Enhanced lipid utilization is coupled to the sickness responses triggered by lipopolysaccharide.

Sickness symptoms exerted via inflammatory responses occur in several infectious and chronic diseases. A growing body of evidence suggests that altered nutrient availability and metabolism are tightly coupled to inflammatory processes. However, the relationship between metabolic shifts and the development of the sickness response has not been explored fully. Therefore, we aimed to evaluate metabolic phenotypes with a mouse model showing sickness symptoms via systemic administration of lipopolysaccharide (LPS) in the present study. LPS injection elevated the lipid utilization and circulating levels of fatty acids. It also increased the levels of ß-hydroxybutyric acid, a ketone body produced from fatty acids. We confirmed the functional connectivity between nutrient utilization and inflammatory responses and demonstrated enhanced lipid utilization in the hypothalamus providing insights into hypothalamic control of sickness responses. Collectively, these findings could help develop new therapeutic strategies to treat patients with severe sickness symptoms associated with infectious and chronic human diseases.

LPS-induced sickness behavior is not affected by selenium but is switched off by psychogenic stress in rats.

Sickness behavior (SB) is considered part of the adaptive behavioral and neuroimmune changes that occur in response to inflammatory processes. However, SB is a motivational state modulated by the environmental context. The objective of this study was to evaluate if selenium could ameliorate symptoms of SB and if stress would affect these responses. We induced SB in rats using lipopolysaccharide (LPS). We choose selenium based on our findings of LPS-exposure decreasing selenium levels in rats. We exposed these rats to a psychogenic stress and studied motivational modulation paradigms, such as cure of the organism, preservation of the species, and fight or flight. We studied ultrasonic vocalizations, open-field behaviors, body weight, and IL-1 beta and IFN-gamma serum levels. LPS-induced SB was evidenced by decreased motor/exploratory activity and increased proinflammatory mediators' levels. Selenium treatment did not exert beneficial effects on SB, revealing that probably the selenium deficiency was not related to SB. When analyzed with the stress paradigm, the behavior of rats was differentially affected. LPS did not affect behavior in the presence of stress. SB was abrogated during stressor events to prioritize survival behaviors, such as fight-or-flight. Contrarily, the association of LPS, selenium, and stress induced SB even during stressor events, revealing that this combination induced a cumulative toxic effect.

Trait-specific effects of exogenous triiodothyronine on cytokine and behavioral responses to simulated systemic infection in male Siberian hamsters.

Seasonal changes in day length enhance and suppress immune function in a trait-specific manner. In Siberian hamsters (Phodopus sungorus) winter-like short days (SDs) increase blood leukocyte concentrations and adaptive T cell dependent immune responses, but attenuate innate inflammatory responses to simulated infections. Thyroid hormone (TH) signaling also changes seasonally and has been implicated in modulation of the reproductive axis by day length. Immunologically, TH administration in long days (LD) enhances adaptive immune responses in male Siberian hamsters, mimicking effects of SDs. This experiment tested the hypothesis that T3 is also sufficient to mimic the effects of SD on innate immune responses. Adult male hamsters housed in LDs were pretreated with triiodothyronine (T3; 1 µg, s.c.) or saline (VEH) daily for 6 weeks; additional positive controls were housed in SD and received VEH, after which cytokine, behavioral, and physiological responses to simulated bacterial infection (lipopolysaccharide; LPS) were evaluated. SD pretreatment inhibited proinflammatory cytokine mRNA expression (i.e. interleukin 1ß, nuclear factor kappa-light-chain-enhancer of activated B cells). In addition, the magnitude and persistence of anorexic and cachectic responses to LPS were also lower in SD hamsters, and LPS-induced inhibition of nest building behavior was absent in SD. T3 treatments failed to affect behavioral (food intake, nest building) or somatic (body mass) responses to LPS in LD hamsters, but one CNS cytokine response to LPS (e.g., hypothalamic TNFα) was augmented by T3. Together these data implicate thyroid hormone signaling in select aspects of innate immune responses to seasonal changes in day length.

Lipopolysaccharide (LPS) induced sickness in early adolescence alters the behavioral effects of the short-chain fatty acid, propionic acid, in late adolescence and adulthood: Examining anxiety and startle reactivity.

Early life immune challenges are risk factors for neurodevelopmental disorders. In adolescence, they elicit behavioral symptoms that resemble clinical disorders. Stressors during this time may alter signaling from the gut microbiome, which increases the risk for psychiatric disorders. It was hypothesized that adolescent immune challenges may interact with a gut bacterial product, the short-chain fatty acid, propionic acid (PPA), to potentiate symptoms of anxiety and sensory abnormality. The present study investigated the effects of repeated lipopolysaccharide (LPS) exposure during early adolescence, on the behavioral effects of PPA in late adolescence and adulthood. Male adolescent rats were injected with LPS (0.2 mg/kg i.p.) or the vehicle on postnatal days (P) 28, P30, P32, and P34. They were later administered either PPA (500 mg/kg i.p.) or the vehicle during late adolescence on P40 and P43, and were subsequently tested on the light-dark anxiety test and acoustic startle response, respectively. In adulthood, the rats were again injected with PPA or the vehicle and tested on the light-dark and acoustic startle tasks on P74 and P77. The results of this study showed that LPS and PPA both decreased locomotor activity. PPA reduced vertical activity, percent prepulse inhibition, and acoustic startle response magnitude. LPS increased anxiogenic behaviors and induced a delayed increase in acoustic startle response magnitude in adulthood. Although no LPS and PPA interactions were found, the results of this study suggest that early adolescent immune activation can induce long-term behavioral changes that resemble the complex phenotypes of clinical disorders.

Flavonoid-Rich Fraction of Ocimum gratissimum Attenuates Lipopolysaccharide-Induced Sickness Behavior, Inflammatory and Oxidative Stress in Mice.

PURPOSE: Ocimum gratissimum L. leaves has been traditionally used for management of febrile illnesses and symptoms typified of sickness behavior. In this work we investigated the modulatory effect of flavonoid-rich fraction of O. gratissimum leaves (EAFOg) on sickness behavior, inflammatory and oxidative stress responses in LPS-challenged mice. METHOD: O. gratissimum leaf was first extracted with n-hexane, chloroform and methanol, and EAFOg was obtained by ethylacetate partitioning of a sequentially resultant methanol extract. The effect of EAFOg (25-100 mg/kg) on acute LPS-induced neurobehavioral impairment in an open field test (OFT) and depressive-like behavior in forced swimming test (FST) was investigated. Serum nitrite and TNF-α, as well as myeloperoxidase (MPO), malondialdehyde (MDA), and reduced glutathione (GSH) levels were determined in liver and brain tissues. RESULT: EAFOg prevented the reduction in locomotor and rearing activity in OFT and the increase in immobility time in FST. The fraction significantly attenuated the elevation of serum TNF- α and nitrite levels. EAFOg reversed LPS-induced increase in MDA, MPO, and nitrite levels and attenuated GSH depletion in liver and brain tissues of mice. CONCLUSION: Flavonoid-rich fraction of O. gratissimum leaf demonstrated significant modulation of LPS-induced sickness behavior, inflammatory and oxidative stress response in mice. This suggests an important therapeutic strategy in slowing down LPS-mediated hepatic and neuronal disease processes.

Bioactive phenolic fraction of Citrus maxima abate lipopolysaccharide-induced sickness behaviour and anorexia in mice: In-silico molecular docking and dynamic studies of biomarkers against NF-κB.

Sickness behaviour, fever, anxiety, anorexia and depression are interrelated phenomena. The citrus fruit peels offering significant low-cost nutritional dietary supplements due to its rejuvenating biological activities. The present study was undertaken to explore the beneficial effect of enriched phenolic fraction of peel (PFMC) in lipopolysaccharide (LPS)-induced sickness behaviour and anorexia in mice. Further, the HPTLC estimation of hesperidin, total phenolic and flavonoid content in PFMC were carried out. In silico molecular docking and dynamic studies of bioactive compounds against NF-κB (1NFK) were also performed. The amount of hesperidin was found to be 55.33 mg/g of PFCM as per the proposed HPTLC method. Total phenolic and flavonoid content was found to be 71 mg of gallic acid/g and 58.1 mg of quercetin/g of PFCM. The single dose of LPS (400 µg/kg, i.p) treatment exhibited significant reduction in food, water intake and behavioural tests and tissue GSH, whereas significantly higher levels of tissue LPO and plasma IL-6 levels compared to normal control. Pre-treatment of PFCM (100 and 200 mg/kg, i.p) and dexamethasone (1 mg/kg, i.p) showed significantly altered the LPS-induced behavioural, anorexia and biochemical parameters. The bioactive compounds such as hesperidin, naringenine, naringin and dexamethasone showed docking score of -22.49, -21.99, -16.43 and -11.12 respectively against NF-κB (1NFK). Among tested bioactive compounds, naringin clearly exhibited higher inhibiting property on target protein structure. The protective effect of PFCM in LPS-induced anorexia and sickness behaviour is due to its antioxidant, anti-inflammatory and appetizing activities, inhibiting IL-6 and NF-κB.

TRIF is a key inflammatory mediator of acute sickness behavior and cancer cachexia.

Hypothalamic inflammation is a key component of acute sickness behavior and cachexia, yet mechanisms of inflammatory signaling in the central nervous system remain unclear. Previous work from our lab and others showed that while MyD88 is an important inflammatory signaling pathway for sickness behavior, MyD88 knockout (MyD88KO) mice still experience sickness behavior after inflammatory stimuli challenge. We found that after systemic lipopolysaccharide (LPS) challenge, MyD88KO mice showed elevated expression of several cytokine and chemokine genes in the hypothalamus. We therefore assessed the role of an additional inflammatory signaling pathway, TRIF, in acute inflammation (LPS challenge) and in a chronic inflammatory state (cancer cachexia). TRIFKO mice resisted anorexia and weight loss after peripheral (intraperitoneal, IP) or central (intracerebroventricular, ICV) LPS challenge and in a model of pancreatic cancer cachexia. Compared to WT mice, TRIFKO mice showed attenuated upregulation of Il6, Ccl2, Ccl5, Cxcl1, Cxcl2, and Cxcl10 in the hypothalamus after IP LPS treatment, as well as attenuated microglial activation and neutrophil infiltration into the brain after ICV LPS treatment. Lastly, we found that TRIF was required for Ccl2 upregulation in the hypothalamus and induction of the catabolic genes, Mafbx, Murf1, and Foxo1 in gastrocnemius during pancreatic cancer. In summary, our results show that TRIF is an important inflammatory signaling mediator of sickness behavior and cachexia and presents a novel therapeutic target for these conditions.

Escitalopram or novel herbal treatments differentially alter cytokine and behavioral responses to immune challenge.

Studies suggest that inflammation is involved in the pathophysiology of depression. The present study examined the effects of the commonly used antidepressant escitalopram, in comparison with a novel herbal treatment (NHT) consisted of Crataegus pinnatifida, Triticum aestivum, Lilium brownii and Fructus Ziziphus jujuba, on cytokine and behavioral responses to an immune challenge. Escitalopram augmented lipopolysaccharide-induced tumor necrosis factor (TNF)-α peripheral secretion and induced a faster kinetics of interleukin-1ß secretion, while marginally reducing sickness behavior. NHT, on the other hand, completely abolished lipopolysaccharide-induced interleukin-1ß and TNFα peripheral secretion and diminished sickness behavior. These findings may have implications for the treatment of depressive symptoms associated with immune activation.

Systemic TNF-α produces acute cognitive dysfunction and exaggerated sickness behavior when superimposed upon progressive neurodegeneration.

Inflammation influences chronic neurodegeneration but its precise roles are not yet clear. Systemic inflammation caused by infection, trauma or co-morbidity can alter the brain's inflammatory status, produce acute cognitive impairments, such as delirium, and drive new pathology and accelerated decline. Consistent with this, elevated systemic TNF-α is associated with more rapid cognitive decline over 6months in Alzheimer's disease patients. In the current study we challenged normal animals and those with existing progressive neurodegeneration (ME7 prion disease) with TNF-α (i.p.) to test the hypothesis that this cytokine has differential effects on cognitive function, sickness behavior and features of underlying pathology contingent on the animals' baseline condition. TNF-α (50µg/kg) had no impact on performance of normal animals (normal brain homogenate; NBH) on working memory (T-maze) but produced acute impairments in ME7 animals similarly challenged. Plasma TNF-α and CCL2 levels were equivalent in NBH and ME7 TNF-challenged animals but hippocampal and hypothalamic transcription of IL-1ß, TNF-α and CCL2 and translation of IL-1ß were higher in ME7+TNF-α than NBH+TNF-α animals. TNF-α produced an exaggerated sickness behavior response (hypothermia, weight loss, inactivity) in ME7 animals compared to that in NBH animals. However a single challenge with this dose was not sufficient to produce de novo neuronal death, synaptic loss or tau hyperphosphorylation that was distinguishable from that arising from ME7 alone. The data indicate that acutely elevated TNF-α has robust acute effects on brain function, selectively in the degenerating brain, but more sustained levels may be required to significantly impact on underlying neurodegeneration.

Kamikihito Ameliorates Lipopolysaccharide-Induced Sickness Behavior via Attenuating Neural Activation, but Not Inflammation, in the Hypothalamic Paraventricular Nucleus and Central Nucleus of the Amygdala in Mice.

Sickness behavior is a series of behavioral and psychological changes that develop in those stricken with cancers and inflammatory diseases. The etiological mechanism of sickness behavior is not known in detail, and consequently there are no established standard therapies. Kamikihito (KKT), a Kampo (traditional Japanese herbal) medicine composed of 14 herbs, has been used clinically to treat psychiatric dysfunction. Previously, we found that KKT ameliorated sickness behavior in mice inoculated with murine colon 26 adenocarcinoma cells. In this study, we examined the effects of KKT on bacterial endotoxin lipopolysaccharide (LPS)-induced sickness behavior in mice. The administration of LPS caused the emotional aspects of sickness behavior, such as loss of object exploration, social interaction deficit, and depressive-like behavior. LPS also induced mRNA expression for cyclooxygenase (COX)-2, interleukin (IL)-1ß and IL-6, and increased the number of c-Fos immunopositive cells in the hypothalamus and amygdala. KKT ameliorated the behavioral changes and reversed the increases in c-Fos immunopositive cells in the two brain regions, but did not influence the mRNA expression. These results suggest that KKT ameliorates sickness behavior via the suppression of neural activation without anti-inflammatory effects, and that KKT has the potential to treat sickness behavior.

Effect of Embelin Against Lipopolysaccharide-induced Sickness Behaviour in Mice.

Sickness behaviour is a coordinated set of adaptive behavioural changes that develop in ill individuals during the course of an infection. It is relevant to understanding depression and some aspects of the suffering that in cancer. Embelin has been reported to possess antiinflammatory, neuroprotective and anxiolytic assets and has been shown to inhibit nuclear factor κB pathway and cytokine production. The present study was undertaken to investigate the effect of embelin isolated from Embelia ribes Burm in lipopolysaccharide (LPS)-induced sickness behaviour in mice. Adult male Swiss albino mice were pre-treated with embelin (10 and 20 mg/kg, p.o.) or dexamethasone (1 mg/kg, i.p.) for 3 days and then challenged with LPS (400 µg/kg, i.p.). At different time intervals of post-LPS challenge, sickness behaviour was evaluated in the animals by battery of behavioural tests (plus maze, open field, light-dark box, forced swim, social behaviour assessment, sucrose preference and food and water intake). Levels of oxidative stress makers (reduced glutathione and lipid peroxidation) in mice brain were also analysed. LPS induced behavioural alterations, anhedonia and anorexia, in mice. Pre-treatment with embelin attenuated behavioural changes induced by LPS. In addition, embelin prevented anhedonia, anorexia and ameliorated brain oxidative stress markers. The experimental outcomes of the present study demonstrated protective effect of embelin in LPS-induced sickness behaviour in mice. Copyright © 2016 John Wiley & Sons, Ltd.

Maternal Fish Oil Supplementation Affects the Social Behavior, Brain Fatty Acid Profile, and Sickness Response of Piglets.

BACKGROUND: Maternal dietary docosahexaenoic acid (DHA) intake is thought to affect development in the offspring. OBJECTIVE: We assessed the impact of maternal dietary DHA on behavior, brain fatty acid (FA) profile, and sickness response of offspring in pigs, a pertinent model for human nutrition. METHODS: Sows (n = 24) were fed a diet with DHA-rich fish oil (FO) (20 g/kg) or high-oleic acid sunflower oil (HOSF) (20 g/kg) from day 61 of gestation through lactation. At 4 wk of age, 4 piglets per litter were weaned and mixed with piglets from other litters. Behavior was observed in 4- to 8-wk-old piglets, and brain FA composition was analyzed at 4 (n = 15) and 14 (n = 12) wk. Thirteen-week-old piglets (n = 48) were subjected to a lipopolysaccharide (LPS) challenge. Body temperature, plasma cytokines, and motivation to approach a familiar human, indicative of a sickness response, were measured. RESULTS: FO-fed pigs displayed more social activities (+262%, P = 0.02), played more (+61%, P = 0.03), and tended to show fewer oral manipulative behaviors directed at pen mates (-25%, P = 0.06) than did HOSF-fed pigs up to 4 wk after weaning. Brain DHA concentrations were higher in FO- than in HOSF-fed pigs up to 10 wk after supplementation (+10-50%, P < 0.001), although differences declined with age. Body temperature (P < 0.001) and tumor necrosis factor α and interferon Î³ concentrations (P < 0.05) increased after LPS injection, but no diet effect was found (P > 0.10). LPS-treated pigs were less likely to approach the human than saline-treated pigs in the HOSF-fed (-29%, P = 0.0003), but not in the FO-fed group (-13%, P = 0.11). CONCLUSIONS: Maternal DHA beneficially affected offspring social behavior after weaning and mildly attenuated sickness behavior after an inflammatory challenge in pigs. These behavioral changes may be mediated by increased brain DHA proportions.

Dissociation between sickness behavior and emotionality during lipopolysaccharide challenge in lymphocyte deficient Rag2(-/-) mice.

Inflammatory diseases are highly associated with affective disorders including depression and anxiety. While the role of the innate immune system on emotionality has been extensively studied, the role of adaptive immunity is less understood. Considering that chronic inflammatory conditions are mediated largely by maladaptive lymphocyte function, the role of these cells on brain function and behavior during inflammation warrants investigation. In the present study we employed mice deficient in lymphocyte function and studied behavioral and inflammatory responses during challenge with bacterial lipopolysaccharides (LPS). Rag2(-/-) mice lacking mature lymphocytes were susceptible to death under sub-septic (5 mg/kg) doses of LPS and survived only to moderate (1 mg/kg) doses of LPS. Under these conditions, they displayed attenuated TNF-alpha responses and behavioral symptoms of sickness when compared with immunocompetent mice. Nevertheless, Rag2(-/-) mice had protracted motivational impairments after recovery from sickness suggesting a specific function for lymphocytes on the re-establishment of motivational states after activation of the innate immune system. The behavioral impairments in Rag2(-/-) mice were paralleled by an elevation in plasma corticosterone after behavioral tests. These results provide evidence that the absence of adaptive immunity may be associated with emotional deficits during inflammation and suggest that depressive states associated with medical illness may be mediated in part by impaired lymphocyte responses.

Synergistic effects of NOD1 or NOD2 and TLR4 activation on mouse sickness behavior in relation to immune and brain activity markers.

Toll-like receptors (TLRs) and nuclear-binding domain (NOD)-like receptors (NLRs) are sensors of bacterial cell wall components to trigger an immune response. The TLR4 agonist lipopolysaccharide (LPS) is a strong immune activator leading to sickness and depressed mood. NOD agonists are less active but can prime immune cells to augment LPS-induced cytokine production. Since the impact of NOD and TLR co-activation in vivo has been little studied, the effects of the NOD1 agonist FK565 and the NOD2 agonist muramyl dipeptide (MDP), alone and in combination with LPS, on immune activation, brain function and sickness behavior were investigated in male C57BL/6N mice. Intraperitoneal injection of FK565 (0.001 or 0.003mg/kg) or MDP (1 or 3mg/kg) 4h before LPS (0.1 or 0.83mg/kg) significantly aggravated and prolonged the LPS-evoked sickness behavior as deduced from a decrease in locomotion, exploration, food intake and temperature. When given alone, FK565 and MDP had only minor effects. The exacerbation of sickness behavior induced by FK565 or MDP in combination with LPS was paralleled by enhanced plasma protein and cerebral mRNA levels of proinflammatory cytokines (IFN-γ, IL-1ß, IL-6, TNF-α) as well as enhanced plasma levels of kynurenine. Immunohistochemical visualization of c-Fos in the brain revealed that NOD2 synergism with TLR4 resulted in increased activation of cerebral nuclei relevant to sickness. These data show that NOD1 or NOD2 synergizes with TLR4 in exacerbating the immune, sickness and brain responses to peripheral immune stimulation. Our findings demonstrate that the known interactions of NLRs and TLRs at the immune cell level extend to interactions affecting brain function and behavior.

Transgenic increase in n-3/n-6 fatty acid ratio protects against cognitive deficits induced by an immune challenge through decrease of neuroinflammation.

Polyunsaturated fatty acids (PUFAs) display immunomodulatory properties in the brain, n-3 PUFAs being able to reduce inflammation whereas n-6 PUFAs are more pro-inflammatory. It has been extensively demonstrated that exposure to a peripheral immune challenge leads to the production and release of inflammatory mediators in the brain in association with cognitive deficits. The question arises whether n-3 PUFA supplementation could downregulate the brain inflammatory response and subsequent cognitive alterations. In this study, we used a genetically modified mouse line carrying the fat-1 gene from the roundworm Caenorhabditis elegans, encoding an n-3 PUFA desaturase that catalyzes conversion of n-6 into n-3 PUFA. Consequently, these mice display endogenously elevated n-3 PUFA tissue contents. Fat-1 mice or wild-type (WT) littermates were injected peripherally with lipopolysaccharide (LPS), a bacterial endotoxin, to induce an inflammatory episode. Our results showed that LPS altered differently the phenotype of microglia and the expression of cytokines and chemokines in Fat-1 and WT mice. In Fat-1 mice, pro-inflammatory factors synthesis was lowered compared with WT mice, whereas anti-inflammatory mechanisms were favored 24 h after LPS treatment. Moreover, LPS injection impaired spatial memory in WT mice, whereas interestingly, the Fat-1 mice showed normal cognitive performances. All together, these data suggest that the central n-3 PUFA increase observed in Fat-1 mice modulated the brain innate immune system activity, leading to the protection of animals against LPS-induced pro-inflammatory cytokine production and subsequent spatial memory alteration.

Inflammation and neural signaling: etiologic mechanisms of the cancer treatment-related symptom cluster.

PURPOSE OF REVIEW: Cancer patients undergoing treatment with cytotoxic chemotherapeutic agents (CCAs) often experience a cluster of treatment-related symptoms, which include fatigue, loss of appetite, disturbed sleep, depressed mood, cognitive difficulties, and changes in body composition. This symptom cluster collectively referred to herein as cancer treatment-related symptoms (CTRSs) decrease quality of life, and physical and social functioning. The preclinical and clinical studies described in this review represent important progress in understanding potential underlying mechanisms of CTRS. RECENT FINDINGS: Recent studies support a role for CCA-induced interleukin-1ß (IL-1ß) signaling in the cause of CTRS. CCAs may share a common ability to activate intracellular stress response pathways to trigger the synthesis, processing, and release of IL-1ß from immune cells. Fatigue, sleep disturbance, and cognitive difficulties in cancer patients exposed to CCAs correlate with plasma levels of IL-6, IL-1 receptor antagonist, and soluble tumor necrosis factor receptor-I/II, surrogate markers of IL-1ß-mediated central nervous system (CNS) inflammation. Additional preclinical work suggests IL-1ß-mediated CNS inflammation may cause CTRS by altering hypothalamic and hippocampal functioning. SUMMARY: Although additional research is necessary to further establish the link between CCA exposure, IL-1ß-mediated inflammatory processes and CTRS, these data provide hints for future studies and therapeutic approaches in ameliorating these symptoms in cancer patients.

L-NAME cotreatment did prevent neither mitochondrial impairment nor behavioral abnormalities in adult Wistar rats treated with vitamin A supplementation.

Vitamin A has been characterized as a potential neurotoxin, because ingestion of such vitamin - or its derivatives, the retinoids - at moderate to high doses elicits a myriad of deleterious effects, from acute intoxication involving head-ache, confusion, and 'pseudo tumor cerebri' to chronic, and perhaps irreversible, abnormalities, including irritability, anxiety, depression, and suicide ideation. Nevertheless, it still remains to be found the mechanism by which vitamin A induces cognitive decline. Based on the fact that vitamin A at clinical doses is a potent pro-oxidant agent to the central nervous system, we performed the present work to analyze whether a cotreatment with L-NAME at 30 mg/kg (four times a week) was able to prevent (or minimize) the biochemical and/or behavioral disturbances resulting from a 28-day daily supplementation with retinol palmitate at doses from 1000 to 9000 IU/kg/day. Then, we investigated mitochondrial function, redox parameters, and the levels of proteins potentially involved in neurodegenerative events, as for instance α-synuclein and receptor for advanced glycation endproducts. Besides, monoamine oxidase enzyme activity was quantified in this work. We observed that L-NAME cotreatment was not completely effective in preventing the redox disturbances induced by vitamin A supplementation. Moreover, L-NAME cotreatment did not affect the behavioral deficits elicited by vitamin A supplementation. We conclude that other parameters rather than NO levels or its derivatives, as for example ONOO(-), take a more important role in mediating the negative effects triggered by vitamin A supplementation.

Fever, sickness behavior, and expression of inflammatory genes in the hypothalamus after systemic and localized subcutaneous stimulation of rats with the Toll-like receptor 7 agonist imiquimod.

The Toll-like receptor 7 (TLR7) agonist imiquimod is used for topical treatment of skin cancers. We studied the consequences of injections of imiquimod into a subcutaneous (s.c.) air pouch or of intraperitoneal (i.p.) injections on the manifestation of fever, sickness behavior, and the peripheral and brain-intrinsic induction of a variety of inflammatory molecules. Rats were given imiqimod s.c. or i.p. (1 or 5 mg/kg). Body temperature, motor activity, and food and water intake were recorded by telemetric devices. Peripheral and brain-intrinsic induction of inflammatory mediators was analyzed by real-time polymerase chain reaction (RT-PCR), bioassays, enzyme-linked immunosorbent assays (ELISAs), and immunohistochemistry. Imiquimod is the first TLR-agonist to produce more potent effects with s.c. than i.p. administration. Peripheral induction of interferons (IFNs) and putative circulating pyrogens corresponded to the magnitude of the illness responses. In the brain, an expression of cytokines (TNFα, IL-1ß, and IL-6) and inducible forms of enzymes for prostaglandin E2 synthesis (COX-2 and mPGES) occurred, which was accompanied by a moderate activation of the transcription factors NFκB and STAT3, and a strong activation of the transcription factor NF-IL6, in cells of specific areas with an open blood-brain barrier. These inflammatory responses noted within the brain were more marked after s.c. administration, than i.p. administration of imiquimod. At a dose of 5 mg/kg, imiquimod causes rather moderate brain-inflammatory responses, which are related to peripheral IFN-expression and possibly mediated by brain-intrinsic activation of NF-IL6 and induction of a proinflammatory cocktail. The lack of a septic-like state in imiquimod-treated rats reinforces the therapeutic use of this drug.

The endocannabinoid arachidonylethanolamide attenuates aspects of lipopolysaccharide-induced changes in energy intake, energy expenditure and hypothalamic Fos expression.

Arachidonylethanolamide (AEA), an endocannabinoid, regulates both appetite and the immune system. The present study investigated in the rat the ability of AEA (1mg/kg, s.c.) to attenuate the lipopolysaccharide (LPS)-induced (100µg/kg, i.p.) changes in metabolic indices and Fos expression within hypothalamic and mesolimbic systems. AEA attenuated LPS-induced fever and hypophagia, abolished LPS-induced decreases in Fos expression within the arcuate and ventromedial nucleus of the hypothalamus, while both AEA and LPS independently increased Fos expression within the nucleus accumbens. These results highlight the importance of hypothalamic and mesolimbic systems in the regulation of appetite and energy partitioning.

Sickness behaviors following medial frontal cortical contusions in male rats.

Behaviors associated with sickness (food consumption, weight maintenance, exploratory activity and grooming frequency) were examined on post-surgical days 1, 3, 5, 7 and 9 in male rats treated with progesterone (4 mg/kg) and/or vehicle. Rats with medial frontal cortex contusions showed reduced food consumption on days 1 and 3 (p < 0.01), reduced weight maintenance on days 1, 3, 5, 7 and 9 (p < 0.01), reduced grooming frequency on day 1 (p < .01), and reduced exploratory activity on day 1 (p < 0.01), after injury compared to sham rats. Contusion induced behaviors were not attenuated with 5 days of progesterone treatment (p > 0.05). Progesterone did reduce lesion size at 9 days after injury (p < 0.05). Our results suggest sickness behaviors occur after traumatic brain injury and that they might not respond to some neurosteroidal agents.