Brain regions involved in the development of acute phase responses accompanying fever in rabbits

Deficient zinc levels and myocardial infarction : association between deficient zinc levels and myocardial infarction: a meta-analysis

The purpose of this study is to clarify the association between Zn levels and myocardial infarction (MI) using a meta-analysis approach. We searched articles in the PubMed, OVID, and ScienceDirect published as of November 2014. Thirteen eligible articles with 2886 subjects from 41 case-control studies were identified. Overall, pooled analysis indicated that subjects with MI had lower Zn levels than healthy controls (standardized mean difference (SMD) = -1.848, 95 % confidence interval (CI) = [-2.365, -1.331]). Further subgroup analysis found that subjects with MI had lower Zn levels than healthy controls in serum (SMD = -1.764, 95 % CI = [-2.417, -1.112]) and hair (SMD = -3.326, 95 % CI = [-4.616, -2.036]), but not in toenail (SMD = -0.396, 95 % CI = [-1.114, 0.322]). The subgroup analysis stratified by type of Zn measurement found a similar pattern in inductively coupled plasma-atomic absorption spectrometry (ICP-AAS) (SMD = -2.442, 95 % CI = [-3.092, -1.753]), but not in neutron activation analysis (NAA) (SMD = -0.449, 95 % CI = [-1.127, 0.230]). Lower Zn levels in MI patients were found both in male (SMD = -3.350, 95 % CI = [-4.531, -2.169]) and female (SMD = -2.681, 95 % CI = [-3.440, -1.922]). And the difference of Zn levels according to MI in Asia (SMD = -2.555, 95 % CI = [-3.267, -1.844]) was greater to that among the population in Europe (SMD = -0.745, 95 % CI = [-1.386, -0.104]), but no difference was found in Oceania (SMD = -0.255, 95 % CI = [-0.600, 0.089]). In conclusion, this meta-analysis indicates that there is a significant association between Zn deficiency and MI. We suggest that a community-based, long-term observation in a cohort design should be performed to obtain better understanding of causal relationships between Zn and MI, through measuring hair Zn at baseline to investigate whether the highest zinc category versus lowest was associated with MI risk.

Comparison of serum zinc levels measured by inductively coupled plasma mass spectrometry in preschool children with febrile and afebrile seizures

Background

Changes in levels of trace elements have been proposed to underlie febrile seizures. Particularly, low zinc levels have been proposed as related factor of febrile seizure. In this study, we investigated whether mean serum zinc levels differed between children with febrile seizure and afebrile seizure.

Methods

Using inductively coupled plasma mass spectrometry, serum zinc levels were measured in 288 children who had been diagnosed with febrile seizures (N=248) and afebrile seizures (N=40). Mean serum zinc levels were compared between the 2 groups.

Results

Mean serum zinc level was 60.5±12.7 µg/dL in the febrile seizure group and 68.9 ±14.5 µg/dL in the afebrile seizure group. A significant difference in serum zinc levels was observed between the febrile and afebrile seizure groups (P<0.001).

Conclusions

Zinc levels in children with febrile seizure were significantly lower than those in children with afebrile seizure.

Effects of electrical stimulation of ventral septal area on firing rates of pyrogen-treated thermosensitive neurons in preoptic anterior hypothalamus from rabbits

Although there is considerable evidence supporting that fever evolved as a host defense response, it is important that the rise in body temperature would not be too high. Many endogenous cryogens or antipyretics that limit the rise in body temperature have been identified. Endogenous antipyretics attenuate fever by influencing the thermoregulatory neurons in the preoptic anterior hypothalamus (POAH) and in adjacent septal areas including ventral septal area (VSA). Our previous study showed that intracerebroventricular (I.C.V.) injection of interleukin-1beta (IL-1beta) affected electrophysiological activities of thermosensitive neurons in VSA regions, and electrical stimulation of POAH reversed the effect of IL-1beta. To further investigate the functional electrophysiological connection between POAH and VSA and its mechanisms in thermoregulation, the firing rates of thermosensitive neurons in POAH of forty-seven unit discharge were recorded by using extracellular microelectrode technique in New Zealand white rabbits. Our results show that the firing rates of the warm-sensitive neurons decreased significantly and those of the cold-sensitive neurons increased in POAH when the pyrogen (IL-1beta) was injected I.C.V. The effects of IL-1beta on firing rates in thermosensitive neurons of POAH were reversed by electrical stimulation of VSA. An arginine vasopressin (AVP) V1 antagonist abolished the regulatory effects of VSA on the firing rates in thermosensitive neurons of POAH evoked by IL-1beta. However, an AVP V2 antagonist had no effects. These data indicated that VSA regulates the activities of the thermosensitive neurons of POAH through AVP V1 but not AVP V2 receptor.

Lower serum zinc in Chronic Fatigue Syndrome (CFS): relationships to immune dysfunctions and relevance for the oxidative stress status in CFS

The present study examines serum zinc concentrations in patients with chronic fatigue syndrome (CFS) versus normal volunteers. Serum zinc levels were determined by means of an atomic absorption method. We found that serum zinc was significantly lower in the CFS patients than in the normal controls. There was a trend toward a significant negative correlation between serum zinc and the severity of CFS and there was a significant and negative correlation between serum zinc and the subjective experience of infection. We found that serum zinc was significantly and negatively correlated to the increase in the alpha2 protein fraction and positively correlated to decreases in the expression of mitogen-induced CD69+ (a T cell activation marker) on CD3+ as well as CD3+CD8+ T cells. These results show that CFS is accompanied by a low serum zinc status and that the latter is related to signs of inflammation and defects in early T cell activation pathways. Since zinc is a strong anti-oxidant, the present results further support the findings that CFS is accompanied by increased oxidative stress. The results of these reports suggest that some patients with CFS should be treated with specific antioxidants, including zinc supplements.

Timecourse and corticosterone sensitivity of the brain, pituitary, and serum interleukin-1beta protein response to acute stress

Activation of peripheral immune cells leads to increases of interleukin-1beta (IL-1beta) mRNA, immunoreactivity, and protein levels in brain and pituitary. Furthermore, IL-1beta in brain plays a role in mediating many of the behavioral, physiological, and endocrine adjustments induced by immune activation. A similarity between the consequences of immune activation and exposure to stressors has often been noted, but the potential relationship between stress and brain IL-1beta has received very little attention. A prior report indicated that exposure to inescapable tailshocks (IS) raised levels of brain IL-1beta protein 2 h after IS, but only in adrenalectomized (and basal corticosterone replaced) subjects. The studies reported here explore this issue in more detail. A more careful examination revealed that IL-1beta protein levels in hypothalamus were elevated by IS in intact subjects, although adrenalectomy, ADX (with basal corticosterone replacement) exaggerated this effect. IL-1beta protein increases were already present immediately after the stress session, both in the hypothalamus and in other brain regions in adrenalectomized subjects, and no longer present 24 h later. Furthermore, IS elevated levels of IL-1beta protein in the pituitary, and did so in both intact and adrenalectomized subjects. IS also produced increased blood levels of IL-1beta, but only in adrenalectomized subjects. Finally, the administration of corticosterone in an amount that led to blood levels in adrenalectomized subjects that match those produced by IS, inhibited the IS-induced rise in IL-1beta in hypothalamus and pituitary, but not in other brain regions or blood.

Inflammatory markers in younger vs elderly normal volunteers and in patients with Alzheimer's disease

BACKGROUND

Recently it has been reported that activation of the inflammatory response system (IRS) may play a role in the aging process and in the pathogenesis of the degenerative changes associated with Alzheimer's disease (SDAT). The aims of the present study were to examine the peripheral IRS in normal aging and in SDAT patients.

METHODS

Serum zinc (Zn), total serum protein (TSP), albumin (Alb), SP electrophoresis, and serum interleukin-6 (IL-6) and the stimulated production of tumor necrosis factor-alpha (TNFalpha) were determined in younger versus elderly healthy subjects and in SDAT patients vs. age-matched, healthy volunteers.

RESULTS

Serum Zn and Alb were significantly lower in elderly than in younger healthy volunteers and were significantly and inversely correlated with age. The production of TNFalpha was significantly higher in elderly than in younger healthy volunteers and was significantly and positively correlated with age. In SDAT patients, no significant changes in serum Zn or TNFalpha production could be found. Serum Alb was significantly lower and serum IL-6 and the alpha1 and alpha2 globulin fractions significantly higher in SDAT patients than in controls.

CONCLUSIONS

Activation of the IRS appears to accompany the normal aging process, i.e. lower serum Zn and Alb and increased TNFalpha production, as well as SDAT, i.e. lower serum Alb and increased serum IL-6 and alpha1 and alpha2 globulin fractions. The findings suggest that not all indicators of IRS activation in SDAT are related to those of the normal ageing process.

Brain sites of action of endogenous interleukin-1 in the febrile response to localized inflammation in the rat

1. Interleukin (IL)-1 is a potent endogenous pyrogen which causes fever when injected into a number of brain sites. However, the brain sites at which endogenous IL-1 acts to influence body temperature remain equivocal. The aim of this study was to determine the effect of local administration of the interleukin-1 receptor antagonist (IL-1ra) into specific sites in the hypothalamus, and other brain regions known to contain receptors for IL-1, on the febrile response of rats to peripheral injection of lipopolysaccharide (LPS) into a subcutaneous air pouch (intrapouch, i.p.o.) that does not lead to LPS appearance in the circulation. 2. Injection of LPS (100 microgram kg-1, i.p.o.) induced a rise in body temperature which commenced 1.5 h after injection and was maximal at 3 h (38.9 +/- 0.2 C, compared with 37.0 +/- 0.1 C at 0 h, n = 6, P < 0.001). Intracerebroventricular (i.c.v.) IL-1ra (500 microgram in 5 microliter) significantly attenuated LPS fever (IL-1ra, 37.7 +/- 0.2 C; saline, 38.9 +/- 0.2 C; n = 6, P < 0.001). Unilateral microinjection of IL-1ra (50 microgram in 0.5 microliter at 0 + 1 h) into the anterior hypothalamus (AH), paraventricular hypothalamic nucleus (PVH), peri-subfornical organ, subfornical organ (SFO) or hippocampus (dentate gyrus and CA3 region) also significantly reduced the fever induced by LPS. 3. The same dose of IL-1ra had no effect on fever when administered into the ventromedial hypothalamus (VMH), organum vasculosum lamina terminalis (OVLT), CA1 field of the hippocampus, striatum or cortex. 4. These data indicate that the action of endogenous IL-1 in the brain during fever is site specific, acting at the AH, PVH, SFO and hippocampus, but not the VMH, OVLT and striatum or cortex.

Selective effects of peripheral lipopolysaccharide administration on contextual and auditory-cue fear conditioning

The reported experiments explore the effects of peripheral LPS administration on learning and memory processes. As measured by the conditioned freezing response, intraperitoneal LPS administration given after conditioning impaired contextual but not auditory-cue fear conditioning in both juvenile (hooded Long Evans) and adult rats (albino Sprague Dawley) of two different strains. This impairment in contextual fear conditioning was not dependent on the presence of the tone. Preexposure to the context eliminated the effect of LPS on contextual fear conditioning, and in addition, LPS given after context preexposure negated the beneficial effects of preexposure on contextual fear. These results suggest that LPS disrupts posttrial memory consolidation processes. In support of the hypothesis that LPS-induced proinflammatory cytokine release is involved in producing the impairment in contextual fear caused by LPS, peripheral interleukin-1 receptor antagonist (IL-1ra) administered subcutaneously at a dose of 100 mg/kg prevented the impairment in contextual fear caused by LPS. These experiments provide evidence for a role of immune activation and cytokine activity in learning and memory processes.

Exposure to acute stress induces brain interleukin-1beta protein in the rat

Peripheral immune stimulation such as that provided by lipopolysaccharide (LPS) has been reported to increase brain levels of IL-1beta mRNA, immunoreactivity, and bioactivity. Stressors produce many of the same neural and endocrine responses as those that follow LPS, but the impact of stressors on brain interleukin-1beta (IL-1beta) has not been systematically explored. An ELISA designed to detect IL-1beta was used to measure levels of IL-1beta protein in rat brain. Brain IL-1beta was explored after exposure to inescapable shock (IS; 100 1.6 mA tail shocks for 5 sec each) and LPS (1 mg/kg) as a positive control. Rats were killed either immediately or 2, 7, 24, or 48 hr after IS. Brains were dissected into hypothalamus, hippocampus, cerebellum, posterior cortex, and nucleus tractus solitarius regions. LPS produced widespread increases in brain IL-1beta, but IS did not. Adrenal glucocorticoids are known to suppress IL-1beta production in both the periphery and brain. Thus, it was possible that the stressor did provide stimulus input to the brain IL-1beta system(s), but that the production of IL-1beta protein was suppressed by the rapid and prolonged high levels of glucocorticoids produced by IS. To test this possibility rats were adrenalectomized or given sham surgery, with half of the adrenalectomized rats receiving corticosterone replacement to maintain basal corticosterone levels. IS produced large increases in brain IL-1beta protein in the adrenalectomized subjects 2 hr after stress, whether basal corticosterone levels had been maintained. Thus elimination of the stress-induced rise in corticosterone unmasked a robust and widespread increase in brain IL-1beta.

Exposure to acute stress induces brain interleukin-1beta protein in the rat

Peripheral immune stimulation such as that provided by lipopolysaccharide (LPS) has been reported to increase brain levels of IL-1beta mRNA, immunoreactivity, and bioactivity. Stressors produce many of the same neural and endocrine responses as those that follow LPS, but the impact of stressors on brain interleukin-1beta (IL-1beta) has not been systematically explored. An ELISA designed to detect IL-1beta was used to measure levels of IL-1beta protein in rat brain. Brain IL-1beta was explored after exposure to inescapable shock (IS; 100 1.6 mA tail shocks for 5 sec each) and LPS (1 mg/kg) as a positive control. Rats were killed either immediately or 2, 7, 24, or 48 hr after IS. Brains were dissected into hypothalamus, hippocampus, cerebellum, posterior cortex, and nucleus tractus solitarius regions. LPS produced widespread increases in brain IL-1beta, but IS did not. Adrenal glucocorticoids are known to suppress IL-1beta production in both the periphery and brain. Thus, it was possible that the stressor did provide stimulus input to the brain IL-1beta system(s), but that the production of IL-1beta protein was suppressed by the rapid and prolonged high levels of glucocorticoids produced by IS. To test this possibility rats were adrenalectomized or given sham surgery, with half of the adrenalectomized rats receiving corticosterone replacement to maintain basal corticosterone levels. IS produced large increases in brain IL-1beta protein in the adrenalectomized subjects 2 hr after stress, whether basal corticosterone levels had been maintained. Thus elimination of the stress-induced rise in corticosterone unmasked a robust and widespread increase in brain IL-1beta.

Lower serum zinc in major depression is a sensitive marker of treatment resistance and of the immune/inflammatory response in that illness

The aims of the present study were to examine i) serum zinc (Zn) and copper (Cu) in treatment resistant depression (TRD); ii) the effects of subchronic antidepressant therapy on these trace elements; and iii) the relationships between serum Zn and Cu and immune/inflammatory markers. Serum Zn was significantly lower in TRD than in normal controls. There was a significant inverse correlation between baseline serum Zn and staging of depression based on severity of prior treatment resistance. There were no significant effects of antidepressive treatment on serum Zn, whereas serum Cu was significantly reduced. There were highly significant correlations between serum Zn and the CD4+/CD8+ T-cell ratio (negative), and total serum protein, serum albumin, and transferrin (all positive). The results suggest that lower serum Zn is a marker of TRD and of the immune/inflammatory response in depression. It is suggested that treatment resistance may bear a relationship with the immune/inflammatory alterations in major depression.

Serum and cerebrospinal fluid zinc levels in children with febrile convulsions

The mechanisms underlying febrile convulsions (FC), which have multiple etiological factors, are not yet clear. The aim of the present study was to determine whether there were any changes in serum and cerebrospinal fluid (CSF) zinc (Zn) levels in children with febrile convulsion during seizures. A total of 102 children were included in the study, with four groups formed as follows: group A, 40 children with FC (aged 9 months to 5 years); group B. 20 children having fever without convulsion (aged 6 months to 5 years); group C, 20 children with afebrile convulsion (aged 6 months to 6 years) and group D, 22 healthy children (aged 5 months to 6 years). Serum and CSF zinc levels for groups A, B and C and serum Zn levels only for group D were measured. The serum Zn levels of 17 children in group A were again measured during healthy periods. Serum Zn levels of groups A, B, C and D had a mean of 0.70 +/- 0.10 mg/dL, 1.07 +/- 0.08 mg/dL. 1.26 +/- 0.32 mg/dL and 1.17 +/- 0.21 mg/dL, respectively, and the values of group A were lower than those of the other three groups (P < 0.001). In group B, serum Zn levels were also lower than those of groups C and D (P < 0.05). The CSF Zn levels of groups A, B and C were found to have a mean of 0.07 +/- 0.02 mg/L, 0.12 +/- 0.02 mg/L and 0.14 +/- 0.04 mg/L, respectively. In group A, the CSF Zn levels were lower than those of groups B and C (P < 0.001), and in group B they were lower than those of group C (P < 0.05). For the 17 patients in group A, serum Zn levels during healthy periods (0.87 +/- 0.10 mg/dL) were found to be higher than the values shortly after seizures, but lower than those of groups B, C and D (P < 0.001). We could not observe any relationship between zinc levels of the serum and CSF and the degree and duration of the fever. These findings suggest that serum and CSF Zn levels decreased during infectious diseases, and that this decrease was more significant in patients with FC.

Immune activation: the role of pro-inflammatory cytokines in inflammation, illness responses and pathological pain states

It has recently become accepted that the activated immune system communicates to brain via release of pro-inflammatory cytokines. This review examines the possibility that pro-inflammatory cytokines (interleukins and/or tumor necrosis factor) mediate a variety of commonly studied hyperalgesic states. We will first briefly review basic immune responses and inflammation. We will then develop the concept of illness responses and provide evidence for their existence and for the dramatic changes in neural functioning that they cause. Lastly, we will examine the potential roles that both pro-inflammatory cytokines and the neural circuits that they activate may play in the hyperalgesic states produced by irritants, inflammatory agents, and nerve damage. The possibility is raised that apparently diverse hyperalgesic states may converge in the central nervous system and activate similar or identical neural circuitry.

Intracerebroventricular interleukin-1 receptor antagonist blocks the enhancement of fear conditioning and interference with escape produced by inescapable shock

Brain interleukin-1 (IL-1) plays a key role in mediating the neural, endocrine, and behavioral consequences of injury and infection. Recent evidence indicates that brain IL-1 may also be important in producing endocrine and neurochemical responses to stressors. The present experiment sought to determine whether intracerebroventricular (i.c.v.) administration of an interleukin-1 receptor antagonist (IL-1ra) would block behavioral effects of a stressor. I.c.v. application of hrIL-1ra before inescapable shock blocked the subsequent interference with escape learning and enhancement of fear conditioning normally produced by this treatment.

Paradoxical conditioning of the plasma copper and corticosterone responses to bacterial endotoxin

The cascade of physiologic mechanisms in response to infection, the acute phase response, is recognized as having a major role in host defense. Two such responses are an increase in plasma copper and activation of the hypothalamic-pituitary-adrenal axis, which are consistently reported to occur during bacterial infection. We aimed to determine whether the alterations in plasma copper and corticosterone were conditionable using the conditioned taste aversion paradigm. The regime involved the pairing of a novel-tasting saccharine solution (the conditioned stimulus) with lipopolysaccharide (the unconditioned stimulus). Seven days after the initial pairing of these stimuli (the test day), the saccharine solution was represented. Animals exposed to this condition displayed a significant decrease in plasma copper levels. In addition, these rats experienced a reduction in plasma corticosterone that was time dependent. Paradoxically, the conditioned response of both these variables were in a direction contrary to that reported during bacterial infection. These results suggest that some acute phase responses may condition as a rebound response, or in an opposing trend to that occurring as the initial reaction.

Anatomic patterns of Fos immunostaining in rat brain following systemic endotoxin administration

To identify brain neurons that participate in the acute phase response, rat brains were examined immunocytochemically for Fos protein following the intravenous administration of bacterial endotoxin (lipopolysaccharide, LPS). Two to three hours after the injection of LPS, 150 micrograms/kg body weight, to adult male Long-Evans rats, a consistent anatomic pattern of Fos immunostained cell nuclei is seen. In the brain stem, prominant Fos immunostaining is induced in tyrosine hydroxylase immunoreactive neurons of the caudal ventral-lateral medulla (the A1 cell group), in both tyrosine hydroxylase positive and negative neurons of nu. tractus solitarius, in the parabrachial nu., and in a few neurons of the locus ceruleus. In the hypothalamus, endotoxin induces Fos expression in magnocellular neurons of the paraventricular and supraoptic nuclei and internuclear cell groups. A higher percentage of oxytocin-immunoreactive cells is double labeled for Fos nuclear immunostaining than vasopressin-immunoreactive cells. A minority of somatostatin immunoreactive periventricular hypothalamic neurons are Fos positive. Other hypothalamic nuclei that contain endotoxin-induced Fos nuclear immunostaining include the parvocellular neurons of the paraventricular nu., the dorsomedial and arcuate nuclei, the lateral hypothalamus, the dorsal hypothalamic area (zona incerta), and the median nucleus of the preoptic area. LPS induces numerous Fos-positive neurons in regions known to respond to a variety of stressful stimuli; these regions include the preoptic area, bed nucleus of the stria terminalis, lateral septum, and the central and medial nuclei of the amygdala. Moreover, Fos nuclear immunostaining is seen in neurons of circumventricular organs: the organum vasculosum of the lamina terminalis, the subfornical organ, and the area postrema. The maximum intensity of Fos nuclear immunostaining occurs 2-3 h after endotoxin administration and declines thereafter. It is attenuated by pretreatment with indomethacin, 25 mg/kg body weight Sc, or dexamethasone, 1 mg/kg IP. These observations are consistent with the participation of a variety of brain neuronal systems in the acute phase response and elucidate the functional neuroanatomy of that response at the cellular level.

Interleukin-6 enhances hepatic transferrin uptake and ferritin expression in rats

To explore a mechanism of interleukin (IL)-6-induced hypoferremia in rats, iron metabolism was investigated both in vivo and in vitro. Recombinant IL-6 was intraperitoneally administered to male Wistar rats and the serial change of parameters related to iron metabolism was examined. After administration of IL-6, plasma IL-6 concentration increased rapidly, reached its maximum in 1 hr and thereafter decreased quickly. Plasma IL-6 3 hr after IL-6 injection (50 micrograms/kg) was 3 units/ml, which is a concentration capable of inducing hepatic 125I-labeled transferrin uptake in vitro using isolated hepatocytes. Plasma iron concentration and transferrin saturation had decreased to approximately one third of the initial level within 3 hr and then recovered. Total iron binding capacity remained unchanged for 6 hr, then began to decrease. Red blood cell count and hemoglobin concentration showed no remarkable changes during this period. By ferrokinetic study with plasma that contained iron 59-labeled transferrin, the plasma iron disappearance half time, calculated from the disappearance curve, was significantly shortened from 55 min to 22 min by IL-6 treatment (p < 0.01). The ferritin concentration in the liver was increased significantly after the administration of IL-6 (p < 0.001), but transiently decreased in the spleen. The plasma ferritin showed a gradual increase during the 6-hr period after IL-6 injection. The uptake of 125I-labeled diferric transferrin by isolated hepatocytes was increased by IL-6 treatment and this increment was inhibited by addition of 100-fold excess unlabeled transferrin. On the other hand, no significant increment of 125I-labeled diferric transferrin uptake was observed in Kupffer cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of electrical stimulation or local anesthesia of the rabbit's hypothalamus on the acute phase response

The effects of electrical stimulation of the rostral hypothalamic region on the acute phase response (APR) were examined in rabbits. As indicators of APR, we measured changes in the plasma concentrations of iron, zinc, copper, and fibrinogen and changes in the red and white blood cell counts. Electrical stimulation of the rostral hypothalamic region near the preoptic and anterior hypothalamic region did not induce any aspect of the APR. However, stimulation near the anteroventral portion of the third ventricle (AV3V) induced responses that were, in part, opposite to those observed in the APR: an increase in the plasma concentration of zinc and a decrease in the circulating leukocyte count. Microinjections of procaine into the brain regions near the AV3V did not induce any changes in the plasma levels of trace metals and fibrinogen but increased the circulating leukocyte count. These results suggest that nonspecific stimulation or inhibition of the rostral hypothalamic region does not induce APR.

Cardiovascular responses induced in free-moving rats by immune cytokines

1. We investigated the effect of intraperitoneal (I.P.) injections of the immune cytokines, interleukin-1 beta (IL-1 beta) and tumour necrosis factor (TNF) on cardiovascular responses in free-moving rats, using a biotelemetry system. 2. The I.P. injection of a small dose of IL-1 beta (1 microgram/kg) induced a monophasic increase in the heart rate, and that of a large dose (10 micrograms/kg) induced biphasic increases in the blood pressure and heart rate. However, the I.P. injection of any of several doses of TNF (1, 10 and 50 micrograms/kg) had no effect on cardiovascular responses in rats. 3. Pre-treatment with I.P. injection of indomethacin (10 mg/kg), an inhibitor of cyclo-oxygenase, significantly suppressed the cardiovascular responses and the increase in the plasma noradrenaline (NA) concentration induced by I.P. injection of IL-1 beta. 4. Microinjection of IL-1 beta (1 and 10 ng) into the preoptic and anterior hypothalamic (PO-AH) region induced dose-dependent increases in the blood pressure and heart rate in rats. These responses were also suppressed by pretreatment with I.P. indomethacin (10 mg/kg). In addition, microinjection of prostaglandin E2 (20 and 100 ng) into the PO-AH region increased blood pressure and heart rate, but that of prostaglandin D2 (100 ng) had no effect. 5. The present results suggest that IL-1 beta stimulates the release of prostaglandins, presumably E series, near regions of the hypothalamus, which act on the hypothalamus to induce activation of the sympathetic nervous system. Subsequently, the blood pressure, heart rate and the plasma level of NA increase.

Fever induced by macrophage inflammatory protein-1 (MIP-1) in rats: hypothalamic sites of action

The purpose of this study was to clarify the central site of action as well as functional characteristics of the febrile response of the cytokine, macrophage inflammatory protein-1 (MIP-1). Guide cannulae for microinjection were implanted stereotaxically in the rat just above the pyrogen and thermosensitive area of the anterior hypothalamic, preoptic area (AH/POA). Following postoperative recovery, the body temperature of each rat (Tbo) was monitored during an experiment by a colonic thermistor probe at 0.5-1.0-h intervals. When MIP-1 was microinjected in a 0.5-microliter volume into the AH/POA in one of eight concentrations ranging from 0.0028 nanograms (ng) to 9.0 ng, an intense monophasic or biphasic fever was evoked. The MIP-1-induced increase in the Tbo of the rat was characterized by its short latency of 15 to 30 min and an inverse dose-response curve. Measures of mean latency and maximal rise in Tbo following MIP-1 confirmed the potency of this dose. Although the dose of 0.028 ng produced a fever of over 2.0 degrees C with a latency of only 15 min or less, the hyperthermic response became less intense as the dose of MIP-1 was increased. An anatomical mapping of sites of microinjection which reacted to MIP-1 in mediating fever revealed that the medial portion of the POA of the rat just rostral to the border of the AH was the region of maximum sensitivity to the cytokine.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of a neuronal interleukin-1 receptor and the corresponding mRNA in the mouse anterior pituitary cell line AtT-20

Interleukin-1 (IL-1) mediates numerous responses on the mouse anterior pituitary cell line AtT-20. We have studied the ligand binding properties of the IL-1 receptors (IL-1R) of the AtT-20 cells and found that they possess 1.5 x 10(3) receptors/cell with a Kd of 0.15 nM for [125I]IL-1 alpha. Using oligonucleotide primers, which define a 236 bp region of the cDNA coding for the cytosolic part of the mouse T-cell IL-1R, and cDNA prepared from AtT-20 cells, we obtained by polymerase chain reaction (PCR) a DNA fragment which was shown to possess an identical sequence to that of the corresponding region of the mouse T-cell IL-1R. Thus the AtT-20 pituitary cell line IL-1 receptor appears to be similar to those found on mouse T-cells and fibroblasts.

Fever and acute-phase response induced in rabbits by intravenous and intracerebroventricular injection of interleukin-6

We investigated the effect of human recombinant interleukin-6 (IL-6) on body temperature and acute-phase response, including changes in plasma levels of iron, zinc, copper, and fibrinogen and in circulating leukocyte count. The intravenous (IV) injection of IL-6 (2 micrograms/kg) produced a monophasic fever. The intracerebroventricular (ICV) injection of IL-6 produced a dose-dependent fever that developed gradually and remained elevated throughout the 5-h recording period. The IV injection of IL-6 decreased the plasma concentration of iron and zinc and increased the circulating leukocyte count. The ICV injection of IL-6 resulted in similar trace metal and leukocyte changes, and increased plasma levels of fibrinogen. These results show that IL-6 can cause fever when injected IV or ICV and induces some acute-phase responses through its action on peripheral target organs and in the central nervous system.

Leucocytosis induced in rabbits by intravenous or central injection of granulocyte colony stimulating factor

1. We investigated the effect of intravenous, intracerebroventricular and intrapreoptic injections of human recombinant granulocyte colony stimulating factor (GCSF) on body temperature and acute phase responses in the rabbit, including changes in the plasma concentration of iron, zinc, copper and fibrinogen and in circulating leucocyte count. 2. Neither intravenous nor intracerebroventricular injection of GCSF had any effect on the body temperature. 3. Both the intravenous and the intracerebroventricular injections of GCSF induced a dose-dependent increase in the circulating leucocyte count but neither affected the plasma concentration of iron, zinc, copper and fibrinogen. Furthermore, intrapreoptic injection of GCSF produced leucocytosis but had no effect on the red blood cell count. 4. The present results suggest that GCSF induces leucocytosis through its action on both the peripheral target organs and the central nervous system.