Some gastrointestinal function regulatory Kampo medicines have modulatory effects on human plasma adrenocorticotropic hormone and cortisol levels with continual stress exposure

Rikkunshi-to, a gastrointestinal function regulatory traditional Chinese herbal (Kampo) medicine, has recently been evaluated for its clinical usefulness in stress and depression. This medicine has modulatory effects on the hypothalamo-pituitary-adrenal axis and autonomic nervous function. We examined the effect of Rikkunshi-to and the other gastrointestinal function regulatory Kampo medicines, Hange-shashin-to, Hange-koboku-to, and Ninjin-to, on the plasma levels of adrenocorticotropic hormone (ACTH) and cortisol under stress conditions by repetitive blood sampling. Rikkunshi-to, Hange-shashin-to, and Hange-koboku-to significantly suppressed increases in plasma ACTH-immunoreactive substance (IS) levels compared with the response to a placebo. Rikkunshi-to and Hange-shashin-to significantly suppressed increases in plasma cortisol levels compared with the response to placebo. Ninjin-to had no significant effect on plasma ACTH-IS and cortisol levels. In this study, Rikkunshi-to, Hange-shashin-to, and Hange-koboku-to (partially) regulated plasma ACTH and cortisol levels under stress. These modulatory effects might be beneficial in stress-related disease and suggest that these medicines have clinical pharmacologic activity.

The high-affinity non-peptide CRH1 receptor antagonist R121919 attenuates stress-induced alterations in plasma oxytocin, prolactin, and testosterone secretion in rats

Evidence from basic and clinical research suggests that hyperactivity of central corticotropin-releasing hormone (CRH) circuits contributes to causality and course of affective disorders. Therefore, CRH receptor antagonists have attracted attention as potential therapeutics. We could previously show that the novel high-affinity non-peptide CRH 1 receptor antagonist R121919 significantly inhibits stress-induced corticotropin release and displays anxiolytic effects in rats selectively bred for high anxiety-related behavior. These animals are characterized by their innate hyper-reactivity of the hypothalamic-pituitary-adrenocortical system linked to an increased emotionality and therefore are suitable for the evaluation of CRH 1 receptor antagonists. Here we show that in addition to its effects on anxiety-related behavior and corticotropin secretion, R121919 attenuates the stress-induced release of corticosterone, prolactin, and oxytocin. Moreover, the decrease in plasma testosterone following exposure to stress is abolished by R121919. Our data indicate that antagonism of CRH 1 receptors may prevent stress-associated endocrine alterations.

Vitamin E and selenium supplementation to alleviate cold-stress-associated deterioration in egg quality and egg yolk mineral concentrations of Japanese quails

The effects of vitamin E (dl-alpha-tocopheryl acetate) and selenium (Se; Na2-SeO3) on egg production, egg quality, and mineral content of egg yolk in Japanese quails reared under a low ambient temperature (6 degrees C) were evaluated. Birds (n=300; 7 wk old) were randomly assigned to 12 treatment groups, 25 birds per group. The birds in a 3 x 2 factorial design received either three levels of vitamin E (125, 250, and 500 mg/kg diet) or two levels of selenium (0.1 or 0.2 mg/kg diet). After 2 wk on feed, six groups of the birds were maintained at 18 degrees C (thermoneutral temperature [TN]), and the other half were acclimated over 3 d to a decreased environmental temperature of 6 degrees C (cold stress [CS]). The performance, egg quality, and mineral content of egg yolk were not influenced by supplemental vitamin E and selenium in quails not exposed to cold stress (p > or = 0.09). Two hundred fifty and 500 mg vitamin E/kg diet compared with 125 mg/kg diet and higher dietary selenium inclusions (0.2 vs 0.1 mg/kg) resulted in a better body weight, egg production, and feed efficiency (p = 0.01) in quails reared under CS. Similarly, egg weight, egg specific gravity, eggshell thickness, and Haugh unit were positively influenced with vitamin E (p = 0.01) and selenium (p < or = 0.05) supplementation. Egg yolk concentrations of Zn, Fe, and Mn were higher with higher dietary vitamin E (p = 0.01) and selenium (p = 0.05). There was no interaction detected for parameters measured in the present study (p > or = 0.3). The results of the present study showed that a combination of 250 or 500 mg vitamin E and 0.2 mg selenium per kilogram of diet provides the greatest effects on performance and egg quality of Japanese quails reared under cold stress and suggest that such a supplementation can be considered as a protective management practice in Japanese quail diets to reduce the detrimental effects of cold stress.

Neurokynurenines (Neky) as Common Neurochemical Links of Stress and Anxiety

The following NEKY have been studied: 1-kynurenine (KYN), 3-hydroxyKYN (3HKYN), kynurenic (KYNA), anthranilic (ANT), 3-hydroxyANT (3HANT), quinolinic (QUIN), picolinic (PICA), xanthurenic (XAN), nicotinic (NIC) acids, 3-indole-pyruvate (IPA), nicotinamide (NAM). NEKY antagonize the central effects of precursors of serotonin (tryptophan and 5-HTP), and tryptamine as well. Seizures induced by central administration of KYN and QUIN are prevented by centrally injected dopamine and diminished by noradrenaline and adrenaline. KYN, 3HANT, PIC and NIC potentiate oxotremorine hypothermia mediated by acetylcholine. Central administration of GABA, glycine or taurine, as well as proline and melatonin, prevented seizures induced by QUIN and KYN. Behavioral inhibitory effects of these amino acids are diminished by pretreament with KYN, 3HKYN and QUIN. Elevation of concentrations of corticosteroids is resulted in rise of level of NEKY due to hormonal induction of liver tryptophan pyrrolase and brain 2,3 dioxigenase. NEKY, in their turn, activate both enzymes. Thus, a "vicious circle" is formed and it supports an elevated level of NEKY for a long time, hours and days. Long-lasting increased concentrations of NEKY in tissues can lead to significant after-effects and numerous pathogenic consequences. One can not exclude that a rise of the level of some NEKY, e.g. KYNA, IPA, PIC and XAN, may play an "adaptogenic" role in stress antagonizing some pathologic effects of KYN and QUIN, e.g. anxiogenic, neurotoxic and proconvulsive. It has been demonstrated that the excitatory NEKY, KYN, 3HKYN, QUIN, possess an anxiogenic activity in the standard animal models of anxiety. NEKY with opposite neuroactivities, namely KYNA, IPA, PICA and XAN, have a pharmacological profile of anxiolytics and antagonize both anxiogenic NEKY and standard anxiogens, like caffeine, pentylenetetrazole and yohimbine. Major emphasis is made on KYN as a putative endogenous anxiogen. Studies on the interaction of NEKY with other endogenous metabolites involved in anxiety (beta-phenylethylamine, cholecystokynine, melatonin) are in progress.

The antagonistic effects of atipamezole and yohimbine on stress-related neurohormonal and metabolic responses induced by medetomidine in dogs

This study aimed to compare the antagonistic effects of atipamezole (40,120, and 320 microg/kg, IM), yohimbine (110 microg/kg, IM), and saline on neurohormonal and metabolic responses induced by medetomidine (20 microg/kg, IM). Five beagle dogs were used in each of the 5 experimental groups in randomized order. Blood samples were taken for 6 h. Medetomidine significantly decreased norepinephrine, epinephrine, insulin, and nonesterified fatty acid levels, and increased plasma glucose levels. Both atipamezole and yohimbine antagonized these effects. The reversal effect of atipamezole was dose-dependency, except on epinephrine. Yohimbine caused prolonged increases in plasma norepinephrine and insulin levels compared to atipamezole, possibly because of its longer half-life elimination. Only yohimbine increased the cortisol levels. Neither glucagon nor lactate levels changed significantly. Based on these findings, when medetomidine-induced sedation is antagonized in dogs, we recommend using atipamezole IM, from 2- to 6-fold the dose of medetomidine, unless otherwise indicated.

[Antiviral and anti-stress activity of the gamma-L-glutamyl-histamine and its derivatives]

Effect of gamma-L-glutamylhistamine gamma-L-Glu-HA and some of its derivatives on the state of nonspecific resistance and antiviral activity was studied using experimental models of influenza virus and herpes simplex virus infections. Activities of natural killer (NK) cells and interferon (IFN) system were measured. The model of physical-emotional stress in mice was used. It was shown that the gamma-L-Glu-HA derivative II can prevent totally or substantially a decrease in the NK activity. This agent also prevents inhibition of synthesis of alpha- and gamma-IFN during the post-stress period. The gamma-L-Glu-HA derivatives II, III, and VII increased the mice resistance to influenza virus type A/Aichi at low infection dose (10LD50). The derivative II showed its protective effect even at high dose of pathogen (100LD50). However, this gamma-L-Glu-HA derivative was virtually ineffective under harsh experimental conditions. Thus, a number of gamma-L-Glu-HA derivatives tested in this work demonstrated immunomodulation activity. These agents were able to normalize parameters of nonspecific immunity. They exerted a pronounced antiviral effect against influenza virus but were virtually ineffective against encephalitis in mice caused by herpes simplex virus, type 1. Of all tested agents, gamma-L-Glu-HA derivative II was found to be the most promising.

Methimazole prevents stress and chemical induced gastropathy in rats

This investigation was undertaken to study the effect of methimazole (MMI) on gastric acid secretion and stress and chemically induced gastric ulcer in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with MMI (10-100 mg/kg, i.p.). The effect of orally administered MMI on water-immersion restraint (WIR) stress, indomethacin and ethanol-induced gastric ulcers was also tested. The level of myeloperoxidase (MPO), non-protein sulfhydryls (NP-SH) and gastric wall mucus was measured in the glandular stomach of rats following ethanol-induced gastric lesions. There was a dose-dependent inhibition of gastric acid secretion and ulcerogen induced gastric lesion formation in the MMI treated rats. Our morphological and histological studies showed a complete prevention of ethanol-induced lesions in the rats treated with high dose (100 mg/kg) of MMI. A significant attenuation of ethanol-induced increase in gastric MPO activity, depletion of NP-SH and reduction of gastric wall mucus was also observed in MMI treated rats. These findings clearly suggest the involvement of endogenous pro-inflammatory agents and oxidative stress in mediating the gastroprotective effect of MMI.

Brain neuropeptide Y (NPY) in stress and alcohol dependence

Neuropeptide Y (NPY), the prototypical member of the NPY-like peptide family, antagonizes behavioral consequences of stress through actions within the brain. This was initially indicated by microinjection studies with NPY receptor ligands, suggesting that NPY Y1 receptors mediate the anti-stress effects of NPY. Behavioral anti-stress actions of NPY are note-worthy in that 1) their magnitude surpasses that of other endogenous compounds; 2) they are produced across a wide range of animal models, normally thought to reflect different aspects of emotionality. These findings suggest that NPY acts with a high potency on a common core mechanism of emotionality and behavioral stress responses. This hypothesis is supported by behavioral studies in genetically modified animals. Increased emotionality, as well as increased alcohol intake, has been reported in mice with a homologous recombination knockout of the preproNPY gene. More detailed studies have been made possible by a transgenic rat system, in which NPY is selectively overexpressed within the hippocampus. These subjects display no overt phenotype under baseline conditions and have a normal endocrine stress response, but lack behavioral responses to stress. These findings point to the potential of the NPY system for developing novel pharmacological treatments of stress-related disorders, including anxiety and depression. Recent data additionally point to a role of NPY in the regulation of alcohol intake, and alcohol dependence emerges as a novel potential indication for compounds targeting the NPY system.

[Serotonin and serotonin receptors in the genesis of stress and adaptation]

The paper presents a current concept of the genesis of stress and adaptation with regard to new data on serotonin and its receptors. There is evidence that stress is transient hypoxia that results from dysfunction of smooth muscles (SM) in the microcirculatory bed (a pharmacological stage) with partial or complete dysfunction of the organ or system where dysfunction has occurred (a clinical stage). Impaired interaction of serotonin with GM serotonin receptors, which occurs with excess serotonin receptor ligands due to various stress factors, underlie the pharmacological and clinical manifestations of stress. The occurrence of transient hypoxia is followed by the activation of antistress (adaptive) processes in the organism with thrombocytic release of serotonin. In endogenous hyperserotoninemia, microcirculation improves, a hypoxic area ceases, and/or damaged and necrotic tissues localize. With this, endogenous serotonin-induced recovery of different organs is the essence of an adaptive process. Clinical and experimental evidence suggesting that exogenous serotonin administration just simulates an elevation in the concentration of endogenous serotonin as a material substrate of the human adaptive system.

Evidences for involvement of nitric oxide in the gastroprotective effect of bromocriptine and cyclosporin A on water immersion stress-induced gastric lesions

Previous studies have been shown that the adrenergic system involves in gastric secretion and pathogenesis of peptic lesion and activation of alpha(2)-adrenoceptors located on the vagus nerve inhibits gastric acid secretion. Bromocriptine, a dopamine receptor agonist, also has alpha(2) agonistic effect and prevents indomethacin-induced gastric ulcer. alpha(2)-Adrenoceptors involve in the release of nitric oxide which has cytoprotective activity in gastric mucosa. Cyclosporin A (CsA) has also been suppressed stress-induced gastric mucosal lesions, dose dependently. The object of this study was to clarify the interaction between the anti-ulcer effect of bromocriptine (2, 4, 8 mg kg(-1)) or cyclosporin A (5, 10, 20 mg kg(-1)) and nitric oxide. Intraperitoneal injections of bromocriptine and cyclosporin A prevented water immersion stress-induced gastric ulcer in rats. L-Nitro-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, increased stress-induced lesions while L-arginine, a precursor of nitric oxide, decreased these lesions. In conclusion, increasing level of nitric oxide by bromocriptine and cyclosporin A may be one of the contributory factors in their protective effects on gastric mucosa.

Neuroanatomical substrates involved in the anxiogenic-like effect of acute fluoxetine treatment

An initial exacerbation of anxiety can be observed in animals and humans treated with selective serotonin reuptake inhibitors (SSRIs). The neurobiological substrates and mechanism(s) underlying this effect are not clear. We used Fos expression as a marker of neuronal activation to investigate effects of acute fluoxetine treatment in rats submitted to two different models of emotional stress, airjet and immobilization. Exposure to both stressors induced Fos expression in various brain regions implicated in fear/anxiety mechanisms. Acute treatment with 5 mg/kg fluoxetine facilitated airjet-induced escape responses and enhanced the airjet-, as well as immobilization-induced Fos expression exclusively in the locus coeruleus (LC), but not in other areas including the amygdala, hypothalamus or septum. Fluoxetine also facilitated airjet-induced noradrenaline efflux in the medial prefrontal cortex, a projection area of LC noradrenergic neurons. A higher dose of fluoxetine (10 mg/kg) did not change escape responses and had no effect on stress-induced Fos expression in the LC, but decreased airjet-induced Fos expression in the medial amygdala. The results indicate that anxiogenic effects of acute fluoxetine treatment occur in a specific dose range and can be mimicked by exacerbation of escape responses in the airjet model. Furthermore, facilitation of escape responses by fluoxetine is linked to enhanced activity in the LC/noradrenaline system.

Functional characteristics of CRH receptors and potential clinical applications of CRH-receptor antagonists

Corticotropin-releasing hormone (CRH) plays a major role in coordinating the behavioral, endocrine, autonomic and immune responses to stress. CRH and CRH-related peptides and their receptors are present in the central nervous system and in a wide variety of peripheral tissues, including the immune, cardiovascular and reproductive systems, and have been associated with the pathophysiology of many disease states. These observations have led to the development of several CRH receptor type-selective antagonists, which have been used experimentally to elucidate the role of CRH and related peptides in physiological and disease processes, such as anxiety and depression, sleep disorders, addictive behavior, inflammatory and allergic disorders, neurological diseases and pre-term labor. Because of the complex network of multiple CRH receptor subtypes and their tissue- and agonist-specific signaling diversity, antagonists need to be developed that can target specific CRH receptor isoform-driven signaling pathways.

Saiko-ka-ryukotsu-borei-to, an herbal medicine, prevents chronic stress-induced disruption of glucocorticoid negative feedback in rats

Exposure to stress is known to precipitate or exacerbate many neuropsychiatric disorders such as depression. Abnormality of the neuroendocrine system, as shown by increased adrenal weight and attenuated glucocorticoid negative feedback, is frequently seen in depression. The aim of the present study is to clarify the usefulness of saiko-ka-ryukotsu-borei-to, an herbal medicine, in the treatment of abnormality of the neuroendocrine system using an experimental stress-depression model. Rats were subjected to water immersion and restraint for 2 h daily for 4 weeks (chronic stress), followed by recovery for 10 days. Saiko-ka-ryukotsu-borei-to was administered during the stress and recovery periods (100, 300, or 1000 mg/kg daily, p.o.) or only during the recovery period (1000 mg/kg). After the recovery period, the adrenal weight was measured, and glucocorticoid feedback ability was evaluated by a dexamethasone suppression test using 30 microg/kg dexamethasone. The administration of saiko-ka-ryukotsu-borei-to during the stress and recovery periods prevented the stress-induced increase in adrenal weight or the attenuated negative feedback in a dose-dependent manner. The administration of saiko-ka-ryukotsu-borei-to during the recovery period alone also ameliorated the abnormality of the neuroendocrine system. These results indicate that saiko-ka-ryukotsu-borei-to is effective against chronic stress-induced abnormality of the neuroendocrine system. Because some symptoms and symptomatic relapses in depressives are attributed to dysfunction of the hypothalamo-pituitary-adrenal axis, the present findings provide information important for prevention and treatment of depression.

Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training. Sea-Air-Land

RATIONALE

When humans are acutely exposed to multiple stressors, cognitive performance is substantially degraded. Few practical strategies are available to sustain performance under such conditions.

OBJECTIVE

This study examined whether moderate doses of caffeine would reduce adverse effects of sleep deprivation and exposure to severe environmental and operational stress on cognitive performance.

METHODS

Volunteers were 68 U.S. Navy Sea-Air-Land (SEAL) trainees, randomly assigned to receive either 100, 200, or 300 mg caffeine or placebo in capsule form after 72 h of sleep deprivation and continuous exposure to other stressors. Cognitive tests administered included scanning visual vigilance, four-choice visual reaction time, a matching-to-sample working memory task and a repeated acquisition test of motor learning and memory. Mood state, marksmanship, and saliva caffeine were also assessed. Testing was conducted 1 and 8 h after treatment.

RESULTS

Sleep deprivation and environmental stress adversely affected performance and mood. Caffeine, in a dose-dependent manner, mitigated many adverse effects of exposure to multiple stressors. Caffeine (200 and 300 mg) significantly improved visual vigilance, choice reaction time, repeated acquisition, self-reported fatigue and sleepiness with the greatest effects on tests of vigilance, reaction time, and alertness. Marksmanship, a task that requires fine motor coordination and steadiness, was not affected by caffeine. The greatest effects of caffeine were present 1 h post-administration, but significant effects persisted for 8 h.

CONCLUSIONS

Even in the most adverse circumstances, moderate doses of caffeine can improve cognitive function, including vigilance, learning, memory, and mood state. When cognitive performance is critical and must be maintained during exposure to severe stress, administration of caffeine may provide a significant advantage. A dose of 200 mg appears to be optimal under such conditions.

Stress, metaplasticity, and antidepressants

A large body of evidence has established a link between stressful life events and development or exacerbation of depression. At the cellular level, evidence has emerged indicating neuronal atrophy and cell loss in response to stress and in depression. At the molecular level, it has been suggested that these cellular deficiencies, mostly detected in the hippocampus, result from a decrease in the expression of brain-derived neurotrophic factor (BDNF) associated with elevation of glucocorticoids. Thus, an increase in expression of BDNF, facilitating both neuronal survival and neurogenesis, is thought to represent a converging mechanism of action of various types of antidepressant treatments (e.g., antidepressant drugs and transcranial magnetic stimulation). However, as also revealed by converging lines of evidence, high levels of glucocorticoids down-regulate hippocampal synaptic connectivity ('negative' metaplasticity), whereas an increase in expression of BDNF up-regulates connectivity in the hippocampus ('positive' metaplasticity). Therefore, antidepressant treatments might not only restore cell density but also regulate higher-order synaptic plasticity in the hippocampus by abolishing 'negative' metaplasticity, and thus restore hippocampal cognitive processes that are altered by stress and in depressed patients. This antidepressant regulatory effect on hippocampal synaptic plasticity function, which may, in turn, suppress 'negative' metaplasticity in other limbic structures, is discussed.

Prenatal exposure to diazepam and alprazolam, but not to zolpidem, affects behavioural stress reactivity in handling-naïve and handling-habituated adult male rat progeny

A gentle long-lasting handling produces persistent neurochemical and behavioural changes and attenuates the impairment in the behavioural reactivity to novelty induced by the prenatal exposure to diazepam (DZ) in adult male rat progeny. This study investigated the consequences of a late prenatal treatment with three GABA/BDZ R agonists (DZ) alprazolam (ALP) and zolpidem (ZOLP)), on different stress-related behavioural patterns, in non-handled (NH), short-lasting handled (SLH) and long-lasting handled (LLH) adult male rats exposed to forced swim test (FST), acoustic startle reflex (ASR) and Vogel test (VT). The effects on motor activity were evaluated in the open field and in the Skinner box. The seizure sensitivity to picrotoxin (PTX) was investigated as an index of the functional state of GABA/BDZ Rs. A single daily s.c. injection of DZ (1.25-2.50 mg/kg) and ALP (0.125-0.250 mg/kg) over gestational days 14-20 induced a decrease in immobility time in the FST in NH rats, no change in SLH rats and an increase in LLH rats; DZ induced an increase in the peak amplitude of the ASR in NH rats, no change in SLH rats and a reduction in LLH rats; ALP was ineffective in all groups. DZ and ALP reduced the number of punished licks in the VT in NH, SLH and LLH rats while the unpunished licks were not modified. DZ decreased locomotion and the lever pressing responses while ALP increased them. DZ and ALP increased the seizure sensitivity to PTX (2.5-4.0 mg/kg i.p.). These findings indicate a convergence on anxiety-related behaviours in the effects of prenatal exposure to DZ and ALP and a differentiation on motor activity. Long-lasting handling was able to overcompensate the increased behavioural stress reactivity induced by the prenatal exposure to DZ and ALP.

Modulation of brain stem monoamines and gamma-aminobutyric acid by NK1 receptors in rats

To understand the role of substance P in stress, anxiety and depression, we have investigated in rats the relationship between NK1 receptors and monoamines or GABA, and between substance P and serotonin (5-HT) in brain stem neurons by immunohistochemical double-staining techniques. In the periaqueductal gray and dorsal raphe nucleus, there was no colocalization between NK1 and 5-HT or between NK1 and tyrosine hydroxylase (a marker for adrenaline and dopamine neurons). However, many GABA-positive neurons (> 50%) were NK1 positive, and some substance P-positive neurons were 5-HT positive as well. Almost all locus coeruleus noradrenaline neurons were NK1 positive. Therefore, substance P may promote stress by activating noradrenaline neurons directly and inhibiting 5-HT neurons indirectly via GABA neurons.

Effects of epidermal growth factor microemulsion formulation on the healing of stress-induced gastric ulcers in rats

The effects of intragastric (i.g.) administration of microemulsion formulation of epidermal growth factor (EGF) on the healing of acute gastric ulcers induced by cold-restraint stress in rats was studied and compared with intraperitoneal (i.p.) administration of solutions. In the microemulsion formulation (W/O), labrafil M 1944 CS was the oil phase. Arlacel 186 and Brij 35 were used as the surfactants. Absolute alcohol and distilled water were used as the co-surfactant and the aqueous phase, respectively. Acute gastric lesions were induced by cold-restraint stress for 4 h in the refrigerator (4.0+/-0.5 degrees C). EGF was administered at a dose of 6 microg/kg per day intraperitoneally and intraperitoneally for 7 days. Basal gastric acid secretion (microequiv. H+/30 min), ulcer score (mm(2)) and tissue mucus levels (microg/g tissue) were measured. Basal gastric secretion was significantly reduced after the administration of EGF microemulsion (ME+EGF) (P<0.05). There was no significant decrease in basal gastric acid secretion following i.p (IPEGF) and i.g (IG-EGF) of EGF administrations of solutions compared to their control groups (P>0.05). The results indicate that the highest reduction in the basal acid secretion was seen after the administration of a microemulsion of EGF formulation. The mean ulcer score was reduced by i.g treatment with the microemulsion dosage form of EGF in 7 days from 15.9+/-1.4 to 1.16+/-0.45 mm(2) and was almost completely healed in four of the animals. The results demonstrate that the ulcer score was significantly reduced in i.p. (IPEGF) solution (P<0.005), i.g (IG-EGF) solution (P<0.01) and i.g. microemulsion (ME+EGF) (P<0.01) treated groups compared to untreated group. In IG-EGF, ME+EGF treated groups, mucus levels increased significantly compared to their control groups(P<0.05 and P<0.01). In contrast, there was no significant change in the mucus levels following i.p. EGF administration (P>0.05).

Postoperative pain management in orthopaedic patients: no differences in pain score, but improved stress control by epidural anaesthesia

BACKGROUND AND OBJECTIVE

To investigate the interactions of postoperative pain and endocrine stress response, three groups of 21 patients each with total knee arthroplasty were compared in a randomized, prospective design. For postoperative pain management, a three-in-one block, an epidural catheter analgesia or an intravenous patient-controlled analgesia was used.

METHODS

After standardized balanced anaesthesia, the pain intensity was measured by a visual analogue scale (VAS). For detection of epinephrine, norepinephrine, antidiuretic hormone, adrenocorticotropic hormone and cortisol in the plasma, blood samples were taken at six time points before and up to 180 min after the start of pain therapy. In addition, systolic arterial pressure, heart rate, partial arterial oxygen saturation, nausea, vomiting and satisfaction of the patients were recorded.

RESULTS

Within 15 min after the start of pain therapy, VAS in all groups was similarly reduced from >40 mm to a range <10 mm (P < 0.001). Initially, all endocrine stress variables exceeded the normal range. Epidural anaesthesia led to a significant decrease of epinephrine and norepinephrine concentrations, while an increase was observed in the group with patient-controlled analgesia, and the decrease in patients with the three-in-one block was less than in patients receiving epidural anaesthesia (P = 0.001). Differences in antidiuretic hormone, adrenocorticotropic hormone and cortisol were less pronounced. Systolic arterial pressure decreased significantly in all groups, particularly in patients with epidural anaesthesia. Partial arterial oxygen saturation and the incidence of nausea and vomiting were comparable. All patients were satisfied with the methods used.

CONCLUSIONS

All methods of pain management led to sufficient analgesia, but they were not accompanied by an adequate reduction in endocrine stress response. Thus, postoperative pain is only a secondary stressor and sufficient analgesia with subjective well-being does not prove a stress-free state. With regard to the reduction of sympathoadrenergic stress response, epidural anaesthesia is superior to the three-in-one block and patient-controlled analgesia. Epidural anaesthesia is recommended particularly for high-risk patients with hypertension, coronary heart disease and diabetes mellitus. In these patients, the reduction of a 'hidden' endocrine stress response in addition to prevention of pain is of special interest.

Multiple feedback mechanisms activating corticotropin-releasing hormone system in the brain during stress

Stress-associated disorders such as melancholic depression are characterized by persistent hypothalamic-pituitary-adrenocortical (HPA) axis activation and intensive anxiety. Corticotropin-releasing hormone (CRH) appears to play an essential role in pathophysiology of such disorders. In an attempt to elucidate possible mechanisms underlying persistent activation of CRH in the central nervous system (CNS), we examined responses of hypothalamic and extrahypothalamic CRH systems to the stressors (immobilization stress or psychological stress) and interactions between these CRH systems and glucocorticoids in rats. We propose multiple feedback loops activating central CRH system: (1) attenuation of glucocorticoid-induced negative feedback on the activity of the hypothalamic and brainstem nuclei during chronic stress, (2) autoregulation of CRH biosynthesis in the hypothalamic paraventricular nucleus (PVN) through up-regulation of Type-1 CRH receptor (CRHR-1), and (3) glucocorticoid-mediated positive effects on the amygdaloid CRH system. Stress initially activates the hypothalamic CRH system, resulting in the hypersecretion of glucocorticoids from the adrenal gland. In addition, the psychological component of the stressor stimulates the amygdaloid CRH system. In the chronic phase of stress, down-regulation of GR in the PVN and other brain structures such as the locus coeruleus (LC) fails to restrain hyperfunction of the HPA axis, and persistent activation of the HPA axis further up-regulates the amygdaloid CRH system. Thus, the hypothalamic and the amygdaloid CRH systems cooperatively constitute stress-responsive, anxiety-producing neurocircuitry during chronic stress, which is responsible for the clinical manifestations of stress-associated disorders. Effects of tricyclic antidepressants (TCAs), which appear to mitigate the above mentioned multiple feedback loop forming the vicious circle to activate central CRH systems, will also be discussed.

Effects of acute and chronic reboxetine treatment on stress-induced monoamine efflux in the rat frontal cortex

Reboxetine is a selective noradrenergic reuptake inhibitor that displays an antidepressant profile in both animal tests and in clinical trials. The present study examined the ability of reboxetine to alter stress-induced increases in norepinephrine, serotonin and dopamine efflux in the frontal cortex in awake behaving rats. Acute systemic administration of reboxetine (0.3-20.0 mg/kg) dose-dependently increased extracellular norepinephrine in the frontal cortex while having no effect on extracellular serotonin. At 20 mg/kg, reboxetine also increased extracellular dopamine. Application of a 20-min tailpinch stress increased extracellular norepinephrine. This effect was greatly potentiated in rats pretreated with reboxetine. Tailpinch did not elicit increases in dopamine in saline treated animals but this stimulus increased dopamine levels following reboxetine pretreatment. Furthermore, chronic administration of reboxetine for 14 days resulted in elevated basal concentrations of extracellular norepinephrine and dopamine and a greater net increase of extracellular norepinephrine and dopamine, but not serotonin, in response to tailpinch compared with vehicle control animals. Taken together, these data support the view that the noradrenergic and dopaminergic systems are modified by reboxetine treatment and may be important factors in the mechanism of action of antidepressant compounds.

The effect of midazolam on stress levels during simulated emergency medical service transport: a placebo-controlled, dose-response study

Patients in the emergency medical service (EMS) may have increased endogenous catecholamines because of pain or fear and may benefit from sedation similar to premedication in the hospital. During a simulated EMS scene call, 72 healthy male volunteers were either transported by paramedics from a third-floor apartment through a staircase with subsequent EMS transport with sirens (three stress groups of n = 12; total, n = 36) or asked to sit on a chair for 5 min and lie down on a stretcher for 15 min (three control groups of n = 12; total, n = 36). Catecholamine plasma samples were measured in the respective stress and control groups at baseline and after placebo IV (n = 12) or 25 (n = 12) or 50 (n = 12) microg/kg of midazolam IV throughout the experiment, respectively. Statistical analysis was performed with analysis of variance; P < 0.05 was considered significant. The Placebo Stress versus Control group, but not the 50 microg/kg Stress Midazolam group, had both significantly increased epinephrine (73 +/- 5 pg/mL versus 45 +/- 5 pg/mL; P < 0.001) and norepinephrine (398 +/- 34 pg/mL versus 278 +/- 23 pg/mL; P < 0.01) plasma levels after staircase transport. After EMS transport, the Placebo Stress versus Control group had significantly increased epinephrine (51 +/- 4 pg/mL versus 37 +/- 4 pg/mL; P < 0.05) but not norepinephrine (216 +/- 24 pg/mL versus 237 +/- 18 pg/mL) plasma levels, whereas no significant differences in catecholamine plasma levels occurred between groups after either 25 or 50 microg/kg of midazolam. In conclusion, simulated EMS patients may be subject to more stress during staircase transport than during transport in an EMS vehicle. Titrating sedation with 25 microg/kg of midazolam significantly reduced endogenous catecholamines but not heart rate.

IMPLICATIONS

Simulated emergency medical service patients were more likely to be stressed when being transported by paramedics through a staircase than in an ambulance. Accordingly, it may be beneficial to inject sedative drugs before initiating transport to ensure patient comfort and safety.

Brain penetrance, receptor occupancy and antistress in vivo efficacy of a small molecule corticotropin releasing factor type I receptor selective antagonist

The present studies were designed to evaluate the competitive binding properties and functional effects of a novel nonpeptide CRF1 receptor antagonist, R121919. R121919 administered in doses of 0.63 to 20 mg/kg p.o. 60 min pretest in Wistar rats dose dependently attenuated the swim stress-induced anxiogenic-like behavior in the elevated plus-maze model of anxiety. Moreover, receptor autoradiography revealed that R121919 dose-dependently occupied brain CRF1 receptors in subjects tested in the plus-maze experiment. Orally administered doses of up to 20 mg/kg R121919 also blunted basal and swim stress-induced pituitary-adrenocortical activation, produced additional anxiolytic-like behavioral actions in the defensive withdrawal and defensive burying paradigms, and functionally antagonized the locomotor stimulatory properties of exogenously administered CRF. Taken together, these results suggest that the anxiolytic-like efficacy of R121919 in attenuating the stress-, novelty-, shock-, and CRF-induced increases in behavioral arousal is correlated with competitive blockade of central CRF1 receptors.

[Effect of hypergravity on the oxidative-antioxidative status of rats]

The adaptogenic and antioxidant properties of new Ukrainian plant drug "Poliphytolum" was investigated on the model of stress, which was caused of hypergravitation 2 and 5 N.m2/kg2 action. It was established that hypergravitation makes typical stressory disturbances in oxidative homeostasis. The normalization action of "Polyphytolum" on lipid peroxidation is more strong in liver, spleen and blood, and less more--in brain. It may be caused of low level the drug in the brain tissue.

[Consciousness during anesthesia for cesarean section]

47 women on which sectio cesarean has been done in occasion of belvic-fetal disproportion, anatomical abnormalities of the pelvis, bad position of presentation. We studies presence of consciousnes spontaneous realtion to pain and possibility for contact according the method of Tunstall M.E. It was proved that the use of benzodiazepin derivate--Dormicum impacts substantially influensences of the studied processes. Introduction anaesthetics (thiopental-kalipsol, dormicum-kalipsol and thiopental and helothan in 0.3%) are reliable protection against the operative stress during sectio cesarean and give adequate anaesthesia until baby is born.

N-Methyl-D-aspartate receptor blockade by dizocilpine prevents stress-induced sudden death in cardiomyopathic hamsters

We previously demonstrated that repeated cold-immobilization stress exposure had lethal effects in cardiomyopathic Syrian hamsters. To clarify the mechanisms of the sudden death, we investigated the effects of N-methyl-D-aspartate (NMDA) receptor blockade by dizocilpine on the sudden death of cardiomyopathic hamsters. Repeated exposure (5 days) to cold-immobilization stress induced a lethal effect in the cardiomyopathic hamsters in agreement with our previous results. Dizocilpine (0.1-10 mg/kg, i.p.), administered just prior to the stress, for 5 consecutive days markedly prevented the lethal effects of the stress. It was further demonstrated that treatment drug significantly reduced the observed increase in organ weights. These results suggest that NMDA receptors have an important role in stress-induced sudden death in cardiomyopathic hamsters and provide the first evidence for the potential therapeutic value of NMDA antagonists against cardiac sudden death.

Does exogenous melatonin influence the free radicals metabolism and pain sensation in rat?

Melatonin has been shown to play a role in antioxidative defence. We therefore studied its effect on oxidative damage to the rat cerebral cortex evoked by painful stimulation and immobilization-induced stress. Moreover, the effect of melatonin on chronic pain perception was examined. Rats were injected with either a high dose of melatonin (100 mg/kg i.p.) or a vehicle for five days and were subjected to painful stimulation or immobilization stress 30 min after the treatment. To determine the degree of oxidative stress, the levels of free radicals, thiobarbituric acid reactive substances (TBARS) as indicators of lipid peroxidation and glutathione peroxidase (GSHPx) were estimated in somatosensory cortex. Pain perception was measured by the tail-flick and plantar test. Melatonin reduced the level of TBARS previously increased by painful stimulation. Melatonin also exhibited a slight analgesic effect in those animals exposed to painful stimulation but its role in free radical scavenging did not contribute to this effect.

Evaluation of the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication

OBJECTIVE

To compare the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication.

ANIMALS

42 client-owned dogs that underwent elective ovariohysterectomy.

PROCEDURE

Each dog was randomly allocated to receive medetomidine and butorphanol tartrate (20 microgram/kg and 0.2 mg/kg, respectively, IM) or acepromazine maleate and butorphanol (0.05 and 0.2 mg/kg, respectively, IM) for preanesthetic medication. Approximately 80 minutes later, anesthesia was induced by administration of propofol and maintained by use of isoflurane in oxygen. Each dog was also given carprofen before surgery and buprenorphine after surgery. Plasma concentrations of epinephrine, norepinephrine, cortisol, and beta-endorphin were measured at various stages during the perioperative period. In addition, cardiovascular and clinical variables were monitored.

RESULTS

Concentrations of epinephrine, norepinephrine, and cortisol were significantly lower for dogs administered medetomidine. Concentrations of beta-endorphin did not differ between the 2 groups. Heart rate was significantly lower and mean arterial blood pressure significantly higher in dogs administered medetomidine, compared with values for dogs administered acepromazine.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that for preanesthetic medications, medetomidine may offer some advantages over acepromazine with respect to the ability to decrease perioperative concentrations of stress-related hormones. In particular, the ability to provide stable plasma catecholamine concentrations may help to attenuate perioperative activation of the sympathetic nervous system.

Social stress exacerbates focal cerebral ischemia in mice

BACKGROUND AND PURPOSE

The purpose of the present study was to determine whether exposure to stress or elevated corticosterone concentrations in the days preceding cerebral ischemia exacerbates ischemic injury as assessed by histological and behavioral outcomes.

METHODS

For 7 consecutive days, male C57/BL6 mice were exposed to social stress for 45 minutes or injected with 1 mg/kg corticosterone or vehicle. The animals exposed to social stress were injected with either 1 mg/kg mifepristone, a glucocorticoid receptor antagonist, or the vehicle 30 minutes before stress. On the seventh day, all animals were trained in a passive avoidance task. Twenty-four hours after training, the animals were subjected to 60 minutes of intraluminal middle cerebral artery occlusion (MCAO) or sham surgery. At 72 hours of reperfusion, the animals were tested for retention of the passive avoidance task, and infarction size was determined.

RESULTS

Animals subjected to chronic social stress or treated with exogenous corticosterone before MCAO exhibited larger infarcts and reduced retention of passive avoidance compared with the nonstressed MCAO control. The effects of social stress on infarct volume and passive avoidance were reversed by pretreatment with mifepristone. There was no difference between stressed and control groups in physiological parameters or reduction of laser-Doppler flow signal during MCAO or reperfusion.

CONCLUSIONS

Prior exposure to social stress increases infarction volume and exacerbates cognitive deficits associated with transient cerebral ischemia. The mechanism underlying the effects of stress on stroke outcome likely involves corticosterone acting through glucocorticoid receptors to increase subsequent ischemia-induced neuronal death.

Neuroendocrine aspects of the response to stress

Disruptions in homeostasis (ie, stress) place demands on the body that are met by the activation of 2 systems, the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS). Stressor-induced activation of the HPA axis and the SNS results in a series of neural and endocrine adaptations known as the "stress response" or "stress cascade." The stress cascade is responsible for allowing the body to make the necessary physiological and metabolic changes required to cope with the demands of a homeostatic challenge. Here we discuss the key elements of the HPA axis and the neuroendocrine response to stress. A challenge to homeostasis (a stressor) initiates the release of corticotropin-releasing hormone (CRH) from the hypothalamus, which in turn results in release of adrenocortiotropin hormone (ACTH) into general circulation. ACTH then acts on the adrenal cortex resulting in release of a species-specific glucocorticoid into blood. Glucocorticoids act in a negative feedback fashion to terminate the release of CRH. The body strives to maintain glucocorticoid levels within certain boundaries and interference at any level of the axis will influence the other components via feedback loops. Over- or underproduction of cortisol can result in the devastating diseases of Cushing's and Addison's, respectively, but less severe dysregulation of the HPA axis can still have adverse health consequences. These include the deposition of visceral fat as well as cardiovascular disease (eg, atherosclerosis). Thus, chronic stress with its physical and psychological ramifications remains a persistent clinical problem for which new pharmacological treatment strategies are aggressively sought. To date, treatments have been based on the existing knowledge concerning the brain areas and neurobiological substrates that subserve the stress response. Thus, the CRH blocker, antalarmin, is being investigated as a treatment for chronic stress because it prevents CRH from having its ultimate effect-a protracted release of glucocorticoids. New therapeutic strategies will depend on the discovery of novel therapeutic targets at the cellular and intracellular level. Advances in molecular biology provide the tools and new opportunities for identifying these therapeutic targets.

Effects of diazepam and stress on lung inflammatory response in OVA-sensitized rats

The influence of stress and diazepam treatment on airway inflammation was investigated in ovalbumin (OVA)-sensitized rats. Animals were injected with OVA plus aluminum hydroxide intraperitoneally (day 0) and boosted with OVA subcutaneously (day 7). From the first to 13th day after sensitization, rats were treated with diazepam, and 1 h later they were placed in a shuttle box where they received 50 mild escapable foot shocks/day preceded by a sound signal (S). Response during the warning (S) canceled shock delivery and terminated the S. On day 14, rats were submitted to a single session of 50 inescapable foot shocks preceded by S and then were challenged with OVA. High levels of stress were detected in shocked animals, manifested as ultrasonic vocalizations. Morphometric analysis of stressed animals revealed a significant increase in both edema and lymphomononucleated cells in airways compared with controls. Diazepam treatment reduced edema in stressed and nonstressed rats. No differences were found in polymorphonucleated cell infiltration. Diazepam treatment reduced lymphomononucleated cell infiltration in stressed animals. These data suggest that stress and diazepam treatment play relevant roles in edema and lymphomononucleated airway inflammation in OVA-sensitized rats.

Extension of life span and stress resistance of Drosophila melanogaster by long-term supplementation with melatonin

According to the free radical theory of aging, free radicals are involved in the production of changes in cellular metabolism that lead to a time-dependent functional decline in all living beings. Consequently, antioxidant and/or free radicals scavengers may retard the aging process. We explored the effect of melatonin on the life span of Drosophila melanogaster (Oregon wild strain). It was presumed that given the antioxidant and free radicals scavenger properties of melatonin, this hormone would prevent oxidative damage to the fly tissues and slow down the process of aging. Melatonin, added daily to the nutrition medium at a concentration of 100 microg/ml, increased significantly the life span of D. melanogaster. The maximum life span was 61.2 days in controls and 81.5 days in melatonin fed flies. Relative to the controls, the percentage increase in the melatonin fed flies was 33.2% in maximum life span, 19.3% in the onset of 90% mortality, and 13.5% in median life span. Furthermore, in a test of superoxide mediated toxicity it was shown that melatonin treatment increased the resistance of D. melanogaster to paraquat. Finally, the augmented resistance to an ambient temperature of 36 degrees C was also a demonstration of the antioxidative protection provided by the hormone.

Behavioural and biochemical studies of citalopram and WAY 100635 in rat chronic mild stress model

Reversal of chronic mild stress (CMS)-induced decrease of sucrose consumption has been studied in rats after 2, 7, 14, and 35 days treatment with imipramine, citalopram (both 10 mg/kg per day, i.p.), WAY 100635 (0.2 mg/kg sc, b.i.d.), and citalopram plus WAY 100635. Bmax, Kd, and functional status [cyclic AMP (cAMP) generation] of beta1-adrenoceptors were assessed in cortical tissue at the same time points. Citalopram reversed CMS-induced reduction of sucrose intake at an earlier time point than imipramine. WAY 100635 was not effective and did not potentiate the effect of citalopram. CMS produced increase of Bmax. Imipramine decreased Bmax in controls (Days 2, 7, 14, and 35) and normalised Bmax in stressed animals (Day 35). Citalopram, WAY 100635, and the combination increased Bmax in stressed animals and controls (Days 14 and 35). Inconsistent changes of Kd values and of cAMP responses to noradrenaline (NA) stimulation were observed. Thus stress- and drug-induced effects on beta1-adrenoceptors do not appear to be a common biochemical marker of antidepressant-like activity in the CMS model.

GABAA-benzodiazepine receptor complex ligands and stress-induced hyperthermia in singly housed mice

Stress-induced hyperthermia (SIH) in singly housed mice, in which the rectal temperature of a mouse is measured twice with a 10-min interval, enables to study the effects of a drug on the basal (T1) and on the stress-enhanced temperature (T2), 10 min later, using the rectal procedure as stressor. SIH (T2-T1) reflects a stress-induced phenomenon sensitive to stress- or anxiety-modifying effects of drugs. Several benzodiazepine agonists (diazepam, chlordiazepoxide, oxazepam and alprazolam) dose-dependently antagonized SIH either in NMRI mice from two different breeders or in BALB/c mice. No major differences in the sensitivity for any of the drugs tested were found between strains or between substrains from different breeders. The selective BZ1 receptor agonists alpidem and zolpidem only at relatively high doses antagonized SIH, whereas flumazenil, FG7142, pentylenetetrazol and phenobarbital did not affect SIH. Alcohol antagonized SIH, and the effects of diazepam could be antagonized by flumazenil. The findings that full BZ receptor agonists have anxiolytic-like effects in the singly housed SIH paradigm are comparable to those previously found in the group-housed version. The singly housed SIH is proposed as a simple and reliable screen for detecting anxiety-like properties of drugs that is valid in every mouse strain tested so far.

Reversal of stress- and CRF-induced anorexia in rats by the synthetic nociceptin/orphanin FQ receptor agonist, Ro 64-6198

RATIONALE

(1S,3aS)-8-(2,3,3,4,5,6-hexahydro-1H-phenalen-1-yl)-1-phenyl-1,3,8-triazaspiro[4.5]decan-4-one (Ro 64-6198), a non-peptidic agonist for the opioid receptor-like1 (ORL1) receptor, exhibits anxiolytic properties in stressful conditions.

OBJECTIVE

The present study was aimed at evaluating whether activation of ORL1 receptors by Ro 64-6198 may reverse the anorectic effect of restraint stress or intracerebroventricular (ICV) CRF injection.

METHODS

In body restraint experiments, 20-h food deprived rats were treated with intraperitoneal (IP) injection of Ro 64-6198 or vehicle. Ten minutes later, they were confined in cylindrical Plexiglas tubes for 60 min and then returned to their cage with food. In CRF experiments, 20-h food deprived rats were IP injected with Ro 64-6198 or vehicle. Ten minutes later, they received ICV CRF, 200 ng/rat or vehicle; food was offered after 20 min.

RESULTS

Intraperitoneal (IP) pretreatment with Ro 64-6198 reversed the hypophagic effect induced by both restraint or CRF; the effect was statistically significant at the three doses tested (0.3, 1.0 or 2.5 mg/kg). ICV administration of the selective ORL1 receptor antagonist [Nphe(1)]NC(1-13)NH(2)(two injections of 33 or 66 microg/rat) abolished the effect of Ro 64-6198 on CRF-induced anorexia. In freely feeding rats, Ro 64-6198 significantly increased feeding at 2.5, but not at 0.3 or 1.0 mg/kg; in food deprived rats, Ro 64-6198 (0.3 or 1.0 mg/kg) did not modify food intake. Thus, reversal of stress- and CRF-induced anorexia by Ro 64-6198 can be evoked at doses lower than those that are hyperphagic. Ro 64-6198 (1 or 2.5 mg/kg) did not modify the anorectic effect of E. coli lipopolysaccharide, suggesting that its effect is selective for stress- or CRF-induced anorexia. Lastly, the benzodiazepine diazepam was unable to reduce the anorectic effect of CRF at the anxiolytic dose of 0.3 mg/kg, and partially reduced it at the hyperphagic dose of 1 mg/kg.

CONCLUSIONS

The results of this study show that the non-peptidic ORL1 receptor agonist Ro 64-6198 markedly and selectively inhibits the anorectic effect of stress and CRF, and provide evidence that this effect is mediated by ORL1 receptors. Thus, Ro 64-6198 may represent an interesting tool for treatment of stress-induced anorexia.

Quetiapine attenuates the immobilization stress-induced decrease of brain-derived neurotrophic factor expression in rat hippocampus

Quetiapine is a new atypical antipsychotic drug widely used in the treatment of schizophrenia and other psychotic disorders. This study examined the influence of quetiapine on the decrease of brain-derived neurotrophic factor (BDNF) expression, induced by chronic immobilization stress, in the hippocampus of the rat. Pretreatment with 10 mg/kg of quetiapine markedly attenuated the stress-induced decrease in levels of BDNF protein, as determined by Western blot analyses, and the reduction of BDNF immunoreactivity, in hippocampal pyramidal and dentate granular neurons. These results suggest that the chronic administration of quetiapine could be neuroprotective to hippocampal neurons in schizophrenia and this effect may be related to its antipsychotic effect in patients with schizophrenia.

Elucidating the antidepressant actions of substance P (NK1 receptor) antagonists

Substance P (NK1 receptor) antagonists (SPAs) are currently the best validated and clinically most advanced novel approach to treating major depressive disorder (MDD), and several compounds are in advanced clinical development. Three years since the discovery of the antidepressant efficacy of MK-869 (Merck & Co Inc), the first in a new class of drugs that act by selectively blocking the actions of substance P, the principle that blocking the NK1 receptor can alleviate major depression has recently been replicated in a placebo-controlled, blinded study. SPAs are active in a range of preclinical assays that detect clinically used antidepressant drugs, but they have a pharmacological profile that is distinct from established drugs. There is preliminary evidence that substance P and NK1 receptor density may be altered in MDD, suggesting a possible link between substance P and depressive pathophysiology. Studies in animals indicate that the psychotherapeutic effects of SPAs may be mediated at least partly through stimulation of hippocampal neurogenesis, by direct blockade of NK1 receptors in the amygdala and its associated output projections, and also via interactions with monoamines. Additional studies are needed to explore these hypothesesfurther.

The effects of antidepressant drug treatments on activator protein-1 binding activity in the rat brain

Since a long-term administration of antidepressant drugs and mood stabilizers is required in the treatment of mood disorders, the regulation of gene expression by these drugs that is mediated by transcription factors, such as activator protein-1 (AP-1) complex, may play an important role in the therapeutic action. In this study, the authors investigated the influence of lithium, antidepressant drugs and stress on AP-1 binding activity in the rat brain. In addition, we examined pretreatment with these drugs on the expression of AP-1 binding activity in response to stress. A gel shift assay was used to measure the levels of AP-1 binding activity. Our results indicate that neither acute nor chronic treatment with antidepressant drugs affects in AP-1 binding activity in the rat frontal cortex or hippocampus. However, the authors found that acute restraint stress for 90 min upregulated the induction of AP-1 binding activity in the rat frontal cortex. In addition, chronic pretreatment with imipramine, but not lithium or paroxetine, downregulated the induction of AP-1 binding activity in response to acute restraint stress in the frontal cortex. The functional classification of antidepressant drugs based on the downregulation of restraint stress-induced AP-1 binding activity may contribute to the advances in our understanding of the pathogenesis of depression.

Sedation and analgesia in intensive care. Medications attenuate stress response in critical illness

The stress response to critical illness can have many deleterious effects. Appropriate use of sedation and analgesia can attenuate the stress response, alleviate pain and anxiety, and improve compliance with care. Agitation responds best to anxiolytic drugs; pain is best relieved by analgesics. A combination of these drugs can act synergistically, because most analgesics provide some degree of sedation. In select cases, neuromuscular blocking agents are required, but they should not be used without concomitant sedation and analgesia. Use of agents needs to be tailored to the needs of individual patients; indications, anticipated length of need, and underlying organ system derangements are important considerations.

Chronic treatment with imipramine or mirtazapine antagonizes stress- and FG7142-induced increase in cortical norepinephrine output in freely moving rats

The effect of repeated administration of imipramine or mirtazapine, two antidepressant drugs with different mechanisms of action, was studied on the stress-induced increase in the extracellular concentration of norepinephrine in the prefrontal cortex of freely moving rats. Exposure to footshock in control rats induced a marked increase in extracellular norepinephrine concentrations in the prefrontal cortex (+120%). Long-term administration with imipramine or mirtazapine (10 mg/kg, i.p., twice or once a day, respectively, for 14 days) reduced (+50%) the effect of stress on basal norepinephrine output. Acute administration of FG7142 (30 mg/kg, i.p.), an anxiogenic benzodiazepine receptor inverse agonist, induced a marked increase in norepinephrine output (+90%) in control rats. In rats chronically treated with imipramine or mirtazapine this effect was completely antagonized. On the contrary, acute administration of these antidepressant drugs failed to reduce stress- and FG7142-induced increase in norepinephrine output. The plastic changes in the sensitivity of norepinephrine neurons to footshock stress and drug-induced anxiogenic stimuli may reveal a new important neuronal mechanism involved in the long-term modulation of emotional state. This action might be relevant for the anxiolytic and antidepressant effect of antidepressant drugs.

Minimally invasive hepatectomy: modulation of systemic reactions to operation or laparoscopic approach?

BACKGROUND

A new concept of surgical stress has been proposed that consists of both aggressiveness of operation and systemic reactions to an operation.

METHODS AND RESULTS

We have investigated a possible modulation of such systemic reactions to operation and have demonstrated the following 3 points: (1) coagulation and fibrinolytic systems are independently activated during hepatectomy and such activation can be modulated by protease inhibitors such as nafamostat mesilate and antithrombin III; (2) elevated thromboxane A2 during hepatectomy is characterized in the prostanoid system, the elevation of thromboxane A2 is inhibited by thromboxane A2 synthetase inhibitor, and postoperative liver injury is reduced; (3) cytokine response induced by hepatectomy is modulated by preoperative administration of methylprednisolone, leading to possible prevention of bacterial translocation. Therefore, modulating systemic reactions to hepatectomy may be important for successful minimally invasive hepatectomy. Another important option for minimally invasive hepatectomy is the use of operative procedures such as laparoscope or thoracoscope. We have investigated the usefulness of a laparoscopic hepatectomy from the standpoints of early and long-term outcome after hepatectomy. Laparoscopic hepatectomy, which is a difficult and dangerous procedure, can be a feasible option and can result in better short-term outcome and a similar long-term outcome after hepatectomy when compared with conventional open hepatectomy. Therefore, the laparoscopic approach is also a viable option for minimally invasive hepatectomy.

CONCLUSIONS

Modulation of systemic reactions to the operation itself and laparoscopic hepatectomy may be new strategies for performing minimally invasive hepatectomy.

Differential effects of benzodiazepines on immune responses in non-stressed and stressed animals

Benzodiazepines (BZDs) used extensively as antianxiety agents are known for their low toxicity. However, a long lasting depression of mitogen stimulated secretion of macrophage-derived cytokines has been shown in offsprings of rats that were exposed to diazepam during pregnancy. The Present study investigates the effects of long term administration of diazepam and alprazolam on humoral and cell-mediated immune responses in adult male Wistar rats and Swiss albino mice. Administration of diazepam (5 mg/kg/day x 7-14 d) and alprazolam (1 mg/kg/day x 7-14 d) produced a significant reduction of anti-SRBC antibody titre, a measure of humoral immune response, and foot pad thickness and % leucocyte migration inhibition (% LMI), measures of cell-mediated immune responses. Administration of diazepam (5 mg/kg, i.p.) or alprazolam (1 mg/kg, i.p.) before subjecting the animals to restraint stress (RS) reversed the immunosuppressive effects of RS. Both per se immunosuppressive effects and attenuation of RS-induced immunosuppression of BZDs was antagonized by flumazenil (10 mg/kg, i.p.), a central BZD receptor antagonist. Thus, BZDs appear to modulate the immune system in non-stressed and stressed adult animals in a differential manner and these effects are mediated via central benzodiazepine receptors.

L-arginine protects against stress-induced gastric mucosal lesions by preserving gastric mucus

1. We have shown that exogenously administered L-arginine protects against water immersion restraint (WIR) stress-induced gastric mucosal lesions in rats through preservation of nitric oxide (NO) generation via constitutive nitric oxide synthase (cNOS), but not inducible nitric oxide synthase (iNOS), in the gastric mucosa. We have also indicated that impaired gastric mucus synthesis and secretion occur through a decrease in gastric cNOS activity in WIR-stressed rats. Therefore, in the presesnt study, we examined whether exogenously administered L-arginine exerts a protective effect against WIR stress-induced gastric mucosal lesions in rats through preservation of gastric mucus synthesis and secretion by NO generated from the administered amino acid via cNOS in the gastric mucosa. 2. Rats were subjected to WIR stress for 3 and 6 h. Either L-arginine (150-600 mg/kg) or D-arginine (600 mg/kg) was injected intraperitoneally 0.5 h prior to WIR stress. Either N(G)-monomethyl L-arginine (L-NMMA; 100 mg/kg) or N(G)-monomethyl D-arginine (D-NMMA; 100 mg/kg) was injected subcutaneously 0.5 h prior to WIR stress. Total NOS, cNOS, iNOS, nitrite and nitrate (breakdown products of NO), hexosamine (an index of gastric mucin) and adherent mucus were assayed in the gastric mucosa. 3. Pretreatment with L-arginine, but not D-arginine, protected against gastric mucosal lesions in rats subjected to WIR stress for 3 and 6 h in a dose-dependent manner. Pretreatment with L-arginine, but not D-arginine, attenuated decreases in hexosamine and adherent mucus concentrations and cNOS activity and increases in total NOS and iNOS activities and nitrite/nitrate concentration in the gastric mucosal tissue of rats subjected to WIR stress for 3 and 6 h in a dose-dependent manner. Both the protective effect of L-arginine against gastric mucosal lesions and the attenuating effect of the amino acid on the decreases in gastric mucosal hexosamine and adherent mucus concentrations and cNOS activity in rats subjected to WIR stress for 6 h were counteracted by cotreatment with L-NMMA, a nitric oxide synthase inhibitor, but not D-NMMA. 4. These results suggest that exogenously administered L-arginine exerts a protective effect against stress-induced gastric mucosal lesions in rats at least partly through preservation of gastric mucus synthesis and secretion by NO produced from the administered amino acid via cNOS in gastric mucosal tissue.

Influence of SAMe on the modifications of brain polyamine levels in an animal model of depression

The mechanism(s) of the antidepressant activity of S-adenosyl-L-methionine (SAMe) have not yet been elucidated. SAMe is essential for the synthesis of polyamines, which have a key role in protein synthesis, cell proliferation, and neuronal plasticity. On the other hand, accumulating data indicate that depression is associated with a reduction in regional brain volume and that antidepressants increase neurogenesis in defined brain regions and also influence neuronal plasticity. Here we show that in a validated rat model of depression (chronic unpredictable mild stress-induced anhedonia) there is a significant reduction of putrescine, spermidine and spermine in the hippocampus, and of only putrescine in the nucleus accumbens septi. SAMe, at a fully antidepressant dose (300 mg/kg i.m., daily for 7 days), completely restores the levels of putrescine in the nucleus accumbens, and restores in part the levels of both spermidine and spermine in the hippocampus. These results may suggest (i) a role for brain polyamines in depression and in reward processes, and (ii) that the antidepressant effect of SAMe may be due, at least in part, to a normalization of putrescine levels in the nucleus accumbens septi.

Antistress effect of oligosaccharides extracted from Morinda officinalis in mice and rats

AIM

To explore the antistress effect of Morinda officinalis (Chinese medicine "Bajitian") oligosaccharides (MW-97) in mice.

METHODS

Male mice and rats were subjected to a variety of unpredictable stressors on a daily basis over 15 d period and then the Vidiomex-V image pattern analytic system was used to observe the spontaneous motor activity. Meanwhile, regular method was used to prepare pathologic section of adrenal gland and blood cells analytic system was used to detect white blood cell (WBC) count (including relative WBC percentages) in peripheral blood. On the end, the serum level of stress hormone was detected using radioimmunoassay.

RESULTS

Chronic stress resulted in diffuse hyperplasia of the adrenal cortex and atrophy of the adrenal medulla in mice, which suggested that stress-adaption failure of the adrenal gland occurred, while adrenal gland of the mice pretreated with MW-97 (100 mg/kg, ip) prior to each stressor for 15 d did not occur any pathologic changes. In addition, chronic stress also significantly reduced the WBC count and relative WBC percentages in the peripheral blood, including the percentage of lymphocytes, monocytes, neutrophils, however, MW-97 (25 and 100 mg/kg) reversed these changes and raised WBC count, along with relative WBC percentages significantly. Furthermore, the serum concentration of testosterone was decreased and corticosterone was increased significantly in chronically stressed animals. MW-97 also declined the serum level of corticosterone and raised level of testosterone. MW-97 had no effects on the spontaneous motor activity in the stressed mice.

CONCLUSION

MW-97 had antistress effect against chronic stress, moreover, MW-97 had no excitatory or inhibitory effects on the CNS, which suggested that MW-97 might become a new kind of antistress agent.

Constituents and pharmacological effects of Eucommia and Siberian ginseng

The bark and leaves of Eucommia ulmoides Oliv (Eucommiaceae) and "Siberian ginseng" (Ezoukogi in Japanese) prepared from the root bark or stem bark of Eleutherococcus senticosus Maxim (Acanthopanax senticosus Harms) have been used as tonic and anti-stress drug. The extracts of Eucommia showed anti-hypertensive, anti-complementary, anti-oxidative, and anti-gastric ulcer effects, and promoting collagen synthesis, accelating granuloma formation, and other pharmacological effects. The Siberian ginseng exhibited anti-fatigue, anti-stress, immuno-enhancing effect, CNS activity, and anti-depressive effect. By now, 40, 28, and 10 compounds have been isolated from Eucommia ulmoides bark, Eucommia ulmoides leaves, and Siberian ginseng, respectively, and their structures were elucidated. Their pharmacological activities were mainly due to lignans and iridoid glycosides.