CD38 Correlates with an Immunosuppressive Treg Phenotype in Lupus-Prone Mice.

CD38 is a transmembrane glycoprotein expressed by T-cells. It has been reported that patients with systemic lupus erythematosus (SLE) showed increased CD38+CD25+ T-cells correlating with immune activation and clinical signs. Contrariwise, CD38 deficiency in murine models has shown enhanced autoimmunity development. Recent studies have suggested that CD38+ regulatory T-cells are more suppressive than CD38- regulatory T-cells. Thus, we have suggested that CD38 overexpression in SLE patients could play a role in regulating immune activation cells instead of enhancing it. This study found a correlation between CD38 with FoxP3 expression and immunosuppressive molecules (CD69, IL-10, CTLA-4, and PD-1) in T-cells from lupus-prone mice (B6.MRL-Faslpr/J). Additionally, B6.MRL-Faslpr/J mice showed a decreased proportion of CD38+ Treg cells regarding wild-type mice (WT). Furthermore, Regulatory T-Cells (Treg cells) from CD38-/- mice showed impairment in expressing immunosuppressive molecules and proliferation after stimulation through the T-cell receptor (TCR). Finally, we demonstrated an increased ratio of IFN-γ/IL-10 secretion in CD38-/- splenocytes stimulated with anti-CD3 compared with the WT. Altogether, our data suggest that CD38 represents an element in maintaining activated and proliferative Treg cells. Consequently, CD38 could have a crucial role in immune tolerance, preventing SLE development through Treg cells.

Maternal behavior, novelty confrontation, and subcortical c-Fos expression during lactation period are shaped by gestational environment.

The environmental context during gestation may modulate the postpartum variations in maternal behaviors observed within different animal species. Most of our experimental knowledge on this phenomenon and its physiological effects have been gained by confronting the pregnant mother with stressful situations, with the consensual results indicating a reduced maternal behavior and a hyper reactivity of stress-related neural paths. Here, in contrast, by exposing nulliparous rats strictly during pregnancy to a standard laboratory environment (STD) or a highly stimulating sensory and social environment (EE), we investigated the hypothesis that subjects frequently exposed to social stimuli and novel situations during pregnancy will show postpartum changes in subcortical brain areas' activity related to the processing of social stimuli and novelty, such that there will be modifications in maternal behavior. We found that EE mothers doubled the levels of licking and grooming, and active hovering over pups during the first postpartum week than STD dams, without a difference in the time of contact with the pups. Associated with these behaviors, EE dams showed increased c-Fos immunoreaction in hypothalamic nuclei and distinct responses in amygdalar nuclei, than STD dams. In the maternal defensive test, EE dams tripled the levels of aggressive behaviors of the STD rats. Additionally, in two different tests, EE mothers showed lower levels of postpartum anxiety-like behaviors when confronted with novel situations. Our results demonstrate that the activity of brain areas related to social behavior is adaptable by environmental circumstances experienced during gestation, presumably to prepare the progeny for these particular conditions.

Increased alcohol consumption in sleep-restricted rats is mediated by delta FosB induction.

The reduction of sleep hours is a public health problem in contemporary society. It is estimated that humans sleep between 1.5 and 2 h less, per night, than 100 years ago. The reduction of sleep hours is a risk factor for developing cardiovascular, metabolic, and psychiatric problems. Previous studies have shown that low sleep quality is a factor that favors relapse in addicted patients. In rodents, sleep deprivation increases the preference for methylphenidate and the self-administration of cocaine. However, it is unknown whether chronic sleep restriction induces voluntary alcohol consumption in rats and whether alcohol intake is associated with delta FosB expression in the brain reward circuit. Potentially, chronic sleep restriction could make the brain vulnerable and consequently promote addictive behavior. Therefore, the present study's objective was to evaluate alcohol consumption in a chronic sleep restriction model and determine the expression of delta FosB in brains of adult rats. For this purpose, male Wistar rats (300-350 g body weight) were divided into four experimental groups (n = 6 each group): control (without manipulation), sleep restriction (SR) for 7 days, SR and ethanol exposure (Ethanol + SR), and a group with just ethanol exposure (Ethanol). At the end of the management, rats were sacrificed, and the brains were dissected and processed for immunohistochemical detection of delta FosB. The results showed that SR stimulates alcohol consumption compared to unrestricted-sleep rats and induces a significant increase in the number of delta FosB-positive cells in brain nuclei within the motivation/brain reward circuit. These results suggest that chronic reduction of sleep hours is a risk factor for developing a preference for alcohol consumption.

c-Fos immunoreactivity in the hypothalamus and reward system of young rats after social novelty exposure.

Socialization is an adaptive behavior during the early stages of life because it helps young animals become independent and determines healthy adult social behavior. Therefore, it is probable that the brain areas involved in the processing of social stimuli are more sensitive to social novelty during early life stages. To test this hypothesis, four groups of young male rats were exposed to different socioenvironmental stimuli; nonsocial physical novelty, social familiarity, social novelty, and a control group which received no stimulation. After stimuli exposure, brains were fixed and cut in coronal sections for c-Fos immunohistochemistry. The number of c-Fos-immunoreactive (c-Fos-ir) neurons in the paraventricular nucleus and supraoptic nucleus, the main producers of oxytocin and vasopressin, was compared, as well as in the nucleus accumbens and ventral pallidum, the main areas involved in reinforced behavior. A significantly higher number of c-Fos-ir neurons were found in animals exposed to social novelty in all areas, except in the supraoptic nucleus. In particular, the increase in c-Fos-ir in the paraventricular nucleus seems to be selective in response to social novelty, while the increase of c-Fos-ir in the nucleus accumbens and ventral pallidum suggests that social novelty during youth is a highly rewarding stimulus compared with social familiarity and nonsocial physical novelty.

Effect of orange juice and tryptamine on the behavior and c-fos expression of Wistar rats.

Recent reports have shown that commercial orange juice is rich in biogenic amines. Consumption of foods containing large amounts of biogenic amines increase hypertensive crisis and high levels of histamine and tyramine, which have been implicated as causative agents in a number of food poisoning episodes. In addition, accumulation of tryptamine in plasma may be associated with mood disorders. The aim of this study was to determine whether chronic administration of orange juice extract and tryptamine affects the behavior and c-fos expression in the rat. For this purpose, Wistar male rats were injected with saline solution, tryptamine or orange juice extract. Sucrose preference test and elevated plus maze were evaluated to determine hedonic and anxiety behavior, respectively. Rats treated with orange juice extract showed increased anxiety behavior and sucrose consumption, similar to those treated with tryptamine. In addition, dorsal raphe nucleus, accumbens nucleus, and hippocampus showed an increase of c-fos positive cells in rats treated with orange juice extract. In conclusion, the chronic and lengthy consumption of orange juice or their derivatives in the diet could be a factor responsible to induce mood disorders and may promote excess caloric consumption.

Characterization of sleep-pattern and neuro-immune-endocrine markers at 24 hour post-injection of a single low dose of lipopolysaccharide in male Wistar rats.

The long-term effect of immune system activation by a low dose of lipopolysaccharide on neuro-immune-endocrine regulation is unclear. Sleep, neurotransmitter concentrations, TNF-α, and corticosterone levels were evaluated in male Wistar rats implanted with conventional sleep recordings. In this work, we found that REM sleep was reduced in the first 4 h post-injection, without affecting the total sleep time, while adrenaline concentration was reduced in the hippocampus at 24 h post-injection of LPS. Our results demonstrated that, although the acute immune response was not evident 24 h after the injection of LPS, it was able to promote the reduction of AD in the hippocampus, which may explain in part the depressive behavior reported in rodents following LPS administration.

Enriched environment attenuates nicotine self-administration and induces changes in ΔFosB expression in the rat prefrontal cortex and nucleus accumbens.

Environment enrichment conditions have important consequences on subsequent vulnerability to drugs of abuse. The present work examined whether exposure to an enriched environment (EE) decreases oral self-consumption of nicotine. Wistar rats were housed either in a standard environment (SE, four rats per standard cage) or in an EE during 60 days after weaning. EE consisted of eight animals housed in larger cages containing a variety of objects such as boxes, toys, and burrowing material that were changed three times a week. After this period, animals were exposed to nicotine for 3 weeks, where animals chose freely between water and a nicotine solution (0.006% in water). Fluid consumption was evaluated on a daily basis. ΔFosB immunohistochemistry in the prefrontal cortex and nucleus accumbens was also performed. Rats of the EE group consumed less nicotine solution (0.25±0.04 mg/kg/day) than SE rats (0.54±0.05 mg/kg/day). EE increased the number of ΔFos-immunoreactive (ΔFos-ir) cells in the nucleus accumbens core and shell and in the prefrontal cortex, compared with animals in the standard condition. However, rats exposed to nicotine in the SE showed higher ΔFos-ir cells in the nucleus accumbens core and shell than nonexposed rats. Nicotine consumption did not modify ΔFos-ir cells in these brain areas in EE animals. These results support the idea of a possible protective effect of the EE on reward sensitivity and the development of an addictive behavior to nicotine.

Sleep-inducing factors.

Kuniomi Ishimori and Henri Piéron were the first researchers to introduce the concept and experimental evidence for a chemical factor that would presumably accumulate in the brain during waking and eventually induce sleep. This substance was named hypnotoxin. Currently, the variety of substances which have been shown to alter sleep includes peptides, cytokines, neurotransmitters and some substances of lipidic nature, many of which are well known for their involvement in other biological activities. In this chapter, we describe the sleep-inducing properties of the vasoactive intestinal peptide, prolactin, adenosine and anandamide.

Rapid eye movement sleep is reduced in prolactin-deficient mice.

Prolactin (PRL) is implicated in the modulation of spontaneous rapid eye movement sleep (REMS). Previous models of hypoprolactinemic animals were characterized by changes in REMS, although associated deficits made it difficult to ascribe changes in REMS to reduced PRL. In the current studies, male PRL knock-out (KO) mice were used; these mice lack functional PRL but have no known additional deficits. Spontaneous REMS was reduced in the PRL KO mice compared with wild-type or heterozygous littermates. Infusion of PRL for 11-12 d into PRL KO mice restored their REMS to that occurring in wild-type or heterozygous controls. Six hours of sleep deprivation induced a non-REMS and a REMS rebound in both PRL KO mice and heterozygous littermates, although the REMS rebound in the KOs was substantially less. Vasoactive intestinal peptide (VIP) induced REMS responses in heterozygous mice but not in KO mice. Similarly, an ether stressor failed to enhance REMS in the PRL KOs but did in heterozygous littermates. Finally, hypothalamic mRNA levels for PRL, VIP, neural nitric oxide synthase (NOS), inducible NOS, and the interferon type I receptor were similar in KO and heterozygous mice. In contrast, tyrosine hydroxylase mRNA was lower in the PRL KO mice than in heterozygous controls and was restored to control values by infusion of PRL, suggesting a functioning short-loop negative feedback regulation in PRL KO mice. Data support the notion that PRL is involved in REMS regulation.

Interleukin-1beta has a role in cerebral cortical state-dependent electroencephalographic slow-wave activity.

STUDY OBJECTIVES: To investigate the hypothesis that interleukin (IL)-1beta is involved in mediating localized electroencephalogram synchronization. DESIGN: We evaluated bilateral cortical electroencephalograms after unilateral local application of IL-1beta onto the somatosensory cortex of rats. Furthermore, we investigated the effects of unilateral application of an IL-1beta inhibitor, the IL-1 soluble receptor, on spontaneous sleep and sleep rebound after sleep deprivation. SETTING: University research laboratory. INTERVENTIONS: N/A. PARTICIPANTS: Rats. MEASUREMENTS AND RESULTS: Neither dose of IL-1beta or the IL-1 soluble receptor affected the duration of non-rapid eye movement sleep or rapid eye movement sleep. Unilateral application of IL-1beta induced state- and frequency-dependent electroencephalogram asymmetries. During non-rapid eye movement sleep, but not during other states, electroencephalographic slow-wave activity was greater on the side that received IL-1beta (10- and 50-ng doses). Electroencephalographic power in the higher frequencies was not affected by IL-1beta in any state. Unilateral application of the IL-1 soluble receptor (0.1, 1.0 and 5.0 microg) had no effect on the spontaneous sleep electroencephalogram. In contrast, unilateral application of the IL-1 soluble receptor (5.0 microg) attenuated sleep deprivation-enhanced electroencephalographic slow-wave power ipsilaterally during non-rapid eye movement sleep. CONCLUSIONS: Results suggest that IL-1beta can induce state-dependent localized increases of electroencephalographic delta wave power, suggesting an enhancement of sleep intensity within the cortex.

Unilateral cortical application of tumor necrosis factor alpha induces asymmetry in Fos- and interleukin-1beta-immunoreactive cells within the corticothalamic projection.

A unilateral microinjection of tumor necrosis factor alpha (TNFalpha) (150 ng) onto the primary somatosensory cortex induces state-dependent asymmetries in electroencephalographic (EEG) slow wave activity during non-rapid eye movement sleep in rats [H. Yoshida, Z. Peterfi, F. Garcia-Garcia, R. Kirkpatrick, T. Yasuda, J.M. Krueger, State-specific asymmetries in EEG slow wave activity induced by local application of TNF alpha, Brain Res. 1009 (2004) 129-136]. In the current study, analogous TNFalpha injections were performed to determine Fos- and interleukin-1beta (IL1beta) immunoreactivity (IR). A unilateral microinjection of TNFalpha increased the number of Fos- and IL1beta-IR cells in the primary somatosensory cortex relative to the contralateral side that received heat-inactivated TNFalpha. These asymmetric TNFalpha-induced increases in the number of Fos- and IL1beta-IR cells were evident along the outside surface of the cortex (mainly layers II and III) in a restricted rostral to caudal zone. Asymmetrical increases in the number of Fos-IR cells were also observed in the subcortical region that receives the main cortical projection from the somatosensory cortex, the somatic region of the reticular nucleus of the thalamus (reticular thalamus). The IL1beta-IR cells double-labeled with glial fibrillary acidic protein (GFAP), suggesting that many of the IL1beta-IR cells were astrocytes. The number of the IL1beta-IR cells in the reticular thalamus increased significantly ipsilateral to the TNFalpha injection. Current results indicated that Fos- and IL1beta-IR may be utilized to study the functional neuroanatomy involved in the TNFalpha-mediated state-dependent enhancement of EEG slow wave activity.

State-specific asymmetries in EEG slow wave activity induced by local application of TNFalpha.

Sleep is posited to be a fundamental property of groups of highly interconnected neurons and regulated in part by activity-dependent sleep regulatory substances such as tumor necrosis factor alpha (TNFalpha). We show that the unilateral local application of TNFalpha onto the somatosensory cortex of rats induced state- and frequency-dependent EEG asymmetries. In contrast, the unilateral injection of a TNFalpha inhibitor, a TNFalpha soluble receptor, attenuated sleep deprivation-enhanced EEG slow wave power ipsilaterally during non-rapid eye movement sleep (NREMS) but not during REMS or waking. Results are consistent with the notion that sleep begins with state changes occurring within small groups of highly interconnected neurons and is driven in part by the local production of sleep regulating substances.