Short-Term Hyperprolactinemia Reduces the Expression of Purinergic P2X7 Receptors during Allergic Inflammatory Response of the Lungs.

PURPOSE: We have previously shown that domperidone-induced short-term hyperprolactinemia reduces the lung's allergic inflammatory response in an ovalbumin antigenic challenge model. Since purinergic receptor P2X7R activity leads to proinflammatory cytokine release and is possibly related to the pathogenesis of allergic respiratory conditions, the present study was designed to investigate a possible involvement of purinergic and prolactin receptors in this phenomenon. METHODS: To induce hyperprolactinemia, domperidone was injected intraperitoneally in rats at a dose of 5.1 mg × kg-1 per day for 5 days. P2X7 expression was evaluated by lung immunohistochemistry while prolactin receptor expression in bronchoalveolar lavage leukocytes was analyzed through flow cytometry. RESULTS: Previous reports demonstrated that rats subjected to short-term hyperprolactinemia exhibited a decrease in leukocyte counts in bronchoalveolar lavage, especially granulocytes. Here, it is revealed that hyperprolactinemia promotes an increased expression of prolactin receptors in granulocytes. Also, increased expression of purinergic P2X7R observed in allergic animals was significantly reduced by hyperprolactinemia. CONCLUSIONS: Both purinergic and prolactin receptor expression changes occur during the anti-asthmatic effect of hyperprolactinemia.

Beta-Adrenergic Blockade Decreases the Neuroimmune Changes in Mice Induced by Cohabitation with an Ehrlich Tumor-Bearing Cage Mate.

OBJECTIVES: Cohabitation with Ehrlich tumor-bearing (ETB) mice induced behavioral, neurochemical, hormonal, and immune effects in the conspecifics as a consequence of stress-induced activation of the sympathetic nervous system (SNS) with catecholamine release. In the current study, the nonspecific ß-AR blocker d,l-propranolol and the specific ß2-AR blocker ICI-118.551 were employed as pharmacological tools to assess the extent to which catecholamines participated in the effects induced by cohabitation with ETB mice. METHODS: Two experiments were performed, 1 with d,l-propranolol treatment and the other with ICI-118.551. One mouse in the experimental group was called the "companion of the sick partner" (CSP) since it was forced to live in the same cage with 2 (experiment 1) or 1 (experiment 2) cage mate that had been i.p. injected with 5 × 106 Ehrlich tumor cells. RESULTS: The d,l-propranolol treatment, but not the ICI-118.551 treatment, attenuated the effects of cohabitation with 2 ETB mice on both open-field behavior and the hypothalamic levels and turnover rate of norepinephrine. The 2 ß-AR blockers were unable to change the serum corticosterone levels and adrenal weights of the CSP mice; however, these drugs abrogated the effects of cohabitation on neutrophil oxidative burst and phagocytosis. Finally, an increase in the 5-HT turnover rate was observed in the olfactory bulb of CSP mice compared to their respective controls, an effect that was not modified by ß-AR blockade. CONCLUSION: These results confirm and strengthen our hypothesis that the SNS is involved in the effects induced by cohabitation with ETB mice and point towards ß2-AR participation in the immune effects analyzed.

The gut-brain axis interactions during heat stress and avian necrotic enteritis.

The gut-brain axis is known to modulate behavioral and immune responses in animals; evidence supporting this modulation in chickens, however, is elusive. Here, we analyzed the effects of heat stress and/orClostridium perfringens (CP) infection on behavior, intestinal morphology, brain activity, and corticosterone serum levels in chickens. Broilers were randomly divided into 5 equal groups: a naïve group (N), a thioglycolate group (T), a thioglycolate heat-stressed group (T/HS35), an infected group (I), and an infected/stressed (I/HS35) group. Broilers in the I and I/HS35 groups were experimentally infected withClostridium perfringensfrom the 15th to the 19th day of life. Heat stress (35±1°C) was constantly applied to the broilers in the stressed groups from the 14th to the 19th day of life. Our data showed that heat stress andC. perfringensinfection produced significant differential responses in the chickens' behavior and in c-fosexpression in the paraventricular nucleus of the hypothalamus (PVN), nucleus taenia of the amygdala (Tn), medial preoptic area (POM), andglobus pallidus (GP) of the chickens. Heat stress ameliorated some of the intestinal lesions and the neuroendocrine changes induced byC. perfringensin the birds. Our results suggest the existence of clear relationships between the degree of intestinal lesions, the chickens' behavioral outcomes, brain activity, and serum levels of corticosterone. Together, they reinforce the importance of neuroimmunomodulation and especially of brain-gut axis interactions.

Maternal immune activation in late gestation increases neuroinflammation and aggravates experimental autoimmune encephalomyelitis in the offspring.

Multiple sclerosis (MS) is characterized by an autoimmune response against myelin antigens driven by autoreactive T cells. Several lines of evidence indicate that environmental factors, such as previous infection, can influence and trigger autoimmune responses. However, the importance of the gestational period, particularly under inflammatory conditions, on the modulation of MS and related neuroinflammation by the offspring is unknown. This study aimed to evaluate the impact of prenatal exposure to lipopolysaccharide (LPS) during late gestation on the neuroinflammatory response in primary mixed glial cultures and on the progression of experimental autoimmune encephalomyelitis (EAE, an animal model of MS) in the offspring. LPS (Escherichia coli 0127:B8, 120µg/kg) was administered intraperitoneally to pregnant C57BL/6J mice on gestational day 17, and the offspring were assigned to two experiments: (1) mixed glial cultures generated using the brain of neonates, stimulated in vitro with LPS, and (2) adult offspring immunized with MOG35-55. The EAE clinical symptoms were followed for 30days. Different sets of animals were sacrificed either during the onset (7days post-immunization [p.i.]), when spleen and lymph nodes were collected, or the peak of disease (20days p.i.), when CNS were collected for flow cytometry, cytokine production, and protein/mRNA-expression analysis. The primary CNS cultures from the LPS-treated group produced exaggerated amounts of IL-6, IL-1ß and nitrites after in vitro stimulus, while IL-10 production was lowered compared to the data of the control group. Prenatal exposure to LPS worsened EAE disease severity in adult offspring, and this worsening was linked to increased CNS-infiltrating macrophages, Th1 cells and Th17 cells at the peak of EAE severity; additionally, exacerbated gliosis was evidenced in microglia (MHC II) and astrocytes (GFAP protein level and immunoreactivity). The IL-2, IL-6 and IL-17 levels in the spleen and lymph nodes were increased in the offspring of the LPS-exposed dams. Our results indicate that maternal immune activation during late gestation predispose the offspring to increased neuroinflammation and potentiate the autoimmune response and clinical manifestation of EAE.

Odor cues released by Ehrlich tumor-bearing mice are aversive and induce psychological stress.

BACKGROUND/AIMS: This study aimed to verify if odor cues released by Ehrlich tumor-bearing mice are aversive and stressful. METHODS: Female mice were divided into a control group and an experimental group. One animal of each experimental pair of mice was inoculated with 5 × 10(6) Ehrlich tumor cells intraperitoneally; the other animal was kept undisturbed and was referred to as a CSP (companion of sick partner). One mouse of each control pair was treated intraperitoneally with 0.9% NaCl (1 mg/kg); the other animal (CHP, companion of healthy partner) was kept undisturbed. RESULTS: It was shown that, in relation to CHP, CSP mice (1) spent less time within the companion zone in a T-maze place preference test, (2) had increased levels of social interaction, (3) had increased levels of plasmatic adrenaline and noradrenaline and (4) displayed no changes in serum corticosterone levels before and after an immobilization stress challenge. It was also shown that (5) cohabitation with 2 tumor-bearing mice was more effective in decreasing neutrophil oxidative burst than cohabitation with 1 sick partner and (6) the presence of a healthy conspecific within the cage of the tumor-injected/CSP pair abrogated the effects of cohabitation on neutrophil activity. These results show that odor cues released by Ehrlich tumor-injected mice are aversive and induce psychological stress. CONCLUSION: We postulate that the aversive response induced by the chemosignals released by Ehrlich tumor-injected animals activates the sympathetic nervous system and causes the neuroimmunal changes that occur in the mice cohabiting with the sick mice.

Effects of cold stress and Salmonella Heidelberg infection on bacterial load and immunity of chickens.

We analysed the effects of cold stress (19 ± 1°C, 6 h /day, from the first to the seventh day of life) applied to specific pathogen free (SPF) chickens. On experimental Day 1 (ED1), chicks were divided into four groups: C (not infected and kept under thermoneutral condition); CS (not infected and cold stressed); PC (Salmonella Heidelberg (SH) infected and kept under thermoneutral condition) and PCS (SH infected and cold stressed). High concentrations of corticosterone were found in the cold stressed birds on ED7 and ED21, with a greater increase in birds of the PCS group. Stress or non-stressed SH-infected birds had high levels of norepinephrine on ED21. On ED21, an increased percentage and number of SH were found in birds of the PCS group. On ED7, a decrease in macrophages presenting MHCII, CD8(+) and CD8(+) γδ cells was observed in the chickens of the CS group. Decrease was observed in CD3(+) cells in the birds of the PCS group and increase in macrophages presenting MHCII cells and of the CD4(+)/CD8(+) ratio in chickens of the CS group on ED21. There was a decrease in CD8(+) γδ cells in birds of the CS group on ED21 and in the CD3(+) and CD8(+)cell numbers in chickens of the PCS group on ED21. Our results suggest that cold stress applied to chickens in the first 7 days of life increases both the hypothalamus pituitary adrenal axis and the sympathetic nervous system activities, leading to long-term immune cell dysfunction, thus allowing increased SH invasion and persistence within the birds' body.

Effects of heat stress on peripheral T and B lymphocyte profiles and IgG and IgM serum levels in broiler chickens vaccinated for Newcastle disease virus.

Multiple factors, such as environment, nutritional status, and disease, induce stress in animals during livestock production. It has been shown that poultry exposed to stressors for prolonged periods had decreases in their performance parameters, mortality and decreased host resistance to pathogenic agents. It seems that early age stress may have long-lasting impact and could possibly modify the expression of their genetic potential on growth performance and immunity. This study aimed to discuss the effects of early-age heat stress on the blood lymphocyte phenotypes (B and T lymphocytes) and plasma immunoglobulin levels (IgM and IgG) in chickens vaccinated against paramixovirus of the Newcastle (NC) disease (LaSota strain). For this purpose, 96 male chickens (Cobb) were divided into 4 groups: 1) control (C), 2) heat-stressed (HS), 3) control vaccinated (C/V), and 4) heat-stressed and Vaccinated (HS/V). The NC vaccine was administered twice on experimental day (ED) 7 and ED14, and the heat stress (38 ± 1°C) was applied from ED2 to ED6. The data showed that HS increased the corticosterone serum levels in the HS group compared with the control groups (C and C/V groups). At ED7, increased concentrations of IgM were observed in birds in the HS and HS/V groups compared with C and C/V animals; chickens from the HS/V group presented increased IgG levels compared with those in the birds of the C group. The heat stress shifted the immune cell profile from B-lymphocyte to a T-cytotoxic and T-helper lymphocyte profile, and this immune cell pattern persisted until the end of the study period. It was concluded that heat stress immunomodulated the immune function response of the chickens to the NC disease vaccine challenge.

Cohabitation with a sick partner increases allergic lung inflammatory response in mice.

The bidirectional relationship between the nervous system and the immune system is relevant for homeostatic organism maintenance. Studies from our laboratory showed that 14days of cohabitation with a sick partner (injected with Ehrlich tumor cells-TAE) produced behavioral, neurochemical, endocrinological and immunological changes. This study analyzes the effects of cohabitation with an Ehrlich tumor-bearing animal on ovalbumin (OVA)-induced lung inflammatory response in mice. Pairs of male mice were divided into three groups: naïve, control and experimental. Animals of the naïve group were kept undisturbed being used for the assessment of basal parameters. One animal of each experimental and control pair of mice was immunized with OVA. On ED(0), these OVA-immunized animals received an OVA booster. At this day (D(0)) the experimental mice that were kept undisturbed were inoculated with 5×10(6) Ehrlich tumor cells; their immunized cage-mates were then referred as to CSP ("companion of sick partner"). The undisturbed mice of each control pair were i.p. treated on D(0) with 0.9% NaCl; their sensitized cage-mates were subsequently referred as CHP ("companion of health partner"). The OVA challenge was performed on CSP and CHP mice on ED(12) and ED(13); blood and tissue collection were performed on ED(14). Fourteen days after cohabitation, in comparison to the CHP mice, the CSP mice displayed the following: (1) an increased number of eosinophils and neutrophils in the BAL, (2) a decreased bone marrow cell count, (3) increased levels of IL-4 and IL-5 and decreased levels of IL-10 and IFN-γ in the BAL supernatant, (5) increased levels of IgG1-OVA, decreased levels of IgG2a-OVA and no changes in OVA-specific IgE in the peripheral blood, (6) increased expression of L-selectin in the BAL granulocytes, (7) decreased tracheal reactivity to methacholine measured in vitro, (8) no changes in plasma corticosterone levels and (9) increased levels of plasmatic noradrenaline. These results suggest that allergic lung inflammatory response exacerbation in CSP mice is a consequence of the psychological stress induced by forced cohabitation with the sick partner. Strong involvement of the sympathetic nervous system (SNS) through adrenaline and noradrenaline release and a shift of the Th1/Th2 cytokine profile toward a Th2 response were considered to be the mechanisms underlying the cell recruitment to the animal's airways.

Maternal immune activation increases the corticosterone response to acute stress without affecting the hypothalamic monoamine content and sleep patterns in male mice offspring.

BACKGROUND/AIMS: Early life experiences are homeostatic determinants for adult organisms. We evaluated the impact of prenatal immune activation during late gestation on the neuroimmune-endocrine function of adult offspring and its interaction with acute stress. METHODS: Pregnant Swiss mice received saline or lipopolysaccharide (LPS) on gestational day 17. Adult male offspring were assigned to the control or restraint stress condition. We analyzed plasmatic corticosterone and catecholamine levels, the monoamine content in the hypothalamus, striatum and frontal cortex, and the sleep-wake cycle before and after acute restraint stress. RESULTS AND CONCLUSION: Offspring from LPS-treated dams had increased baseline norepinephrine levels and potentiated corticosterone secretion after the acute stressor, and no effect was observed on hypothalamic monoamine content or sleep behavior. The offspring of immune-activated dams exhibited impairments in stress-induced serotonergic and dopaminergic alterations in the striatum and frontal cortex. The data demonstrate a distinction between the plasmatic levels of corticosterone in response to acute stress and the hypothalamic monoamine content and sleep patterns. We provide new evidence regarding the influence of immune activation during late gestation on the neuroendocrine homeostasis of offspring.

Effects of long-term heat stress in an experimental model of avian necrotic enteritis.

Stressful conditions are predisposing factors for disease development. Heat stress is one of the most important stressors in poultry production. The reemergence of some previously controlled diseases [e.g., avian necrotic enteritis (NE)] has been extensively reported. The combination of bacterial infection and certain environmental factors have been reported to trigger the disease. The aim of this study was to analyze the effects of long-term heat stress (35 ± 1°C) on the development of NE in broiler chickens. For this purpose, 60 male broiler chickens were divided into the following 6 groups: control group (C), heat stressed control group (C/HS35), thioglycolate group (T), thioglycolate heat-stressed group (T/HS35), infected group (I), and infected heat-stressed group (I/HS35). The poultry of groups I and I/HS35 were experimentally infected with Clostridium perfringens via their feed from 15 to 21 d of life. Heat stress (35 ± 1°C) was constantly applied to the birds of the stressed groups from 14 to 21 d of life. The infected and heat-stressed broiler chickens presented a trend toward a decrease in gross lesion scores and significantly lower microscopic scores of necrosis in the duodenum and jejunum (P < 0.05), lower fusion of villi in the duodenum (P < 0.05), and lower congestion scores in the jejunum and ileum (P < 0.05) in relation to infected and non-heat-stressed chickens. Broilers of I/HS35 group also exhibited small number of heterophils in the duodenum and jejunum compared with those of the I group (P < 0.05). Furthermore, the duodenum and jejunum of infected and heat-stressed broilers showed lower number of clostridia on the intestinal mucosa (P < 0.05). Data were discussed in light of a heat stress induced reduction on intestinal inflammation via a decrease in heterophil migration to the intestinal mucosa, which in turn might have reduced tissue damage during inflammation, hence preventing the development of a more severe form of NE.

Chlorella vulgaris treatment ameliorates the suppressive effects of single and repeated stressors on hematopoiesis.

The reports regarding the mutual influence between the central nervous system and the immune system constitute a vast and somewhat controversial body of literature. Stress is known to disturb homeostasis, impairing immunological functions. In this study, we investigated the hematopoietic response of Chlorella vulgaris (CV)-treated mice exposed to single (SST) and repeated stress (RST). We observed a reduction in the numbers of hematopoietic progenitors (HP) in the bone marrow and long-term bone marrow cultures (LTBMC) using flow cytometry and a coinciding decrease in the number of granulocyte-macrophage colonies (CFU-GM) after treatment with both stressors, but SST caused a more profound suppression. We observed a proportional increase in the colony-stimulating activity (CSA) of the serum of animals subjected to SST or RST. In the bone marrow, SST and RST induced a decrease in both mature myeloid and lymphoid populations but did not affect pluripotent hematopoietic progenitors (Lin(-)Sca-1(+)c-kit(+), LSK), and again, a more profound suppression was observed after SST. We further quantified the levels of interleukin-1α (IL-1α) and interleukin-6 (IL-6) and the number of myeloid cells in LTBMC. Both SST and RST reduced the levels of these cytokines to similar degrees. The myeloid population was also reduced in LTBMC, and SST induced a more intense suppression. Importantly, CV treatment prevented the changes produced by SST and RST in all of the parameters evaluated. Together, our results suggest that CV treatment is an effective tool for the prophylaxis of myelosuppression caused by single or repeated stressors.

Actions of translocator protein ligands on neutrophil adhesion and motility induced by G-protein coupled receptor signaling.

The 18 kDa translocator protein (TSPO) also known as the peripheral benzodiazepine receptor (PBR), mediates the transportation of cholesterol and anions from the outer to the inner mitochondrial membrane in different cells types. Although recent evidences indicate a potential role for TSPO in the development of inflammatory processes, the mechanisms involved have not been elucidated. The present study investigated the ability of the specific TSPO ligands, the isoquinoline carboxamide PK11195 and benzodiazepine Ro5-4864, on neutrophil recruitment promoted by the N-formylmethionyl-leucyl-phenylalanine peptide (fMLP), an agonist of G-protein coupled receptor (GPCR). Pre-treatment with Ro5-4864 abrograted fMLP-induced leukocyte-endothelial interactions in mesenteric postcapillary venules in vivo. Moreover, in vitro Ro5-4864 treatment prevented fMLP-induced: (i) L-selectin shedding and overexpression of PECAM-1 on the neutrophil cell surface; (ii) neutrophil chemotaxis and (iii) enhancement of intracellular calcium cations (iCa(+2)). Intriguingly, the two latter effects were augmented by cell treatment with PK11195. An allosteric agonist/antagonist relation may be suggested, as the effects of Ro5-4864 on fMLP-stimulated neutrophils were reverted by simultaneous treatment with PK11195. Taken together, these data highlight TSPO as a modulator of pathways of neutrophil adhesion and locomotion induced by GPCR, connecting TSPO actions and the onset of an innate inflammatory response.

Hypoactivity of the central dopaminergic system and autistic-like behavior induced by a single early prenatal exposure to lipopolysaccharide.

The aim of the present study was to evaluate the behavioral patterns associated with autism and the prevalence of these behaviors in males and females, to verify whether our model of lipopolysaccharide (LPS) administration represents an experimental model of autism. For this, we prenatally exposed Wistar rats to LPS (100 µg/kg, intraperitoneally, on gestational day 9.5), which mimics infection by gram-negative bacteria. Furthermore, because the exact mechanisms by which autism develops are still unknown, we investigated the neurological mechanisms that might underlie the behavioral alterations that were observed. Because we previously had demonstrated that prenatal LPS decreases striatal dopamine (DA) and metabolite levels, the striatal dopaminergic system (tyrosine hydroxylase [TH] and DA receptors D1a and D2) and glial cells (astrocytes and microglia) were analyzed by using immunohistochemistry, immunoblotting, and real-time PCR. Our results show that prenatal LPS exposure impaired communication (ultrasonic vocalizations) in male pups and learning and memory (T-maze spontaneous alternation) in male adults, as well as inducing repetitive/restricted behavior, but did not change social interactions in either infancy (play behavior) or adulthood in females. Moreover, although the expression of DA receptors was unchanged, the experimental animals exhibited reduced striatal TH levels, indicating that reduced DA synthesis impaired the striatal dopaminergic system. The expression of glial cell markers was not increased, which suggests that prenatal LPS did not induce permanent neuroinflammation in the striatum. Together with our previous finding of social impairments in males, the present findings demonstrate that prenatal LPS induced autism-like effects and also a hypoactivation of the dopaminergic system.

The neuroimmune changes induced by cohabitation with an Ehrlich tumor-bearing cage mate rely on olfactory information.

Cohabitation for 14 days with Ehrlich tumor-bearing mice was shown to increase locomotor activity, to decrease hypothalamic noradrenaline (NA) levels, to increase NA turnover and to decrease innate immune responses and decrease the animals' resistance to tumor growth. Cage mates of a B16F10 melanoma-bearer mice were also reported to show neuroimmune changes. Chemosignals released by Ehrlich tumor-bearing mice have been reported to be relevant for the neutrophil activity changes induced by cohabitation. The present experiment was designed to further analyze the effects of odor cues on neuroimmune changes induced by cohabitation with a sick cage mate. Specifically, the relevance of chemosignals released by an Ehrlich tumor-bearing mouse was assessed on the following: behavior (open-field and plus maze); hypothalamic NA levels and turnover; adrenaline (A) and NA plasmatic levels; and host resistance induced by tumor growth. To comply with such objectives, devices specifically constructed to analyze the influence of chemosignals released from tumor-bearing mice were employed. The results show that deprivation of odor cues released by Ehrlich tumor-bearing mice reversed the behavioral, neurochemical and immune changes induced by cohabitation. Mice use scents for intraspecies communication in many social contexts. Tumors produce volatile organic compounds released into the atmosphere through breath, sweat, and urine. Our results strongly suggest that volatile compounds released by Ehrlich tumor-injected mice are perceived by their conspecifics, inducing the neuroimmune changes reported for cohabitation with a sick companion.

3,4-methylenedioxymethamphetamine (ecstasy) decreases inflammation and airway reactivity in a murine model of asthma.

OBJECTIVE: 3,4-Methylenedioxymethamphetamine (MDMA), or ecstasy, is a synthetic drug used recreationally, mainly by young people. It has been suggested that MDMA has a Th cell skewing effect, in which Th1 cell activity is suppressed and Th2 cell activity is increased. Experimental allergic airway inflammation in ovalbumin (OVA)-sensitized rodents is a useful model to study Th2 response; therefore, based on the Th2 skewing effect of MDMA, we studied MDMA in a model of allergic lung inflammation in OVA-sensitized mice. METHODS: We evaluated cell trafficking in the bronchoalveolar lavage fluid, blood and bone marrow; cytokine production; L-selectin expression and lung histology. We also investigated the effects of MDMA on tracheal reactivity in vitro and mast cell degranulation. RESULTS: We found that MDMA given prior to OVA challenge in OVA-sensitized mice decreased leukocyte migration into the lung, as revealed by a lower cell count in the bronchoalveolar lavage fluid and lung histologic analysis. We also showed that MDMA decreased expression of both Th2-like cytokines (IL-4, IL-5 and IL-10) and adhesion molecules (L-selectin). Moreover, we showed that the hypothalamus-pituitary-adrenal axis is partially involved in the MDMA-induced reduction in leukocyte migration into the lung. Finally, we showed that MDMA decreased tracheal reactivity to methacholine as well as mast cell degranulation in situ. CONCLUSIONS: Thus, we report here that MDMA given prior to OVA challenge in OVA-sensitized allergic mice is able to decrease lung inflammation and airway reactivity and that hypothalamus-pituitary-adrenal axis activation is partially involved. Together, the data strongly suggest an involvement of a neuroimmune mechanism in the effects of MDMA on lung inflammatory response and cell recruitment to the lungs of allergic animals.

A possible role to nitric oxide in the anti-inflammatory effects of amitriptyline.

Antidepressants are reported to display anti-inflammatory effects. Nitric oxide (NO), in turn, has a key role in inflammation. The objective of the present study was to evaluate the effect of amitriptyline co-administered with L-NAME (a NO synthase inhibitor) on certain parameters of acute inflammatory response in rats, as a form to investigate a possible participation of NO in the anti-inflammatory effects of amitriptyline. For this, two animal models were used: carrageenan-induced paw edema and acute peritonitis. In the last one, peritoneal exudate, adhesion molecules expression by peripheral blood leukocytes and serum cytokines levels were evaluated. In a noninflammatory condition, serum levels of nitrates were determined. L-NAME induced a potentiation of the anti-inflammatory effects of amitriptyline (p < 0.05) in the paw edema model; however, these effects were not abrogated when L-NAME was substituted by L-arginine administration. A decrease in both leukocyte concentration and total number of cells in the peritoneal exudate and a reduction in the total serum levels of nitrates were observed with co-administration of L-NAME and amitriptyline (p < 0.05). No significant differences among groups were found concerning the expression of adhesion molecules by peripheral blood leukocytes (p > 0.05). There was a significant decrease on IL-1ß and TNF-α serum levels in the experimental groups when compared to the control animals. Together the present results and the literature suggest that the anti-inflammatory effects of amitriptyline may be due to a decrease in NO production. A decrease in IL-1ß/TNF-α serum levels may also be implicated in the results observed.

Long-term maternal separation differentially alters serum corticosterone levels and blood neutrophil activity in A/J and C57BL/6 mouse offspring.

OBJECTIVES: In this work, we searched for maternal separation effects on serum corticosterone levels and blood neutrophil activity in adult male A/J and C57BL/6 mouse offspring. METHODS: 40 male A/J mice and 40 male C57BL/6 mice were divided within each strain into two groups. Mice in the maternal separation group were separated from their mothers (1 h/day) on postnatal days 0-13. Mice in the control group were left undisturbed. On postnatal day 45, blood was drawn from all mice and used to assess neutrophil activity by flow cytometry and serum corticosterone levels by radioimmunoassay. RESULTS: The results showed that each mouse strain responded differently to maternal separation, but in both cases, serum corticosterone levels were affected. In both strains, adult mice that experienced maternal separation showed lower serum corticosterone levels than control mice. In relation to control mice kept together with their mothers, the levels of serum corticosterone were 72.7 and 36.36% lower in A/J and C57BL/6 mice submitted to maternal separation, respectively. The current findings showed that maternal separation increased neutrophil activity in mice after reaching adulthood. The observed effects, although in the same direction, differed between A/J and C57BL/6 mice. Maternal separation increased both the percentage and intensity of phagocytosis in C57BL/6 mice, but had no effects on A/J mice. Furthermore, maternal separation increased basal and propidium iodide-labeled Staphylococcus aureus-induced oxidative burst in A/J mice but did not affect oxidative burst in C57BL/6 mice. Finally, phorbol myristate acetate-induced oxidative burst increased in both strains. CONCLUSION: These results indicate that early maternal separation increases innate immunity, most likely by modifying hypothalamus-pituitary-adrenal axis activity. This suggests that maternal separation is a good model for stress which produces long-term neuroimmune changes whatever the animal species and strain used.

Neuroimmune interactions in stress.

Stress has long been recognized as a putative modulator of immunity. Several clinical and experimental reports point to a role of physical and psychological stressors on progression or resistance to disease. Nonetheless, literature in this field is sometimes controversial due to the wide variety of stressors employed and parameters of immunity analyzed. This variation should not be considered a consequence of methodological inaccuracy. The stress response, although theoretically stereotyped in nature, may lead to slightly different outcomes according to several modifiers. Our group has compared the effects of several stressors over different parameters of brain activity, behavior, immunity and glucocorticoid levels. These data show altogether that while increased turnover of noradrenaline in the hypothalamus, along with anxiety-like behaviors and increase in serum corticosterone are present very often, the magnitude of changes in immunity may vary considerably. Thus, we review data from our group generated over the past decade to support that effects of stressors on immunity and behavior highly depend on their specifics, animal model, frequency, duration, intensity, perception, and coping by the stressed animal.

Prenatal lipopolysaccharide reduces social behavior in male offspring.

OBJECTIVE: This study investigated the relationship between maternal sickness behavior during pregnancy and offspring development and behavior. METHODS: Pregnant Wistar rats were administered with lipopolysaccharide (LPS, 100 microg/kg, i.p.) on gestation day (GD) 9.5. Dams' sickness behavior was analyzed, and at birth, offspring number and weight were evaluated. Male offspring was evaluated through physical development, play behavior, adult social interaction, plus maze studies and morphological analysis of the brain. RESULTS: Results, with respect to the control group, showed that: (1) LPS decreased general activity, food intake, and weight gain in dams, but no pyrexia was observed following treatment; (2) LPS reduced litter size, but no alterations in physical development were observed; (3) LPS reduced play behavior parameters in baby rats; (4) LPS decreased adult social interaction; (5) no alterations were observed between groups on plus maze studies; (6) no differences were observed between groups on morphological analyses of the brain. CONCLUSION: These data reveal that LPS administered on GD 9.5 impaired male offspring's social behavior in infancy and adulthood. These results may be related to an alteration in motivational states or/and increased anxiety.

Prenatal lipopolysaccharide exposure affects maternal behavior and male offspring sexual behavior in adulthood.

OBJECTIVE: This study investigates the effects of prenatal lipopolysaccharide (LPS) exposure on the maternal behavior of pregnant rats and the physical development and sexual behavior of their male offspring in adulthood. METHODS: For two experiments, pregnant rats were injected with LPS (250 microg/kg, i.p.) on gestation day (GD) 21. In the first experiment, the maternal behavior (postnatal day, PND, 6) and the dam's open-field general activity (PND7) were evaluated. In the second experiment, the maternal pre- and postnatal parameters, the pup's development, the offspring's sexual behavior in adulthood, and the pup's organ weights were assessed. RESULTS: Compared to the control group, the LPS-treated dams presented reduced maternal behavior, decreased general activity, a smaller body weight difference between GD21 and PND1, a greater number of perinatal deaths, and smaller litters. For the male pups, LPS treatment resulted in a decreased body weight on PND2, whereas the anogenital distance and the day of testis descent were not modified. The male sexual behavior was impaired by prenatal LPS. Particularly the number of ejaculating animals was reduced. The testis weight was also lower in the prenatally LPS-treated rats than in the control rats. CONCLUSION: We propose that prenatal LPS exposure on GD21 acts as an imprinting factor that interferes with the programming of brain sexual determination in offspring.