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.