The role of protein synthesis in the hypothalamic mechanism mediating pyrogen fever

Anisomycin induces hair cell death and blocks supporting cell proliferation in zebrafish lateral line neuromast

Ototoxicity of drugs is an important inducement for hearing loss. Anisomycin is a candidate drug for parasite, cancer, immunosuppression, and mental disease. However, the ototoxicity of anisomycin has not been examined. In this study, the ototoxicity of anisomycin was evaluated using zebrafish lateral line. We found the zebrafish treated with anisomycin during lateral line development could inhibit hair cell formation in a time- and dose-dependent manner. After neuromasts are mature with differentiated hair cells by 5 day post-fertilization, anisomycin could induce hair cell loss effectively through chronic exposure rather than acute exposure. TUNEL assay and qPCR of apoptosis related genes tp53, casp8, casp3a, and casp3b indicated that cell apoptotic was induced by chronic anisomycin exposure. Furthermore, knocking down tp53 with antisense morpholino could attenuate the hair cell loss induced by anisomycin. In addition, we found that anisomycin chronic exposure also inhibited the proliferation of supporting cell. Together, these results indicate that chronic anisomycin exposure could induce hair cell death and block supporting cell proliferation, which causes hair cell loss in zebrafish neuromast. This study provides primary ototoxicity evaluation for anisomycin.

Pharmaceutical metabolic down-regulation by protein synthesis inhibition in a conscious rat model

Pharmaceutically induced metabolic down-regulation may be a useful therapeutic adjunct when tissue oxygen supply is restricted. We hypothesized that protein synthesis inhibition in a non-hibernating species should lower oxygen demand, resulting in aerobic metabolic rate depression at the whole animal level. We compared metabolic responses and measures of systemic oxygenation of conscious catheterized rats given either protein synthesis inhibition (PSI) agents or carrier controls (normal saline and DMSO). Core temperature was measured by implanted transmitters, and VO2 was determined in an open flow-through metabolic chamber at 25 degrees C. Mean arterial pressure MAP and heart rate HR were determined from arterial pressure transducer tracings; arterial blood gases and lactate were sampled every 15 min. PSI rats exhibited an immediate transient decline in VO2, followed by a secondary decline to new resting levels; VO2 for the first hour was significantly lower than that for rats receiving DMSO vehicle. Unlike controls, PSI rats showed an overall 3.5 degrees C decline in core temperature, coupled with increased arterial lactate. There were no differences in MAP and HR of PSI rats compared to controls. Although hypothermic response to toxic agents typical of rodents cannot be ruled out completely, the mild hypothermia and reduced VO2 exhibited by PSI rats may be partially attributed to the action of protein synthesis agents.

Role of interleukin-1 beta, interleukin-6 and macrophage inflammatory protein-1 beta in prostaglandin-E2-induced hyperthermia in rats

The purpose of this study was to investigate the role of pyrogenic cytokines, such as IL-1 beta, IL-6 and MIP-1 beta, in the mechanisms underlying the hyperthermic response of rats to central injection of PGE2. Thus, specific murine neutralizing antibodies against these cytokines were micro-injected directly into the anterior hypothalamic, preoptic area (AH/POA) of unrestrained rats just before intracerebroventricular injection of PGE2. The significant hyperthermia induced by PGE2 was markedly suppressed by micro-injection of anti-IL-6 and partially attenuated by anti-IL-1 beta. However, the micro-injection of anti-MIP-1 beta failed to alter the hyperthermic response. The results indicate that PGE2-induced hyperthermia is presumably mediated through actions of IL-6 on the thermosensitive cells of the AH/POA and confirm that distinct and alternate pathways exist in the rat brain for the induction of fever.

Fever: causes and consequences

The present review distinguishes pathogenic, neurogenic, and psychogenic fever, but focuses largely on pathogenic fever, the hallmark of infectious disease. The data presented show that a complex cascade of events underlies pathogenic fever, which in broad outline - and with frank disregard of contradictory data - can be described as follows. An invading microorganism releases endotoxin that stimulates macrophages to synthesize a variety of pyrogenic compounds called cytokines. Carried in blood, these cytokines reach the perivascular spaces of the organum vasculosum laminae terminalis (OVLT) and other regions near the brain where they promote the synthesis and release of prostaglandin (PGE2). This prostaglandin then penetrates the blood-brain barrier to evoke the autonomic and behavioral responses characteristic of fever. But then once expressed, fever does not continue unchecked; endogenous antipyretics likely act on the septum to limit the rise in body temperature. The present review also examines fever-resistance in neonates, the blunting of fever in the aged, and the behaviorally induced rise in body temperature following infection in ectotherms. And finally it takes up the question of whether fever enhances immune responsiveness, and through such enhancement contributes to host survival.

Fever evoked by macrophage inflammatory protein-1 (MIP-1) injected into preoptic or ventral septal area of rats depends on intermediary protein synthesis

Macrophage inflammatory protein-1 (MIP-1), a novel cytokine composed of alpha/beta subunits, is released from macrophages during infection. MIP-1 injected intravenously in the rabbit or into the anterior hypothalamic, preoptic area (AH/POA) of the rat causes an intense fever, which is not blocked by prostaglandin synthesis inhibitors, ibuprofin or indomethacin, respectively. The purpose of this study was to determine the role of de novo protein synthesis on the fever evoked by MIP-1 applied to thermosensitive cells of the AH/POA. Guide cannulae were implanted bilaterally above the AH/POA or ventral septal area (VSA) and medially above the third cerebral ventricle in each of 11 male Sprague-Dawley rats. Following postoperative recovery, body temperature (Tb) was monitored by a colonic thermistor probe. The bilateral microinjection of MIP-1 in a dose of 14 pg per 0.5 microliters into the AH/POA caused a biphasic elevation in Tb to 0.9 +/- 0.2 degrees C within 1.0 h, which reached 1.5 +/- 0.2 degrees C within 3.0 h, and persisted for over 6.0 h. An identical injection of MIP-1 into the VSA increased Tb biphasically to 0.1 +/- 0.1 degrees C within 1.0 h and to 0.8 +/- 0.3 degrees C within 3.0 h. The infusion into the third ventricle of 80 micrograms/10 microliters of the inhibitor of protein synthesis, anisomycin, either 10 or 30 min before the microinjection of MIP-1 into the AH/POA, attenuated significantly the rise in Tb for 1.0 to 3.0 h or 2.5 to 3.0 h, respectively. These results coincide with the earlier finding that anisomycin inhibits both endotoxin- and IL-1 beta-induced fevers.(ABSTRACT TRUNCATED AT 250 WORDS)

Action of cyclosporine on fever induced in rats by intrahypothalamic injection of macrophage inflammatory protein-1 (MIP-1)

In order to examine the central mechanism of pyrexic action of macrophage inflammatory protein-1 (MIP-1), guide cannulae for injections were implanted stereotaxically just above the anterior hypothalamic, pre-optic area of the rat. Following post-operative recovery, the body temperature (Tb) of each rat was monitored by a colonic thermistor probe over a test interval of 4 hr. Injected in a 0.5 microliter volume into the anterior hypothalamic pre-optic area, MIP-1, in a dose of 5.6 or 28 pg, evoked an intense fever with a latency of 15-30 min. Pretreatment of the anterior hypothalamic pre-optic area with 1.0 microgram cyclosporine A (CsA), delivered in a volume of 0.5 microliter, delayed the onset of the fever induced by 5.6 pg MIP-1, injected at the same site. Similar injections of CsA also attenuated significantly the magnitude of the fever, following either the 5.6 or 28 pg dose of MIP-1. As a systemic control, 15 mg/kg CsA was administered intraperitoneally, 2.0 hr before the injection of MIP-1 in the anterior hypothalamic pre-optic area. By this route, CsA also delayed the rise in temperature but the fever induced by 5.6 pg MIP-1 reached the same magnitude as that after MIP-1 alone. Conversely, intraperitoneal administration of CsA did not antagonize the pyrexic response evoked by 28 pg MIP-1, injected into the anterior hypothalamic pre-optic area, but rather enhanced the fever.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypothalamic indomethacin fails to block fever induced in rats by central macrophage inflammatory protein-1 (MIP-1)

This investigation examined the extent to which the activity of a prostaglandin (PG) in the anterior hypothalamic, preoptic area (AH/POA) of the rat plays a role in the intense fever induced by macrophage inflammatory protein-1 (MIP-1) applied directly to this anatomical region. For the microinjection of both a PG synthesis inhibitor, indomethacin, and MIP-1 into sites within the AH/POA, guide cannulae were implanted chronically just above this pyrogen-reactive region. Postoperatively, the body temperature (Tb) of each rat was monitored in the unrestrained condition by means of a colonic thermistor probe. MIP-1 microinjected into the AH/POA in a 0.5-microliter volume evoked a biphasic fever when given in a dose of 5.6 picograms (pg) and a monophasic fever in a dose of 28 pg. The latency of the febrile response was ordinarily 15 min with an asymptote of 1.5 degrees C reached ordinarily within 2.0-2.5 h. When the cytokine-reactive site in the AH/POA was pretreated with indomethacin microinjected in an efficacious dose of 0.5 microgram, the MIP-1 fever evoked by 5.6 pg was not inhibited. Further, pretreatment of AH/POA sites with indomethacin prior to the higher 28-pg dose of MIP-1 delayed the febrile response but did not block it. As a systemic control, indomethacin also was administered intraperitoneally in a dose of 5.0 mg/kg, again 15 min prior to the microinjection of MIP-1 into the AH/POA. In this case, indomethacin only partially attenuated but did not block the fever evoked by either dose of MIP-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Macrophage inflammatory protein-1: unique action on the hypothalamus to evoke fever

Macrophage inflammatory protein (MIP-1) administered systemically causes a fever not blocked by a prostaglandin (PGE) synthesis inhibitor. The purpose of this study was to examine the central mechanism of pyrexic action of this cytokine in the unrestrained rat. After guide cannulae for microinjection were implanted stereotaxically just above the anterior hypothalamic preoptic area (AH/POA), the body temperature of each rat was monitored by a colonic thermistor probe. Saline control vehicle or MIP-1 was microinjected into the AH/POA in one of eight concentrations ranging from 0.0028-9.0 ng per 0.5 mu 1 volume. MIP-1 induced a biphasic or monophasic fever of short latency characterized by an inverse dose-response curve. The potency of MIP-1 was in the femtomolar (10(-15)) range with the lowest dose of 0.028 ng producing a fever of over 2.0 degrees C with a latency of 15 min or less. To determine whether a PGE mediates MIP-1 fever, indomethacin was administered either intraperitoneally in a dose of 5.0 mg/kg or directly into the MIP-1 injection site in a dose of 0.5 microgram/0.5 mu 1, both injected 15 min before MIP-1. Pretreatment of the injection site in the AH/POA with indomethacin failed to prevent the febrile response evoked by MIP-1 injected at the same locus. Further, the dose of systemic indomethacin, which blocks PGE-induced fever in the rat, attenuated only partially the MIP-1 fever. The results demonstrate that MIP-1 is the most potent endopyrogen discovered thus far, and that its action is directly in the region of the hypothalamus which contains both thermosensitive and pyrogen-sensitive neurons. The local action of MIP-1 on cells of the AH/POA in evoking fever is unaffected by the PGE inhibitor which indicates, therefore, that a cellular mechanism operates in the hypothalamus to evoke fever independently of the central synthesis of a PGE.

Characteristics of pyrogen fevers are altered in the aged rabbit

The febrile response to both intravenous and intracerebral administration of pyrogens was investigated in young and old male New Zealand White rabbits. Intravenous bacterial pyrogen evoked biphasic fevers in both groups of animals. However, the fevers in the group of older rabbits were significantly less than in younger animals. In contrast, intravenous injection of endogenous pyrogen produced identical fevers in the two groups. Bacterial and endogenous pyrogens injected into a lateral cerebral ventricle evoked marked febrile responses of long duration in both young and old rabbits. The responses of the old rabbits were significantly less than those of the younger ones. Finally, direct microinjection of prostaglandin E1 into tissue sites within the anterior hypothalamic preoptic area elicited short latency hyperthermic responses which were significantly less in the older rabbits. Analysis of ear skin temperatures during fever demonstrated that some of the differences may, in part, be due to altered vasoconstrictor responses in the peripheral vasculature. Thus, these data indicate that the febrile response is altered with increasing age in the rabbit.

Changes in body temperature after administration of antipyretics, LSD, delta 9-THC and related agents: II

Antipyretics, in particular acetaminophen, aspirin and ibuprofen, constitute the single most important class of drugs used therapeutically for an effect on body temperature. Hallucinogens exert prominent actions on the central nervous system, and it is not surprising that, like so many other centrally-acting agents, they too often affect temperature. This compilation primarily covers the considerable amount of data published from 1981 through 1985 on the interactions of these drugs and thermoregulation, but data from many earlier papers not included in a previous compilation are also tabulated. The effects of agents not classically considered as antipyretics on temperatures of febrile subjects are also covered. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent.

Changes in body temperature after administration of adrenergic and serotonergic agents and related drugs including antidepressants: II

This survey continues a second series of compilations of data regarding changes in body temperature induced by drugs and related agents. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on the presence of special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent. Most of the papers were published from 1980 to 1984 but data from many earlier papers are also tabulated.

alpha-Melanocyte-stimulating hormone infused ICV fails to affect body temperature or endotoxin fever in the cat

Permanent cannulae for intracerebroventricular (ICV) infusion were implanted bilaterally in cats following stereotaxic procedures. After colonic temperature was recorded for a one-hour baseline, a 300 microliter ICV infusion was given of CSF control vehicle, 1:100 dilution of W3110 E. coli endotoxin (10(8) organisms/ml) or alpha-melanocyte-stimulating hormone (alpha-MSH) in one of seven doses ranging from 50.0 ng to 50.0 micrograms. Whereas ICV E. coli always induced an intense and prolonged fever of rapid onset, alpha-MSH infused similarly was essentially without effect on the deep body temperature of the normothermic cat. When each of the doses of alpha-MSH was infused ICV, either during the rising phase of an E. coli fever or after the febrile response had reached its asymptote, the core temperature of the cat was unaffected. Similarly, a mixture of E. coli combined with alpha-MSH given ICV failed to alter the characteristics of the rapidly developing fever produced in the cat by this endotoxin. On the other hand, either excess Ca++ ions (50 mM) given ICV or the antipyretic drug. Dipyrone, administered systematically during the course of an endotoxin fever effectively attenuated the animal's elevated body temperature. These results demonstrate that alpha-MSH is apparently neither involved in the central mechanisms underlying normal thermoregulation, nor does it act as an endogenous antipyretic in the cat as has been postulated in another species.

Changes in body temperature after administration of acetylcholine, histamine, morphine, prostaglandins and related agents: II

This survey continues a second series of compilations of data regarding changes in body temperature induced by drugs and related agents. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on the presence of special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent. Most of the papers were published since 1979, but data from many earlier papers are also tabulated.

Changes in body temperature after administration of amino acids, peptides, dopamine, neuroleptics and related agents: II

This survey begins a second series of compilations of data regarding changes in body temperature induced by drugs and related agents. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on the presence of special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent. Most of the papers were published since 1978, but data from many earlier papers are also tabulated.

Inhibition of brain protein synthesis suppresses the release of prostaglandin E2 in febrile rabbits

In rabbits the third cerebral ventricle was perfused using a push-pull cannula. Prostaglandin E2 concentration in the perfusate was measured by radioimmunoassay. Prostaglandin concentration rose during fever induced by an intraventricular injection of endogenous pyrogen. Both fever and the increased prostaglandin concentration were suppressed by the intraventricular injection of 100 micrograms of the protein synthesis inhibitor, anisomycin. A possible interpretation of the findings is that anisomycin inhibits the formation of phospholipase A2. If this is true, the implication is that phospholipase A2 has a rapid turnover in brain.

Central effects of dibutyryl cyclic AMP and GMP on the temperature in conscious rabbits

Intracerebroventricular (i.c.v.) administration of dibutyryl cyclic AMP (Db-cAMP)- and dibutyryl cyclic GMP (Db-cGMP)-induced hyperthermia in rabbits. Central administration of 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 62711), a selective inhibitor of cAMP phosphodiesterase, only accentuated the hyperthermia due to Db-cAMP whereas a selective inhibitor of cGMP phosphodiesterase, 2-O-proproxyphenyl-8-azapurin-6-one (M and B 22948), only potentiated the hyperthermia caused by Db-cGMP. The hyperthermia due to Db-cAMP and Db-cGMP was not mediated through prostaglandins (PG). In contrast, central administration of an alpha-adrenergic receptor antagonist, phenoxybenzamine, or a beta-adrenergic receptor antagonist, sotalol, only attenuated the hyperthermic response to Db-cAMP while a cholinergic muscarinic receptor antagonist, atropine, specifically antagonized Db-cGMP-induced hyperthermia. I.c.v. administration of a protein synthesis inhibitor, anisomycin, did inhibit the hyperthermia due to Db-cAMP and Db-cGMP. Opiate antagonist, naloxone, did not antagonize Db-cAMP- and Db-cGMP-induced hyperthermia. These results suggest that a protein mediator is implicated in the induction of hyperthermia by Db-cAMP and Db-cGMP and that cAMP and cGMP may be involved through alpha/beta-adrenergic and cholinergic muscarinic receptors respectively in the central regulation of heat production/conservation in rabbits.

Prostacyclin-induced hyperthermia: implication of a protein mediator

Intracerebroventricular administration of prostacyclin (PGI2) at room temperature (21 degrees C) induced dose-related hyperthermia in rabbits and also produced hyperthermia at low (4 degrees C) and high (30 degrees C) ambient temperatures. The PGI2-induced hyperthermia was not mediated by its stable metabolite 6-keto prostaglandin F1 alpha. Of the three anion transport systems (iodide, hippurate and liver-like) present in the choroid plexus, only the liver transport system seems to be important to central inactivation of pyrogen, prostaglandin E2 (PGE2) and the PGI2. Iodipamide (an inhibitor of the liver transport system) augmented the hyperthermia produced by PGI2, PGE2 and pyrogen. Phenoxybenzamine and pimozide had no thermolytic effect on PGI2-induced hyperthermia. After norepinephrine (NE) and dopamine levels were depleted by 6-hydroxydopamine, PGI2 still induced hyperthermia. Indomethacin and SC-19220 (a PG antagonist) did not antagonize PGI2-induced hyperthermia. Furthermore, the hyperthermia due to PGI2 was not accentuated by theophylline. In contrast, the hyperthermic response to PGI2 was attenuated by central administration of the protein synthesis inhibitor, anisomycin. These results indicate that PGI2-induced hyperthermia is not mediated by NE, dopamine, PGS, cyclic AMP, but, rather, that a protein mediator is implicated in the induction of fever by PGI2.

Inhibition, by trichothecene antibiotics, of brain protein synthesis and fever in rabbits

1. To test further the hypothesis that brain protein synthesis is necessary for fever, three structurally similar trichothecene antibiotics were injected into the cerebral ventricles of rabbits. They were 3,15-diacetoxy-12-hydroxytrichothec-9-ene (DAHT), 3,15-didesacetyl-calonectrin (DDAC) and T-2 toxin. Their actions on hypothalamic incorporation of [14C]leucine and fever were compared. 2. DDAC (60 micrograms) and T-2 toxin (10 micrograms) strongly inhibited leucine incorporation and fever. DAHT (60 micrograms) did not diminish fever and had a smaller effect upon leucine incorporation. 3. The findings strengthen considerably earlier suggestions that brain protein synthesis is an essential step in pyrogenesis.