Cyclosporine A affects open field behavior in DA rats

The Effects of Fingolimod (FTY720) on Leukocyte Subset Circulation cannot be Behaviourally Conditioned in Rats

Suppression of immune functions can be elicited by behavioural conditioning using drugs such as cyclosporin A or rapamycin. Nevertheless, little is known about the underlying mechanisms and generalisability of this phenomenon. Against this background, the present study investigated whether the pharmacological properties of fingolimod (FTY720), an immunosuppressive drug widely applied to treat multiple sclerosis, can be conditioned in rats by means of taste-immune associative learning. For this purpose, a conditioned taste avoidance paradigm was used, pairing the presentation of a novel sweet drinking solution (saccharin or sucrose) as conditioned stimulus (CS) with therapeutically effective doses of FTY720 as unconditioned stimulus (US). Subsequent re-exposure to the CS at a later time point revealed that conditioning with FTY720 induced a mild conditioned taste avoidance only when saccharin was employed as CS. However, on an immunological level, neither re-exposure with saccharin nor sucrose altered blood immune cell subsets or splenic cytokine production. Despite the fact that intraperitonally administered FTY720 could be detected in brain regions known to mediate neuro-immune interactions, the present findings show that the physiological action of FTY720 is not inducible by mere taste-immune associative learning. Whether conditioning generalises across all small-molecule drugs with immunosuppressive properties still needs to be investigated with modified paradigms probably using distinct sensory CS. Moreover, these findings emphasize the need to further investigate the underlying mechanisms of conditioned immunomodulation to assess the generalisability and usability of associative learning protocols as supportive therapies in clinical contexts.

Young human alpha synuclein transgenic (BAC-SNCA) mice display sex- and gene-dose-dependent phenotypic disturbances

Parkinson's disease (PD) is a common neurodegenerative movement disorder, characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta and the accumulation of aggregated alpha synuclein (aSyn). The disease often presents with early prodromal non-motor symptoms and later motor symptoms. Diagnosing PD based purely on motor symptoms is often too late for successful intervention, as a significant neuronal loss has already occurred. Furthermore, the lower prevalence of PD in females is not well understood, highlighting the need for a better understanding of the interaction between sex and aSyn, the crucial protein for PD pathogenesis. Here, we conducted a comprehensive phenotyping study in 1- to 5-month-old mice overexpressing human aSyn gene (SNCA) in a bacterial artificial chromosome (BAC-SNCA). We demonstrate a SNCA gene-dose-dependent increase of human aSyn and phosphorylated aSyn, as well as a decrease in tyrosine hydroxylase expression in BAC-SNCA mice, with more pronounced effects in male mice. Phosphorylated aSyn was already found in the dorsal motor nucleus of the vagus nerve of 2-month-old mice. This was time-wise associated with significant gait altrations in BAC-SNCA mice as early as 1 and 3 months of age using CatWalk gait analysis. Furthermore, anxiety-related behavioral tests revealed an increase in anxiety levels in male BAC-SNCA mice. Finally, 5-month-old male BAC-SNCA mice exhibited a SNCA gene-dose-dependent elevation in energy expenditure in automated home-cage monitoring. For the first time, these findings describe early-onset, sex- and gene-dose-dependent, aSyn-mediated disturbances in BAC-SNCA mice, providing a model for sex-differences, early-onset neuropathology, and prodromal symptoms of PD.

Treatment with the calcineurin inhibitor and immunosuppressant cyclosporine A impairs sensorimotor gating in Dark Agouti rats

RATIONALE

Calcineurin is a protein regulating cytokine expression in T lymphocytes and calcineurin inhibitors such as cyclosporine A (CsA) are widely used for immunosuppressive therapy. It also plays a functional role in distinct neuronal processes in the central nervous system. Disturbed information processing as seen in neuropsychiatric disorders is reflected by deficient sensorimotor gating, assessed as prepulse inhibition (PPI) of the acoustic startle response (ASR).

OBJECTIVE

Patients who require treatment with immunosuppressive drugs frequently display neuropsychiatric alterations during treatment with calcineurin inhibitors. Importantly, knockout of calcineurin in the forebrain of mice is associated with cognitive impairments and symptoms of schizophrenia-like psychosis as seen after treatment with stimulants.

METHODS

The present study investigated in rats effects of systemic acute and subchronic administration of CsA on sensorimotor gating. Following a single injection with effective doses of CsA, adult healthy male Dark Agouti rats were tested for PPI. For subchronic treatment, rats were injected daily with the same doses of CsA for 1 week before PPI was assessed. Since calcineurin works as a modulator of the dopamine pathway, activity of the enzyme tyrosine hydroxylase was measured in the prefrontal cortex and striatum after accomplishment of the study.

RESULTS

Acute and subchronic treatment with the calcineurin inhibitor CsA disrupted PPI at a dose of 20 mg/kg. Concomitantly, following acute CsA treatment, tyrosine hydroxylase activity was reduced in the prefrontal cortex, which suggests that dopamine synthesis was downregulated, potentially reflecting a stimulatory impact of CsA on this neurotransmitter system.

CONCLUSIONS

The results support experimental and clinical evidence linking impaired calcineurin signaling in the central nervous system to the pathophysiology of neuropsychiatric symptoms. Moreover, these findings suggest that therapy with calcineurin inhibitors may be a risk factor for developing neurobehavioral alterations as observed after the abuse of psychomotor stimulant drugs.

Intra-prefrontal cyclosporine potentiates ketamine-induced fear extinction in rats

Several brain regions, including the medial prefrontal cortex (mPFC), are important in the process of fear extinction learning. Ketamine is a glutamate N-methyl-D-aspartate (NMDA) receptor antagonist, which is shown to play a role in extinction modulation. Ketamine and calcineurin (CN), an intracellular protein phosphatase, have several common targets in the cells. Therefore, in the present study, our aim is to investigate the possible role of calcineurin in the mPFC on the enhancing effects of ketamine in fear extinction. First, different doses of a CN inhibitor, cyclosporine-A (CsA), were micro-injected into the infralimbic (IL) region of the mPFC prior to extinction training in a classical conditioning model in rats. Next, sub-effective doses of CsA (Intra-mPFC) and ketamine (i.p.) were co-administered in another cohort of rats to find their possible interactions. Enzymatic activity of calcineurin was measured in the IL-mPFC following drug administration. We used the elevated plus-maze (EPM) and open field (OF) test for further behavioral assessments. The results showed that CsA can enhance the extinction of conditioned fear and inhibit the enzyme CN at a dose of 20 nM. The combination of sub-effective doses of CsA (5 nM) and ketamine (10 mg/kg) could again enhance the extinction of fear and reduce CN activity in the region. Our results propose that inhibition of CN in the IL-mPFC is involved in the extinction of fear and ketamine enhancement of extinction is probably mediated by reducing CN activity in this part of the brain.

Aqueous Coriandrum sativum L. extract promotes neuroprotection against motor changes and oxidative damage in rat progeny after maternal exposure to methylmercury

This study aimed to investigate the effects of Coriandrum sativum aqueous extract (CSAE) on the rat progeny of mothers exposed to methylmercury (MeHg). The presence of bioactive compounds and CSAE's antioxidant capacity been evaluated, and the offspring were assessed for their total mercury levels, motor behavioral parameters and oxidative stress in the cerebellum. The analysis of the bioactive compounds revealed significant amounts of polyphenols, flavonoids, and anthocyanins, as well as a variety of minerals. A DPPH test showed the CSAE had important antioxidant activity. The MeHg + CSAE group performed significantly better spontaneous locomotor activity, palmar grip strength, balance, and motor coordination in behavioral tests compared the MeHg group, as well as in the parameters of oxidative stress, with similar results to those of the control group. The MeHg + CSAE group also had significantly reduced mercury levels in comparison to the MeHg group. Based on the behavioral tests, which detected large locomotor, balance, and coordination improvements, as well as a reduction in oxidative stress, we conclude that CSAE had positive functional results in the offspring of rats exposed to MeHg.

Applications and limitations of behaviorally conditioned immunopharmacological responses

The importance of placebo responses for the treatment of various medical conditions has increasingly been recognized, whereas knowledge and systematic application in clinical settings are still sparse. One possible application for placebo responses in pharmacotherapy is given by learning paradigms, such as behaviorally conditioned immunosuppression, aiming at drug dose reduction while maintaining therapeutic efficacy of drug treatment. In an established learning paradigm of conditioned taste aversion/avoidance (CTA) in both, rats and humans, respectively, a novel-tasting drinking solution (conditioned stimulus, CS) is paired with an injection of the immunosuppressive drug cyclosporine A (CsA) as unconditioned stimulus (US). The conditioned response, evoked by re-presenting the CS alone at a later time, is reflected by avoidance behavior of consuming the solution (conditioned taste aversion; CTA) and a diminished interleukin (IL)-2 and interferon (IFN)-γ cytokine production as well as mRNA expression of rat splenic T cells or human peripheral T lymphocytes, closely mimicking the immunosuppressive effects of CsA. However, due to unreinforced CS-re-exposure conditioned responses progressively decreases over time (extinction), reflecting a considerable challenge for potential clinical applications of this learned immunosuppression. The present article discusses and critically reviews actual approaches, applications but also limitations of learning paradigms in immune pharmacotherapy.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

The placebo effect has often been considered a nuisance in basic and particularly clinical research. This view has gradually changed in recent years due to deeper insight into the neuro-bio-behavioral mechanisms steering both the placebo and nocebo responses, the evil twin of placebo. For the neuroscientist, placebo and nocebo responses have evolved as indispensable tools to understand brain mechanisms that link cognitive and emotional factors with symptom perception as well as peripheral physiologic systems and end organ functioning. For the clinical investigator, better understanding of the mechanisms driving placebo and nocebo responses allow the control of these responses and thereby help to more precisely define the efficacy of a specific pharmacological intervention. Finally, in the clinical context, the systematic exploitation of these mechanisms will help to maximize placebo responses and minimize nocebo responses for the patient's benefit. In this review, we summarize and critically examine the neuro-bio-behavioral mechanisms underlying placebo and nocebo responses that are currently known in terms of different diseases and physiologic systems. We subsequently elaborate on the consequences of this knowledge for pharmacological treatments of patients and the implications for pharmacological research, the training of healthcare professionals, and for the health care system and future research strategies on placebo and nocebo responses.

Calcineurin inhibition blocks within-, but not between-session fear extinction in mice

Memory extinction involves the formation of a new associative memory that inhibits a previously conditioned association. Nonetheless, it could also depend on weakening of the original memory trace if extinction is assumed to have multiple components. The phosphatase calcineurin (CaN) has been described as being involved in extinction but not in the initial consolidation of fear learning. With this in mind, we set to study whether CaN could have different roles in distinct components of extinction. Systemic treatment with the CaN inhibitors cyclosporin A (CsA) or FK-506, as well as i.c.v. administration of CsA, blocked within-session, but not between-session extinction or initial learning of contextual fear conditioning. Similar effects were found in multiple-session extinction of contextual fear conditioning and in auditory fear conditioning, indicating that CaN is involved in different types of short-term extinction. Meanwhile, inhibition of protein synthesis by cycloheximide (CHX) treatment did not affect within-session extinction, but disrupted fear acquisition and slightly impaired between-session extinction. Our results point to a dissociation of within- and between-session extinction of fear conditioning, with the former being more dependent on CaN activity and the latter on protein synthesis. Moreover, the modulation of within-session extinction did not affect between-session extinction, suggesting that these components are at least partially independent.

Neurobehavioral consequences of small molecule-drug immunosuppression

60 years after the first successful kidney transplantation in humans, transplant patients have decent survival rates owing to a broad spectrum of immunosuppressive medication available today. Not only transplant patients, but also patients with inflammatory autoimmune diseases or cancer benefit from these life-saving immunosuppressive and anti-proliferative medications. However, this success is gained with the disadvantage of neuropsychological disturbances and mental health problems such as depression, anxiety and impaired quality of life after long-term treatment with immunosuppressive drugs. So far, surprisingly little is known about unwanted neuropsychological side effects of immunosuppressants and anti-proliferative drugs from the group of so called small molecule-drugs. This is partly due to the fact that it is difficult to disentangle whether and to what extent the observed neuropsychiatric disturbances are a direct result of the patient's medical history or of the immunosuppressive treatment. Thus, here we summarize experimental as well as clinical data of mammalian and human studies, with the focus on selected small-molecule drugs that are frequently employed in solid organ transplantation, autoimmune disorders or cancer therapy and their effects on neuropsychological functions, mood, and behavior. These data reveal the necessity to develop immunosuppressive and anti-proliferative drugs inducing fewer or no unwanted neuropsychological side effects, thereby increasing the quality of life in patients requiring long term immunosuppressive treatment. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.

Short-term treatment with the calcineurin inhibitor cyclosporine A decreases HPA axis activity and plasma noradrenaline levels in healthy male volunteers

Treatment with the selective calcineurin inhibitor and immunosuppressive drug cyclosporine A (CsA) is associated with neurotoxicity and neurocognitive impairments. Whether and to what extent CsA is inducing alterations of the neuroendocrine status is unknown so far. Therefore, the present study investigated the effect of short-term CsA treatment on hypothalamus-pituitary-adrenal (HPA) axis activity and catecholamine release as well as state anxiety in healthy male subjects. Treatment with CsA significantly reduced plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, and noradrenaline whereas adrenaline levels and state anxiety remained unaffected. Future studies should analyze the mechanisms of CsA-induced effects on neuroendocrine variables, neurocognitive functions and mood.

Acute systemic rapamycin induces neurobehavioral alterations in rats

Rapamycin is a drug with antiproliferative and immunosuppressive properties, widely used for prevention of acute graft rejection and cancer therapy. It specifically inhibits the activity of the mammalian target of rapamycin (mTOR), a protein kinase known to play an important role in cell growth, proliferation and antibody production. Clinical observations show that patients undergoing therapy with immunosuppressive drugs frequently suffer from affective disorders such as anxiety or depression. However, whether these symptoms are attributed to the action of the distinct compounds remains rather elusive. The present study investigated in rats neurobehavioral consequences of acute rapamycin treatment. Systemic administration of a single low dose rapamycin (3mg/kg) led to enhanced neuronal activity in the amygdala analyzed by intracerebral electroencephalography and FOS protein expression 90min after drug injection. Moreover, behavioral investigations revealed a rapamycin-induced increase in anxiety-related behaviors in the elevated plus-maze and in the open-field. The behavioral alterations correlated to enhanced amygdaloid expression of KLK8 and FKBP51, proteins that have been implicated in the development of anxiety and depression. Together, these results demonstrate that acute blockade of mTOR signaling by acute rapamycin administration not only causes changes in neuronal activity, but also leads to elevated protein expression in protein kinase pathways others than mTOR, contributing to the development of anxiety-like behavior. Given the pivotal role of the amygdala in mood regulation, associative learning, and modulation of cognitive functions, our findings raise the question whether therapy with rapamycin may induce alterations in patients neuropsychological functioning.

Learned placebo responses in neuroendocrine and immune functions

The phenomenon of learned placebo responses in neuroendocrine and immune functions is a fascinating example of communication between the brain and both the endocrine and peripheral immune systems. In this chapter, we will give a short overview of afferent and efferent communication pathways, as well as the central mechanisms, which steer the behavioral conditioned immune response. Subsequently, we will focus on data that provides evidence for learned immune responses in experimental animals and learned neuroendocrine and immune placebo responses in humans. Finally, we will take a critical look at these learning protocols, to determine whether or not they can be considered a viable additional treatment option to pharmacological regimens in clinical routine. This is fundamental, since there are still a number of issues, which need to be solved, such as the potential reproducibility, predictability, and extinction of the learned neuroendocrine and immune responses. Together, these findings not only provide an excellent basis to increase our understanding of human biology but may also have far reaching clinical implications. They pave the way for the ultimate aim of employing associative learning protocols as supportive treatment strategies in pharmacological regimens. As a result, medication levels may be reduced, as well as their unwanted side effects, providing a maximized therapeutic outcome to the benefit of the patient.

CD4⁺ but not CD8⁺ T cells revert the impaired emotional behavior of immunocompromised RAG-1-deficient mice

An imbalanced immune system has long been known to influence a variety of mood disorders including anxiety, obsessive-compulsive disorders and depression. In this study, we sought to model the impact of an immunocompromised state on these emotional behaviors using RAG-1⁻/⁻ mice, which lack T and B cells. We also investigated the relative contribution of CD4⁺ or CD8⁺ T cells to these manifestations using RAG-1⁻/⁻/OT-II and RAG-1⁻/⁻/OT-I transgenic mice, respectively. Our results show that RAG-1⁻/⁻ mice present a significant increase in digging and marble-burying activities compared with wild-type mice. Surprisingly, these anxiety-like behaviors were significantly reverted in RAG-1⁻/⁻/OT-II but not RAG-1⁻/⁻/OT-I transgenic mice. Immunodepletion experiments with anti-CD4 or anti-CD8 in C57/BL6 mice or repopulation studies in RAG-1⁻/⁻ mice did not reproduce these findings. Microarray analysis of the brain of RAG-1⁻/⁻ and RAG-1⁻/⁻/OT-II mice revealed a significantly different gene fingerprint, with the latter being more similar to wild-type mice than the former. Further analysis revealed nine main signaling pathways as being significantly modulated in RAG-1⁻/⁻ compared with wild-type mice. Taken together, these results suggest that life-long rather than transient immunodeficient conditions influence the emotional behaviors in mice. Most interestingly, these effects seem to correlate with a specific absence of CD4⁺ rather than CD8⁺ T cells. Validation of these findings in man might provide new clues on the mechanism by which early life immune modulation might impact mood response in adults and provide a further link between immune and emotional well-being.

Neurobehavioural activation during peripheral immunosuppression

Like other physiological responses, immune functions are the subject of behavioural conditioning. Conditioned immunosuppression can be induced by contingently pairing a novel taste with an injection of the immunosuppressant cyclosporine A (CsA) in an associative learning paradigm. This learned immunosuppression is centrally mediated by the insular cortex and the amygdala. However, the afferent mechanisms by which the brain detects CsA are not understood. In this study we analysed whether CsA is sensed via the chemosensitive vagus nerve or whether CsA directly acts on the brain. Our experiments revealed that a single peripheral administration of CsA increases neuronal activity in the insular cortex and the amygdala as evident from increased electric activity, c-Fos expression and amygdaloid noradrenaline release. However, this increased neuronal activity was not affected by prior vagal deafferentation but rather seems to partially be induced by direct action of CsA on cortico-amygdaloid structures and the chemosensitive brainstem regions area postrema and nucleus of the solitary tract. Together, these data indicate that CsA as an unconditioned stimulus may directly act on the brain by a still unknown transduction mechanism.

Decreased IFN-γ and IL-12 levels in panic disorder

OBJECTIVE

The aim of this study is to assess the measures of proinflammatory cytokines in patients with panic disorder in comparison with the healthy subjects.

METHODS

Twenty three patients with panic disorder with or without agoraphobia and twenty three controls were recruited for the study. Plasma samples of all subjects were analyzed for TNF-α, IFN-γ, IL-1β, IL-2, IL-6, and IL-12 concentrations and NK-cell activity is measured in the peripheral blood samples of the subjects.

RESULTS

We found significant differences on the mean values of IL-12 (p=0.01) and IFN-γ (p=0.02) between the panic disorder and control groups. In a logistic regression analysis, IFN-γ values were significant statistical predictors of the presence of panic disorder (B=-0.07, SE=0.03, p=0.04).

CONCLUSION

The most important implication of our results is to suggest a relation between panic disorder and low levels of IFN-γ, compatible with the results of the animal studies showing that IFN-γ plays a role by acting to regulate the development of anxiety-like behaviors.

Long term behavioral effects of functional dopaminergic neurons generated from human neural stem cells in the rat 6-OH-DA Parkinson's disease model. Effects of the forced expression of BCL-X(L)

Parkinson's disease (PD) motor symptoms are caused by the progressive degeneration of ventral mesencephalic (VM) dopaminergic neurons (DAn) in the Substantia Nigra pars compacta (SNpc). Cell replacement therapy for PD is based on the concept that the implantation of DAn in the striatum can functionally restore the dopamine levels lost in the disease. In the current study we have used an immortalized human VM neural stem cell line (hVM1) that generates DAn with the A9 phenotype. We have previously found that the forced expression of Bcl-X(L) in these cells enhances DAn generation and improves, short-term, d-amphetamine-induced rotation after transplantation in the 6-OH-DA rat model of PD 2-month post-grafting. Since functional maturation of human A9 DAn in vivo requires long survival times, in the present study we investigated the behavioral amelioration induced by the transplantation of these precursors (naïve and Bcl-X(L)-modified) in the striatum of Parkinsonian rats for up to 5 months. The main findings observed are an improvement on drug-induced behaviour and importantly, in spontaneous behavior tests for both cell-transplanted groups. Finally, we have also tested whether the grafts could ameliorate cognitive performance in PD, in addition to motor deficits. Significant difference was observed for T-maze alternation test in the cell-transplanted animals as compared to sham operated ones. To our knowledge, this is the first report showing an amelioration in spontaneous motor behavior and in cognitive performance in Parkinsonian animals after receiving human VM neural stem cell grafts. Histological studies confirmed that the grafts generated mature dopaminergic cells.

Stress and traumatic brain injury: a behavioral, proteomics, and histological study

Psychological stress and traumatic brain injury (TBI) can both result in lasting neurobehavioral abnormalities. Post-traumatic stress disorder and blast induced TBI (bTBI) have become the most significant health issues in current military conflicts. Importantly, military bTBI virtually never occurs without stress. In this experiment, we assessed anxiety and spatial memory of rats at different time points after repeated exposure to stress alone or in combination with a single mild blast. At 2 months after injury or sham we analyzed the serum, prefrontal cortex (PFC), and hippocampus (HC) of all animals by proteomics and immunohistochemistry. Stressed sham animals showed an early increase in anxiety but no memory impairment at any measured time point. They had elevated levels of serum corticosterone (CORT) and hippocampal IL-6 but no other cellular or protein changes. Stressed injured animals had increased anxiety that returned to normal at 2 months and significant spatial memory impairment that lasted up to 2 months. They had elevated serum levels of CORT, CK-BB, NF-H, NSE, GFAP, and VEGF. Moreover, all of the measured protein markers were elevated in the HC and the PFC; rats had an increased number of TUNEL-positive cells in the HC and elevated GFAP and Iba1 immunoreactivity in the HC and the PFC. Our findings suggest that exposure to repeated stress alone causes a transient increase in anxiety and no significant memory impairment or cellular and molecular changes. In contrast, repeated stress and blast results in lasting behavioral, molecular, and cellular abnormalities characterized by memory impairment, neuronal and glial cell loss, inflammation, and gliosis. These findings may have implications in the development of diagnostic and therapeutic measures for conditions caused by stress or a combination of stress and bTBI.

Blockade of mineralocorticoid and glucocorticoid receptors reverses stress-induced motor impairments

AIM

Stress and glucocorticoids can influence movement performance and pathologies of the motor system. The classic notion assumes that the glucocorticoid receptor (GR) mediates the majority of stress-induced behavioral changes. Nevertheless, recent findings have attributed a more prominent role to the mineralocorticoid receptor (MR) in modulating behavior. The purpose of this study was to dissociate the impact of MR versus GR activation in movement and stress-associated motor disruption.

METHODS

Groups of male and female rats were tested in skilled reaching and open field behavior and treated peri-orally with either agonists or antagonists for MR and GR, respectively.

RESULTS

Selective acute activation of MR (aldosterone) and GR (dexamethasone) decreased movement success with a magnitude similar to stress-induced impairment in male and female animals. By contrast, antagonist treatment to block MR (RU-28318) or GR (Mifepristone, RU-486) prevented motor impairments caused by acute restraint stress or corticosterone treatment. Moreover, both antagonists reversed chronic stress- and glucocorticoid-induced motor impairments to values comparable to baseline levels. Higher success rates in treated animals were accompanied by improved performance of skilled limb movements. In addition, combined treatment with MR and GR antagonists had additive benefit on aim and advance towards the reaching target.

CONCLUSION

These observations suggest that MR or GR equally influence motor system function with partially synergistic effects. Males and females show comparable responses to MR and GR activation or blockade. The need for balanced activation of MRs and GRs in motor control requires consideration in intervention strategies to improve performance in health and disease.

Chronic administration of cyclosporine A changes expression of BDNF and TrkB in rat hippocampus and midbrain

Neurotrophins, including the brain-derived neurotrophic factor (BDNF), are essential for regulating neuronal differentiation in developing brains. BDNF and its receptor tyrosine kinase receptor B (TrkB) are involved in neuronal signaling, survival and plasticity. Cyclosporine A (CsA) is a potent immunosuppressive agent which prevents allograft rejection in organ transplantation and various immunological diseases. We investigated whether chronic administration of CsA decreases BDNF gene expression in rats, and the influence of CsA on mRNA levels of TrkB receptors was also examined. For 30 days of CsA (10 mg/kg/day) administration, the expression of BDNF and TrkB mRNA was significantly decreased in the hippocampus and midbrain, but there was no significant difference in the cortex. CsA (0, 1, 5 10, 15 ug/ml) down-regulated BDNF and TrkB gene expression through cultured SH-SY5Y cells, as did all-trans retinoic acid (ATRA), and there was no effect on cell viability. These experimental results indicate that suppression of the BDNF and TrkB mRNA, protein level of BDNF expression in the hippocampus and midbrain may be related to altered behavior observed following chronic administration of CsA. A common mechanism of adverse effects of CsA induced depressive symptoms may involve neurotoxicity mediated by down-regulation of brain BDNF and TrkB.

Impact of cyclosporine upon emotional and social behavior in mice

BACKGROUND

Cyclosporine induces psychological side effects but its mechanisms of action remain to be elucidated.

METHODS

Mice were injected with cyclosporine (0, 10, 60 mg/kg intraperitoneal) and indexes of both anxiety-related and social behaviors were examined. Release of serotonin and dopamine in the prefrontal cortex was also investigated by microdialysis.

RESULTS

Intraperitoneal administration of cyclosporine increased cyclosporine concentrations in the blood and brains in mice. Cyclosporine administration at a higher-dose reduced motor activity, increased indexes of anxiety-related behavior, and decreased an index of social interaction. The administration reduced release of serotonin and dopamine in the prefrontal cortex. Clozapine administration abolished the reduced release of dopamine and partially restored the index of social behavior in cyclosporine-injected mice.

CONCLUSIONS

This in vivo model suggests that cyclosporine at a high dose induced hypo-function of the prefrontal cortex as a result of reduced release of serotonin and dopamine, increased anxiety-related behavior, and disturbed social behavior. Clozapine partially restored an index of social behavior. The present findings are pathologically relevant in patients who take cyclosporine.

Cyclosporine treatment of anal furunculosis in 26 dogs

OBJECTIVES

To evaluate the effect of cyclosporine on anal furunculosis lesions in 26 dogs.

METHODS

Lesions were graded as mild in 11 dogs, moderate in eight and severe in seven. Each dog was treated with approximately 4 mg/kg cyclosporine orally every 12 hours until the lesions resolved or showed no further improvement. Residual lesions were resected surgically.

RESULTS

Eighteen dogs (69 per cent) experienced complete resolution, seven (27 per cent) improved but had residual lesions and one (4 per cent) showed no improvement. The mean duration of treatment until resolution or no further improvement was 8.8 weeks (range four to 24 weeks). Nine dogs (35 per cent) experienced recurrence. Six were from the group that had shown complete resolution and three were from the group that had surgery. Fifteen dogs (58 per cent) developed side effects to cyclosporine, although none required treatment to be discontinued. Mean duration of follow-up was 6.8 months (range one to 20 months).

CLINICAL SIGNIFICANCE

Cyclosporine was effective at resolving or reducing anal furunculosis lesions in 25 of 26 dogs (96 per cent). However, residual or recurrent lesions remain a potential problem, and surgical resection or long-term cyclosporine treatment may be necessary in some dogs.

Magnesium Attenuates Post-Traumatic Depression/Anxiety Following Diffuse Traumatic Brain Injury in Rats

OBJECTIVE

Magnesium (Mg) declines after traumatic brain injury (TBI), a decline believed associated with ensuing neuronal cell death and subsequent functional impairment. While Mg's effects on motor and cognitive deficits following TBI have been well studied, few studies have addressed post-traumatic depression as an outcome parameter, despite its being a major clinical problem with an incidence of between 6 and 77%. We investigated the incidence of post-traumatic depression/anxiety in an animal model of diffuse TBI, and explored the use of magnesium sulfate (MgSO(4)) as an interventional treatment.

METHODS

Diffuse TBI was induced in 32 anesthetized, adult, male Sprague-Dawley rats, using the 2 m impact-acceleration model of injury. At 30 min after injury, half of the rats received 250 micromol/kg i.v. MgSO(4); the other half served as non-treated controls. Before and for 6 weeks after injury, the open-field, spontaneous activity test was used to determine post-traumatic depression/anxiety relative to pre-injury. In this test, animals are placed in a 1-meter square box with 100 squares marked on the base. The number of squares entered in a 5-min period is recorded. Incidence of post-traumatic depression/anxiety was defined as the number of animals demonstrating a reduction in spontaneous activity to less than 100 squares in 5 min. Prior to injury, rats typically entered a mean of 201 +/- 12 (SEM) squares over a 5 min observation period.

RESULTS

At 1 week after injury, non-treated animals had a mean core of 62 +/- 13. The incidence of post-traumatic depression/anxiety in these animals was 61%, which is similar to that observed clinically. In contrast, animals treated with MgSO(4) had a mean activity score of 144 +/- 23 at 1 week after TBI and an incidence of depression/anxiety of less than 30%. The significant difference between groups persisted for the entire 6-week observation period.

CONCLUSIONS

The improvement in post-traumatic depression/anxiety conferred by Mg adds further weight to available evidence of Mg's benefit as a neuroprotective agent after TBI.

Endotoxin exposure in utero increases ethanol consumption in adult male offspring

Epidemiological studies have suggested that adverse experiences in utero predispose individuals to neurobehavioral disorders including drug abuse in adulthood. The present study was designed to examine the hypothesis that maternal endotoxin exposure during pregnancy increases ethanol consumption in adult offspring. Pregnant Sprague-Dawley rats were subjected to lippopolysaccharide (LPS, 1.0 mg/kg, s.c.) treatment on alternate days throughout pregnancy. Adult male offspring were tested for ethanol consumption by using a free-access and two bottle choice paradigm. The animals exposed to LPS showed increased ethanol intake and preference as well as decreased rearing activity in the open field test. These data suggest that maternal infection during pregnancy might precipitate alcohol drinking behavior in adult offspring and this effect might be due, at least in part, to elevated levels of anxiety.

Extreme reduction of dipeptidyl peptidase IV activity in F344 rat substrains is associated with various behavioral differences

The enzyme and binding protein dipeptidyl peptidase IV (DPPIV/CD26) has a unique enzymatic specificity in cleaving dipeptides from neuropeptides, chemokines, and hormones. Thus, DPPIV is potentially involved in the regulation of functions of the immune, endocrine, and nervous systems. In the present study, we compared DPPIV-deficient, mutant Japanese [F344/DuCrj(DPPIV-)] and German [F344/Crl(Ger/DPPIV-)] F344 rat substrains with a wild-type-like F344 substrain [F344/Crl(Por)] from the United States in a multitiered strategy using a number of different behavioral tests. General health, neurological and motor functions, and sensory abilities of the different F344 substrains were not different. A reduced body weight and a reduced water consumption were observed in mutant animals. DPPIV-deficient rats exhibited increased pain sensitivity in a non-habituated hot plate test, indicative of a reduced stress-induced analgesia. In line with this finding, reduced stress-like responses in tasks like the open field (OF), social interaction (SI), and passive avoidance test were found. Differences in DPPIV-like activity appear to be involved in neurophysiological processes because DPPIV-deficient animals were less susceptible to the sedative effects of ethanol. The varying phenotypes of the F344 substrains are likely to be mediated by differential degradation of DPPIV substrates such as substance P, glucagon-like peptide (GLP)-1, enterostatin, and especially neuropeptide Y (NPY). Potentially, DPPIV-deficient substrains represent an important tool for biomedical research, focusing on the involvement of DPPIV and its substrates in behavioral and physiological processes.

Behavioral phenotyping of mice in pharmacological and toxicological research

The evaluation of behavioral effects is an important component for the in vivo screening of drugs or potentially toxic compounds in mice. Ideally, such screening should be composed of monitoring general health, sensory functions, and motor abilities, right before specific behavioral domains are tested. A rational strategy in the design and procedure of testing as well as an effective composition of different well-established and reproducible behavioral tests can minimize the risk of false positive and false negative results in drug screening. In the present review we describe such basic considerations in planning experiments, selecting strains of mice, and propose groups of behavioral tasks suitable for a reliable detection of differences in specific behavioral domains in mice. Screening of general health and neurophysiologic functions (reflexes, sensory abilities) and motor function (pole test, wire hang test, beam walking, rotarod, accelerod, and footprint) as well as specific hypothesis-guided testing in the behavioral domains of learning and memory (water maze, radial maze, conditioned fear, and avoidance tasks), emotionality (open field, hole board, elevated plus maze, and object exploration), nociception (tail flick, hot plate), psychiatric-like conditions (porsolt swim test, acoustic startle response, and prepulse inhibition), and aggression (isolation-induced aggression, spontaneous aggression, and territorial aggression) are described in further detail. This review is designed to describe a general approach, which increases reliability of behavioral screening. Furthermore, it provides an overview on a selection of specific procedures suitable for but not limited to behavioral screening in pharmacology and toxicology.

Postnatal lipopolysaccharide-induced illness predisposes to periodontal disease in adulthood

The long-term consequences of neonatal lipopolysaccharide (LPS) exposure on adult behavioral and neuroendocrine stress responsiveness as well as on the clinical course of periodontal disease were assessed in male Lewis rats. At 3 and 5 days of age, pups were administered either saline (SHAM) or LPS or were left undisturbed. After postnatal treatment, mothers licked LPS-treated pups significantly more. In adult LPS rats of 3-5 months of age, home cage activity indicated changes of the diurnal rhythmicity. Furthermore, SHAM- and LPS-treated animals displayed treatment-specific signs of increased anxiety in social interaction, elevated plus maze, holeboard, and open field tests. At 7 months of age, a dramatic increase of periodontal fiber loss in LPS rats was associated with increased plasma interleukin-6 levels. In contrast, SHAM treatment caused high plasma interferon-gamma cytokine levels and protective effects in periodontal disease. Parameters of the response to novelty were significantly correlated with later disease susceptibility. Thus, LPS-induced early postnatal illness modulates the adult behavioral responsiveness to stress and predisposes to periodontal disease.

Postnatal maternal deprivation aggravates experimental autoimmune encephalomyelitis in adult Lewis rats: reversal by chronic imipramine treatment

Stressful experiences can modulate multiple sclerosis, but stress protection is currently not considered a treatment option. Here, we show that maternal deprivation, an adverse stress experience in infancy, increases emotionality in behavioral tests of adult female Lewis rats and concomitantly causes a more severe course of experimental autoimmune encephalomyelitis. Treatment of these effects in adulthood by chronic antidepressants (imipramine) reversed the behavioral symptoms and attenuated the course of the encephalomyelitis in deprived rats. Increased IL-4 plasma levels accompanied the protective-like effects of antidepressants. In contrast, attempts to prevent these effects in infancy by tactile stimulation aggravated the encephalomyelitis, possibly by decreasing corticosterone and increasing IFN-gamma levels during the disease. This indicates that antidepressants exert protective effects in an animal model of multiple sclerosis, and suggests that drugs modifying stress responsiveness may have a potential role as adjuvant treatment of the disease.

Cyclosporin A, FK506 and rapamycin produce multiple, temporally distinct, effects on memory following single-trial, passive avoidance training in the chick

Few studies have used a pharmaco-behavioural methodology to directly investigate roles for the calcium-dependent protein phosphatase calcineurin (CaN) in memory formation, due partly to the absence of specific inhibitory agents. A number of drugs with different inhibitory profiles were used to examine this issue in groups of chicks trained on a single-trial, passive-avoidance task. Bilateral intracranial administration of the immunosuppressants FK506 and cyclosporin A (CyA) led to two temporally distinct effects, distinguished by the concentration of drug required and the effective time of administration relative to training. In addition to inhibiting CaN, CyA and FK506 inhibit distinct classes of peptidyl prolyl-cis/trans-isomerases (PPIases). Other agents known to inhibit these enzymes, including the Map kinase inhibitor Rapamycin, also induced memory deficits in a complex, dose- and time-of-administration-dependent, manner. The data fail to conclusively implicate CaN in memory formation, but are consistent with proposals that a phosphatase cascade may participate in an early stage of information storage. PPIases may be required at a later stage to catalyse the folding of new or translocated proteins, the synthesis of which is required for formation of long-term memory, although other possible explanations for the data remain to be investigated.

Behavioral and immune changes in v-Ha-ras transgenic mice

Transgenic mice (Oncomice) with an activated v-Ha-ras oncogene under the control of the mouse mammary tumor virus promoter develop mammary tumors. We wondered if the expression of the v-Ha-ras oncogene product would induce changes in mice behavioral activity, that could be associated with alterations in their immune system. Behavior was evaluated in an open field study considering line crossings and rears. Oncomice consistently showed less activity than FVB mice. Lieber-DeCarli diet decreased both types of activity in both strains. Cocaine treatment increased line crossings in both strains. Oncomice spleen and thymus cell supernatants contained higher levels of IL-2. Oncomice serum had higher levels of IL-1alpha. Our results suggest a direct association between higher levels of IL-1alpha and lower open field activity. Therefore, we can infer that the increased level of IL-1alpha found in Oncomice, could have a key role in oncogene induced immune and behavioral changes, and could be a requirement to facilitate its transforming activity.

The influence of a targeted deletion of the IFNgamma gene on emotional behaviors

Evidence suggests that interferon-gamma (IFNgamma) plays an important role in CNS function and development. While the paucity of agents that selectively modify IFNgamma production or interaction with its receptors makes analyses of its potential behavioral relevance difficult, mice with null mutations of the IFNgamma gene have been used to investigate the potential role of IFNgamma in emotional behaviors. C57Bl/6 (B6) mice with null mutations of the IFNgamma gene (IFNgamma (-/-)) showed significantly increased emotionality compared to the wild-type (IFNgamma (+/+)) B6 mice. This was manifested in performance in the elevated plus maze as well as increased defecation scores and decreased locomotor activity both in novel environments and following a sonic stimulus. In contrast, the general level of emotionality of both IFNgamma (+/+) and (-/-) BALB/c (C) mice was substantially greater than that of either of the B6 mouse groups. While C IFNgamma (-/-) showed increased immobility in response to novelty, other indices of emotionality of C IFNgamma (-/-) mice were not significantly different from those of the C IFNgamma (+/+) mice. In summary, the lack of IFNgamma appears to contribute to increased emotionality, but the basal behaviors of the parental strain (e.g., BALBc) may overshadow the expression of this emotionality. While mice with null mutations of the IFNgamma gene may be useful tools for investigating the role of IFNgamma in brain function and behavior, the influence of the parent strain genome(s) on the behaviors in question must be taken into account.

Brain NPY Y1 receptors rapidly mediate the behavioral response to novelty and a compartment-specific modulation of granulocyte function in blood and spleen

Neuropeptide Y (NPY) alters behavioral activity and innate immune functions of rats within minutes of intracerebroventricular (i.c.v.) application. Using combinations of the Y1-5a,b(6) agonist NPY, the Y1,3,5 agonist [Leu31-Pro34]NPY (LP-NPY), and the selective Y1 antagonist BIBP3226 (BIBP), we investigated whether the NPY-Y1 receptor (Y1R) subtype regulates NPY-induced behavioral and immunological effects at 15 min after i.c.v. application. Administration of both NPY and LP-NPY decreased rearing activity in the open field and suppressed granulocyte function in the blood. These effects were blocked by BIBP pre-treatment. In contrast to the blood, NPY and BIBP+NPY treatments stimulated granulocyte function within the splenic compartment. In addition, a blood leukophilia composed of granulocytes and NK cells was induced by NPY only. We conclude that the tested early effects of NPY are mediated by either the Y1R (rearing, blood granulocyte function), or a non-Y1R (splenic granulocyte function), or by a combined receptor activation (leukocyte mobilization). Furthermore, the immunological effects of NPY demonstrate compartment specificity.