Adam Roman

Gender-specific behavioral and immunological alterations in an animal model of autism induced by prenatal exposure to valproic acid.

Autism is a severe behavioral disorder characterized by pervasive impairments in social interactions, deficits in verbal and non-verbal communication, and stereotyped behaviors, with a four times higher incidence in boys than in girls. The core symptoms are frequently accompanied by a spectrum of neurobehavioral and immunological derangements, including: aberrant sensitivity to sensory stimulation, anxiety, and decreased cellular immune capacity. Recently, a new potential rodent model of autism induced by prenatal exposure to valproic acid (VPA rats) has been proposed. In order to determine if gender has an influence on alterations observed in VPA rats, male and female rats have been evaluated in a battery of behavioral, immunological, and endocrinological tests. A plethora of aberrations has been found in male VPA rats: lower sensitivity to pain, increased repetitive/stereotypic-like activity, higher anxiety, decreased level of social interaction, increased basal level of corticosterone, decreased weight of the thymus, decreased splenocytes proliferative response to concanavaline A, lower IFN-gamma/IL-10 ratio, and increased production of NO by peritoneal macrophages. Female VPA rats exhibited only increased repetitive/stereotypic-like activity and decreased IFN-gamma/IL-10 ratio. Sexual dimorphism characteristics for measured parameters have been observed in both groups of animals, except social interaction in VPA rats. Our results confirm existence of similarities between the observed pattern of aberrations in VPA rats and features of disturbed behavior and immune function in autistic patients, and suggest that they are gender-specific, which is intriguing in light of disproportion in boys to girls ratio in autism.

Effect of mild chronic stress, as a model of depression, on the immunoreactivity of C57BL/6 mice

Numerous studies correlate the state of depression with some abnormalities in the immune response, such as increased numbers of white blood-cells, alterations in sub-populations of leucocytes, suppression of cytotoxic activity of natural-killer cells, increased levels of some autoantibodies and acute-phase proteins. Some of these changes have been attributed to autoimmunological reactions. While the possibilities to evaluate some reactions in depressed patients are limited, an animal model of depression could well simulate this clinical situation, and the chronic mild state of stress is a well accepted one. After undergoing stress for three-weeks, C57BL/6 mice demonstrate in the present study a decrease in thymus weight, as well as increased interleukin-1 and decreased interleukin-2 production. Splenocytes of the depressed mice exert a decrease in natural-killer-cell activity, in the proliferative response to Concanavalin-A, interleukin-1 and anti-CD3 monoclonal antibodies and an increase in the proliferative response to lipopolysaccharides and pokeweed mitogens. Our results also suggest that chronic stress-induced activation of suppressor cells in the spleen, due to elimination of CD8+ cells, increase the proliferation of splenocytes in response to mitogens of T cells.

A new animal model of (chronic) depression induced by repeated and intermittent lipopolysaccharide administration for 4 months

Chronic activation of immune-inflammatory and oxidative and nitrosative stress (O&NS) pathways plays an important role in the pathophysiology of clinical depression. Increased IgA responses directed against LPS of gram-negative bacteria, indicating increased bacterial translocation, may be one of the drivers underpinning these pathways. There is a strong association between signs of bacterial translocation and chronicity of depression and O&NS, but not pro-inflammatory cytokines. The aims of the present study were to: (1) develop a new neurobehavioral model of (chronic) depression (anhedonic behavior) that may reflect chronic LPS stimulation and is associated with increased oxidative stress, and (2) to delineate the effects of fluoxetine on this new depression model. We established that in female mice repeated LPS injections once daily for 5 days (from 750 μg/kg to a maximal dose 1250 μg/kg; increasing doses for the first three days which were then gradually decreased on day 4 and 5) at a one-month interval and this repeated for 4 consecutive months induced chronic anhedonia (estimated by the preference to drink a 1% sucrose) lasting for at least 7 weeks. Chronic LPS administration significantly decreased thymus weight, proliferative activity of splenocytes, production of interferon (IFN)γ and interleukin-(IL)10, and increased superoxide and corticosterone production. Treatment with fluoxetine for 3 weeks abolished the neurobehavioral effects of LPS. The antidepressant effect of fluoxetine was accompanied by increased production of IL-10 and reduced superoxide and corticosterone production. Our results suggest that repeated intermittent LPS injections to female mice may be a useful model of chronic depression and in particular for the depressogenic effects of long standing activation of the toll-like receptor IV complex.

Concomitant administration of fluoxetine and amantadine modulates the activity of peritoneal macrophages of rats subjected to a forced swimming test

Recent studies show that administration of a non-competitive NMDA receptor antagonist, amantadine (AMA), potentiates the action of antidepressant drugs. Since antidepressants may modulate functioning of the immune system and activation of a pro-inflammatory response in depressive disorders is frequently reported, the aim of the present study was to examine whether a combined administration of AMA and the antidepressant, fluoxetine (FLU), to rats subsequently subjected to a forced swimming test (FST) modifies the parameters of macrophage activity, directly related to their immunomodulatory functions, i.e., arginase (ARG) activity and synthesis of nitric oxide (NO). We found that 10 mg/kg AMA and 10 mg/kg FLU, ineffective in FST for antidepressant-like activity when administered alone, increased the ARG/NO ratio in macrophages when administered concomitantly. This effect was accompanied by a decrease of cellular adherence. Concurrently, the basal metabolic activity of the cells measured with reduction of resazurin, and intracellular host defense as assessed by a synthesis of superoxide anion, were not affected by such antidepressive treatment. Our data indicate that co-administration of AMA and FLU decreases the pro-inflammatory properties of macrophages and causes a redirection of immune response toward anti-inflammatory activity, as one can anticipate in the case of an effective antidepressive treatment.

Effect of bioactive substances found in rapeseed, raspberry and strawberry seed oils on blood lipid profile and selected parameters of oxidative status in rats

Rapeseed, strawberry and raspberry seed oils are a rich source of polyunsaturated fatty acids and antioxidants such as tocols, bioflavonoids and phytosterols. The aim of the study was to determine changes in the blood lipid profile of rats fed with rapeseed, strawberry and raspberry seed oils and their effects on selected parameters of oxidative status. The experiment was carried out on male Wistar rats. The oils were administered by oral gavage for 5 weeks once daily at the dose of about 0.8 ml per rat. Blood samples were taken before and after supplementation period. The activity of superoxide dismutase (SOD) and glutathione peroxidase (cGPx) was assessed in erythrocytes and contents of triglycerides (TG), total cholesterol, low-density fraction of cholesterol (LDL) and high-density fraction of cholesterol (HDL) were assessed in plasma. The experiment shows that oils supplemented in the diet for 5 weeks had no significant effect on the level of triglyceride (TG), total cholesterol as well as HDL and LDL fractions. Reduced activity of cGPX and SOD in the group of rats receiving raspberry and strawberry seed oils suggests that these native oils may contribute to oxidative stability (improves antioxidant status). Thus, strawberry and raspberry seed oils can be considered as special biological oils, which constitute potential nutraceuticals reducing oxidative stress.

Macrophages and depression – A misalliance or well-arranged marriage?

Depression is a severe medical condition with multiple manifestations and diverse, largely unknown etiologies. The immune system, particularly macrophages, plays an important role in the pathology of the illness. Macrophages represent a heterogeneous population of immune cells that is dispersed throughout the body. The central nervous system is populated by several types of macrophages, including microglia, perivascular cells, meningeal and choroid plexus macrophages and pericytes. These cells occupy different brain compartments and have various functions. Under basal conditions, brain macrophages support the proper function of neural cells, organize and preserve the neuronal network and maintain homeostasis. As cells of the innate immune system, they recognize and react to any disturbances in homeostasis, eliminating pathogens or damaged cells, terminating inflammation and proceeding to initiate tissue reconstruction. Disturbances in these processes result in diverse pathologies. In particular, tissue stress or malfunction, both in the brain and in the periphery, produce sustained inflammatory states, which may cause depression. Excessive release of proinflammatory mediators is responsible for alterations of neurotransmitter systems and the occurrence of depressive symptoms. Almost all antidepressive drugs target monoamine or serotonin neurotransmission and also have anti-inflammatory or immunosuppressive properties. In addition, non-pharmacological treatments, such as electroconvulsive shock, can also exert anti-inflammatory effects. Recent studies have shown that antidepressive therapies can affect the functional properties of peripheral and brain macrophages and skew them toward the anti-inflammatory M2 phenotype. Because macrophages can affect outcome of inflammatory diseases, alleviate sickness behavior and improve cognitive function, it is possible that the effects of antidepressive treatments may be, at least in part, mediated by changes in macrophage activity.

α1-Adrenergic receptor subtypes in the central nervous system: insights from genetically engineered mouse models

α1-Adrenergic receptors (α1-ARs) are important players in peripheral and central nervous system (CNS) regulation and function and in mediating various behavioral responses. The α1-AR family consists of three subtypes, α1A, α1B and α1D, which differ in their subcellular distribution, efficacy in evoking intracellular signals and transcriptional profiles. All three α1-AR subtypes are present at relatively high densities throughout the CNS, but the contributions of the individual subtypes to various central functions are currently unclear. Because of the lack of specific ligands, functionally characterizing the α1-ARs and discriminating between the three subtypes are difficult. To date, studies using genetically engineered mice have provided some information on subtype-related functions of the CNS α1-ARs. In this mini-review, we discuss several CNS processes where the α1-ARs role has been delineated with pharmacological tools and by studies using mutated mice strains that infer specific α1-AR subtype functions through evaluation of behavioral phenotypes.

Effect of repeated administration of paroxetine and electroconvulsive shock on the proliferative response of lymphocytes and the synthesis of nitric oxide by macrophages in rats

Objectives: We sought to determine whether chronic administration of paroxetine and electroconvulsive shock (ECS), given separately or jointly, changes the proliferative response of T and B lymphocytes stimulated by mitogens and affect the production of nitric oxide (NO) by peritoneal macrophages. Methods: The experiment was conducted on male Wistar rats receiving treatment once daily for 12 consecutive days. Control animals were injected intraperitoneally (ip) with sterile distilled water (2 mL/kg) and were subjected to sham ECS. Paroxetine was administered ip in a dose of 10 mg/kg of body weight. ECS (150 mA, 50 Hz, 0.5 seconds) was delivered through ear clips. For combined treatment, paroxetine was given 30 minutes before ECS. The rats were killed 24 hours after the last treatment. Then, the proliferative response of splenocytes was induced by concanavalin A (Con A), lipopolysaccharide (LPS), or pokeweed mitogen and those of thymocytes by Con A and was later assessed by a standard [3H]-thymidine incorporation assay. The spontaneous or induced (with LPS) NO synthesis in peritoneal macrophages was assessed as nitrite accumulation in 24-hour culture supernatants using the Griess reaction. Results: Only chronic treatment with ECS alone significantly increased the proliferative response of splenocytes to stimulation with Con A or LPS. The response of thymocytes was not changed in any group tested. Both the spontaneous NO synthesis and that induced with LPS in macrophages were significantly decreased only in rats receiving ECS. Conclusions: We suggest that the ECS-induced suppression of NO synthesis by macrophages, resulting from the noradrenergic component of ECS action, may be responsible for the enhanced proliferative response of lymphocytes. Our data are in line with the results of other authors indicating that paroxetine and/or ECS modulate the immune system indirectly via the neuroendocrine system. The relatively high efficacy of ECS in the therapy for depression may be attributable to the ECS-evoked long-lasting changes in the immune system, which supports the macrophage theory of depression.

Chronic treatment with electroconvulsive shock may modulate the immune function of macrophages.

Objective: To determine the effect of single and chronic electroconvulsive shock (ECS) administration on the immunoregulatory functions of macrophages. Methods: Male Wistar rats received single or chronic treatment with ECS (150 mA, 50 Hz, 0.5 seconds) delivered through ear clips, once a day for 10 consecutive days, or sham ECS administered likewise. The rats were killed 24 hours after the last treatment, and peritoneal macrophages were cultured in vitro for 3 or 36 hours for a subsequent determination of their metabolic activity. The ability of macrophages to reduce Alamar Blue, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), and nitrotetrazolium blue chloride and pinocytosis, adherence, and vitality, as well as synthesis of nitric oxide and arginase activity, was assessed. Results: We found statistically significant changes in the biological properties of macrophages which occurred after 36 hours of incubation, especially in cultures stimulated with lipopolysaccharide; in contrast, no differences were observed between groups assessed after 3 hours of incubation. Rats receiving chronic 10-fold ECS showed a substantial increase in the metabolic activity of macrophages, reflected as their ability to reduce Alamar Blue and MTT and to increase arginase activity, accompanied with a marked but statistically insignificant decrease in nitric oxide synthesis compared with respective controls. Conclusions: Our results suggest that chronic treatment with ECS may induce long-lasting changes in the activity of peritoneal macrophages. Attenuation of their proinflammatory properties indicates that ECS can change the primarily immunoregulatory functions of macrophages.

The Beneficial Impact of Antidepressant Drugs on Prenatal Stress-Evoked Malfunction of the Insulin-Like Growth Factor-1 (IGF-1) Protein Family in the Olfactory Bulbs of Adult Rats.

Insulin-like growth factor-1 (IGF-1) promotes the growth, differentiation, and survival of both neurons and glial cells, and it is believed to exert antidepressant-like activity. Thus, disturbances in the IGF-1 system could be responsible for the course of depression. To date, there have been no papers showing the impact of chronic antidepressant treatment on the IGF-1 network in the olfactory bulb (OB) in an animal model of depression. Prenatal stress was used as model of depression. Twenty-four 3-month-old male offspring of control and stressed mothers were subjected to behavioral testing (forced swim test). The mRNA expression of IGF-1 and IGF-1 receptor (IGF-1R) and the protein level of IGF-1 and its phosphorylation, as well as the concentrations of IGF-binding proteins (IGFBP-2, -4, -3, and -6), were measured in OBs before and after chronic imipramine, fluoxetine, or tianeptine administration. Adult rats exposed prenatally to stressful stimuli displayed not only depression-like behavior but also decreased IGF-1 expression, dysregulation in the IGFBP network, and diminished mRNA expression, as well as IGF-1R phosphorylation, in the OB. The administration of antidepressants normalized most of the changes in the IGF-1 system of the OB evoked by prenatal stress. These results suggested a beneficial effect of chronic antidepressant drug treatment in the alleviation of IGF-1 family malfunction in OBs in an animal model of depression.