Radiological interventions for soft tissue injuries in sport

Injection therapy has played an integral role in the rehabilitation of sports injuries for many years. The athlete's primary goal is a rapid return to sporting activity. This may be achieved by a combination of either a temporary or permanent reduction in pain, and by a pharmacological or physiological effect that promotes or accelerates a healing response. A wide variety of pharmacological agents are used. However, there is often a lack of good evidence that quantifiable effects can be achieved. There are restrictions on the use of some pharmaceutical agents. This article reviews the various pharmacological agents and bioactive substrates that are available, and discusses the current evidence base of their use in common sports injuries.

Participation of brainstem monoaminergic nuclei in behavioral depression

Several lines of research have now suggested the controversial hypothesis that the central noradrenergic system acts to exacerbate depression as opposed to having an antidepressant function. If correct, lesions of this system should increase resistance to depression, which has been partially but weakly supported by previous studies. The present study reexamined this question using two more recent methods to lesion noradrenergic neurons in mice: intraventricular (ivt) administration of either the noradrenergic neurotoxin, DSP4, or of a dopamine-β-hydroxylase-saporin immunotoxin (DBH-SAP ITX) prepared for mice. Both agents given 2 weeks prior were found to significantly increase resistance to depressive behavior in several tests including acute and repeated forced swims, tail suspension and endotoxin-induced anhedonia. Both agents also increased locomotor activity in the open field. Cell counts of brainstem monoaminergic neurons, however, showed that both methods produced only partial lesions of the locus coeruleus and also affected the dorsal raphe or ventral tegmental area. Both the cell damage and the antidepressant and hyperactive effects of ivt DSP4 were prevented by a prior i.p. injection of the NE uptake blocker, reboxetine. The results are seen to be consistent with recent pharmacological experiments showing that noradrenergic and serotonergic systems function to inhibit active behavior. Comparison with previous studies utilizing more complete and selective LC lesions suggest that mouse strain, lesion size or involvement of multiple neuronal systems are critical variables in the behavioral and affective effects of monoaminergic lesions and that antidepressant effects and hyperactivity may be more likely to occur if lesions are partial and/or involve multiple monoaminergic systems.

Decreased immobility in swimming test by homologous interferon-alpha in mice accompanied with increased cerebral tryptophan level and serotonin turnover

Animal models are used to decipher the pathophysiology of IFN-alpha-induced psychiatric complications in humans. However, the behavioral effects of IFN-alpha in rodents remain highly controversial. In contrast to homologous IFN-alpha, our recent study revealed that human IFN-alpha, which was used in many previous investigations, had no biological activity in mice. To evaluate the behavioral effects of homologous IFN-alpha in mice, adult C57BL/6J mice were treated with carrier-free murine IFN-alpha and tested on a number of behavioral paradigms. Surprisingly, contrary to previous reports, IFN-alpha treatment decreased the time spent immobile in the forced-swimming test after a single intraperitoneal injection at 2 x 10(6)IU/kg, whereas general locomotor activity was not altered. The elevated plus-maze (EPM) test showed a trend toward an increased anxiety profile in IFN-alpha-treated mice. The tail-suspension and light dark exploration test revealed no difference between IFN-alpha-treated and control animals. Interestingly, neurochemical analysis revealed significantly increased concentrations of tryptophan and 5-hydroxyindoleacetic acid (5-HIAA)/serotonin (5-HT) ratios following IFN-alpha treatment in selected brain regions. Thus, systemic murine IFN-alpha treatment increases swimming time in mice. Increased cerebral serotonin turnover as well as increased tryptophan concentrations, induced by IFN-alpha, implicates serotonergic neurotransmission in behavioral dysfunction caused by this innate immune mediator.

Possible dopaminergic stimulation of locus coeruleus alpha1-adrenoceptors involved in behavioral activation

alpha(1)-Adrenoceptors of the locus coeruleus (LC) have been implicated in behavioral activation in novel surroundings, but the endogenous agonist that activates these receptors has not been established. In addition to the canonical activation of alpha(1)-receptors by norepinephrine (NE), there is evidence that dopamine (DA) may also activate certain brain alpha(1)-receptors. This study examined the contribution of DA to exploratory activity in a novel cage by determining the effect of infusion of various dopaminergic and adrenergic drugs into the mouse LC. It was found that the D2/D3 agonist, quinpirole, which selectively blocks the release of CNS DA, produced a dose-dependent and virtually complete abolition of exploration and all movement in the novel cage test. The quinpirole-induced inactivity was significantly attenuated by coinfusion of DA but not by the D1 agonist, SKF38390. Furthermore, the DA attenuation of quinpirole inactivity was blocked by coinfusion of the alpha(1)-adrenergic receptor antagonist, terazosin, but not by the D1 receptor antagonist, SCH23390. LC infusions of either quinpirole or terazosin also produced profound inactivity in DA-beta-hydroxylase knockout (Dbh -/-) mice that lack NE, indicating that their behavioral effects were not due to an alteration of the release or action of LC NE. Measurement of endogenous DA, NE, and 5HT and their metabolites in the LC during exposure to the novel cage indicated an increase in the turnover of DA and NE but not 5HT. These results indicate that DA is a candidate as an endogenous agonist for behaviorally activating LC alpha(1)-receptors and may play a role in the activation of this nucleus by novel surroundings.

The role of corticotropin-releasing factor and noradrenaline in stress-related responses, and the inter-relationships between the two systems

Substantial evidence indicates that brain neurons containing and secreting noradrenaline and corticotropin-releasing factor (CRF) are activated during stress, and that physiological and behavioural responses observed during stress can be induced by exogenous administration of CRF and adrenoceptor agonists. This review focusses on the evidence for the involvement of these two factors in stress-related responses, and the inter-relationships between them. The possible abnormalities of these two systems in depressive illness are also discussed.

Effects of chronic and acute stressors and CRF on depression-like behavior in mice

The effects of chronic footshock (CFS) on behavioral responses of CD1 mice to acute footshock and restraint were studied in tests commonly used to assess antidepressant treatments. Adult male mice were subjected to 20 min of footshock daily for 14-16 days, and then tested in the tail suspension test (TST) and the forced swim test (FST). CFS treatment did not alter immobility in the TST when mice were tested before the footshock on that day. However, when the TST was performed after the footshock, immobility decreased in both control and CFS mice. In the FST, chronic footshock significantly increased the time spent floating when mice were tested before footshock on that day. However, when the FST was performed immediately after the footshock, floating decreased in the CFS mice, but not in previously unshocked mice. Restraint, shortly before the FST, decreased floating in both CFS and unshocked mice. Thus, CFS induced depression-like activity in the FST, but not in the TST, whereas acute footshock or restraint immediately before testing induced antidepressant-like effects in both the TST and the FST. In unshocked mice, intracerebroventricular corticotropin-releasing factor (CRF) consistently decreased immobility in the TST and the FST, with significant effects at the 100ng dose. The same dose of CRF depressed activity in the open field, so that these changes in immobility are unlikely to reflect a change in overall activity. CRF thus mimicked the effects of the acute stressors in the TST and the FST. Responses to icv CRF were attenuated by chronic footshock suggesting that CFS desensitizes the brain to CRF. CFS treatment did not alter basal concentrations of ACTH and corticosterone in blood plasma. Acute footshock increased the plasma concentrations of the hormones but in CFS mice these responses were attenuated, significantly for plasma ACTH. Acute footshock activated brain dopamine, norepinephrine and serotonin metabolism, and increased tryptophan concentrations in the brain. In CFS mice, these responses were attenuated, significantly for hypothalamic NE.

Infection as a stressor: a cytokine-mediated activation of the hypothalamo-pituitary-adrenal axis?

Infections are associated with increased plasma concentrations of adrenocorticotropic hormone (ACTH) and corticosterone. Hypothalamo-pituitary-adrenal (HPA) responses have also been observed with immunological stimuli that are not infective. Although such responses have been suggested to be mediated by ACTH secreted by lymphocytes, adrenocortical activation by immunological stimuli requires a functional pituitary. The most likely mechanism by which immunological stimuli activate the HPA axis involves production of cytokines by lymphocytes. The prime candidate is interleukin 1 (IL-1), because IL-1 production follows activation of the immune system and IL-1 administration is a potent activator of the HPA axis. However, other cytokines, such as tumour necrosis factor, may also be involved. Most immunological stimuli and IL-1 also activate both peripheral and central noradrenergic neurons. IL-1-induced activation of the HPA axis in vivo depends upon secretion of corticotropin-releasing factor (CRF), an intact pituitary, and the ventral noradrenergic bundle which innervates the CRF-containing neurons in the paraventricular nucleus (PVN) of the hypothalamus. Besides elevating body temperature, administration of IL-1 elicits a number of behavioural responses in rats and mice, including anorexia, increased sleep time, decreased investigation of novel objects and other animals, increased defensive withdrawal and other behaviours characteristic of sickness. Some of these responses can be reversed by CRF-antagonists and mimicked by CRF administration. Thus, endogenous production of IL-1 can account for a range of physiological and behavioural responses characteristic of sickness. Nevertheless, definitive evidence that IL-1 mediates these responses in sick animals is lacking.

Effects of chronic footshock, restraint and corticotropin-releasing factor on freezing, ultrasonic vocalization and forced swim behavior in rats

The effects of chronic footshock (CFS) or chronic restraint (CRS) on the behavioral responses to acute footshock and corticotropin-releasing factor (CRF) were studied. Male rats were subjected to either footshock or restraint daily, or left undisturbed (Quiet). After 7 or 14 days treatment, they were placed in an unfamiliar footshock chamber and three footshocks administered at 20s intervals and subsequent freezing and ultrasonic vocalizations (USV's) were recorded. Context-conditioned freezing and USV's were recorded when rats were replaced in the chamber in which they had received the three footshocks. Prior CFS treatment decreased acute footshock-induced freezing and USV's, whereas it increased conditioned freezing and slightly increased conditioned USV's. CRS did not affect footshock-induced freezing, but in contrast to CFS, strongly increased USV's. Intracerebroventricular CRF (30 or 100ng) alone did not elicit freezing in either Quiet or CFS rats, nor did it have any effect on shock-induced freezing in either group. However, CRF increased conditioned freezing in Quiet, but not in CFS rats. CRF alone did not trigger USV's, but slightly increased shock-induced USV's in both Quiet and CFS rats, and significantly increased conditioned USV's in CFS rats. In the forced swim test (FST), chronic footshock did not induce consistent effects, although there was a trend to increased immobility. However, CRF increased immobility. In striking contrast to CFS, chronic restraint consistently decreased immobility. It is concluded that chronic stress has lasting effects on defensive responses. However, not all chronic stress procedures exert the same effects and thus different forms of stress may activate different neural mechanisms. The fact that CFS diminished shock-induced freezing and the effects of CRF on conditioned freezing suggests that CFS desensitizes the brain to CRF. On the other hand, the enhancement of conditioned freezing by CFS, and of conditioned USV's by CRF in CFS rats, indicates more complex effects.

Effects of interleukin-1beta and lipopolysaccharide on behavior of mice in the elevated plus-maze and open field tests

It has been postulated that infections, inflammatory processes and resulting cytokines may be causative factors in emotional disorders, including depression and anxiety. Support for this possibility has been sought in studies of animal behavior following administration of interleukin-1 (IL-1) and lipopolysaccharide (LPS). However, such treatments induce a variety of behavioral responses, collectively known as sickness behavior, some of which could affect the performance in tests used to assess anxiety and depression. Thus the effects of peripheral administration of IL-1beta and LPS on the behavior of mice were studied in the elevated plus-maze (EPM) and the open field (OF). Mouse IL-1beta (30, 100, 300, and 1000 ng) was injected intraperitoneally 30 or 60 min, and LPS (0.5, 1 and 5 microg) 120 min before the tests. IL-1beta and LPS induced dose-dependent decreases in open arm entries and the time spent on the open arms in the EPM, effects considered to reflect anxiety-like behavior. However, entries to all arms were also reduced in a dose-dependent manner, indicating a decrease in general activity. In the OF, IL-1beta and LPS decreased the number of line crossings in the center of the field, that can also be considered to reflect anxiety-like behavior. However, this effect was accompanied by a similar decrease in line crossings in the periphery, as well as in rears and climbs. Thus the doses of IL-1beta and LPS necessary to induce these effects also decreased locomotor activity in the EPM and OF. Therefore, the behavioral responses induced by IL-1beta and LPS in the EPM and the OF considered to reflect anxiety must be interpreted in the light of this reduction in overall activity. Thus the results do not provide unequivocal support for the suggestion that LPS or IL-1 mediate anxiety. Nevertheless, because infections, endotoxins, and the ensuing cytokines cause alterations in CNS norepinephrine and serotonin, they may contribute to emotionality, and perhaps to anxiety.

The roles of corticotropin-releasing factor-related peptides and their receptors in the cardiovascular system

Corticotropin-releasing factor (CRF), CRF-related peptides and their receptors are present in the central nervous system and in peripheral tissues including the immune, reproductive and cardiovascular systems. CRF and urocortin (urocortin 1) bind to the CRF receptor type 1 (CRF(1) receptor) and the CRF receptor type 2 (CRF(2) receptor), whereas urocortin 2 (formerly known as stresscopin related peptide) and urocortin 3 (formerly known as stresscopin) bind with high affinity to the CRF(2) receptor. Recent studies show that urocortin 1, urocortin 2 and urocortin 3 are potent regulators of cardiovascular function. This review highlights the role of cardiovascular CRF and related peptides and its relevance in mediating the adaptive response of the cardiovascular system to stressful conditions.

Relationships among the behavioral, noradrenergic, and pituitary-adrenal responses to interleukin-1 and the effects of indomethacin

Peripheral administration of interleukin-1 (IL-1) is known to activate the hypothalamo-pituitary-adrenal axis (HPA axis) and brain noradrenergic systems. We studied the relationship between these responses using in vivo microdialysis to assess the release of hypothalamic norepinephrine (NE), while simultaneously sampling blood for ACTH and corticosterone, and monitoring body temperature and behavior in freely moving rats. Rats were implanted with microdialysis probes in the medial hypothalamus, with intravenous catheters, and with telethermometers in the abdomen. Each rat was injected with saline and IL-1beta (1 microg ip) in random order, monitoring microdialysate NE, body temperature and plasma ACTH and corticosterone for 2-4 h after injection. Saline injections were followed by transient increases in microdialysate NE and in plasma ACTH and corticosterone. IL-1beta injections resulted in prolonged elevations of microdialysate NE, as well as plasma ACTH and corticosterone, and body temperature. IL-1beta also induced shivering and a prolonged depression of locomotor activity. Pretreatment with indomethacin (10 mg/kg sc) prevented the IL-1beta-induced increases in body temperature and the apparent increase in hypothalamic NE release, but only attenuated the IL-1beta-induced shivering and the increase in plasma ACTH. The results indicate a close temporal relationship between the release of NE and HPA axis activation. Such a relationship is also supported by the similar effects of indomethacin pretreatment on NE and ACTH. The shivering is likely involved in the increase in body temperature, but indomethacin only attenuated the shivering while it blocked the fever. However, the effects of indomethacin clearly indicate that neither the increase in body temperature nor the increase in hypothalamic NE release was essential for HPA axis activation. These results suggest that hypothalamic NE is involved in the IL-1-induced HPA axis activation, but that this is not the only mechanism by which the HPA axis is activated by intraperitoneally injected IL-1.

Effects of cytokines and infections on brain neurochemistry

Administration of cytokines to animals can elicit many effects on the brain, particularly neuroendocrine and behavioral effects. Cytokine administration also alters neurotransmission, which may underlie these effects. The most well studied effect is the activation of the hypothalamo-pituitary-adrenocortical (HPA) axis, especially that by interleukin-1 (IL-1). Peripheral and central administration of IL-1 also induces norepinephrine (NE) release in the brain, most markedly in the hypothalamus. Small changes in brain dopamine (DA) are occasionally observed, but these effects are not regionally selective. IL-1 also increases brain concentrations of tryptophan, and the metabolism of serotonin (5-HT) throughout the brain in a regionally nonselective manner. Increases of tryptophan and 5-HT, but not NE, are also elicited by IL-6, which also activates the HPA axis, although it is much less potent in these respects than IL-1. IL-2 has modest effects on DA, NE and 5-HT. Like IL-6, tumor necrosis factor-α (TNFα) activates the HPA axis, but affects NE and tryptophan only at high doses. The interferons (IFN's) induce fever and HPA axis activation in man, but such effects are weak or absent in rodents. The reported effects of IFN's on brain catecholamines and serotonin have been very varied. However, interferon-γ, and to a lesser extent, interferon-α, have profound effects on the catabolism of tryptophan, effectively reducing its concentration in plasma, and may thus limit brain 5-HT synthesis.Administration of endotoxin (LPS) elicits responses similar to those of IL-1. Bacterial and viral infections induce HPA activation, and also increase brain NE and 5-HT metabolism and brain tryptophan. Typically, there is also behavioral depression. These effects are strikingly similar to those of IL-1, suggesting that IL-1 secretion, which accompanies many infections, may mediate these responses. Studies with IL-1 antagonists, support this possibility, although in most cases the antagonism is incomplete, suggesting the existence of multiple mechanisms. Because LPS is known to stimulate the secretion of IL-1, IL-6 and TNFα, it seems likely that these cytokines mediate at least some of the responses, but studies with antagonists indicate that there are multiple mechanisms. The neurochemical responses to cytokines are likely to underlie the endocrine and behavioral responses. The NE response to IL-1 appears to be instrumental in the HPA activation, but other mechanisms exist. Neither the noradrenergic nor the serotonergic systems appear to be involved in the major behavioral responses. The significance of the serotonin response is unknown.

Effect of subdiaphragmatic vagotomy on the noradrenergic and HPA axis activation induced by intraperitoneal interleukin-1 administration in rats

The vagus nerve is thought to participate in signal transduction from the immune system to the CNS. The role of the vagus in the physiological, behavioral and neurochemical responses to intraperitoneally (ip) injected interleukin-1beta (IL-1beta) was studied using awake subdiaphragmatically vagotomized rats. The rats were injected ip with saline and IL-1beta (1 microg/rat) in random order. For the next 2-4 h, they were monitored for locomotor activity, body temperature via abdominally implanted telethermometers, hypothalamic norepinephrine (NE) secretion using in vivo microdialysis and blood sampled via intravenous catheters to determine concentrations of ACTH and corticosterone to assess hypothalamo-pituitary-adrenocortical (HPA) axis activation. Saline injections were followed by transient increases in locomotor activity, body temperature, dialysate NE and plasma concentrations of ACTH and corticosterone. These responses were not significantly altered by vagotomy. IL-1beta injections resulted in short-lived increases in shivering and longer decreases in locomotor activity, as well as a delayed modest fever. IL-1beta also induced prolonged elevations of hypothalamic microdialysate NE, as well as plasma ACTH and corticosterone. Similar responses were observed regardless of the order of the saline and IL-1beta injections. Subdiaphragmatic vagotomy prevented the IL-1-induced increases in body temperature and the increase in dialysate NE, and markedly attenuated the increases in plasma ACTH and corticosterone. The results indicate close temporal relationships between the apparent release of NE and the increase in body temperature and the HPA activation. This together with the effects of vagotomy suggests that the activation of NE in turn increases body temperature and activates the HPA axis. However, because IL-1beta induces a limited HPA activation in subdiaphragmatically vagotomized rats, the vagus nerve does not appear to be the only route by which ip IL-1beta can activate the HPA axis. It is suggested that IL-1beta-induced vagal activation of hypothalamic NE is the major mechanism of HPA activation at low doses of IL-1beta. However, IL-1beta can also exert direct effects on IL-1 receptors on cerebral blood vessels, activating cyclooxygenases and hence synthesis of prostaglandins which in turn can affect body temperature, behavior and HPA axis activation.

Feeding, exploratory, anxiety- and depression-related behaviors are not altered in interleukin-6-deficient male mice

Interleukin-6 (IL-6) has been implicated in behavioral responses associated with inflammation, sickness behavior and various nervous system disorders. We studied a range of different behaviors in IL-6-knockout (IL-6ko) and wild-type (WT) male mice. No significant differences were observed in ambulatory, exploratory, and stereotypic activities in home or novel cages, in an open field (OF), in the multicompartment chamber (MCC), or in the elevated plus-maze (EPM). IL-6ko mice shed fewer fecal boli than WT mice in the OF, in novel cages and in the MCC although this effect was not statistically significant in the OF. In novel cages, intraperitoneal (i.p.) injection of IL-6 (1 microg) depressed ambulatory activity slightly more in IL-6ko than in WT mice. Restraint and interleukin-1beta (IL-1beta, 100 ng i.p.) decreased exploration of mice in the MCC and EPM, but there was no indication of altered sensitivity in IL-6ko mice. No significant differences were detected in the tail suspension and the Porsolt forced swim tests. IL-1beta and lipopolysaccharide (LPS 1 microg i.p.) injection depressed sweetened milk and solid food intake similarly in IL-6ko and WT mice, but IL-6 had no effect, suggesting that IL-6 is not involved in these effects of IL-1 or LPS. However, IL-1beta and LPS depressed body weight more in WT than in IL-6ko mice. Plasma corticosterone and basal concentrations of catecholamines, indoleamines and their metabolites in several brain regions were similar. The responses in these measures to IL-1beta and LPS were also similar, except that there were no significant changes in tryptophan and serotonin metabolism in IL-6ko mice. This may reflect a role for IL-6 in the tryptophan and serotonin responses to IL-1 and LPS. It is concluded that the lack of IL-6 is not associated with substantial alterations in several different mouse behaviors, and in the responses to restraint, IL-1beta, IL-6 and LPS.

Physiological and behavioral responses to interleukin-1beta and LPS in vagotomized mice

It is well established that peripheral administration of interleukin-1 (IL-1) and lipopolysaccharide (LPS) can activate the hypothalamo-pituitary-adrenocortical (HPA) axis, alter brain catecholamine and indoleamine metabolism, and affect behavior. However, the mechanisms of these effects are not fully understood. Stimulation of afferents of the vagus nerve has been implicated in the induction of Fos in the brain, changes in body temperature, brain norepinephrine, and some behavioral responses. In the present study, the IL-1beta- and LPS-induced changes in certain behaviors, HPA axis activation, and catecholamine and indoleamine metabolism were studied in mice following subdiaphragmatic vagotomy. IL-1beta and LPS induced the expected decreases in sweetened milk, food intake, and locomotor activity, and the responses to IL-1beta, but not LPS, were slightly attenuated in vagotomized mice. Subdiaphragmatic vagotomy also attenuated the IL-1beta- and LPS-induced increases in plasma ACTH and corticosterone, but the attenuations of the responses to IL-1beta were only marginally significant. There were also slight reductions in the responses in catecholamine and serotonin metabolism, and the increases in brain tryptophan in several brain regions. These results indicate that the vagus nerve is not the major pathway by which abdominal IL-1beta and LPS effect behavioral, HPA and brain catecholamine and indoleamine responses in the mouse. These results resemble those we observed in subdiaphragmatically vagotomized rats, but in that species the subdiaphragmatic vagotomy markedly attenuated the ACTH and corticosterone responses, and prevented the hypothalamic noradrenergic activation, as well as the fever. Overall the results indicate that the various responses to peripheral IL-1 and LPS involve multiple mechanisms including vagal afferents, and that there are species differences in the relative importance of the various mechanisms.

Reduced ingestion of sweetened milk induced by interleukin-1 and lipopolysaccharide is associated with induction of cyclooxygenase-2 in brain endothelia

Previous studies have shown that interleukin-1 (IL-1) and lipopolysaccharide (LPS) administration to animals induces behavioral changes, including a reduction in feeding. These effects of IL-1 and LPS have been shown to be sensitive to inhibitors of cyclooxygenase (COX).

OBJECTIVES

To determine the relationships between induction of COX-2 in the brain with IL-1beta- and LPS-induced changes in body temperature, plasma corticosterone and feeding.

METHODS

Mice were injected with intraperitoneal doses of IL-1beta and LPS that decreased feeding. The induction of COX-2 was studied immunocytochemically in the brain, in parallel with core body temperature, the drinking of sweetened milk, and plasma concentrations of corticosterone.

RESULTS

COX-2 immunoreactivity (ir) was sparse in the brains of the untreated mice, but IL-1beta and LPS both increased its expression. This COX-2 induction appeared to be confined to blood vessels, and was not markedly region specific. Induction was evident 30 min after IL-1 or LPS, and was greater at 90 than at 30 min. COX-2-ir in the parenchyma did not change significantly. Thus induction of COX-2 occurred in brain endothelia in parallel with the reduction in feeding. This is consistent with the previously determined sensitivity of IL-1-induced changes in feeding to selective COX-2 inhibitors, and the responses to IL-1 in COX-2-deficient mice. The time courses of the IL-1- and LPS-induced increases in plasma corticosterone paralleled those in the reduction in milk drinking, however, the changes in body temperature appeared later.

CONCLUSIONS

Endothelial COX-2 may be involved in IL-1- and LPS-induced decreases in milk drinking, and possibly in the HPA axis activation. The decreased milk drinking may occur when IL-1 and LPS bind to receptors on brain endothelial cells subsequently inducing COX-2 and the production of prostanoids which elicit the reductions in milk drinking. Thus the behavioral effects of peripherally administered IL-1 and LPS appear to be mediated by multiple mechanisms, including endothelial COX-2, and vagal afferents.

Mechanisms and Significance of the Increased Brain Uptake of Tryptophan

Changes in brain tryptophan concentrations may affect the synthesis of brain serotonin (5-hydroxytryptamine, 5-HT). Concentrations of tryptophan are regulated more than those of any other amino acid. Such stimuli as acute stress, carbohydrate ingestion, and treatment with various drugs increase the brain content of tryptophan. Treatment of rats and mice with interleukin-1 (IL-1), interleukin-6 (IL-6), lipopolysaccharide (LPS), and beta-adrenoceptor agonists, as well as a variety of stressors, such as footshock and restraint, all increase brain concentrations of tryptophan. The peak effect following both acute stress and beta-adrenoceptor agonist administration occurs within 30-60 min, whereas the peak effect following LPS and the cytokines occurs much later at around 4-8 h. Experiments using the ganglionic blocker chlorisondamine, and beta-adrenoceptor antagonists suggest that the sympathetic nervous system plays an important role in the modulation of brain tryptophan concentrations. The mechanisms involved in the increases observed in brain tryptophan are discussed, as well as their possible biological significance.

Effects of interleukin-1 and endotoxin in the forced swim and tail suspension tests in mice

Male CD-1 mice were administered interleukin-1beta (IL-1beta) and bacterial endotoxin (lipopolysaccharide, LPS) and subsequently tested in the tail suspension test (TST), the Porsolt forced swim test (FST), and in the open field. IL-1beta (100, 300 and 1000 ng/mouse) injected intraperitoneally (i.p.) 90 min before the test induced a dose-dependent increase in the time spent immobile in the TST and the time spent floating in the FST. These responses were statistically significant only at the higher doses of IL-1beta (300 and 1000 ng). Nevertheless, all three doses of IL-1beta significantly decreased line crossings and rears in the open field and depressed food intake and body weight. Very similar effects were induced by LPS. Doses of 1 and 5 mug i.p. increased immobility time in the TST and floating time in the FST, but the same doses strongly depressed locomotor activity and body weight. These results indicate that both IL-1beta and LPS can induce depression-like effects in the TST and the FST. However, the doses necessary to induce these changes reduced feeding and activity in an open field, so that the effects observed in the FST and TST could be attributed to a general reduction in locomotor activity. Thus the results obtained in these two animal tests commonly used to test antidepressant properties do not provide strong support for an IL-1 hypothesis of depression.

Cytokines as mediators of depression: what can we learn from animal studies?

It has recently been postulated that cytokines may cause depressive illness in man. This hypothesis is based on the following observations: 1. Treatment of patients with cytokines can produce symptoms of depression; 2. Activation of the immune system is observed in many depressed patients; 3. Depression occurs more frequently in those with medical disorders associated with immune dysfunction; 4. Activation of the immune system, and administration of endotoxin (LPS) or interleukin-1 (IL-1) to animals induces sickness behavior, which resembles depression, and chronic treatment with antidepressants has been shown to inhibit sickness behavior induced by LPS; 5. Several cytokines can activate the hypothalamo-pituitary-adrenocortical axis (HPAA), which is commonly activated in depressed patients; 6. Some cytokines activates cerebral noradrenergic systems, also commonly observed in depressed patients; 7. Some cytokines activate brain serotonergic systems, which have been implicated in major depressive illness and its treatment. The evidence for each of these tenets is reviewed and evaluated along with the effects of cytokines in classical animal tests of depression. Although certain sickness behaviors resemble the symptoms of depression, they are not identical and each has distinct features. Thus the value of sickness behavior as an animal model of major depressive disorder is limited, so that care should be taken in extrapolating results from the model to the human disorder. Nevertheless, the model may provide insight into the etiology and the mechanisms underlying some symptoms of major depressive disorder. It is concluded that immune activation and cytokines may be involved in depressive symptoms in some patients. However, cytokines do not appear to be essential mediators of depressive illness.

Fast 1H-13C correlation data for use in automatic structure confirmation of small organic compounds

A method of speeding up the acquisition of 1H-13C correlation data has been developed. It is applicable in situations where the experiment time is determined by the need to sample the second dimension adequately rather than by signal-to-noise ratio requirements. Two spectra with different, reduced, 13C sweep widths are measured, time being saved by reducing the number of increments in line with the reduction in the sweep width. Rules are presented for the selection of the two reduced sweep widths so that the correct 13C chemical shifts can be easily and unambiguously calculated. The benefits and limitations of this approach, in the context of the structure confirmation of small (MW < or = 450) organic compounds, is discussed. The use of a third spectrum to resolve problems that may be encountered when proton signals overlap is demonstrated.

Potential role for nonesterified fatty acids in β-adrenoceptor-induced increases in brain tryptophan

We tested the hypothesis that beta2- and beta3-adrenergic receptor-mediated increases in brain tryptophan are due to the liberation of fatty acids, which in turn displace tryptophan from its albumin-binding site and thus facilitate its entry into the brain. Male CD-1 mice were injected with subtype-selective beta-adrenergic agonists 1h before brain samples were collected for analysis of tryptophan content by HPLC with electrochemical detection, and blood samples were collected for analysis of total and free tryptophan and nonesterified fatty acid (NEFA) concentrations. The beta2-selective agonist, clenbuterol (0.1 mg/kg), increased concentrations of tryptophan in all brain regions studied and decreased plasma total tryptophan, but had no effect on plasma free tryptophan or NEFAs. The beta3-selective agonists, BRL 37344 (0.2 mg/kg) or CL 316243 (0.01 mg/kg), increased brain tryptophan, plasma NEFAs and free tryptophan. Pretreatment with nicotinic acid (500 mg/kg), an inhibitor of lipolysis, almost completely prevented the increase in plasma free tryptophan and NEFAs, and attenuated the increase in brain tryptophan induced by CL 316243. These results suggest that beta2- and beta3-adrenergic agonists increase brain tryptophan by a mechanism other than the liberation of NEFAs. Nonetheless, beta3-adrenergic agonists appear to increase brain tryptophan by a mechanism that may depend partially on elevations of plasma NEFAs.

Increased insulin is not required for β2-adrenoceptor-induced increases in mouse brain tryptophan

The current study tested the hypothesis that beta(2)-adrenoceptor-mediated increases in brain tryptophan are caused by increased insulin secretion. Male mice were treated with streptozotocin (40 mg/kg) for 5 days to induce experimental diabetes. Control and diabetic mice were treated with the beta(2)-adrenoceptor agonist, clenbuterol (0.1 mg/kg), 1 h before selected brain regions were dissected for analysis by high performance liquid chromatography (HPLC) with electrochemical detection for tryptophan content, and plasma was collected for analysis of total and free tryptophan and glucose concentrations. Clenbuterol increased brain tryptophan and plasma glucose and decreased plasma total tryptophan but did not alter plasma free tryptophan. There were no significant differences in brain or plasma tryptophan between control and streptozotocin-treated mice. In a separate experiment, pretreatment of the mice with an insulin antibody did not prevent the clenbuterol-induced increases in brain tryptophan. These results suggest that beta(2)-adrenoceptor agonists increase brain tryptophan by a mechanism that does not involve changes in insulin.

Brain Circuits Involved in Corticotropin-Releasing Factor-Norepinephrine Interactions during Stress

Corticotropin-releasing factor (CRF)- and norepinephrine (NE)-containing neurons in the brain are activated during stress, and both have been implicated in the behavioral responses. NE neurons in the brain stem can stimulate CRF neurons in the hypothalamic paraventricular nucleus (PVN) to activate the hypothalamic-pituitary-adrenocortical axis and may affect other CRF neurons. CRF-containing neurons in the PVN, the amygdala, and other brain areas project to the area of the locus coeruleus (LC), and CRF injected into the LC alters the electrophysiologic activity of LC-NE neurons. Neurochemical studies have indicated that CRF applied intracerebroventricularly or locally activates the LC-NE system, and microdialysis and chronoamperometric measurements indicate increased NE release in LC-NE terminal fields. However, chronoamperometric studies indicated a significant delay in the increase in NE release, suggesting that the CRF input to LC-NE neurons is indirect. The reciprocal interactions between cerebral NE and CRF systems have been proposed to create a "feed-forward" loop. It has been postulated that a sensitization of such a feed-forward loop may underlie clinical depression. However, in the majority of studies, repeated or chronic stress has been shown to decrease the behavioral and the neurochemical responsivity to acute stressors. Repeated stress also seems to decrease the responsivity of LC neurons to CRF. These results do not provide support for a feed-forward hypothesis. However, a few studies using certain tasks have indicated sensitization, and some other studies have suggested that the effect of CRF may be dose dependent. Further investigations are necessary to establish the validity or otherwise of the feed-forward hypothesis.

A cytokine-based neuroimmunologic mechanism of cancer-related symptoms

While many of the multiple symptoms that cancer patients have are due to the disease, it is increasingly recognized that pain, fatigue, sleep disturbance, cognitive dysfunction and affective symptoms are treatment related, and may lead to treatment delays or premature treatment termination. This symptom burden, a subjective counterpart of tumor burden, causes significant distress. Progress in understanding the mechanisms that underlie these symptoms may lead to new therapies for symptom control. Recently, some of these symptoms have been related to the actions of certain cytokines that produce a constellation of symptoms and behavioral signs when given exogenously to both humans and animals. The cytokine-induced sickness behavior that occurs in animals after the administration of infectious or inflammatory agents or certain proinflammatory cytokines has much in common with the symptoms experienced by cancer patients. Accordingly, we propose that cancer-related symptom clusters share common cytokine-based neuroimmunologic mechanisms. In this review, we provide evidence from clinical and animal studies that correlate the altered cytokine profile with cancer-related symptoms. We also propose that the expression of coexisting symptoms is linked to the deregulated activity of nuclear factor-kappa B, the transcription factor responsible for the production of cytokines and mediators of the inflammatory responses due to cancer and/or cancer treatment. These concepts open exciting new avenues for translational research in the pathophysiology and treatment of cancer-related symptoms.

Are the symptoms of cancer and cancer treatment due to a shared biologic mechanism? A cytokine-immunologic model of cancer symptoms

BACKGROUND

Cancers and cancer treatments produce multiple symptoms that collectively cause a symptom burden for patients. These symptoms include pain, wasting, fatigue, cognitive impairment, anxiety, and depression, many of which co-occur. There is growing recognition that at least some of these symptoms may share common biologic mechanisms.

METHODS

In November 2001, basic and clinical scientists met to consider evidence for a cytokine-immunologic model of symptom expression along with directions for future research.

RESULTS

The characteristics of cytokine-induced sickness behavior in animal models have much in common with those of symptomatic cancer patients. Sickness behavior refers to a set of physiologic and behavioral responses observed in animals after the administration of infectious or inflammatory agents or certain proinflammatory cytokines. In some cases, these responses can be prevented by cytokine antagonists. A combination of animal and human research suggests that several cancer-related symptoms may involve the actions of proinflammatory cytokines.

CONCLUSIONS

Based on the similarities between cancer symptoms and sickness behavior, the authors discussed approaches to further test the implications of the relationship between inflammatory cytokines and symptoms for both symptom treatment and symptom prevention.

Activation of beta2- and beta3-adrenergic receptors increases brain tryptophan

Brain tryptophan concentrations are increased by various stressful treatments, an effect that can be prevented by beta-adrenoceptor antagonists. This study aimed to determine the beta-adrenergic subtype responsible for the tryptophan response. Male CD-1 mice received intraperitoneal injections of nonselective and subtype-selective beta-adrenergic antagonists 20 min before subtype-selective beta-agonists. Selected brain regions were dissected for analysis of tryptophan content by high-performance liquid chromatography with electrochemical detection. The beta(2)-selective agonist clenbuterol (0.3 mg/kg) induced increases in brain tryptophan that reached a peak ( approximately 60%) 1 h following injection and small but statistically significant increases ( approximately 20%) in 5-hydroxyindoleacetic acid: serotonin ratios 2 h following injection. The beta(1)-selective agonist dobutamine (10 mg/kg) produced less robust increases ( approximately 40%) in brain tryptophan, whereas the beta(3)-selective agonists BRL 37344 (0.2 mg/kg (+/-)-(R*,R*)-[4-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]amino)propyl] phenoxy]acetic acid sodium)) and CL 316243 [0.1 mg/kg disodium 5-[(2R)-2-([(2R)-2-(3-chlorophenyl)-2-hydroxyethyl]amino)propyl]-1,3-benzodioxole-2,2-dicarboxylate)] resulted in larger increases (80 to 100%). Pretreatment with the beta(2)-selective antagonist ICI 118551 (0.5 mg/kg (+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxyl]-3-[(1-methylethyl)amino]-2-butanol) attenuated the increases in tryptophan induced by both clenbuterol (0.1 mg/kg) and dobutamine (10 mg/kg). Pretreatment with the beta(1/2)-selective antagonist propranolol (2.5 mg/kg), the beta(3)-selective antagonist SR 59230A [1.5, 2.5, 5, or 20 mg/kg (3-(2-ethylphenoxy)-1[1S)-1,2,3,4-tertahydronaphth-1-yl-amino]-(2S)-2-propanol oxalate)], or ICI 118551 (0.5 mg/kg) did not prevent the BRL 37344-induced increase in brain tryptophan, whereas the beta(1/2/3)-antagonist bupranolol (10 mg/kg) attenuated it. CL 316243 had no effect on brain tryptophan in beta(3)-receptor knockout mice, whereas clenbuterol increased brain tryptophan, indicating that beta-adrenergic modulation of brain tryptophan occurs in the absence of beta(3)-receptors. We conclude that activation of either beta(2)- or beta(3)-adrenergic receptors, but not beta(1)-adrenergic receptors, increases mouse brain tryptophan content.

HPA axis activation and neurochemical responses to bacterial translocation from the gastrointestinal tract

Stress can cause migration of indigenous bacterial flora from the gut to the peritoneum, a phenomenon known as bacterial translocation. Destruction of the cell walls of gram-negative bacteria can result in the production of endotoxin (lipopolysaccharide, LPS), which is the likely cause of sepsis. Exogenously administered LPS can activate the hypothalamo-pituitary-adrenal (HPA) axis as well as brain noradrenergic and indoleaminergic systems. Thus, it is possible that activations of these systems associated with laboratory stressors in rats and mice could be attributed to bacterial translocation and LPS production. To test this hypothesis we conducted experiments on the time course of bacterial translocation in response to restraint in mice, while measuring HPA and neurochemical responses. These experiments failed to show good correlations between the occurrence of bacterial translocation and HPA and neurochemical activations, suggesting that the later responses were not linked to bacterial translocation. This conclusion was supported by the observation of normal neurochemical responses to restraint in germ-free mice. In further experiments, translocation of Salmonella typhimurium, a bacterium that readily translocates in unstressed animals, was associated with HPA activation and noradrenergic and indoleaminergic responses, indicating that bacterial translocation can indeed activate the HPA axis and brain amines. However, the above experiments suggest that this is not the mechanism by which restraint activates these systems.

Hippocampal noradrenergic responses to CRF injected into the locus coeruleus of unanesthetized rats

Intracerebral administration of corticotropin-releasing factor (CRF) activates cerebral noradrenergic neurons. Direct infusion of CRF into the locus coeruleus (LC) increases norepinephrine (NE) release in the cortex and hippocampus as assessed by in vivo microdialysis. In a recent study using in vivo chronoamperometry in anesthetized rats, CRF injected into the LC increased apparent NE release in the hippocampus, but did so after a significant delay, much longer than observed following infusion of glutamate into the same site. Because this delay may have been an artifact of the urethane anesthesia, we developed a method for chronoamperometric recording from the hippocampus of unanesthetized rats. CRF infusion into the LC of such animals induced an increase in the apparent release of hippocampal NE after a mean delay of about 7 min, reached a peak around 16 min after CRF, and dissipated within 30 min. Thus the response closely resembled that previously reported in urethane-anesthetized rats. As in anesthetized rats, glutamate infused into the same site resulted in a much more rapid response (starting within 1 min and with a peak around 7 min). These results suggest that the urethane anesthesia does not substantially alter hippocampal NE release following infusion of CRF into the LC, and that the relatively long delay in the response is not an artifact of the anesthesia. The large differences in the responses to glutamate and CRF suggest that the effects of CRF are not exerted directly on receptors on LC neurons, and more likely reflect indirect actions on other cells in this region.

Distinct roles for cyclooxygenases 1 and 2 in interleukin-1-induced behavioral changes

Interleukin-1 (IL-1) induces hypophagia, which can be reduced by cyclooxygenase (COX) inhibitors. Earlier studies with COX knockout (COXko) mice suggested that COX2 was more important for hypophagia than COX1. However, behavioral responses occur long before COX2 is induced. Hypophagia was assessed in mice by measuring the intake of sweetened milk in a brief period. The intake was reduced within 30 min after intraperitoneal injection of IL-1beta and was depressed for about 2 h. When milk intake was measured 30 to 40 min after IL-1beta, COX1ko mice showed an attenuated response, whereas COX2ko mice responded more like wild-type animals. By contrast, 90 to 120 min after IL-1beta COX1ko mice responded normally, whereas COX2ko mice showed only small responses. The COX2-selective inhibitor, celecoxib, failed to alter the response to IL-1beta 30 min after administration, but low doses antagonized the effects of IL-1beta at 90 to 120 min. The COX1-selective inhibitor, SC560, attenuated both the early and late responses, but a larger effect at 30 min than at 90 min suggested a role for COX1 at the earlier time. These results suggest that shortly after IL-1beta administration, COX1 is the major enzyme involved in the reduction of milk intake, whereas at later times COX2 is more important, paralleling its induction. Celecoxib also attenuated the milk intake response observed 2 h after lipopolysaccharide (LPS), and the reductions of food pellet intake and body weight induced by IL-1beta and LPS in the subsequent 24 h, suggesting that the role of COX2 may be more significant biologically than that of COX1.

Effects of interleukin-1beta on food-maintained behavior in the mouse

The present studies compared the effect of parenteral administration of the proinflammatory cytokine interleukin-1beta (IL-1beta) on food-seeking behavior under various conditions. IL-1beta (100 ng/mouse) decreased home cage consumption of sweetened milk to a greater extent in ad libitum fed mice than in mice that were food-restricted to maintain 85-90% of their free-feeding body weight. When operant responding for milk was maintained under a fixed-ratio 10 response (FR10) schedule of milk delivery, IL-1beta (30-300 ng/mouse) significantly decreased milk-maintained responding in mice fed ad libitum, but not in food-restricted mice. When food-restricted mice were trained under either an FR4 or FR32 response schedule of milk delivery, IL-1beta (100-300 ng/mouse) produced significant decreases in FR32, but not in FR4 responding. When responding was maintained under a progressive-ratio 10 response (PR10) schedule of milk delivery, IL-1beta (30-300 ng/mouse) dose-dependently decreased breaking points. These results indicate that the effects of IL-1beta on food-maintained behavior depend on both the level of motivation (as assessed by food restriction) and on the response cost for the milk (as assessed by ratio requirement). These findings suggest that motivational factors may be capable of attenuating some of the behavioral effects of these agents.

Recombinant pre-pro-Concanavalin A (jack bean) is stable but of low solubility

The cDNA for pre-pro-Concanavalin A (pre-pro-ConA) was cloned into the cytoplasmic expression vector pKK233-2 to give rise to pCONEXP2 which was used to express the lectin precursor. Pre-pro-ConA is stable and is not transposed and ligated to form the mature protein. No signal peptide removal is observed. The solubility of pre-pro-ConA could not be increased by guanidine hydrochloride denaturation/dilution treatment.

A rapid and facile method for the dereplication of purified natural products

A new approach to the use of commercial databases for the dereplication of purified natural products has been developed. This is based on searching a text file that links each structure with its molecular weight and an exact count of the number of methyl, methylene, and methine groups it contains. Analysis of such a text file, constructed from a database containing more than 126,000 natural product structures, revealed that these data, readily measured using MS and NMR spectroscopy, are highly discriminating. The identification of an alkaloid and a sesquiterpene using this new approach is described.

Cyclooxygenase 1 is not essential for hypophagic responses to interleukin-1 and endotoxin in mice

Numerous studies have shown that the effects of interleukin-1 (IL-1) and endotoxin (LPS) on behavior are sensitive to cyclooxygenase (COX) inhibitors. However, neither the location of the COX involved nor the specific isoform, COX1 or COX2, is known. A previous study using selective COX1 and COX2 inhibitors did not provide an unequivocal answer. Therefore, we tested the response of sweetened milk ingestion to IL-1 and LPS in mice in which the COX1 or the COX2 gene was deleted (COX1ko and COX2ko). When IL-1beta was administered 90 min before the milk, COX1ko mice showed responses similar to those of normal mice. In contrast, COX2ko mice exhibited responses considerably less than normal, with some mice showing no response. Indomethacin pretreatment almost prevented the feeding responses to IL-1 in normal and COX1ko mice. The milk intake response to LPS in COX1ko mice was like that of normal mice. The results from COX1ko mice suggest that COX1 is not necessary for the decreased milk intake following IL-1 and LPS. The results from COX2ko mice are consistent with the involvement of COX2 in the IL-1-induced depression of milk intake, but other mechanisms may effect decreases in sweetened milk intake.

The role of CRH in behavioral responses to stress

Corticotropin-releasing hormone (CRH) and urocortin in the central nervous system affect behavior and can enhance behavioral responses to stressors. The action of CRH-related peptides is mediated through multiple receptors that differ markedly in their pharmacological profiles and anatomical distribution. Comparative pharmacology of CRH receptor agonists suggests that CRH, urocortin, sauvagine and urotensin consistently mimic, and CRH receptor antagonists consistently lessen, functional consequences of stressor exposure. Recently, important advances have been made in understanding the CRH system and its role in behavioral responses to stress by the development of specific CRH receptor antagonists, application of antisense oligonucleotides and development of transgenic mice lacking peptides and functional receptors. This review summarizes recent findings with respect to components of the CRH system and their role in stress-induced behavioral responses.

Cytokine activation of the HPA axis

The observation that administration of interleukin-1 (IL-1) to animals activates the hypothalamo-pituitary-adrenocortical (HPA) axis stimulated great interest in the significance and mechanism of this response, and in whether other cytokines have similar activities. Interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF alpha) share HPA-activating activity, although they are less potent and effective than IL-1, whereas IL-2 and interferon alpha(IFN alpha) lack activity. Small increases in body temperature occur in response to IL-1, IL-6 and TNF alpha, but these changes are prevented by inhibitors of cyclooxygenase (COX) and do not appear to be related to the HPA-activation. The rapid HPA-activating effects of IL-1 are impaired by COX inhibitors, but the more prolonged HPA activation associated with intraperitoneal injections is not affected, indicating multiple mechanisms for IL-1-induced HPA activation. The HPA response to IL-6 is not sensitive to COX inhibitors, but that to TNF alpha appears to be. The HPA-activating activity of IL-1 is associated with increases in the apparent release of brain noradrenaline (NA) and serotonin (5-HT), but not dopamine, as well as with increased brain tryptophan. The NA changes, but not these in serotonin metabolism and tryptophan, are prevented by COX inhibitors. IL-6 has effects on serotonin and tryptophan like those of IL-1, but no detected effect on NA. TNF alpha has some effect on NA and tryptophan, but only at relatively high doses. IFN alpha lacks activity on these neurochemicals. Manipulation of noradrenergic, but not serotonergic systems alters the IL-1-induced HPA activation, suggesting the involvement of NA. However, brain NA does not appear to be essential for HPA activation in mice.

Peripheral interleukin-6 administration increases extracellular concentrations of serotonin and the evoked release of serotonin in the rat striatum

Previous studies have indicated that peripheral administration of interleukin-6 (IL-6) increases brain concentrations of tryptophan and 5-hydroxyindoleacetic acid (5-HIAA), the major catabolite of serotonin (5-HT). To determine whether these changes were related to increased synaptic release of 5-HT, we studied the responses to peripheral administration of IL-6 by in vivo microdialysis and in vivo amperometry. Intraperitoneal injection of recombinant IL-6 resulted in an elevation of microdialysate concentrations of 5-HT in the rat striatum. Also, amperometric measurements indicated that i.p. IL-6 enhanced the 5-HT-like signal obtained from the striatum following electrical stimulation of the dorsal raphe nucleus. These results indicate that the increases in brain concentrations of 5-HIAA observed in earlier studies indeed reflect increased synaptic release of 5-HT.

The reductions in sweetened milk intake induced by interleukin-1 and endotoxin are not prevented by chronic antidepressant treatment

Administration of interleukin-1 (IL-1) and endotoxin (lipopolysaccharide, LPS) to rodents can decrease food intake, a behavioral response resembling the diminution of appetite observed in human depression. IL-1 and LPS are known to affect cerebral neurotransmission involving norepinephrine and serotonin, both of which have been implicated in feeding behavior and in the pharmacotherapy of depression in man. The ability of chronic antidepressant treatment to attenuate LPS-induced depressed feeding in rats has been cited as evidence that cytokines may be involved in human depression. Thus, we studied the effects of chronic treatment with the tricyclic antidepressant, imipramine, and the novel antidepressant, venlafaxine, on the sweetened milk intake challenged with intraperitoneally injected IL-1 beta and LPS. Chronic (from 2 to 8 weeks) treatment of the mice with imipramine (10 mg/kg once or twice daily) or venlafaxine (10 and 20 mg/kg/day) did not significantly alter the decreases in milk intake in response to mIL-1 beta or LPS. In some experiments, chronic imipramine slightly decreased body weight and slightly increased milk intake, but not food pellet intake. Venlafaxine had none of these effects. Analysis of variance did not indicate any significant interactions between the antidepressant and IL-1 or LPS treatments. These results indicate that chronic treatment with antidepressants does not significantly alter the responses to IL-1 or LPS in the mouse sweetened milk model of sickness behavior.

Modelling to solve odour problems

The use of dispersion modelling is a powerful tool to establish levels of treatment required to remove odour complaints. Odour is an extremely sensitive issue and is key to the public perception of wastewater environmental protection. This paper describes a case study of the successful resolution of long-standing odour problems at the East Worthing Wastewater Treatment Works (WTW), on the South Coast of England, utilising modelling and appropriate treatment technologies. A number of odour surveys have been conducted on the site to identify the major sources on the works, which were found to be the sludge press house and the primary settlement tanks, situated only 10 metres from the nearest properties. As a result attempts to resolve the odour problem have been made including the covering of identified sources, treating extract using activated carbon filters and installing perfume sprays. During the site development all sources were contained and ventilated to a 60,000 m3/hr Jones & Attwood ODORGARD unit. Its requirement was to ensure that no receptor was exposed to a concentration in excess of 4 ouEm3 (Odour units), in accordance with the odour planning condition. Dispersal modelling was performed to determine the maximum permissible outlet concentration. The results of the modelling exercise established that emissions from the odour control plant should not exceed 675 ouEm3 to ensure that the receptor standard was attained. An optimisation programme was conducted to ensure that the unit was providing the optimum level of treatment prior to taking the olfactometry samples. Following the plant's optimisation the results of the olfactometry analysis confirmed that the discharge levels were below the required 670 ouEm3. Since completion of the sludge treatment centre scheme there have been no registered odour complaints directed at the East Worthing WTW, and the local air quality has been greatly improved for the residents surrounding the works.

Bacterial translocation can increase plasma corticosterone and brain catecholamine and indoleamine metabolism

The potential contribution of stress-induced bacterial translocation to the activation of the hypothalamo-pituitary-adrenocortical (HPA) axis and brain biogenic amines was assessed. Mice were restrained for various periods, and brain concentrations of tryptophan, catecholamines, serotonin, and their metabolites, plasma corticosterone, and the translocation of viable bacteria from the gastrointestinal tract to the mesenteric lymph nodes, spleen, and liver were measured. Restraint induced the translocation of indigenous gram-positive bacteria in only a small proportion of animals, but translocation of gram-negative bacteria did not occur. Restraint induced short-lived increases in plasma corticosterone and brain amine metabolism, whereas bacterial translocation was slower and persisted long after the HPA axis and neurochemical responses had dissipated. When mice were infected with Salmonella typhimurium, spontaneous translocation occurred and plasma corticosterone, interleukin-6 concentrations, and brain catecholamine and indoleamine metabolism were elevated. These findings indicate that the translocation of indigenous gastrointestinal bacteria did not contribute to the HPA axis and neurochemical changes induced by restraint. However, translocation of nonindigenous S. typhimurium with or without restraint did induce HPA and neurochemical responses.

The role of CRF receptor subtypes in stress-induced behavioural responses

The actions of corticotropin-releasing factor (CRF) and CRF-related peptides in the brain and periphery are mediated through multiple receptors. Two CRF receptor subtypes that differ markedly in their pharmacological profiles and anatomical distribution have been identified and characterized. Important advances have been made in understanding CRF and its actions through the development of specific CRF receptor antagonists, application of antisense oligonucleotides, and the production of transgenic mice lacking functional CRF(1) receptors. This chapter describes recent findings with respect to CRF-related peptides and CRF receptors and their role in stress-induced behaviours.

The role of cyclooxygenases in endotoxin- and interleukin-1-induced hypophagia

Endotoxin (lipopolysaccharide, LPS) and interleukin-1 (IL-1) reduce food intake in rodents. Cyclooxygenase (COX) inhibitors have long been known to attenuate these responses, but recent work has revealed the existence of two distinct isoforms of the enzyme, COX1 and COX2, with different characteristics and functions. Therefore, we reassessed the COX involvement using inhibitors with different selectivities for COX1 and COX2. Feeding was assessed in nondeprived mice by measuring the intake of sweetened milk in a 30-minute period, as well as daily food pellet intake. LPS and IL-1beta consistently reduced milk intake. Treatment of the mice with the selective COX1 inhibitor, piroxicam, attenuated the hypophagic responses to IL-1 and LPS. Similar results were obtained with diclofenac. The hypophagic responses to LPS and IL-1beta were not affected by the COX2-selective inhibitors nimesulide and NS-398 at doses considered selective for COX2, but were inhibited by higher doses. Pretreatment of the mice with aspirin, an irreversible inhibitor of COX1 and COX2, prevented the hypophagic response to IL-1, 16 h, but not 40 h later. Taken together, these results suggest that COX1 may be the major isozyme involved in the hypophagic responses to LPS and IL-1, but a role for COX2 cannot be excluded. We also studied the combination of a COX inhibitor with the IL-1 receptor antagonist protein. Consistent with earlier results, both the IL-1 receptor antagonist (IL-1ra) and indomethacin attenuated the hypophagic responses to LPS. Combination of the two treatments produced additive results almost completely preventing the hypophagic response. Because indomethacin almost completely prevented the hypophagic response to IL-1, this additivity suggests that there are multiple mechanisms by which LPS induces hypophagia.

Footshock-induced changes in brain catecholamines and indoleamines are not mediated by CRF or ACTH

Stressful treatments have long been associated with increased activity of brain catecholaminergic and serotonergic neurons. An intracerebroventricular (icv) injection of the corticotropin-releasing factor (CRF) also activates brain catecholaminergic neurons. Because brain CRF-containing neurons appear to be activated during stress, it is possible that CRF mediates the catecholaminergic activation. This hypothesis has been tested by assessing the responses in brain catecholamines and indoleamines to footshock in mice pretreated icv with a CRF receptor antagonist, and in mice lacking the gene for CRF (CRFko mice). Consistent with earlier results, icv administration of CRF increased catabolites of dopamine and norepinephrine, but failed to alter tryptophan concentrations or serotonin catabolism. A brief period of footshock increased plasma corticosterone and the concentrations of tryptophan and the catabolites of dopamine, norepinephrine and serotonin in several brain regions. Mice injected icv with 25 microg alpha-helical CRF(9-41) prior to footshock had neurochemical responses that were indistinguishable from controls injected with vehicle, while the increase in plasma corticosterone was slightly attenuated in some experiments. CRFko mice exhibited neurochemical responses to footshock that were indistinguishable from wild-type mice. However, whereas wild-type mice showed the expected increase in plasma corticosterone, there was no such increase in CRFko mice. Similarly, hypophysectomized mice also showed normal neurochemical responses to footshock, but no increase in plasma corticosterone. Hypophysectomy itself elevated brain tryptophan and catecholamine and serotonin metabolism. Treatment with ACTH icv or peripherally failed to induce any changes in cerebral catecholamines and indoleamines. These results suggest that CRF and its receptors, and ACTH and other pituitary hormones, are not involved in the catecholamine and serotonin responses to a brief period of footshock.

Hippocampal norepinephrine-like voltammetric responses following infusion of corticotropin-releasing factor into the locus coeruleus

Intracerebroventricular (i.c.v.) administration of corticotropin-releasing factor (CRF) increases the activity of noradrenergic neurons in the locus coeruleus (LC) assessed by electrophysiological and neurochemical studies. It has been suggested that this effect of i.c.v. CRF is exerted directly on LC noradrenergic (LC-NE) neurons. Infusion of CRF directly into the LC increases cortical and hippocampal release of norepinephrine (NE) as indicated by in vivo microdialysis studies, but the electrophysiological studies have shown both increases and decreases. The present study used in vivo voltammetry to study changes in the extracellular concentrations of NE in the rat hippocampus in response to infusion of CRF (100 ng) into the LC. When the infusion cannula was located in or very close to the LC, the immediate response to CRF was a small decrease in the NE-like oxidation current, followed by a robust increase after about 6-7 min. The oxidation current reached a peak around 13 min and returned to baseline by about 30 min after CRF infusion. By contrast with CRF, infusion of glutamate into the LC increased the oxidation current with a delay of around 30 s and a peak within 90 s. The responses to LC infusion of CRF in rats treated with DSP-4 to deplete hippocampal NE were substantially smaller than those in untreated rats, suggesting that the oxidation signals in untreated rats reflected changes in concentrations of NE. The response to glutamate was markedly augmented by pretreatment with the NE reuptake inhibitor, desmethylimipramine, suggesting that the observed responses reflected changes in NE. Infusion of the same dose of CRF into brain structures outside the LC did not elicit consistent changes in oxidation current in the hippocampus. The time course of the responses to CRF is compatible with previously reported electrophysiological responses of LC-NE neurons to CRF and with neurochemical evidence indicating that CRF can affect the activity of LC-NE neurons. The results indicate that CRF may act in or close to the LC to induce release of hippocampal NE, but the delayed response to CRF compared with that to glutamate, suggests that CRF does not directly activate LC-NE neurons.

Lack of evidence for a role of serotonin in interleukin-1-induced hypophagia

Interleukin-1 (IL-1) administration depresses food intake in rodents. IL-1 is known to increase the metabolism of serotonin, which is known to affect feeding behavior. Thus, serotonin is an obvious candidate for a mediator of the hypophagic response to IL-1. Therefore, we tested the ability of serotonergic agonists and antagonists to alter the hypophagic responses to IL-1 and bacterial lipopolysaccharide (LPS). Hypophagia was assessed in ad lib-fed mice by recording the intake of sweetened milk in a 30-min period. Acute intraperitoneal administration of mouse IL-1beta reliably decreased milk intake. This hypophagic response was not affected by any of the serotonin antagonists tested, including 5-HT(1A) (WAY100135 and propranolol), 5-HT(1B) (GR127935), 5-HT(2) (ritanserin, ketanserin, SB206553, and RS102221), mixed 5-HT(1/2) (methysergide and metergoline), and 5-HT(3) (tropisetron) receptor antagonists. The 5-HT(1A) agonists (8-OH-DPAT and ipsapirone) and a 5-HT(1B) agonist (CGS12066B) known to decrease the activity of serotonergic neurons, also had no effect. Mice pretreated with 5,7-dihydroxytryptamine to deplete brain serotonin ate less, but, nevertheless, displayed similar hypophagic responses to mIL-1beta or LPS. The results suggest that serotonin is not involved in the decrease in short-term milk intake induced by mIL-1beta or LPS in mice that have been fed ad lib.

Catecholamine, indoleamine and corticosteroid responses in mice bearing tumors

The neurochemical and endocrine responses to inoculation of mice with the murine lymphoma cell line AW5E was studied. This cell line was chosen because it is NK cell lysis resistant and thus does not induce a normal immune response. Immune activation has long been known to be a potent stimulator of the hypothalamo-pituitary-adrenocortical (HPA) axis as well as brain catecholamine and indoleamine metabolism, involving increases in the brain concentrations of catabolites of norepinephrine (NE) and serotonin (5-HT), as well as free tryptophan. Mice injected intravenously with AW5E tumor cells exhibited small increases in plasma corticosterone and hypothalamic NE and 5-HT catabolites one day after injection. There were no significant changes after 6 or 8 days, but a sustained increase in hypothalamic NE and 5-HT metabolism appeared 10 days after injection. There were similar, but more limited changes in the brain stem and prefrontal cortex. On the last day tested (day 14), plasma corticosterone was slightly elevated, as were hypothalamic dopamine, NE and 5-HT catabolites and tryptophan. These results indicate that inoculation with AW5E tumor cells increases brain catecholamine and serotonin metabolism, the hypothalamus being the most sensitive region. The most marked increases occurred in the few days preceding death, and thus may be associated with the pathology of the tumor growth.

Effects of the IL-1 receptor antagonist on the IL-1- and endotoxin-induced activation of the HPA axis and cerebral biogenic amines in mice

Endotoxin (lipopolysaccharide, LPS) and interleukin-1 (IL-1) are known to activate the hypothalamo-pituitary- adrenocortical (HPA) axis, as well as brain norepinephrine (NE) and indoleamine metabolism. Because LPS administration is known to induce the synthesis and secretion of IL-1, it has been proposed that IL-1 is the endogenous mediator of the response to LPS. This proposal has been tested using various antagonists of IL-1 with varied results. Therefore we have re-examined this question using a wide range of doses of the interleukin-1- receptor antagonist protein (IL-1ra) at various times after intraperitoneal LPS. The results indicate that IL-1ra at doses more than adequate to prevent responses to exogenously administered IL-1beta, failed to significantly attenuate the increases in plasma ACTH and corticosterone and the cerebral catecholamine and indoleamine responses induced by intraperitoneal LPS in mice. IL-1ra was also ineffective when plasma ACTH and corticosterone were measured at longer times after LPS, although some trends towards attenuations were occasionally observed at 4 or 6 h. The latter is consistent with the time course of IL-1 induction by LPS. Intracerebroventricular administration of IL-1ra attenuated the endocrine and neurochemical responses to intraperitoneal IL-1beta. However, intracerebroventricular IL-1ra failed to antagonize the HPA and neurochemical responses to intraperitoneal administration of LPS or to intravenous IL-1beta. In all of these experiments, there were very close parallels between the HPA and the neurochemical responses, especially that of NE. We conclude that IL-1 does not mediate the HPA or the neurochemical responses to intraperitoneal LPS, although it may contribute in a minor way to the late HPA responses. However, IL-1 within the CNS may contribute to the responses to intraperitoneal IL-1, but not to intraperitoneal LPS or intravenous IL-1.