (34 degrees C for 8 h/d; heat stress, HS). Both TN and HS were fed either on a basal (control) diet or the basal diet supplemented with 400 microg of Cr/kg (Cr group), 0.5 mg of biotin/kg of diet (biotin group) or both (Cr + Biotin group). 3. Supplementing the diet of heat-stressed quails with chromium picolinate improved live weight gain, feed intake, feed efficiency and carcase traits. Biotin supplementation during TN and HS conditions did not have any beneficial effects on body weight gain, feed intake, feed efficiency or carcase traits. 4. Either in combination or alone, chromium picolinate increased serum concentrations of vitamins C and E, but decreased MDA, glucose and cholesterol concentrations in birds kept at high ambient temperature. There was no difference in vitamins C and E and MDA concentrations between birds given chromium picolinate and birds receiving chromium picolinate plus biotin, while glucose and cholesterol levels were significantly lower in all groups. The lowest concentrations of cholesterol and glucose were found in the combination group under both TN and HS conditions. An interaction between diet and temperature was detected for glucose and cholesterol concentrations. 5. Excretion rates for zinc, iron and chromium were lower in TN groups than in the corresponding HS groups. Supplementing diet with chromium picolinate and chromium picolinate plus biotin decreased excretion of minerals while biotin alone did not effect excretion of minerals. 6. Chromium supplementation, but not biotin supplementation, attenuated the decline in performance and antioxidant status resulting from heat stress.

CHANGES IN VISUAL EVOKED POTENTIALS, LIPID PEROXIDATION AND ANTIOXIDANT ENZYMES IN RATS EXPOSED TO RESTRAINT STRESS: EFFECT OF L-CARNITINE

The purpose of our study was to investigate the effects of L-carnitine on lipid peroxidation, Visual Evoked Potentials (VEPs) and antioxidant enzyme activities such as superoxide dismutase and catalase in rats exposed to chronic restraint stress. Forty male Wistar rats, aged three months were used. They were equally divided into four groups: control (C), the group exposed to restraint stress (R), the group treated with L-carnitine(L) and the group exposed to stress and treated with L-carnitine (RL). Chronic restraint stress was applied for 21 days (1 h/day) and L-carnitine (50 mg/kg/day) was given by gavage to the L and RL groups for the same period. Brain and retina levels of thiobarbituric acid reactive substances (TBARS) were significantly increased in the R group and were not altered in the L group compared to the C group. Brain and retina TBARS levels were lower in the RL group than in the R group. Brain and retina superoxide dismutase and catalase activities were significantly decreased in the L and R groups compared to the C group. L-carnitine pretreatment had no significant effect on superoxide dismutase and catalase activity in the RL group. All latencies of VEP components were prolonged in the R and L groups with respect to the C group. L-carnitine increased the latencies of all VEP components in the L group whereas shortened them in the RL group compared to their control groups. L-carnitine may be a promising agent for the prevention of VEP and TBARS alterations caused by stress.

Effect of pioglitazone treatment on endoplasmic reticulum stress response in human adipose and in palmitate-induced stress in human liver and adipose cell lines

Obesity and elevated cytokine secretion result in a chronic inflammatory state and may cause the insulin resistance observed in type 2 diabetes. Recent studies suggest a key role for endoplasmic reticulum stress in hepatocytes and adipocytes from obese mice, resulting in reduced insulin sensitivity. To address the hypothesis that thiazolidinediones, which improve peripheral insulin sensitivity, act in part by reducing the endoplasmic reticulum stress response, we tested subcutaneous adipose tissue from 20 obese volunteers treated with pioglitazone for 10 wk. We also experimentally induced endoplasmic reticulum stress using palmitate, tunicamycin, and thapsigargin in the human HepG2 liver cell line with or without pioglitazone pretreatment. We quantified endoplasmic reticulum stress response by measuring both gene expression and phosphorylation. Pioglitazone significantly improved insulin sensitivity in human volunteers (P = 0.002) but did not alter markers of endoplasmic reticulum stress. Differences in pre- and posttreatment endoplasmic reticulum stress levels were not correlated with changes in insulin sensitivity or body mass index. In vitro, palmitate, thapsigargin, and tunicamycin but not oleate induced endoplasmic reticulum stress in HepG2 cells, including increased transcripts CHOP, ERN1, GADD34, and PERK, and increased XBP1 splicing along with phosphorylation of eukaryotic initiation factor eIF2alpha, JNK1, and c-jun. Although patterns of endoplasmic reticulum stress response differed among palmitate, tunicamycin, and thapsigargin, pioglitazone pretreatment had no significant effect on any measure of endoplasmic reticulum stress, regardless of the inducer. Together, our data suggest that improved insulin sensitivity with pioglitazone is not mediated by a reduction in endoplasmic reticulum stress.

The influence of Sutherlandia frutescens on adrenal steroidogenic cytochrome P450 enzymes

AIM OF THE STUDY

The aim of this study was to investigate whether Sutherlandia frutescens, subsp. microphylla (family: Fabaceae/Leguminosa), which is traditionally used to treat symptoms of chronic stress generally associated with increased circulating glucocorticoids, influences the biosynthesis of these glucocorticoids.

METHODS

We investigated the interaction of Sutherlandia frutescens with cytochrome P450 enzymes, CYP17 and CYP21, which catalyse key reactions in glucocorticoid biosynthesis. The binding of progesterone and pregnenolone to these enzymes and their metabolism were assayed in the presence of extracts and the bioactive compounds, l-canavanine, pinitol, GABA, flavonoids and triterpenoid glucosides present in the shrub.

RESULTS

While the aqueous and methanol extracts inhibited the type I progesterone-induced difference spectrum (p<0.05), inhibition of pregnenolone binding (p=0.25) was negligible, with the aqueous extract exhibiting greater inhibition. The triterpenoid fraction inhibited both the type I pregnenolone- and progesterone-induced difference spectra and elicited a type II difference spectrum in the absence of substrate. Both pregnenolone and progesterone metabolism were inhibited by the aqueous extract, the inhibition of CYP21 being greater than that of CYP17, influencing the flux through glucocorticoid precursor pathways.

CONCLUSION

This attenuation of adrenal P450 enzymes may thus demonstrate a possible mechanism by which Sutherlandia frutescens reduces glucocorticoid levels and alleviates symptoms associated with stress.

Effect of seabuckthorn leaf extracts on circulating energy fuels, lipid peroxidation and antioxidant parameters in rats during exposure to cold, hypoxia and restraint (C-H-R) stress and post stress recovery

The present study was carried out to study mechanism of adaptogenic activity of seabuckthorn leaf extract, administered orally in rats both in single and five doses at a dose of 100mg/kg body weight 30min prior to C-H-R exposure. The efficacy of the extract was studied on circulating energy fuels, lipid peroxidation and anti-oxidant parameters in rats on attaining the T(rec) 23 degrees C during C-H-R exposure and after recovery (T(rec) 37 degrees C) from C-H-R induced hypothermia. Single dose treatment in rats restricted rise in blood malondialdehyde (MDA) levels and decrease in glutathione (GSH) and catalase (CAT) levels. Both single and five doses also restricted the rise in serum free fatty acids (FFA) and lactate dehydrogenase (LDH) levels on attaining T(rec) 23 degrees C during C-H-R exposure, suggesting more efficient utilization of FFA for energy production and better maintained cell membrane permeability. This suggested that the adaptogenic activity of the extract might be due to its anti-oxidative activity, maintained blood glucose levels, better utilization of FFA and improved cell membrane permeability.

Exogenous agmatine has neuroprotective effects against restraint-induced structural changes in the rat brain

Agmatine is an endogenous amine derived from decarboxylation of arginine catalysed by arginine decarboxylase. Agmatine is considered a novel neuromodulator and possesses neuroprotective properties in the central nervous system. The present study examined whether agmatine has neuroprotective effects against repeated restraint stress-induced morphological changes in rat medial prefrontal cortex and hippocampus. Sprague-Dawley rats were subjected to 6 h of restraint stress daily for 21 days. Immunohistochemical staining with beta-tubulin III showed that repeated restraint stress caused marked morphological alterations in the medial prefrontal cortex and hippocampus. Stress-induced alterations were prevented by simultaneous treatment with agmatine (50 mg/kg/day, i.p.). Interestingly, endogenous agmatine levels, as measured by high-performance liquid chromatography, in the prefrontal cortex and hippocampus as well as in the striatum and hypothalamus of repeated restraint rats were significantly reduced as compared with the controls. Reduced endogenous agmatine levels in repeated restraint animals were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. Moreover, administration of exogenous agmatine to restrained rats abolished increases of arginine decarboxylase protein levels. Taken together, these results demonstrate that exogenously administered agmatine has neuroprotective effects against repeated restraint-induced structural changes in the medial prefrontal cortex and hippocampus. These findings indicate that stress-induced reductions in endogenous agmatine levels in the rat brain may play a permissive role in neuronal pathology induced by repeated restraint stress.

Effects of phytoncides on blood pressure under restraint stress in SHRSP

1. Phytoncides are volatile substances released mainly from trees. We studied whether phytoncides can reduce stress responses in stroke-prone spontaneously hypertensive rats (SHRSP). 2. Under the restraint stress, SHRSP exposed to phytoncides showed lower blood pressure than those without the exposure (186.8 +/- 3.9 vs 207.7 +/- 3.4 mmHg, respectively, P < 0.01 by Student's t-test). 3. Consistent with the observation above, the plasma concentration of catecholamines under the restraint stress was lower in the phytoncides group than in the control group. 4. Based on these results, we concluded that phytoncides reduced the cardiovascular response to restraint stress in SHRSP.

Haematology and behaviour of pullets transported by road and administered with ascorbic acid during the hot-dry season

The effects of ascorbic acid (AA) on pullets transported by road for 6h during the hot-dry season were investigated. Forty Shika Brown pullets administered orally with AA just before transportation served as experimental, while another 40 pullets given sterile water only served as control. Blood samples analyzed before and after transportation in control pullets showed a decrease (P<0.05) in packed cell volume and haemoglobin values, and a significant (P<0.05) increase in the values of heterophil/lymphocyte ratio, total protein and basophil counts post-transportation. In experimental pullets, the post-transportation values were not different (P>0.05) from those obtained pre-transportation. The result showed that the transportation was stressful in control pullets. The behavioural activities of the pullets' post-transportation period indicated that AA facilitated the transition of the state of depression that followed excitation back to excitation immediately after transportation. In conclusion, AA administration ameliorated the adverse effect of road transportation stress during the hot-dry season.

Stress-induced remodeling of lymphoid innervation

Lymphoid organs have long been known to harbor neural fibers from the sympathetic division of the autonomic nervous system, but recent studies suggest a surprising degree of plasticity in the density of innervation. This review summarizes data showing that behavioral stress can increase the density of catecholaminergic neural fibers within lymphoid organs of adult primates. Stress-induced neural densification is associated with increased expression of neurotrophic factors, and functional consequences include alterations in lymph node cytokine expression and increased replication of a lymphotropic virus. The finding that behavioral stress can tonically alter lymph node neural structure suggests that behavioral factors could exert long-term regulatory influences on the initiation, maintenance, and resolution of immune responses.

Possible mechanism of adaptogenic activity of seabuckthorn (Hippophae rhamnoides) during exposure to cold, hypoxia and restraint (C–H–R) stress induced hypothermia and post stress recovery in rats

The present study was carried out to investigate mechanism of adaptogenic activity of seabuckthorn dry leaves aqueous lyophilized extract, administered in rats at a dose of 100 mg/kg body weight prior to cold (5 degrees C)-hypoxia (428 mmHg)-restraint (C-H-R) exposure up to fall of T(rec) 23 degrees C and recovery (T(rec) 37 degrees C) from C-H-R induced hypothermia. The effect of extract treatment was studied on key metabolic regulatory enzymes in blood, liver and muscle and tissue glycogen in rats on attaining T(rec) 23 degrees C and post stress recovery of T(rec) 37 degrees C. In control rats during C-H-R exposure on attaining T(rec) 23 degrees C there was significant decrease in enzyme activities of blood hexokinase (HK), citrate synthase (CS) and glucose-6-phosphate dehydrogenase (G-6-PD); liver CS; and in muscle glycogen, and CS and G-6-PD activities. In control rats on recovery of T(rec) 37 degrees C there was also a significant decrease in liver and muscle glycogen levels along with decreased enzyme activities of blood G-6-PD; liver CS; and liver and muscle G-6-PD. This suggested that during severe stressful exposure to C-H-R and post stress recovery the aerobic metabolism as well as hexose monophosphate (HMP) pathway is suppressed. The single and five doses extract treatment restricted the decrease or better maintained tissue glycogen and enzyme activities, viz. HK, phosphofructokinase (PFK), CS and G-6-PD, in blood, liver and muscle, during C-H-R exposure (T(rec) 23 degrees C) and recovery of T(rec) 37 degrees C. The results suggest that seabuckthorn extract treatment caused a trend for shifting anaerobic metabolism to aerobic during C-H-R exposure and post stress recovery.

Nitrous oxide (N2O) prevents latent pain sensitization and long-term anxiety-like behavior in pain and opioid-experienced rats

Improving rehabilitation after a severe tissue injury does not only require a reduction in pain, but also requires alleviation of negative affects, particularly anxiety. Although opioids remain unsurpassed analgesics to relieve moderate to severe pain, it has been shown that they also induce latent pain sensitization leading to long-lasting hyperalgesia via N-methyl-D-aspartate-(NMDA)-dependent pronociceptive systems. The present study evaluated the ability of nitrous oxide (N2O), a gas with NMDA antagonist properties, to prevent latent pain sensitization and long-term anxiety-like behavior (ALB) in rats with pain and opioid experiences. On D0, the pro-inflammatory drug carrageenan was injected in one hind paw of rats treated with fentanyl (4x100 microg/kg subcutaneously). Nociceptive threshold was evaluated with the paw pressure vocalization test. Rats were re-exposed to carrageenan or exposed to repeated non-nociceptive environmental stress (NNES) 2-3 weeks later. Rats were also challenged in the elevated plus-maze 2 weeks after fentanyl administration for evaluating ALB. The preventive effects of a single 4 h 50/50% N2O-O2 exposure performed on D0 was evaluated. Fifty percent N2O strongly reduced hyperalgesia induced by a first inflammation and its enhancement by fentanyl, and prevented exaggerated hyperalgesia induced by second inflammatory pain or NNES. Moreover, we provide first evidence that a high fentanyl dose induces long-term ALB 2 weeks after its administration. When associated with fentanyl, 50% N2O prevented such long-term ALB. These results suggest that a single exposure to N2O could improve post-injury pain management and facilitate rehabilitation especially when potent analgesics as opioids have to be used.

Endoplasmic reticulum stress as a novel therapeutic target in heart diseases

The endoplasmic reticulum (ER) is a multifunctional organelle responsible for the synthesis and folding of proteins as well as calcium storage and signaling. Perturbations of ER function cause ER stress leading to the unfolded protein response (UPR), which includes inhibition of protein synthesis, protein refolding and clearance of misfolded proteins. The UPR aims at restoring cellular homeostasis, however, prolonged ER stress can trigger apoptosis. ER stress-induced apoptosis has been implicated in the pathogenesis of various diseases such as brain ischemia/reperfusion, neurodegeneration, diabetes and, most recently, myocardial infarction and heart failure. Initial events leading to UPR and apoptosis in the heart include protein oxidation and disturbed calcium handling upon ischemia/reperfusion, and forced protein synthesis during cardiac hypertrophy. While XBP-1 and ATF6-mediated induction of ER chaperones seems to protect the heart from ischemia/reperfusion injury, the PERK/ATF4/CHOP branch of the UPR might transmit proapoptotic signals. The precise mechanism of ER stress-induced cardiomyocyte apoptosis remains elusive, however, recent data suggest that the mitochondrial apoptotic machinery is recruited through the upregulation of Puma, a proapoptotic member of the Bcl-2 family. Importantly, suppression of Puma activity prevented both ER stress and ischemia/reperfusion-induced cardiomyocyte loss, highlighting the ER stress pathways as potential therapeutic targets in cardiovascular diseases.

The intervention of antioxidant therapy on platelet adhesion and immunomodulation in experimental physical stress

During effort overstress the reactive oxygen species act chiefly on unsaturated lipids, inducing the formation of certain peroxidation products. We have investigated malondialdehide (MDA), platelet adhesion index, and immunological activation parameters during effort overstress and administration of vitamins E and C. Biochemical measurements were performed on erythrocytes and heart homogenate. In the vitamin E supplemented group, the platelet adhesion index was constantly correlated with the MDA level (p < 0.001). There is a protecting effect concerning the oxidative stress in animals pretreated with vitamin E and C, which is expressed through the diminution of the MDA quantity both in the erythrocyte and in the heart. The physical effort required by swimming led to a decrease in the NBT test values and in the activity of the serum complement. The steady administration of vitamin E in the effort overstress, due to its antioxidant properties, causes the progressive decrease in peroxidation and platelet adhesion.

Inappropriate continuation of stress ulcer prophylactic therapy after discharge

BACKGROUND

Medications for stress ulcer prophylaxis are appropriately started in critically ill patients with risks for developing stress ulcers. It is unknown whether these drugs are discontinued once the risk factors are removed.

OBJECTIVE

To assess the duration of stress ulcer prophylactic therapy in critically ill patients.

METHODS

A retrospective chart review was conducted at a multidisciplinary, 24 bed medical/surgical intensive care unit (ICU) of a university-affiliated tertiary referral medical center. Three hundred ninety-four patients fulfilled eligibility criteria during the study period of July 1, 2005, through September 30, 2005. Patients were considered to be appropriately discharged from the hospital on gastric acid suppressants if they met any of the following criteria: continued mechanical ventilation, gastroesophageal reflux disease, peptic ulcer disease, history of gastrointestinal ulceration or bleeding within the past year, prescribed medications used for stress ulcer prophylaxis prior to admission, gastrointestinal bleed during hospitalization, or prescriber indication of reason to continue therapy.

RESULTS

Three hundred fifty-seven patients received stress ulcer prophylaxis during their ICU stay. Of these, 80% continued on gastric acid suppressants on transfer from the ICU, with 60% of the therapy being inappropriate. The percentage of critically ill patients discharged from the hospital with inappropriate prescription of gastric acid suppressants was 24.4%. Based on the average wholesale cost, the total cost for unnecessary gastric acid suppressant therapy within the follow-up period was $13,973.

CONCLUSIONS

Gastric acid suppressant medications initially prescribed for stress ulcer prophylaxis are frequently prescribed inappropriately on discharge for patients who were initially admitted to the medical/surgical ICU.

Constituents of Ocimum sanctum with antistress activity

Three new compounds, ocimumosides A (1) and B (2) and ocimarin (3), were isolated from an extract of the leaves of holy basil (Ocimum sanctum), together with eight known substances, apigenin, apigenin-7-O-beta-D-glucopyranoside, apigenin-7-O-beta-D-glucuronic acid ( 4), apigenin-7- O-beta- d-glucuronic acid 6''-methyl ester, luteolin-7-O-beta-D-glucuronic acid 6''-methyl ester, luteolin-7-O-beta-D-glucopyranoside, luteolin-5-O-beta-D-glucopyranoside, and 4-allyl-1-O-beta-D-glucopyronosyl-2-hydroxybenzene (5), and two known cerebrosides. The structures of the new compounds were determined on the basis of extensive 1D and 2D NMR spectroscopic analysis. The new compounds (1- 3) and the known compounds 4 and 5 were screened at a dose of 40 mg/kg body weight for acute stress-induced biochemical changes in male Sprague-Dawley rats. Compound 1 displayed promising antistress effects by normalizing hyperglycemia, plasma corticosterone, plasma creatine kinase, and adrenal hypertrophy. Compounds 2 and 5 were also effective in normalizing most of these stress parameters. In contrast, compounds 3 and 4 were ineffective in normalizing any of these effects.

Possible GABAergic Modulation in the Protective Effect of Zolpidem in Acute Hypoxic Stress-induced Behavior Alterations and Oxidative Damage

Hypoxia is an environmental stressor that is known to elicit alterations in both the autonomic nervous system and endocrine functions. The free radical or oxidative stress theory holds that oxidative reactions are mainly underlying neurodegenerative disorders. In fact among complex metabolic reactions occurring during hypoxia, many could be related to the formation of oxygen derived free radicals, causing a wide spectrum of cell damage. In present study, we investigated possible involvement of GABAergic mechanism in the protective effect of zolpidem against acute hypoxia-induced behavioral modification and biochemical alterations in mice. Mice were subjected to acute hypoxic stress for a period of 2 h. Acute hypoxic stress for 2 h caused significant impairment in locomotor activity, anxiety-like behavior, and antinocioceptive effect in mice. Biochemical analysis revealed a significant increased malondialdehyde, nitrite concentrations and depleted reduced glutathione and catalase levels. Pretreatment with zolpidem (5 and 10 mg/kg, i.p.) significantly improved locomotor activity, anti-anxiety effect, reduced tail flick latency and attenuated oxidative damage (reduced malondialdehyde, nitrite concentration, and restoration of reduced glutathione and catalase levels) as compared to stressed control (hypoxia) (P < 0.05). Besides, protective effect of zolpidem (5 mg/kg) was blocked significantly by picrotoxin (1.0 mg/kg) or flumazenil (2 mg/kg) and potentiated by muscimol (0.05 mg/kg) in hypoxic animals (P < 0.05). These effects were significant as compared to zolpidem (5 mg/kg) per se (P < 0.05). Present study suggest that the possible involvement of GABAergic modulation in the protective effect of zolpidem against hypoxic stress.

CCR5 Blockade Modulates Inflammation and Alloimmunity in Primates

Pharmacologic antagonism of CCR5, a chemokine receptor expressed on macrophages and activated T cells, is an effective antiviral therapy in patients with macrophage-tropic HIV infection, but its efficacy in modulating inflammation and immunity is only just beginning to be investigated. In this regard, the recruitment of CCR5-bearing cells into clinical allografts is a hallmark of acute rejection and may anticipate chronic rejection, whereas conventionally immunosuppressed renal transplant patients homozygous for a nonfunctional Delta32 CCR5 receptor rarely exhibit late graft loss. Therefore, we explored the effects of a potent, highly selective CCR5 antagonist, Merck's compound 167 (CMPD 167), in an established cynomolgus monkey cardiac allograft model. Although perioperative stress responses (fever, diminished activity) and the recruitment of CCR5-bearing leukocytes into the graft were markedly attenuated, anti-CCR5 monotherapy only marginally prolonged allograft survival. In contrast, relative to cyclosporine A monotherapy, CMPD 167 with cyclosporine A delayed alloantibody production, suppressed cardiac allograft vasculopathy, and tended to further prolong graft survival. CCR5 therefore represents an attractive therapeutic target for attenuating postsurgical stress responses and favorably modulating pathogenic alloimmunity in primates, including man.

Behavioral and biochemical studies of total furocoumarins from seeds of Psoralea corylifolia in the chronic mild stress model of depression in mice

Depression is related to alterations of the monoamine oxidase (MAO), hypothalamic-pituitary-adrenal (HPA) axis, and oxidative systems, and some antidepressants achieve their therapeutic effects through alteration of following biochemical markers of depression: MAO-A and MAO-B activities, cortisol levels, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels. The seeds of Psoralea corylifolia, otherwise known as Buguzhi, have long been used for treatments of various symptoms associated with aging in China. Furocoumarins are the most widespread secondary metabolites in this species. The present study was designed to evaluate the potential antidepressant-like activity of total furocoumarins of P. corylifolia (TFPC) in the chronic mild stress (CMS) model of depression. Mice subjected to CMS exhibited a reduction in sucrose intake. Conversely, brain MAO-A and MAO-B activities, plasma cortisol levels, and liver SOD activity and MDA levels were increased following CMS exposures. The time-course for reversal of CMS-induced deficits in sucrose consumption by TFPC was dose-dependent. Thus, the statistically significant effect of the higher dose of TFPC (50 mg/kg body wt.) was observed after 3 days of treatment, while 6 days of treatment were required in the group receiving a lower dose (30 mg/kg body wt.) of TFPC. TFPC reversed these biochemical changes. These results suggest that TFPC may possess potent and rapid antidepressant properties that are mediated via MAO, the HPA axis and oxidative systems and these antidepressant actions could make TFPC a potentially valuable drug for the treatment of depression in the elderly.

The pharmacology of Ro 64-6198, a systemically active, nonpeptide NOP receptor (opiate receptor-like 1, ORL-1) agonist with diverse preclinical therapeutic activity

The NOP receptor (formerly referred to as opiate receptor-like 1, ORL-1, LC132, OP(4), or NOP(1)) is a G protein-coupled receptor that shares high homology to the classic opioid MOP, DOP, and KOP (mu, delta, and kappa, respectively) receptors and was first cloned in 1994 by several groups. The NOP receptor remained an orphan receptor until 1995, when the endogenous neuropeptide agonist, known as nociceptin or orphanin FQ (N/OFQ) was isolated. Five years later, a group at Hoffmann-La Roche reported on the selective, nonpeptide NOP agonist Ro 64-6198, which became the most extensively published nonpeptide NOP agonist and a valuable pharmacological tool in determining the potential of the NOP receptor as a therapeutic target. Ro 64-6198 is systemically active and achieves high brain penetration. It has subnanomolar affinity for the NOP receptor and is at least 100 times more selective for the NOP receptor over the classic opioid receptors. Ro 64-6198 ranges from partial to full agonist, depending on the assay. Preclinical data indicate that Ro 64-6198 may have broad clinical uses, such as in treating stress and anxiety, addiction, neuropathic pain, cough, and anorexia. This review summarizes the pharmacology and preclinical data of Ro 64-6198.

Cross-sensitization and cross-tolerance between exogenous cannabinoid antinociception and endocannabinoid-mediated stress-induced analgesia

Footshock stress induces both endocannabinoid mobilization and antinociception. The present studies investigated behavioral plasticity in cannabinoid antinociceptive mechanisms following repeated activation using the tail-flick test. A secondary objective was to ascertain whether blockade of stress antinociception by the CB(1) antagonist rimonabant could be attributed to changes in locomotor activity. The cannabinoid agonist WIN55,212-2 induced hypoactivity in the open field relative to vehicle-treated controls. By contrast, rimonabant, administered at a dose that virtually eliminated endocannabinoid-mediated stress antinociception, failed to alter locomotor behavior (i.e. time resting, ambulatory counts, distance traveled) in rats subjected to the same stressor. Rats exposed acutely to footshock were hypersensitive to the antinociceptive effects of WIN55,212-2 and Delta(9)-tetrahydrocannabinol (Delta(9)-THC). The converse was also true; acute Delta(9)-THC and WIN55,212-2 administration potentiated stress antinociception, suggesting a bidirectional sensitization between endocannabinoid-mediated stress antinociception and exogenous cannabinoid antinociception. Stress antinociception was also attenuated following chronic relative to acute treatment with WIN55,212-2 or Delta(9)-THC. Repeated exposure to footshock (3 min/day for 15 days), however, failed to attenuate antinociception induced by either footshock stress or WIN55,212-2. Our results demonstrate that endocannabinoid-mediated stress antinociception cannot be attributed to motor suppression. Our results further identify a functional plasticity of the cannabinoid system in response to repeated activation. The existence of cross-sensitization between endocannabinoid-mediated stress antinociception and exogenous cannabinoid antinociception suggests that these phenomena are mediated by a common mechanism. The observation of stress-induced hypersensitivity to effects of exogenous cannabinoids may have clinical implications for understanding marijuana abuse liability in humans.

Antidepressant and antistress activity of GC-MS characterized lipophilic extracts ofGinkgo bilobaleaves

Lipophilic extracts of Ginkgo biloba L. leaves were tested for their possible role on rodent models of depression and stress. Lipophilic extracts of Ginkgo leaves (LEG) at (50 and 100 mg/kg, p.o.) exhibited dose dependent, significant antidepressant activity in the behavioral despair test and learned helplessness rodent model of depression. The activities were comparable to that of imipramine (15 mg/kg) and EGb 761 (50 mg/kg). In the cold immobilization stress induced gastric ulcer model of stress, only the LEG showed a significant reduction in the ulcer index. GC-MS characterization of this bioactive extract was found to be rich in a group of 6-alkyl salicylates (6-AS), along with a fatty alcohol, fatty acids and cardanols. The n-heptadecenyl salicylate represented 60% of the 6-AS. Notable was the absence of dihydroxy alkylphenols which are linked to allergic reactions similar to the urushiols present in poison ivy. In commercial products of Ginkgo, these dihydroxy phenols as well as the favorable 6-AS are removed during enrichment of flavonol glycosides and terpenic lactones. The current findings suggest that intact carboxylic acid groups containing 6-AS are the bioactive components of the lipophilic extract of Ginkgo leaves with antidepressant and antistress activities.

Acute effects of nicotine on restraint stress-induced anxiety-like behavior, c-Fos expression, and corticosterone release in mice

Clinical evidence suggests that nicotine reduces anxiety in stressful situations. In the present study, we investigated the effect of nicotine on restraint-enhanced anxiety-like behavior, c-Fos expression, an index of neuronal activation in the brain, and plasma corticosterone. Two-hour restraint stress-enhanced anxiety-like behavior in the elevated plus-maze (EPM) and nicotine hydrogen tartrate (0.25 mg/kg, i.p.) attenuated the stress-induced changes. Pretreatment with the centrally acting nicotinic antagonist, mecamylamine (2 mg/kg), blocked nicotine's effects. In addition, restraint led to significant increases of c-Fos expression in several brain regions related to stress or anxiety including paraventricular hypothalamic nucleus (PVN), lateral hypothalamic area (LH), central amygdaloid nucleus (CeA), medial amygdaloid nucleus (MeA) and cingulate and retrosplenial cortices (Cg/RS), paraventricular thalamic nucleus (PVT), and basolateral amygdaloid nucleus (BLA). Nicotine attenuated the restraint-induced expression of c-Fos in the PVN, LH, CeA, MeA, and Cg/RS, while leaving the BLA and PVT unaffected. In contrast, nicotine did not reverse the increased levels of plasma corticosterone induced by restraint. These findings suggest that nicotine may modify the stress-induced behavioral changes via regulating the neuronal activation in selected brain regions rather than affecting hypothalamo-pituitary-adrenocortical axis hormone responses.

Que reste-t-il de l'insuffisance surrénale post-corticothérapie?

Adrenal insufficiency (AI) induced by glucocorticoids was first described more than 50 years ago in patients undergoing surgical stress. Although considered the most frequent cause of AI, the true incidence of this complication of glucocorticoid treatment remains unknown. No factors are known to predict AI after glucocorticoid treatment. In particular, neither the dose nor the duration of treatment seems predictive. The minimum dose of cortisol necessary for the body to cope with medical or surgical stress is unknown. The adrenocorticotropin test is often used during corticosteroid withdrawal because it is well correlated with adrenal response to surgical stress, but not with clinical events. Studies over the past 15 years have shown that the perioperative risk of AI has been overestimated and that hydrocortisone doses should be decreased. A prospective study of patients after steroid withdrawal is the only means of assessing the true incidence of this complication to propose a rational strategy to prevent it.

Neuropsychobiological evidence for the functional presence and expression of cannabinoid CB2 receptors in the brain

For over a decade, until recently, it was thought that marijuana acts by activating brain-type cannabinoid receptors called CB1, and that a second type called CB2 cannabinoid receptor was found only in peripheral tissues. Neuronal CB2 receptors in the brain had been controversial. We reported the discovery and functional presence of CB2 cannabinoid receptors in the mammalian brain that may be involved in depression and drug abuse and this was supported by reports of identification of neuronal CB2 receptors that are involved in emesis. RT-PCR, immunoblotting, hippocampal cultures, immunohistochemistry, transmission electron microscopy, and stereotaxic techniques with behavioral assays were used to determine the functional expression of CB2 cannabinoid receptors in the rat brain and mouse brain exposed to chronic mild stress or treated with abused drugs. RT-PCR analyses supported the expression of brain CB2 receptor transcripts at levels much lower than those of CB1 receptors. In situ hybridization revealed CB2 mRNA in cerebellar neurons of wild-type but not of CB2 knockout mice. Abundant CB2 receptor immunoreactivity (iCB2) in neuronal and glial processes was detected in the brain. The effect of direct CB2 antisense oligonucleotide injection into the brain and treatment with JWH015 in motor function and plus-maze tests also demonstrated the functional presence of CB2 cannabinoid receptors in the central nervous system. In humans, there was a high incidence of Q63R polymorphism in the CB2 gene in Japanese alcoholics and depressed subjects. Contrary to the prevailing view that CB2 cannabinoid receptors are restricted to peripheral tissues and predominantly in immune cells, we demonstrated that CB2 cannabinoid receptors and their gene transcripts are widely distributed in the brain. This multifocal expression of iCB2 in the brain suggests that CB2 receptors may play broader roles than previously anticipated and may therefore be exploited as new targets in the treatment of depression and substance abuse.

"Green odor" inhalation reduces the skin-barrier disruption induced by chronic restraint stress in rats: physiological and histological examinations

We investigated whether inhalation of green odor (a mixture of equal amounts of trans-2-hexenal and cis-3-hexenol) prevents the skin-barrier disruption induced by chronic restraint stress in rats. To this end, transepidermal water loss (TEWL) was measured as an index of the disruption of skin-barrier function, whereas light- and electron-microscope examinations were performed to observe histological changes in the skin of the stressed animals. In addition, the effects on TEWL induced by chronic administration of a glucocorticoid, dexamethasone (DEX), were examined. Chronic restraint stress (8 h per day for 14 days) increased TEWL (vehicle + stress group). This effect (and the chronic stress-induced increase in adrenal weight) was prevented in rats that inhaled green odor at the beginning of each day's restraint (2 h each day for 14 days; green odor + stress group). Electron-microscope studies revealed that rats in the green odor + stress group possessed sufficient intercorneocyte lipids to create an effective skin barrier, although these had apparently been decreased in the vehicle + stress group. Daily administration of DEX for 14 days increased TEWL. The present results suggest that chronic stress-induced disruption of the skin barrier in rats can be reduced or prevented by green odor (possibly at least in part through an inhibitory effect on the stress-induced activation of the hypothalamo-pituitary-adrenocortical axis).

The CRF1 receptor antagonist R121919 attenuates the neuroendocrine and behavioral effects of precipitated lorazepam withdrawal

RATIONALE

Corticotropin-releasing factor (CRF) is the primary physiologic regulator of the hypothalamic-pituitary-adrenal (HPA) axis and serves to globally coordinate the mammalian stress response. Hyperactivity of central nervous system CRF neurotransmission, acting primarily via the CRF(1) receptor, has been strongly implicated in the pathophysiology of depression and anxiety. Furthermore, there is evidence of enhanced CRF transcription, release, and neuronal activity after the administration of and withdrawal from several drugs of abuse, including cannabis, cocaine, ethanol, and morphine. Treatment with CRF antagonists has been demonstrated to reduce the severity of certain drug withdrawal symptoms, implicating a specific role for activation of CRF neurons in mediating the anxiogenic and stress-like reactions observed after abrupt drug discontinuation.

OBJECTIVES/METHODS

To extend these findings, we investigated whether pretreatment with the selective CRF(1) receptor antagonist R121919 decreases the behavioral and neuroendocrine activation observed after the precipitation of benzodiazepine (BZ) withdrawal in BZ-dependent rats.

RESULTS

Pretreatment with R121919 attenuated the subsequent HPA axis activation, behavioral measures of anxiety, and expression of the CRF gene in the paraventricular nucleus of the hypothalamus, as measured by CRF heteronuclear RNA, which occurs after flumazenil-precipitation of withdrawal from the BZ, lorazepam.

CONCLUSIONS

These results indicate that the activation of CRF neuronal systems may be a common neurobiological mechanism in withdrawal from drugs of abuse and moreover, that the CRF(1) receptor subtype plays a major role in mediating the effects of CRF on neuroendocrine and behavioral responses during BZ withdrawal. Therefore, CRF(1) receptor antagonists may be of therapeutic utility in the treatment of drug withdrawal syndromes.

Arginine in the critical care setting

Arginine is a nonessential amino acid in the normal physiological state that becomes conditionally essential during periods of hypermetabolic stress. Recent literature supports the hypothesis that arginine plays an important role in the intermediary metabolism of the critically ill patient. Current critical care literature is conflicting on arginine use in the clinical setting, with some proposing it as a panacea, whereas others report it as poison. Multiple individual reports and at least 5 major meta-analyses using combinations of immune-modulating nutrients have reported mostly beneficial results, but few have evaluated the effects of arginine when given as a single supplemental nutrient. This review attempts to objectively analyze the literature and evaluate the potential role of arginine in the critical care setting.

Reduced 5-HT1A- and GABAB receptor function in dorsal raphé neurons upon chronic fluoxetine treatment of socially stressed rats

Autoinhibitory serotonin 1A receptors (5-HT(1A)) in dorsal raphé nucleus (DRN) have been implicated in chronic depression and in actions of selective serotonin reuptake inhibitors (SSRI). Due to experimental limitations, it was never studied at single-cell level whether changes in 5-HT(1A) receptor functionality occur in depression and during SSRI treatment. Here we address this question in a social stress paradigm in rats that mimics anhedonia, a core symptom of depression. We used whole cell patch-clamp recordings of 5-HT- and baclophen-induced G-protein-coupled inwardly rectifying potassium (GIRK) currents as a measure of 5-HT(1A)- and GABA(B) receptor functionality. 5-HT(1A)- and GABA(B) receptor-mediated GIRK-currents were not affected in socially stressed rats, suggesting that there was no abnormal (auto)inhibition in the DRN on social stress. However, chronic fluoxetine treatment of socially stressed rats restored anticipatory behavior and reduced the responsiveness of 5-HT(1A) receptor-mediated GIRK currents. Because GABA(B) receptor-induced GIRK responses were also suppressed, fluoxetine does not appear to desensitize 5-HT(1A) receptors but rather one of the downstream components shared with GABA(B) receptors. This fluoxetine effect on GIRK currents was also present in healthy animals and was independent of the animal's "depressed" state. Thus our data show that symptoms of depression after social stress are not paralleled by changes in 5-HT(1A) receptor signaling in DRN neurons, but SSRI treatment can alleviate these behavioral symptoms while acting strongly on the 5-HT(1A) receptor signaling pathway.

[Stress response under continuous infusion of remifentanil compared to bolus doses of fentanyl assessed by levels of cytokines, C-reactive protein, and cortisol during and after abdominal hysterectomy]

OBJECTIVES

Surgery and anesthetic method have immunomodulating effects on hemodynamic response and stress. We compared the effects of 2 intraoperative analgesic regimens on patients undergoing abdominal hysterectomy.

MATERIAL AND METHODS

We conducted a randomized double-blind trial in ASA 1 and 2 patients undergoing abdominal hysterectomy under balanced anesthesia. Twenty-nine patients were randomized to 2 groups. One group received analgesia by infusion of remifentanil plus morphine and nonsteroidal anti-inflammatory drugs as rescue medications; the other received conventional analgesia with bolus doses of fentanyl according to changes in hemodynamic variables. We measured levels of proinflammatory (interleukin [IL]-6) and antiinflammatory (IL-10) cytokines, cortisol, and C-reactive protein preoperatively, at incision, and at 1, 4 and 24 hours after surgery.

RESULTS

There were no significant differences between the 2 groups in terms of the markers studied at baseline. In each group, however, there were significant changes from baseline at the various points in time. IL-6 and IL-10 levels were significantly elevated (P < .05) at 4 hours. The changes in cortisol levels were significantly different at 1 and 4 hours. Finally, there were significant increases in C-reactive protein at 24 hours.

CONCLUSIONS

Unlike other clinical trials, our study detected no differences between the 2 techniques in response to surgical stress evaluated by analyzing concentrations of pro- and anti-inflammatory cytokines, cortisol, and C-reactive protein.

Protective effect of melatonin against multistress condition induced lipid peroxidation via measurement of gastric mucosal lesion and plasma malondialdehyde levels in rats

AIM

To study the protective effect of a natural antioxidant, melatonin, against multistress condition induced lipid peroxidation via determination of gastric damage and plasma malondialdehyde (MDA) level by high performance liquid chromatography in rats.

METHODS

We compared indomethacin-induced gastric damage and MDA plasma level in three groups of rats: unoperated, bile duct ligated and sham-operated and evaluated the role of the melatonin on gastric damage and plasma MDA level. Indomethacin and melatonin were injected intraperitoneally in doses of 50 mg/kg and 20 mg/kg, respectively. Animals were killed 4 h after indomethacin injection.

RESULTS

Indomethacin induced more severe gastric damage and plasma MDA level in bile duct ligated animals was significantly higher (3.1 +/- 0.04 micromol/L) than sham (2.8 +/- 0.04 micromol/L) and unoperated animals (1.4 +/- 0.08 micromol/L). Pretreatment with melatonin reduced indomethacin-induced gastric damage and plasma MDA level.

CONCLUSION

Considering the results of this study, we suggest that in multistress conditions the intensity of gastric damage and the plasma MDA level are great and melatonin reduces the negative effect of lipid peroxidation and cell damage by oxidative stress in multistress conditions due to its antioxidizing activity.

Effect of Ovary Lipid of Skipjack Tuna on Rat Serum Components after Stress Application

Lipid extracted from the ovary of skipjack tuna by the method that we developed is rich in phospholipid-type docosahexaenoic acid. The ovary lipid of skipjack tuna (OLS) was studied for its anti-stress activity in male Wistar rats, focusing on stress-related blood components: recovery from stress was examined after application of water immersion restraint stress. As a result, serum corticosterone (CORT) secretion was inhibited and decreased rapidly after stress application in rats given OLS compared with control rats. As CORT acts as a glucocorticoid, non-esterified fatty acid (NEFA) is expected to increase by stress application. However, the concentration tended to be lower in rats given OLS than in control rats. With respect to OLS concentration, OLS increased serum dehydroepiandrosterone, secretion concentration-dependently. In addition, as with the recovery study, it tended to inhibit the increase in NEFA. These results indicate that OLS may have an anti-stress activity against acute stress.

Overseas Survey of the Effect of Cedrol on the Autonomic Nervous System in Three Countries

To clarify the influences of ethnic and regional characteristics, and differences in perception on the cedrol effect on autonomic nerve activity, we compared women in their 20s-40s in Norway, Thailand, and Japan. A questionnaire survey of sense of stress and sleep conditions was performed at the same time. The degree of perceived stress, using a 30-item checklist, was highest in Japanese women. The mean stress score exceeded 5.0 in Japanese women, significantly higher than in Thai women (p<0.05) and Norwegian women (p<0.01). Sleeping time was shortest in Japanese women in all generations among the three countries. As the index of autonomic nervous activity, the miosis rate (ratio of pupil-diameter variation after light stimulus to initial pupil diameter) in pupillary light reflex was measured before and after cedrol inhalation. The miosis rate significantly increased after cedrol exposure compared to that before exposure in all three countries, suggesting that the parasympathetic nervous system became dominant. These findings suggested that cedrol produces a sedative effect in people of the three countries despite differences in the ethnic and living environments.

Schizandra chinensis andScutellaria baicalensis counter stress behaviors in mice

The individual and combined antistress effects of the fruit of Schizandra chinensis and the radix of Scutellaria baicalensis were evaluated using a mouse acute stress model. Stress consisted of immobilization and electric foot shocks over 5 days. Mice were treated with herbal extracts for 7 days before exposing the animals to stress. Before each stressor presentation, the mice were treated with each herbal extract. Reduced locomotor activity and the percentage of time spent in the open arms of an elevated plus-maze under stress were recovered by treatment with the extract containing equal amounts of S. chinensis and S. baicalensis (CB11) at 200 and 400 mg/kg (p < 0.05). The effects of CB11 were greater than the effects of S. chinensis or S. baicalensis alone. CB11 treatment (100, 200 and 400 mg/kg) significantly reduced serum corticosterone levels (p < 0.05). Spleen size and the serum interleukin-2 level decreases induced by stress were prevented by CB11 (200 mg/kg) (p < 0.05). Taken together, these results suggest that S. chinensis and S. baicalensis in equal amounts could be used to treat stress disorders, in part, by preventing corticosterone and IL-2 level changes and ameliorating stress-related behavior parameters.

Methylphenidate treatment recovers stress-induced elevated dendritic spine densities in the rodent dorsal anterior cingulate cortex

Exposing pups of the rodent species Octodon degus to periodic separation stress during the first three postnatal weeks leads to behavioral alterations, which include reduced attention towards an emotional stimulus and motoric hyperactivity. These behavioral changes, which are reminiscent of symptoms of attention deficit hyperactivity disorder (ADHD), are paralleled by synaptic changes in the dorsal anterior cingulate cortex (ACd), a limbic cortex region, which plays a key role in the modulation of attentional and executive functions. ADHD is typically treated with methylphenidate (MP), a drug acting on the dopaminergic system. However, the effect of chronic MP-treatment on neuronal and synaptic maturation in the developing brain is unknown. Applying the Golgi-Cox stainining technique, we tested in which way chronic MP-treatment interferes with dendritic and synaptic development in the ACd and whether this treatment can restore the stress-induced changes of neuronal connectivity. We found that chronic treatment with 1 mg/kg MP recovers stress-induced changes of spine densities in the ACd. Furthermore, MP-treatment resulted in increased dendritic length and complexity in both, stressed as well as unstressed control animals. These results indicate that synaptic reorganization as well as dendritic growth in the prefrontal cortex continue into prepuberty and are modulated by MP-treatment.

Effect of bovine lactoferrin on the immune responses of captive bottlenosed dolphins (Tursiops truncatus) being transported over long distances

Bovine lactoferrin was administered orally, in feed, to six bottlenosed dolphins (Tursiops truncatus) before they were transported for approximately six hours; their stress responses were compared with those of five untreated dolphins. During the journey the dolphins had an increased plasma concentration of cortisol, and lymphopenia, eosinopenia and mild neutrophilia, indicating a stress response. The administration of lactoferrin did not affect the function of the dolphins' polymorphonuclear leucocytes, but affected their leucogram by maintaining the number of circulating eosinophils.

Carbamylated erythropoietin ameliorates the metabolic stress induced in vivo by severe chronic hypoxia

Ischemia and chronic hypoxia (CH) trigger a variety of adverse effects arising from metabolic stress that injures cells. In response to reduced O2, hypoxia-inducible factor 1alpha (HIF-1alpha) activates erythropoietin (Epo) as well as many other target genes that counteract the effects of O2 deficiency. Epo produced by the kidney stimulates erythrocyte production, leading to decreased HIF-1alpha production by improved tissue O2 delivery. However, Epo is produced by many other tissues, and it is currently unclear to what extent, if any, locally produced Epo modulates HIF-1alpha expression. Derivatives of Epo that possess tissue-protective activities but do not stimulate erythropoiesis [e.g., carbamylated Epo (CEpo)] are useful tools with which to determine whether exogenous Epo modulates HIF-1alpha in the absence of changes in hemoglobin concentration. We compared the effects of CH (6.5% O2 for 10 days) with or without CEpo administered by daily s.c. injection (10 microg/kg of body weight). CEpo administration did not alter the survival rate, weight loss, or increased hemoglobin concentration associated with CH. Therefore, CEpo does not directly suppress HIF-mediated erythropoiesis. CEpo does, however, prevent CH-induced neuronal increases of HIF-1alpha and Epo receptor-associated immunoreactivity (a measure of stress) while reducing the apoptotic index. In contrast, the myocardium did not exhibit increased HIF-1alpha expression during CH, although CEpo did reduce the apoptotic index. These observations therefore demonstrate that CEpo administration reduces the metabolic stress caused by severe CH, resulting in improved cellular survival independent of erythrocyte production.

Targeting Components of the Stress System as Potential Therapies for the Metabolic Syndrome: The Peroxisome-Proliferator-Activated Receptors

The three peroxisome-proliferator-activated receptor (PPAR) subtypes PPAR-alpha, PPAR-gamma, and PPAR-delta are ligand-activated transcription factors of the nuclear receptor family. PPARs form obligate heterodimers with the retinoid X receptor, which bind to peroxisome-proliferator-response elements (PPREs). PPAR-alpha is expressed mainly in liver, brown fat, kidney, heart, and skeletal muscle; PPAR-gamma in intestine and adipose tissue; PPAR-alpha and PPAR-gamma are both expressed in vascular endothelium, smooth muscle cells, macrophages, and foam cells; PPAR-delta in skeletal muscle, human embryonic kidney, intestine, heart, adipose tissue, developing brain, and keratinocytes. Intense interest in the development of drugs with new mechanisms of action for the metabolic syndrome has focused attention on nuclear receptors, such as PPARs that function as regulators of energy homeostasis. Agonists of PPAR-alpha and PPAR-gamma are currently used to treat diabetic dyslipidemia and type 2 diabetes. Dual PPAR-alpha/gamma agonists and PPAR-alpha/gamma/delta pan-agonists are under investigation for treatment of cardiovascular disease and the metabolic syndrome. Selective PPAR modulators (SPPARMs) are PPAR ligands that possess desirable efficacy and improved tolerance. Efforts are being made to identify novel partial agonists or antagonists for PPAR-gamma in order to combine their antidiabetic and antiobesity effects. Glucocorticoids are major mediators of the stress response and could be the link between stress and PPAR activator signaling and thus may affect the downstream metabolic pathways involved in fuel homeostasis.

Hippocampal cytogenesis correlates to escitalopram-mediated recovery in a chronic mild stress rat model of depression

From clinical studies it is known that recurrent depressive episodes associate with a reduced hippocampal volume. Conversely, preclinical studies have shown that chronic antidepressant treatment increases hippocampal neurogenesis. Consequently, it has been suggested that a deficit in hippocampal neurogenesis is implicated in the pathophysiology of depression. To study a potential correlation between recovery and hippocampal cytogenesis, we established the chronic mild stress (CMS) rat model of depression. When rats are subjected to CMS, several depressive symptoms develop, including the major symptom anhedonia. Rats were exposed to stress for 2 weeks and subsequently to stress in combination with antidepressant treatment for 4 consecutive weeks. The behavioral deficit measured in anhedonic animals is a reduced intake of a sucrose solution. Prior to perfusion animals were injected with bromodeoxyuridine (BrdU), a marker of proliferating cells. Brains were sectioned horizontally and newborn cells positive for BrdU were counted in the dentate gyrus and tracked in a dorsoventral direction.CMS significantly decreased sucrose consumption and cytogenesis in the ventral part of the hippocampal formation. During exposure to the antidepressant escitalopram, given as intraperitoneally dosages of either 5 or 10 mg/kg/day, animals distributed in a bimodal fashion into a group, which recovered (increase in sucrose consumption), and a subgroup, which refracted treatment (no increase in sucrose consumption). Chronic treatment with escitalopram reversed the CMS-induced decrease in cytogenesis in the dentate gyrus of the ventral hippocampal formation, but in recovered animals only. Our data show a correlation between recovery from anhedonia, as measured by cessation of behavioral deficits in the CMS model, and an increase in cytogenesis in the dentate gyrus of the ventral hippocampal formation.

Effects of supplemental L-tryptophan on serotonin, cortisol, intestinal integrity, and behavior in weanling piglets

Stress occurs in intensive pig farming when piglets are weaned and mixed. In this study, we investigated whether this stress might be reduced with elevated dietary levels of Trp. The effects of supplemental dietary Trp (5 g/kg of feed, as-fed basis) were tested on the neuroendocrine system, intestinal integrity, behavior, and growth performance in nursery pigs, both before and after mixing. Mixing occurred 5 d after weaning and diet introduction. On d 4, 5, and 6, Trp-fed pigs vs. control pigs showed approximately a 2-fold elevation in plasma Trp concentrations (68 +/- 7 vs. 32 +/- 2 micromol/L; P < 0.001), a 38% increase in hypothalamic serotonin turnover as measured by 5-hydroxyindoleacetic acid:5-hydroxytryptamine (P < 0.001), and an 11 to 18% increase (P < 0.05) in the intestinal villus height:crypt depth. Before (d 4) and at (d 5) mixing, saliva but not plasma cortisol concentrations were reduced (P < 0.02) by approximately 2-fold in Trp-fed pigs vs. control pigs. Intestinal paracellular (horseradish peroxidase) and transcellular (fluorescein isothiocyanate) transport of macromolecules were not affected by dietary treatment, but mixing induced a 2-fold reduction (P < 0.05) in transcellular transport. Behavioral responses (lying and standing) at mixing were not affected by dietary treatment, except on d 10 after diet introduction when Trp supplementation induced more lying and less standing (P < 0.02). Average daily gain and ADFI were not different among dietary groups (P > 0.10). In conclusion, supplemental dietary Trp (5 g/kg) to piglets increased hypothalamic serotonergic activity, reduced the salivary cortisol response to mixing, improved intestinal morphology, and reduced physical activity 10 d after diet introduction. Consequently, diets containing high Trp levels improved neuroendocrine components of stress and increased gastrointestinal robustness but did not affect behavioral reactivity in nursery pigs during weaning and mixing.

Stress and brain atrophy

Studies in animals showed that stress is associated with changes in hippocampal function and structure, an effect mediated through decreased neurogenesis, increased glucocorticoids, and/or decreased brain derived neurotrophic factor. Antidepressants and some anticonvulsants block the effects of stress and/or promote neurogenesis in animal studies. Patients with posttraumatic stress disorder (PTSD) have been shown to have smaller hippocampal volume on magnetic resonance imaging and deficits in hippocampal-based memory. Symptom activation is associated with decreased anterior cingulate and medial prefrontal function, which is proposed as the neural correlate of a failure of extinction seen in these patients. Treatment with antidepressants and phenytoin reverse hippocampal volume reduction and memory deficits in PTSD patients, suggesting that these agents may promote neurogenesis in humans.

Stress-Induced Oxidative Changes in Brain

Numerous systems and organs are affected by stress. In this review we will focus on the effects in brain. Some of the most impressive effects of the stress in brain are the atrophy of hippocampal dendrites or even the reduction of the hippocampal size observed in brains from subjects exposed to severe or chronic stress. Obviously, before reaching this point of damage there are many other processes taking place in the stressed CNS. The release of glucocorticoids is one of the first features of the stress response. Glucocorticoids can result in neurotoxicity through different mechanisms, including modifications in the energy metabolism or via an increase in excitatory amino acids such as glutamate in the extracellular space. Glutamate can induce neuronal excitotoxicity. This sequence of events leads to the activation of TNFalpha convertase (TACE) and TNFalpha release in brain of rats subjected to restraint stress. One of the multiple effects exerted by this cytokine is to initiate the translocation of the transcription factor NFkappaB to neuronal nuclei. NFkappaB activation results in the induction of iNOS and COX2, two enzymes responsible for a great portion of the neurological damage produced in models of stress.

CRF signaling: molecular specificity for drug targeting in the CNS

Corticotrophin-releasing factor (CRF) is the key mediator of the central nervous system response needed to adapt to stress. If adaptation fails, hypersecretion of CRF continues and produces, via CRF type 1 receptors, symptoms pertaining to cognition, appetite, sleep and anxiety, implicating CRF as a causal factor in affective disorders. Clinical studies with CRF receptor 1 antagonists support a novel pharmacological strategy for treating stress-related disorders. Here we summarize recent information obtained on CRF receptor 1 signaling and propose the concept of a more focused pharmacological intervention based on the signaling pathways involved. Recent findings suggest that CRF activates, via the same CRF receptor 1, different signaling pathways in specific areas of the brain. This intracellular and neuroanatomical signaling specificity will facilitate the search for less pleiotropic antagonists and new chemical compounds that modulate signal transduction in a site-specific manner.

Melanin-concentrating hormone (MCH) reverts the behavioral effects induced by inescapable stress

The aim of this work was to investigate if MCH modifies the feeding and freezing responses in rats exposed to stressful stimuli. We used a basic version of contextual fear, where one group of rats were placed in a novel environment and two different groups were exposed to footshock paradigms, one of them escapable and the other one inescapable. At the end of each treatment, freezing and feeding were measured. Only the animals exposed to inescapable footshock paradigm showed significant increase in the food intake and freezing behavior in comparison to the control animals. The MCH administration (intra-hippocampal or intra-amygdaline) reverted these effects elicited by inescapable footshock. Results presented in this paper lead us to the assumption that the anxiolytic effect of the peptide is responsible for the reversion of the IS effects.

Effect of different non-chloride sodium sources on the performance of heat-stressed broiler chickens

1. One hundred and eighty 1-d-old broiler chicks were used to evaluate the effect upon broiler performance during severely hot summer months of three different sodium salts: sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3) and sodium sulphate (Na2SO4), in starter and finisher diets having an identical electrolyte balance (DEB) of 250 mEq/kg. 2. The non-chloride sodium salts were added to contribute the same amount of sodium and were substituted at the expense of builder's sand in the basal diets containing common salt (NaCl) as Na and Cl source. 3. Each diet was fed to three experimental units having 15 chicks each until 42 d of age. Severe heat-stress conditions, maintained in the rearing room, were indicated by high average weekly room temperature (minimum 29.3 degrees C; maximum 38.0 degrees C). 4. Diets containing sodium salts gave better body weight gain, feed intake and feed to gain ratio than the control diet. Sodium salts also enhanced water intake as well as water to feed intake ratio. This effect was more pronounced in broilers fed NaHCO3 supplement (with NaCl in the basal diets). 5. The increased water intake resulted in lower body temperature in heat-stressed birds fed NaHCO3 supplemented diet than in birds fed other sodium salts. A lower mortality rate was noted with NaHCO3 (15.15%), Na2CO3 (13.64%) and Na2SO4 (15.15%) supplements than with the control (33.33%) treatment. 6. Better carcase and parts yield were observed in sodium supplemented broilers. Sodium salts reduced the alkalotic pH and enhanced the blood sodium content, which ultimately improved the blood electrolyte balance and overall performance of heat-stressed broilers. 7. Supplementing broiler diets with sodium salts improved the live performance of heat-stressed broilers and better productive performance was noted with NaHCO3 than other sodium supplements.