FTY720 (Fingolimod), a modulator of sphingosine-1-phosphate receptors, increases baseline hypothalamic-pituitary adrenal axis activity and alters behaviors relevant to affect and anxiety

An unraveled mystery: What's the role of brain sphingolipids in neurodegenerative and psychiatric disorders

Sphingolipids are a class of lipids highly expressed in brain, especially in the myelin sheath of white matter. In recent years, with the development of lipidomics, the role of brain sphingolipids in neurological disorders have raised lots of interests due to their function in neuronal signal transduction and survival. Although not thoroughly investigated, some previous studies have indicated that sphingolipids homeostasis are closely linked to the etiology and development of some neurological disorders. For example, disrupted sphingolipids level have been found in clinic patients with neurological disorders, such as neurodegeneration and psychiatric disorders. Conversely, intervention of sphingolipids metabolism by modulating activity of related enzymes also could result in pathological deficits identified in neurological disorders. Moreover, the alteration of sphingolipids catabolic pathway in the brain could be partly represented in cerebrospinal fluid and blood tissues, which show diagnostic potential for neurological disorders. Therefore, our review aims to summarize and discuss the known contents of bioactive sphingolipid metabolism with their related studies in neurodegenerative and psychiatric disorders, to help understand the potential mechanism underlying sphingolipid regulation of neural function and provide possible directions for further study. The new perspectives in this promising field will open up new therapeutic options for neurological disorders.

Sphingosine-1-phosphate receptor 3 activation promotes sociability and regulates transcripts important for anxiolytic-like behavior

We previously demonstrated that sphingosine-1-phosphate receptor 3 (S1PR3) in the medial prefrontal cortex (mPFC) prevents reductions in sociability normally caused by stress. S1PR3 is a ubiquitously expressed G-protein coupled receptor that regulates immune system function, although its regulation of other biological processes is not well understood. Pharmacological activators of S1PR3 might provide important insights for understanding the neural substrates underlying sociability. Here we show that in mice, systemic injections of an S1PR3-specific agonist, CYM5541, promotes sociability in males and females whereas an S1PR3-specific antagonist, CAY10444, increases amygdala activation and increases social avoidance, particularly in females. S1PR3 expression is increased in the mPFC and dentate gyrus of females compared to males. RNA sequencing in the mPFC reveals that S1PR3 activation alters the expression of transcripts related to immune function, neurotransmission, transmembrane ion transport, and intracellular signaling. This work provides evidence that S1PR3 agonists, which have classically been used as immune modulators, might also be used to promote social behavior and, potentially, relieve symptoms of social anxiety. S1PR3 might be an important hub gene for mitigating maladaptive effects of stress as it reduces inflammatory processes, increases transcripts linked to anxiolytic neurotransmission, and promotes social behavior.

Brain region specific regulation of anandamide (down) and sphingosine-1-phosphate (up) in association with anxiety (AEA) and resilience (S1P) in a mouse model of chronic unpredictable mild stress

Chronic unpredictable and unavoidable stress is associated with mental health problems such as depression and anxiety, whereas cycles of stress and stress relief strengthen resilience. It has been suggested that increased breakdown of brain endocannabinoids (eCB) promotes a feeling of adversity. To assess the impact of stress on bioactive lipid homeostasis, we analyzed eCB, sphingolipids, and ceramides in seven brain regions and plasma in a mouse model of chronic unpredictable mild stress. Chronic unpredictable mild stress (CUMS) was associated with low levels of anandamide in hippocampus and prefrontal cortex in association with indicators of anxiety (elevated plus maze). Oppositely, CUMS caused elevated levels of sphingosine-1-phosphate (S1P d18:1) and sphinganine-1-phosphate (S1P d18:0) in the midbrain and thalamus, which was associated with readouts of increased stress resilience, i.e., marble burying and struggling in the tail suspension tests. In the periphery, elevated plasma levels of ceramides revealed similarities with human major depression and suggested unfavorable effects of stress on metabolism, but plasma lipids were not associated with body weight, sucrose consumption, or behavioral features of depression or anxiety. The observed brain site-specific lipid changes suggest that the forebrain succumbs to adverse stress effects while the midbrain takes up defensive adjustments.

Behavioral Analyses in Dark Agouti Rats Following Repeated Systemic Treatment With Fingolimod (FTY720)

BACKGROUND

Studies in experimental animals revealed that acute and chronic treatment with small-molecule immunosuppressive drugs lead to neurobehavioral alterations in rodents.

METHODS

Against this background, this study investigated behavioral alterations in rats after repeated administration of FTY720, an immunosuppressive drug used for the treatment of multiple sclerosis, employing the open field, elevated plus maze, and dark/light tests.

RESULTS

Compared to controls, repeated FTY720 treatment affected behavior in rats, reflected by a reduction in distance traveled as well as increased time engaged in freezing in the open field and elevated plus maze. Furthermore, the time spent freezing in the elevated plus maze test positively correlated with FTY720 concentrations in the amygdala and insular cortex, two brain regions involved in regulation of emotionality. Since no changes in plasma corticosterone levels were observed, stress effects due to treatment, behavioral testing, or handling can be ruled out.

CONCLUSION

The present findings indicate that treatment with FTY720 did not induce typical anxiety-like behavioral patterns in otherwise healthy rats as seen following treatment with other immunosuppressive drugs. Nevertheless, it remains of great importance to evaluate behavioral effects in clinical practice to shed more light onto possible detrimental side effects emerging during treatment with small-molecule immunosuppressive drugs.

Role of Sphingosine-1-Phosphate Signaling Pathway in Pancreatic Diseases

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolic product produced via the phosphorylation of sphingosine by sphingosine kinases (SPHKs), serving as a powerful modulator of various cellular processes through its interaction with S1P receptors (S1PRs). Currently, this incompletely understood mechanism in pancreatic diseases including pancreatitis and pancreatic cancer, largely limits therapeutic options for these disorders. Recent evidence indicates that S1P significantly contributes to pancreatic diseases by modulating inflammation, promoting pyroptosis in pancreatic acinar cells, regulating the activation of pancreatic stellate cells, and affecting organelle functions in pancreatic cancer cells. Nevertheless, no review has encapsulated these advancements. Thus, this review compiles information about the involvement of S1P signaling in exocrine pancreatic disorders, including acute pancreatitis, chronic pancreatitis, and pancreatic cancer, as well as prospective treatment strategies to target S1P signaling for these conditions. The insights presented here possess the potential to offer valuable guidance for the implementation of therapies targeting S1P signaling in various pancreatic diseases.

Therapeutic Potential of Fingolimod on Psychological Symptoms and Cognitive Function in Neuropsychiatric and Neurological Disorders

Neuropsychiatric and neurological disorders pose a significant global health burden, highlighting the need for innovative therapeutic approaches. Fingolimod (FTY720), a common drug to treat multiple sclerosis, has shown promising efficacy against various neuropsychiatric and neurological disorders. Fingolimod exerts its neuroprotective effects by targeting multiple cellular and molecular processes, such as apoptosis, oxidative stress, neuroinflammation, and autophagy. By modulating Sphingosine-1-Phosphate Receptor activity, a key regulator of immune cell trafficking and neuronal function, it also affects synaptic activity and strengthens memory formation. In the hippocampus, fingolimod decreases glutamate levels and increases GABA levels, suggesting a potential role in modulating synaptic transmission and neuronal excitability. Taken together, fingolimod has emerged as a promising neuroprotective agent for neuropsychiatric and neurological disorders. Its broad spectrum of cellular and molecular effects, including the modulation of apoptosis, oxidative stress, neuroinflammation, autophagy, and synaptic plasticity, provides a comprehensive therapeutic approach for these debilitating conditions. Further research is warranted to fully elucidate the mechanisms of action of fingolimod and optimize its use in the treatment of neuropsychiatric and neurological disorders.

Neurolipidomic insights into anxiety disorders: Uncovering lipid dynamics for potential therapeutic advances

Anxiety disorders constitute a spectrum of psychological conditions affecting millions of individuals worldwide, imposing a significant health burden. Historically, the development of anxiolytic medications has been largely focused on neurotransmitter function and modulation. However, in recent years, neurolipids emerged as a prime target for understanding psychiatric pathogenesis and developing novel medications. Neurolipids influence various neural activities such as neurotransmission and cellular functioning, as well as maintaining cell membrane integrity. Therefore, this review aims to elucidate the alterations in neurolipids associated with an anxious mental state and explore their potential as targets of novel anxiolytic medications. Existing evidence tentatively associates dysregulated neurolipid levels with the etiopathology of anxiety disorders. Notably, preclinical investigations suggest that several neurolipids, including endocannabinoids and polyunsaturated fatty acids, may hold promise as potential pharmacological targets. Overall, the current literature tentatively suggests the involvement of lipids in the pathogenesis of anxiety disorders, hinting at potential prospects for future pharmacological interventions.

Fingolimod Modulates the Gene Expression of Proteins Engaged in Inflammation and Amyloid-Beta Metabolism and Improves Exploratory and Anxiety-Like Behavior in Obese Mice

Obesity is considered a risk factor for type 2 diabetes mellitus, which has become one of the most important health problems, and is also linked with memory and executive function decline. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that regulates cell death/survival and the inflammatory response via its specific receptors (S1PRs). Since the role of S1P and S1PRs in obesity is rather obscure, we examined the effect of fingolimod (an S1PR modulator) on the expression profile of genes encoding S1PRs, sphingosine kinase 1 (Sphk1), proteins engaged in amyloid-beta (Aβ) generation (ADAM10, BACE1, PSEN2), GSK3β, proapoptotic Bax, and proinflammatory cytokines in the cortex and hippocampus of obese/prediabetic mouse brains. In addition, we observed behavioral changes. Our results revealed significantly elevated mRNA levels of Bace1, Psen2, Gsk3b, Sphk1, Bax, and proinflammatory cytokines, which were accompanied by downregulation of S1pr1 and sirtuin 1 in obese mice. Moreover, locomotor activity, spatially guided exploratory behavior, and object recognition were impaired. Simultaneously, fingolimod reversed alterations in the expressions of the cytokines, Bace1, Psen2, and Gsk3b that occurred in the brain, elevated S1pr3 mRNA levels, restored normal cognition-related behavior patterns, and exerted anxiolytic effects. The improvement in episodic and recognition memory observed in this animal model of obesity may suggest a beneficial effect of fingolimod on central nervous system function.

The role of the immune system in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) develops in a subset of individuals upon exposure to traumatic stress. In addition to well-defined psychological and behavioral symptoms, some individuals with PTSD also exhibit elevated concentrations of inflammatory markers, including C-reactive protein, interleukin-6, and tumor necrosis factor-α. Moreover, PTSD is often co-morbid with immune-related conditions, such as cardiometabolic and autoimmune disorders. Numerous factors, including lifetime trauma burden, biological sex, genetic background, metabolic conditions, and gut microbiota, may contribute to inflammation in PTSD. Importantly, inflammation can influence neural circuits and neurotransmitter signaling in regions of the brain relevant to fear, anxiety, and emotion regulation. Given the link between PTSD and the immune system, current studies are underway to evaluate the efficacy of anti-inflammatory treatments in those with PTSD. Understanding the complex interactions between PTSD and the immune system is essential for future discovery of diagnostic and therapeutic tools.

[Effect of somatostatin on postoperative gastrointestinal function and stress level in children with acute abdomen: a prospective randomized controlled study]

OBJECTIVES

To study the effect of somatostatin on postoperative gastrointestinal function and stress level in children with acute abdomen.

METHODS

A total of 102 children with acute abdomen who underwent surgery in Xuzhou Children's Hospital from August 2019 to June 2021 were enrolled as subjects and were randomly divided into an observation group and a control group, with 51 children in each group. The children in the control group were given conventional treatment such as hemostasis and anti-infective therapy after surgery, and those in the observation group were given somatostatin in addition to conventional treatment. Peripheral blood samples were collected from both groups before surgery and on days 1 and 5 after surgery. The two groups were compared in terms of the serum levels of endothelin-1 (ET-1), adrenocorticotropic hormone (ACTH), cortisol, gastrin, and motilin, postoperative recovery, and the incidence rate of complications.

RESULTS

There was no significant difference in the serum levels of ET-1, ACTH, cortisol, gastrin, and motilin between the two groups before surgery (P>0.05). Compared with the control group, the observation group had significantly lower serum levels of ET-1, ACTH, and cortisol on days 1 and 5 after surgery (P<0.05) and significantly higher levels of motilin and gastrin on day 5 after surgery (P<0.05). Compared with the control group, the observation group had significantly shorter time to first passage of flatus, first bowel sounds, and first defecation after surgery, as well as a significantly shorter length of hospital stay (P<0.05). The incidence rate of complications in the observation group was significantly lower than that in the control group (6% vs 24%, P<0.05).

CONCLUSIONS

In children with acute abdomen, somatostatin can significantly reduce postoperative stress response, improve gastrointestinal function, and reduce the incidence rate of complications, thereby helping to achieve a good prognosis.