Prednisone induces cognitive dysfunction, neuronal degeneration, and reactive gliosis in rats

Chemobrain in blood cancers: How chemotherapeutics interfere with the brain's structure and functionality, immune system, and metabolic functions

Cancer treatment brings about a phenomenon not fully clarified yet, termed chemobrain. Its strong negative impact on patients' well-being makes it a trending topic in current research, interconnecting many disciplines from clinical oncology to neuroscience. Clinical and animal studies have often reported elevated concentrations of proinflammatory cytokines in various types of blood cancers. This inflammatory burst could be the background for chemotherapy-induced cognitive deficit in patients with blood cancers. Cancer environment is a dynamic interacting system. The review puts into close relationship the inflammatory dysbalance and oxidative/nitrosative stress with disruption of the blood-brain barrier (BBB). The BBB breakdown leads to neuroinflammation, followed by neurotoxicity and neurodegeneration. High levels of intracellular reactive oxygen species (ROS) induce the progression of cancer resulting in increased mutagenesis, conversion of protooncogenes to oncogenes, and inactivation of tumor suppression genes to trigger cancer cell growth. These cell alterations may change brain functionality, as well as morphology. Multidrug chemotherapy is not without consequences to healthy tissue and could even be toxic. Specific treatment impacts brain function and morphology, functions of the immune system, and metabolism in a unique mixture. In general, a chemo-drug's effects on cognition in cancer are not direct and/or in-direct, usually a combination of effects is more probable. Last but not least, chemotherapy strongly impacts the immune system and could contribute to BBB disruption. This review points out inflammation as a possible mechanism of brain damage during blood cancers and discusses chemotherapy-induced cognitive impairment.

The stress of losing sleep: Sex-specific neurobiological outcomes

Sleep is a vital and evolutionarily conserved process, critical to daily functioning and homeostatic balance. Losing sleep is inherently stressful and leads to numerous detrimental physiological outcomes. Despite sleep disturbances affecting everyone, women and female rodents are often excluded or underrepresented in clinical and pre-clinical studies. Advancing our understanding of the role of biological sex in the responses to sleep loss stands to greatly improve our ability to understand and treat health consequences of insufficient sleep. As such, this review discusses sex differences in response to sleep deprivation, with a focus on the sympathetic nervous system stress response and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We review sex differences in several stress-related consequences of sleep loss, including inflammation, learning and memory deficits, and mood related changes. Focusing on women's health, we discuss the effects of sleep deprivation during the peripartum period. In closing, we present neurobiological mechanisms, including the contribution of sex hormones, orexins, circadian timing systems, and astrocytic neuromodulation, that may underlie potential sex differences in sleep deprivation responses.

Psycho-Behavioural Changes in Dogs Treated with Corticosteroids: A Clinical Behaviour Perspective

Simple Summary

Corticosteroids hormones are central to stress responses and, along with other hormones and neurotransmitters, contribute to the onset of physiological and behavioural changes aimed at helping the animal cope with anticipated demand. Both the human and animal literature suggest that exposure to systemic exogenous corticosteroid treatments can be associated with negative emotional states. In this paper, the potential behavioural effects of exogenous corticosteroid treatment on dogs and other species are discussed to show why consideration should be given to this matter when prescribing these drugs.

Abstract

Arousal and distress are often important factors in problematic behaviours, and endogenous corticosteroids are important mediators in the associated stress responses. Exogenous corticosteroid treatments have been reported to change behaviour in human patients and laboratory animals, with similar changes also noted in pet dogs. These behaviours not only potentially adversely impact the welfare of the dogs, but also the quality of life of their owners. Indeed, corticosteroids can bias sensitivity towards aversion in dogs. A decrease in behaviours associated with positive affective states, such as play and exploratory behaviours, together with an increase in aggression and barking have also been described in dogs. According to the available literature, human patients with pre-existing psychiatric disorders are more at risk of developing behavioural side effects due to corticosteroid treatments. It is reasonable to consider that the same may happen in dogs with pre-existing behavioural problems. In this paper, the possible behavioural side effects of exogenous corticosteroids are summarised to help inform and support veterinarians prescribing these drugs.

Mathematical processing is affected by daily but not cumulative glucocorticoid dose in patients with systemic lupus erythematosus

OBJECTIVES

The impact of glucocorticoids on neurocognitive performance in patients with SLE is not fully addressed. We aimed to study the effect of daily and cumulative glucocorticoid dose on neurocognitive performance in SLE patients.

METHODS

Consecutive SLE patients and gender- and age-matched healthy controls (HCs) underwent the computer-based Automated Neuropsychological Assessment Matric (ANAM), which evaluates eight neurocognitive domains including learning, recall, visual perception, mental rotation, short-term memory, attention, sustained attention and working memory. The total and individual-domain throughput scores (TPSs) and the presence of cognitive dysfunction (total TPS <1.5 s.d. below the mean TPS of HCs) were compared between SLE patients and HCs. Within the SLE group, univariate and independent associations between prednisolone dose (daily and cumulative) and individual-domain TPS were studied by univariate and multivariable linear regression, respectively.

RESULTS

A total of 96 SLE patients and 96 HCs were studied. SLE patients scored significantly worse across all the neurocognitive domains and had a significantly lower mean total TPS (P < 0.001) and a higher prevalence of cognitive dysfunction compared with HCs (25.0 vs 7.3%, P = 0.001). In SLE patients, daily prednisolone dose was significantly and negatively correlated with mathematical-processing TPS, which probes working memory (P = 0.018). No significant correlation between cumulative prednisolone dose and any of the individual-domain TPSs was found. In multivariable regression, higher daily prednisolone dose and doses >9 mg daily remained independently associated with lower mathematical-processing TPSs (P = 0.031).

CONCLUSION

Daily prednisolone dose ≥9 mg, but not cumulative glucocorticoid dose, had an independent negative impact on mathematical processing in SLE patients.

Behavioural abnormalities in children with new-onset nephrotic syndrome receiving corticosteroid therapy: results of a prospective longitudinal study

BACKGROUND

Corticosteroid therapy can cause behavioural abnormalities in children with nephrotic syndrome. The objective of this study was to explore the timing of the appearance of abnormalities in their first episode.

METHODS

Forty-five children with a first episode of idiopathic nephrotic syndrome (30 aged 2-5 and 15 aged 6-14 years) were assessed for behavioural problems using the Child Behaviour Checklist (CBCL) before, and after 6 and 12 weeks of oral steroid treatment. Sixty healthy children were included as controls.

RESULTS

In both age groups, marked abnormalities of externalising behaviour were noticed, specifically in the domains of aggressive behaviour and attention problems. Clinical range or borderline externalising abnormalities were present in 73% of the younger children and 60% of the schoolchildren after 6 weeks of treatment. In the schoolchildren, abnormal internalising behaviour was also noted at 6 weeks, in 40% at borderline level and in 20% within the clinical range. Elevated scores were observed for the anxious/depressed and withdrawn/depressed domains. Most changes persisted at the 12-week observation.

CONCLUSIONS

Children of both age groups showed significant attention problems and aggressive and abnormal externalising behaviour within 6 weeks of starting treatment. Parents should be informed and counselled about this potential adverse effect of steroid therapy.

Long-term hydrocephalus alters the cytoarchitecture of the adult subventricular zone

Hydrocephalus can develop secondarily to a disturbance in production, flow and/or absorption of cerebrospinal fluid. Experimental models of hydrocephalus, especially subacute and chronic hydrocephalus, are few and limited, and the effects of hydrocephalus on the subventricular zone are unclear. The aim of this study was to analyze the effects of long-term obstructive hydrocephalus on the subventricular zone, which is the neurogenic niche lining the lateral ventricles. We developed a new method to induce hydrocephalus by obstructing the aqueduct of Sylvius in the mouse brain, thus simulating aqueductal stenosis in humans. In 120-day-old rodents (n=18 per group), the degree of ventricular dilatation and cellular composition of the subventricular zone were studied by immunofluorescence and transmission electron microscopy. In adult patients (age>18years), the sizes of the subventricular zone, corpus callosum, and internal capsule were analyzed by magnetic resonance images obtained from patients with and without aqueductal stenosis (n=25 per group). Mice with 60-day hydrocephalus had a reduced number of Ki67+ and doublecortin+cells on immunofluorescence, as well as decreased number of neural progenitors and neuroblasts in the subventricular zone on electron microscopy analysis as compared to non-hydrocephalic mice. Remarkably, a number of extracellular matrix structures (fractones) contacting the ventricular lumen and blood vessels were also observed around the subventricular zone in mice with hydrocephalus. In humans, the widths of the subventricular zone, corpus callosum, and internal capsule in patients with aqueductal stenosis were significantly smaller than age and gender-matched patients without aqueductal stenosis. In summary, supratentorial hydrocephalus reduces the proliferation rate of neural progenitors and modifies the cytoarchitecture and extracellular matrix compounds of the subventricular zone. In humans, this similar process reduces the subventricular niche as well as the width of corpus callosum and internal capsule.

Prednisolone induces microglial activation in the subnucleus caudalis of the rat trigeminal sensory complex

Prednisolone is a member of synthetic glucocorticoids which are widely used to treat chronic inflammatory diseases. In this study, neuronal degeneration and cell death, and glial reaction were investigated in the rat trigeminal ganglion (TG) and brainstem after subcutaneous injection of prednisolone for 7 days. Expression of c-Jun activating transcription factor 3 and caspase-3 was absent or infrequent in the TG, and cranial sensory and motor nuclei of saline- and prednisolone-treated animals. In these animals, distribution of calcitonin gene-related peptide-immunoreactive (-IR) neurons and nerve fibers was similar in the brainstem. In addition, the number of Iba1- and glial fibrillary acidic protein (GFAP)-IR cells with some processes in the brainstem was barely affected by prednisolone treatment. However, the treatment increased ramification of Iba1-IR processes in the subnucleus caudalis of the trigeminal sensory complex. Prednisolone scarcely influenced the morphology of GFAP-IR cells in the brainstem. Expression of p38 mitogen-activated protein kinase was very rare in the brainstem of saline- and prednisolone-treated animals. The present study suggests that microglia are activated by prednisolone in the subnucleus caudalis of the trigeminal sensory complex. The glucocorticoid may affect nociceptive transmission in the brainstem.

The stressed synapse: the impact of stress and glucocorticoids on glutamate transmission

Mounting evidence suggests that acute and chronic stress, especially the stress-induced release of glucocorticoids, induces changes in glutamate neurotransmission in the prefrontal cortex and the hippocampus, thereby influencing some aspects of cognitive processing. In addition, dysfunction of glutamatergic neurotransmission is increasingly considered to be a core feature of stress-related mental illnesses. Recent studies have shed light on the mechanisms by which stress and glucocorticoids affect glutamate transmission, including effects on glutamate release, glutamate receptors and glutamate clearance and metabolism. This new understanding provides insights into normal brain functioning, as well as the pathophysiology and potential new treatments of stress-related neuropsychiatric disorders.

Beyond the joints: neurological involvement in rheumatoid arthritis

Although arthritis is the most notable component, rheumatoid arthritis (RA) is a systemic inflammatory disorder where extra-articular manifestations are common; among them, central and peripheral nervous system involvement is frequent and associated with significant morbidity and, in some cases, reduced life span. It may produce a myriad of symptoms and signs ranging from subtle numbness in a hand, to quadriparesis and sudden death. Central and peripheral neurologic manifestations may arise from structural damage produced by RA in diarthroidal joints, by the systemic inflammatory process of the disease itself or by the drugs used to treat it. Neurologic syndromes may appear suddenly or developed slowly through months, and emerge early or after years of having RA. Neurologic manifestations may be easily overlooked or incorrectly assigned to peripheral arthritis unless the attending physician is aware of these complications. In this article, we review neurologic involvement in RA patients with emphasis on clinical approach for early detection.

Responses of glial cells to stress and glucocorticoids

A growing body of evidence suggests that glial cells are involved in practically all aspects of neural function. Glial cells regulate the homeostasis of the brain, influence the development of the nervous system, modulate synaptic activity, and carry out the immune response inside the brain. In addition, they play an important role in the restoration of the nervous system after damage, and they also participate in various neurodegenerative disorders. In a similar way, the importance of stress and glucocorticoids (GCs) on brain function is being increasingly recognized. Within the brain, stress hormones target both neurons and glial cells. Through their actions on these cells, glucocorticoids exert organizational functions on various processes of the developing brain and contribute to neuronal plasticity in the adult brain. Moreover, stress and glucocorticoids have become especially attractive in the study of a number of neurodegenerative disorders. However, studies on the mechanisms behind glucocorticoid-induced regulation of brain function have been classically focused on their effects on neurons. In this review, we start by describing the main functions of glial cells and then proceed to present data highlighting the effects of stress and GCs on brain function. We conclude the review by presenting recent evidence linking stress and glucocorticoids to glial cell function.

Behavioural abnormalities in children with nephrotic syndrome--an underappreciated complication of a standard treatment?

Behaviour and psychosocial adjustment are impaired in children with steroid-sensitive idiopathic nephrotic syndrome (SSNS). Both illness-related variables and family climate play a role. Steroid treatment-both short- and long-term-is an important contributor among other determinants. The exact mechanisms by which steroids lead to behavioural alterations in humans is unclear. Optimizing the benefit/risk ratio of steroid treatment in children with SSNS is a constant goal.

Anxiety after cardiac arrest/cardiopulmonary resuscitation: exacerbated by stress and prevented by minocycline

BACKGROUND AND PURPOSE

Stress is an important risk factor for cardiovascular disease; however, most of the research on this topic has focused on incidence rather than outcome. The goal of this study was to determine the effects of prior exposure to chronic stress on ischemia-induced neuronal death, microglial activation, and anxiety-like behavior.

METHODS

In Experiment 1, mice were exposed to 3 weeks of daily restraint (3 hours) and then subjected to either 8 minutes of cardiac arrest/cardiopulmonary resuscitation (CA/CPR) or sham surgery. Anxiety-like behavior, microglial activation, and neuronal damage were assessed on postischemic Day 4. In Experiment 2, mice were infused intracerebroventricularly with minocycline (10 microg/day) to determine the effect of inhibiting post-CA/CPR microglial activation on the development of anxiety-like behavior and neuronal death.

RESULTS

CA/CPR precipitated anxiety-like behavior and increased microglial activation and neuronal damage within the hippocampus relative to sham surgery. Prior exposure to stress exacerbated these measures among CA/CPR mice, but had no significant effect on sham-operated mice. Treatment with minocycline reduced both neuronal damage and anxiety-like behavior among CA/CPR animals. Anxiety-like behavior was significantly correlated with measures of microglial activation but not neuronal damage.

CONCLUSIONS

A history of stress exposure increases the pathophysiological response to ischemia and anxiety-like behavior, whereas inhibiting microglial activation reduces neuronal damage and mitigates the development of anxiety-like behavior after CA/CPR. Thus, modulating inflammatory signaling after cerebral ischemia may be beneficial in protecting the brain and preventing the development of affective disorders.

Deflazacort: a glucocorticoid with few metabolic adverse effects but important immunosuppressive activity

Deflazacort (DFZ) is a synthetic glucocorticoid that has few adverse effects on glucose and calcium metabolism and fewer deleterious effects on the neuronal population. Therefore, it may have a crucial role in the treatment of patients with autoimmune disorders associated with central nervous system or metabolic affectations. To date, the pharmacologic safety profile of DFZ is considered similar to that of other glucocorticoids. Nevertheless, cumulative clinical and laboratory evidence suggests that DFZ has, in fact, greater immunosuppressive activity than was previously thought. Therefore, it is possible that DFZ increases the risk of acquiring opportunistic infection compared with other synthetic glucocorticoids. Additional pharmacologic studies are needed to fully establish the immunosuppressive potency of DFZ and, consequently, to determine the appropriate ratio of bioequivalence in humans.

Chronic glucocorticoids increase hippocampal vulnerability to neurotoxicity under conditions that produce CA3 dendritic retraction but fail to impair spatial recognition memory

We previously found that chronic stress conditions producing CA3 dendritic retraction and spatial memory deficits make the hippocampus vulnerable to the neurotoxin ibotenic acid (IBO). The purpose of this study was to determine whether exposure to chronic corticosterone (CORT) under conditions that produce CA3 dendritic retraction would enhance CA3 susceptibility to IBO. Male Sprague Dawley rats were chronically treated for 21 d with CORT in drinking water (400 microg/ml), and half were given daily injections of phenytoin (40 mg/kg), an antiepileptic drug that prevents CA3 dendritic retraction. Three days after treatments stopped, IBO was infused into the CA3 region. Conditions producing CA3 dendritic retraction (CORT and vehicle) exacerbated IBO-induced CA3 damage compared with conditions in which CA3 dendritic retraction was not observed (vehicle and vehicle, vehicle and phenytoin, CORT and phenytoin). Additionally, spatial recognition memory was assessed using the Y-maze, revealing that conditions producing CA3 dendritic retraction failed to impair spatial recognition memory. Furthermore, CORT levels in response to a potentially mild stressor (injection and Y-maze exposure) stayed at basal levels and failed to differ among key groups (vehicle and vehicle, CORT and vehicle, CORT and phenytoin), supporting the interpretations that CORT levels were unlikely to have been elevated during IBO infusion and that the neuroprotective actions of phenytoin were not through CORT alterations. These data are the first to show that conditions with prolonged glucocorticoid elevations leading to structural changes in hippocampal dendritic arbors can make the hippocampus vulnerable to neurotoxic challenges. These findings have significance for many disorders with elevated glucocorticoids that include depression, schizophrenia, Alzheimer's disease, and Cushing's disease.

Deflazacort induced stronger immunosuppression than expected

Prednisone (PDN) impairs cognitive functioning and brain structures in humans and animals. Deflazacort (DFZ) is a synthetic glucocorticoid claimed to have lesser side effects than prednisone. The objective of this study was to assess whether chronic administration (90 days) of DFZ produces less neuronal degeneration and glial reactivity than PDN. Male Swiss-Wistar rats were studied. Controls received 0.1 ml distilled water orally. The PDN group received prednisone 5 mg per kg per day orally, and the DFZ group received deflazacort 6 mg per kg per day orally. This model had to be assembled in three different occasions due to excess mortality in the DFZ group. A fourth model was assembled using only the DFZ group and slides of water and PDN-exposed rats from a previous study were used as comparators. The index of degenerated neurons and the number and cytoplasmic transformation of astrocytes and microglia cells were evaluated in the prefrontal cortex, CA1, and CA3 hippocampus. The results show that the overall mortality was 49% in the DFZ group, 4.5% in the PDN group, and none of the controls died. Routine necropsy showed infection in multiple organs. The PDN group had two times higher neuronal degeneration in the prefrontal cortex, almost 11 times in CA1, and four times in CA3 hippocampus when compared with controls and DFZ group. Astrocytes reactivity was increased in the PDN- and DFZ-exposed rats compared with controls. The DFZ group showed an average of four times less microgial cells in the three studied regions when compared with controls and the PDN group. In conclusion, it seems that DFZ at the equivalent licensed dose produced a stronger immunosuppressive effect--systemic and in brain tissue--than PDN, but induced less neuronal damage. The immunosuppressant magnitude of DFZ should be further studied in clinical settings.

What is the functional significance of chronic stress-induced CA3 dendritic retraction within the hippocampus?

Chronic stress produces consistent and reversible changes within the dendritic arbors of CA3 hippocampal neurons, characterized by decreased dendritic length and reduced branch number. This chronic stress-induced dendritic retraction has traditionally corresponded to hippocampus-dependent spatial memory deficits. However, anomalous findings have raised doubts as to whether a CA3 dendritic retraction is sufficient to compromise hippocampal function. The purpose of this review is to outline the mechanism underlying chronic stress-induced CA3 dendritic retraction and to explain why CA3 dendritic retraction has been thought to mediate spatial memory. The anomalous findings provide support for a modified hypothesis, in which chronic stress is proposed to induce CA3 dendritic retraction, which then disrupts hypothalamic-pituitary-adrenal axis activity, leading to dysregulated glucocorticoid release. The combination of hippocampal CA3 dendritic retraction and elevated glucocorticoid release contributes to impaired spatial memory. These findings are presented in the context of clinical conditions associated with elevated glucocorticoids.

Steroid-induced alterations of mood and behavior in children during treatment for acute lymphoblastic leukemia

Despite their therapeutic utility, children may experience emotional and behavioral side effects from steroids during treatment for leukemia. However, clinical manifestations and treatment options have rarely been described in the pediatric literature. The aim of this current paper is to address this knowledge gap via four brief case examples and a review of the literature. In addition, we review recent data to indicate how concurrent use of antifolates may place these children at particular risk for adverse psychological reactions.

Effects of progesterone on the inflammatory response to brain injury in the rat

The effects of progesterone on the cellular inflammatory response to frontal cortex injury were examined on postsurgical days 1, 3, 5, 7 and 9 in male rats treated with progesterone (4 mg/kg) and/or vehicle. Rats with bilateral contusions showed increased levels of edema on days 1, 3 and 5, more reactive astrocytes on days 3, 5, 7 and 9, and more macrophages/activated microglia on days 1, 3, 5 and 9 compared to shams. The number of neurons in the medial dorsal nucleus (MDN) of the thalamus reduced on days 5 and 9 after injury compared to shams. Progesterone reduced edema levels and increased the accumulation of macrophages/activated microglia compared to vehicle controls (p<0.025); however, these changes in the inflammatory response were not related to MDN neuronal survival. Our results confirm the possibility that one way progesterone mediates its neuroprotective effects following injury is through its actions on the inflammatory response.