Bogusława Budziszewska

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.

Essential elements in depression and anxiety. Part II

In this paper we continue to discuss the involvement of essential elements in depression and anxiety, and the possible mechanisms that link elements to the neurobiology underlying depression/anxiety. The present paper is focused on copper, selenium, manganese, iodine and vanadium. Different aspects of relationship between elements and depression or anxiety are reviewed, e.g. the association of the amount of an element in a diet or the serum level of an element and depressive or anxiety-like symptoms. Moreover, the relation of selected elements to the pathophysiology of depression or anxiety is discussed in the context of enzymes which require these elements as co-factors and are involved in the underlying pathophysiology of these disorders.

The role of the GPR39 receptor in zinc deficient-animal model of depression

During the last decade it has been shown that zinc may activate neural transmissions via the GPR39 Zn(2+)-sensing receptor, which can be involved in the regulation of neuronal plasticity. According to the neurotrophic hypothesis of depression, decreased brain derived neurotrophic factor (BDNF) levels in depressed patients play a key role in the pathogenesis of this disorder. BDNF, similarly as zinc, is known to be involved in the process of neuron survival and the regulation of neuronal plasticity. The aim of the present study was to determine whether the administration of a 6-week diet deficient in zinc would cause depressive-like behaviour and if such behavioural alterations would correlate with changes in the expression of the BDNF protein and GPR39 receptor. In the first part of the present study the animal behaviour after a 6-week zinc-deficient diet, in the forced swim test (FST) was investigated. In the second part expression of the GPR39 and BDNF protein level in the frontal cortex was measured using the Western Blot method. Administration of a zinc-deficient diet for 6 weeks increased immobility time in the FST by 24%, so exerted depression-like behaviour. A biochemical study showed a significant reduction in GPR39 (by 53%) and BDNF (by 49%) protein expression in the frontal cortex in mice receiving the zinc deficient diet for 6 weeks. Our study provides evidence that the GPR39 Zn(2+)-sensing receptor may be responsible for lowering the BDNF protein level and in consequence may be involved in the pathogenesis of depression.

Zinc deficiency alters responsiveness to antidepressant drugs in mice

BACKGROUND There is some evidence coming from preclinical and clinical studies suggesting a relationship between dietary zinc intake and depressive symptoms. The aim of the study was to determine whether zinc deficiency alters the response to antidepressants with a different mechanism of action. We examine also whether these changes are related to activity of the hypothalamic-pituitary-adrenal HPA axis. METHODS Male CD-1 mice were assigned to groups according to diet and antidepressant administration. To evaluate animal behavior, the immobility time in the forced swim test (FST) and locomotor activity were measured. To determine serum zinc levels the flame atomic absorption spectroscopy (FAAS) was used. The serum corticosterone was determined by radioimmunoassay (RIA). RESULTS Antidepressants administered to zinc-deprived mice induced an altered response in the FST when compared to animals fed with an adequate diet. There were no changes in locomotor activity. Animals subjected to a zinc-deficient diet showed a significant reduction in serum zinc levels, which was normalized by antidepressant treatment. An increase in serum corticosterone concentrations in mice fed with a zinc-deficient diet and treated with antidepressants was observed, so it can be concluded that reduced levels of zinc contribute hyperactivation of the HPA axis. CONCLUSION The results of this study suggest that a diet with a reduced zinc level alters antidepressant action, which is associated with a reduction in the serum zinc level and rise in the corticosterone level. The results of this study may indicate the involvement of zinc deficiency in the pathogenesis of depression.

Effects of ethylene glycol ethers on cell viability in the human neuroblastoma SH-SY5Y cell line

Ethylene glycol ethers (EGEs) are a class of chemicals used extensively in the manufacture of a wide range of domestic and industrial products, which may result in human exposure and toxicity. Hematologic and reproductive toxicity of EGEs are well known whereas their action on neuronal cell viability has not been studied so far. In the present study, we investigated the effects of some EGEs on cell viability and on the hydrogen peroxide-induced damage in the human neuroblastoma (SH-SY5Y) cells. It has been found that 2-phenoxyethanol in a concentration-dependent manner (5-25 mM, 24 h) increased the basal and H(2)O(2)-induced lactate dehydrogenase (LDH) release and 3-[4,5-dimethylthiazol-2-yl]2,5-diphenyl tetrazolium bromide (MTT) reduction. 2-Butoxyethanol given alone did not affect LDH release and MTT reduction but concentration-dependently enhanced the cytotoxic effect of H(2)O(2). 2-Isopropoxyethanol significantly and concentration-dependently (1-25 mM) increased the basal LDH release and attenuated MTT reduction, but did not potentiate the cytotoxic effect of H(2)O(2). Contrary to this, 2-methoxyethanol did not show a cytotoxic effect while 2-ethoxyethanol at high concentrations intensified the hydrogen peroxide action. This study demonstrated that among the EGEs studied, 2-phenoxyethanol showed the most consistent cytotoxic effect on neurons in in vitro conditions and enhanced the hydrogen peroxide action. 2-Isopropoxyethanol had also a potent cytotoxic effect, but it did not enhance the hydrogen peroxide action, whereas 2-butoxyethanol only potentiated cytotoxic effect of H(2)O(2). It is concluded that the results of the present study should be confirmed in in vivo conditions and that some EGEs, especially 2-phenoxyethanol, 2-butoxyethanol and 2-isopropoxyethanol, may be responsible for initiation or exacerbation of neuronal cell damage.

Antidepressants attenuate the dexamethasone-induced decrease in viability and proliferation of human neuroblastoma SH-SY5Y cells: a involvement of extracellular regulated kinase (ERK1/2).

Excessive glucocorticoid levels in depressed patients have been associated with atrophic changes in some brain regions, but only few studies suggest that some antidepressants can interfere with deleterious effect of glucocorticoids on neuronal cells. The aim of the present study was to examine the effect of dexamethasone (DEX), a synthetic glucocorticoid and some antidepressants from different chemical groups (imipramine, desipramine, amitriptyline, citalopram, fluoxetine, reboxetine and tianeptine) on SH-SY5Y cells cultured in the medium containing steroid-free serum. DEX in concentrations from 1 to 100 μM did not change LDH release but exposure to 10 μM and 100 μM DEX for 24, 48 and 72 h caused a significant reduction in cell viability and proliferation as confirmed by MTT reduction and BrdU ELISA assays, respectively. Twenty four-hour incubation of cells with antidepressants (0.05-10 μM) and DEX (10 μM) showed that imipramine, amitriptyline, desipramine, citalopram and fluoxetine at concentrations from 0.1 up to 1 μM, reboxetine (0.1 μM) and tianeptine (0.05 μM) prevented the DEX-induced decreases in cell viability and proliferation rate. The protective effects of antidepressants were ameliorated by inhibitors of MAPK/ERK1/2, but not PI3-K/Akt pathway as shown for imipramine, fluoxetine and reboxetine. Moreover, Western blot analysis showed the decrease in the activated form of ERK1/2 (p-ERK) after DEX treatment and this effect was inhibited by imipramine. Thus, the reduction in SH-SY5Y cell viability caused by DEX appears to be related to its antiproliferative activity and some antidepressant drugs in low concentrations attenuate this effect by mechanism which involves the activation of MAPK/ERK1/2 pathway.

Stimulatory effect of antidepressant drug pretreatment on progression of B16F10 melanoma in high-active male and female C57BL/6J mice

The effect of a two-week desipramine or fluoxetine (10 mg/kg, i.p.) pretreatment on B16F10 melanoma growth in 3-5 month old female and male C57BL/6J mice differing in behavioral characteristics (high- vs. low-active) was compared. Antidepressant pretreatment increased metastasis formation, shortened the survival, decreased splenocyte anti-tumor natural killer cell cytotoxicity (in vitro), and the pro-inflammatory cytokine IL-12p40, IFN-γ production while it increased anti-inflammatory cytokine IL-10 production in high-active males (desipramine) or females (fluoxetine). The obtained results emphasize a stimulatory effect of pretreatment with antidepressants on progress of B16F10 melanoma that depends on gender and behavioral characteristics of the animal.

Inhibition of 2,4-dinitrofluorobenzene-induced contact hypersensitivity reaction by antidepressant drugs

BACKGROUND Contact hypersensitivity (CHS) induced by a topical application of hapten - 2,4-dinitrofluorobenzene (DNFB), is a T cytotoxic (Tc)1-cell-mediated antigen-specific type of skin inflammation. Recently, it has been shown that antidepressant drugs inhibit the T helper (Th)1-mediated CHS reaction induced by picryl chloride. The aim of present study was to establish the effect of two-week desipramine or fluoxetine administration on the CHS reaction induced by DNFB. METHODS Balb/c (H-2(d)) male mice were divided into six groups: 1) vehicle-treated negative control group; 2) desipramine-treated negative control group; 3) fluoxetine-treated negative control group; 4) vehicle-treated DNFB group (positive control group); 5) desipramine-treated DNFB group; 6) fluoxetine-treated DNFB group. T lymphocytes proliferation was determined by incorporation of [(3)H]-thymidine to DNA of concanavalin A stimulated cells. ELISA test was used for estimation of cytokines production. RESULTS The antidepressants significantly suppressed the CHS reaction mediated by Tc1 cells: desipramine by 55% and fluoxetine by 54% compared to the positive control. Moreover, the antidepressants decreased the proliferative activity of splenocytes and the ability of splenocytes to produce interleukin (IL)-6 and interferon (IFN)-γ and increased IL-10 production by the lymph node (LN) cells of DNFB-treated mice. CONCLUSION The results of the present study show that the Tc1-dependent reactivity to DNFB is significantly suppressed by antidepressant drugs, which suggests their inhibitory effect on Tc1 mediated immunity.

Effects of PB190 and PB212, new σ receptor ligands, on glucocorticoid receptor-mediated gene transcription in LMCAT cells

The hyperactivity of the hypothalamic-pituitary-adrenocortical (HPA) axis is often observed in patients with major depression. It has even been implicated in the pathophysiology of this disease. Some antidepressant drugs (ADs) inhibit glucocorticoid receptor (GR) function under in vitro conditions. The σ(1) receptor agonists reveal potential antidepressant activity in animals, moreover, igmesine is promising as an AD in humans. As already shown, σ receptors are involved in stress-induced responses (e.g., conditioned fear stress in mice). The aim of the present study was to find out whether the new selective σ receptor ligands, PB190 and PB212, are able to affect directly the endocrine system activity. To this end, we evaluated their influence on GR function in mouse fibroblast cells (L929), stably transfected with mouse mammary tumor virus-chloramphenicol acetyltransferase (MMTV-CAT) plasmid (LMCAT cells). Fluvoxamine, a selective serotonin reuptake inhibitor, recognized as a σ(1) receptor agonist was used for comparison. The obtained results showed that both PB190 and PB212 (potential σ(1) receptor agonist and antagonist, respectively) like fluvoxamine, decreased the corticosterone-induced CAT activity in a concentration-dependent manner. The significance of this fact remains ambiguous and requires further studies.

Working memory deficits and alterations of ERK and CREB phosphorylation following withdrawal from cocaine self-administration.

BACKGROUND The mechanisms underlying memory functions during withdrawal from the chronic drug use are poorly understood. METHODS We assessed learning and spatial working memory using the delayed alternation assay (T-maze) in rats, previously subjected to cocaine self-administration. The T-maze training was conducted 1-5 weeks after cocaine cessation; working memory efficacy was assessed at 5-8 weeks of drug withdrawal. After behavioral training and testing, the rats were sacrificed and the levels of p-CREB/CREB and p-ERK2/ERK2 in several brain areas were measured. The same molecular assessment was performed in rats with cocaine injections, but forced to drug abstinence in home cages. RESULTS After 5 weeks of cocaine withdrawal from self-administration, a significant impairment of working memory under increased working memory load (inter-trial delay extended to 30s), with no changes at baseline conditions (inter-trial delay 10s), was noticed. Neither acquisition phase nor working memory performance measured 6-8 weeks after the last drug intake differed between cocaine or saline pretreated rats. Upon T-maze training and 8-week withdrawal, cocaine-pretreated rats had higher levels of p-CREB/CREB in prefrontal cortex and dorsal striatum and lower in hippocampus compared to saline rats. Increased levels of p-ERK2/ERK2 were observed in dorsal striatum, hippocampus and decreased in nucleus accumbens. In cocaine-pretreated caged rats no changes in p-CREB/CREB levels were observed, while ERK2 levels either decreased (frontal cortex) or increased (nucleus accumbens). CONCLUSION Our results suggest that cocaine self-administration results in cognitive impairments and alterations in ERK/CREB signaling pathway long after discontinuation of drug use.