Faculty Bibliography

In this essay, we propose an association between Franz Kafka's novel, The Trial, and phenomenological and neurobiological processes in schizophrenia. We begin by presenting a summary of the plot, pointing to some of its remarkable literary aspects. We next compare the mental processes of dissociation, disorientation and delusion as represented in the novel with phenomenological processes that take place in the prodromal states of schizophrenia. We discuss how such disorders of the self and disorders of thought, both crucial aspects of the schizophrenic experience, appear in The Trial and in other literary and private writings by Franz Kafka. We relate how these disorders may arise from the false attribution of salience and false associative learning caused by hyperactivity of dopaminergic function associated with chaotic firing of dopaminergic neurons. Finally, we show how Kafka leads not just the protagonist of The Trial, but even more the reader to experience a quasi-delusional state. We discuss the relationship between the perturbation of thought and disorientation of mind evoked by the novel in the reader and the need of our brains for empathy and predictability.

Franz Kafka's Letter to His Father is one of the greatest examples in world literature of memory of a traumatic childhood. In it, the author takes a retrospective journey through his life, recollecting and analyzing the reasons for the estrangement and hostility between a father and a son. This essay considers Letter to His Father in the light of current knowledge about autobiographical memory. The essay first sets forth basic aspects of Kafka's life in order to place Letter to His Father in the context of Kafka's biography, and then presents Kafka's relevance to the literature and thought of the twentieth and twenty-first centuries. The essay then considers the different forms of childhood abuse and their consequences in light of evidence from neurodevelopmental psychology. We present evidence about the relationship between trauma and the construction of self-image. Furthermore, we discuss the subjectivity of Kafka's recollections from the perspective of recent advances in neurobiology. Memory is shown to be dynamic, selective, inherently malleable and dependent on perception, which is a subjective construction, in which the brain interprets and gives coherence to experienced stimuli. We consider the inaccuracy of memory, which is related to neuroplastic changes in the brain that take place over time: consolidation, reconsolidation and transformation. Finally, the relationship between literature and autobiography in the Kafkaesque universe is considered.

AIMS: We have investigated the antihyperalgesic effects of limonene in mice that received intrathecal injection of gp120. MAIN METHODS: Male Swiss mice received gp120, IL-1beta or TNF-alpha intrathecally or sterile saline as a control. A mechanicalsensitivity test was performed at 2 and 3h after the injection. Spinal cord and blood samples were isolated for protein quantification. KEY FINDINGS: Intrathecal administration of gp120 increased mechanical sensitivity measured with an electronic Von Frey apparatus, at 2 and 3h after the injections. Limonene administered orally prior to gp120 administration significantly decreased this mechanical sensitivity at 3h after the gp120 injection. In addition, intrathecal injection of gp120 increased IL-1beta and IL-10 in serum, and limonene prevented the ability of gp120 to increase these cytokines. Limonene also inhibited TNF-alpha and IL-1beta-induced mechanical hyperalgesia. Western blot assay demonstrated limonene was capable of increasing SOD expression in the cytoplasm of cells from spinal cord at 4h after intrathecal IL-1beta injection. SIGNIFICANCE: These results demonstrate that gp120 causes mechanical hyperalgesia and a peripheral increase in IL-1beta and IL-10, and that prior administration of limonene inhibits these changes. Also limonene modulates the activation of SOD expression in the spinal cord after spinal IL-1beta application. The ability of limonene to inhibit the mechanical hyperalgesia induced by gp120, TNF-alpha and IL-1beta emphasizes the anti-inflammatory action of limonene, specifically its ability to inhibit cytokine production and its consequences.

Lithium (Li+) is a drug widely employed for treating bipolar disorder, however the mechanism of action is not known. Here we study the effects of Li+ in cultured hippocampal neurons on a synaptic complex consisting of delta-catenin, a protein associated with cadherins whose mutation is linked to autism, and GRIP, an AMPA receptor (AMPAR) scaffolding protein, and the AMPAR subunit, GluA2. We show that Li+ elevates the level of delta-catenin in cultured neurons. delta-catenin binds to the ABP and GRIP proteins, which are synaptic scaffolds for GluA2. We show that Li+ increases the levels of GRIP and GluA2, consistent with Li+-induced elevation of delta-catenin. Using GluA2 mutants, we show that the increase in surface level of GluA2 requires GluA2 interaction with GRIP. The amplitude but not the frequency of mEPSCs was also increased by Li+ in cultured hippocampal neurons, confirming a functional effect and consistent with AMPAR stabilization at synapses. Furthermore, animals fed with Li+ show elevated synaptic levels of delta-catenin, GRIP, and GluA2 in the hippocampus, also consistent with the findings in cultured neurons. This work supports a model in which Li+ stabilizes delta-catenin, thus elevating a complex consisting of delta-catenin, GRIP and AMPARs in synapses of hippocampal neurons. Thus, the work suggests a mechanism by which Li+ can alter brain synaptic function that may be relevant to its pharmacologic action in treatment of neurological disease.

mGluR long-term depression (mGluR-LTD) is a form of synaptic plasticity induced at excitatory synapses by metabotropic glutamate receptors (mGluRs). mGluR-LTD reduces synaptic strength and is relevant to learning and memory, autism, and sensitization to cocaine; however, the mechanism is not known. Here we show that activation of Group I mGluRs in medium spiny neurons induces trafficking of GluA2 from the endoplasmic reticulum (ER) to the synapse by enhancing GluA2 binding to essential COPII vesicle proteins, Sec23 and Sec13. GluA2 exit from the ER further depends on IP3 and Ryanodine receptor-controlled Ca2+ release as well as active translation. Synaptic insertion of GluA2 is coupled to removal of high-conducting Ca2+-permeable AMPA receptors from synapses, resulting in synaptic depression. This work demonstrates a novel mechanism in which mGluR signals release AMPA receptors rapidly from the ER and couple ER release to GluA2 synaptic insertion and GluA1 removal.

Phosphorylation of GluA1, a subunit of AMPA receptors (AMPARs), is critical for AMPAR synaptic trafficking and control of synaptic transmission. cGMP-dependent protein kinase II (cGKII) mediates this phosphorylation, and cGKII knockout (KO) affects GluA1 phosphorylation and alters animal behavior. Notably, GluA1 phosphorylation in the KO hippocampus is increased as a functional compensation for gene deletion, while such compensation is absent in the prefrontal cortex. Thus, there are brain region-specific effects of cGKII KO on AMPAR trafficking, which could affect animal behavior. Here, we show that GluA1 phosphorylation levels differ in various brain regions, and specific behaviors are altered according to region-specific changes in GluA1 phosphorylation. Moreover, we identified distinct regulations of phosphatases in different brain regions, leading to regional heterogeneity of GluA1 phosphorylation in the KO brain. Our work demonstrates region-specific changes in GluA1 phosphorylation in cGKII KO mice and corresponding effects on cognitive performance. We also reveal distinct regulation of phosphatases in different brain region in which region-specific effects of kinase gene KO arise and can selectively alter animal behavior.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases characterized by memory loss and cognitive impairment. Whereas most AD cases are sporadic, some are caused by mutations in early-onset familial AD (FAD) genes. One FAD gene encodes presenilin 1 (PS1), and a PS1 mutation in methionine 146 impairs homeostatic synaptic plasticity (HSP). We have previously shown that Ca2+ and calcineurin activity are critical regulators of HSP. Here, we confirm that endoplasmic reticulum-mediated Ca2+ signals are increased in mutant PS1 neurons. We further show that calcineurin activity is abnormally elevated in the mutant and that inhibition of increased calcineurin activity stabilizes GluA1 phosphorylation, promoting synaptic trafficking of Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, contributing to the recovery of impaired HSP found in the mutant. Because HSP is suggested to have roles during learning and memory formation, increased calcineurin activity-induced impairment of HSP can cause cognitive decline in FAD. Thus, reducing abnormally increased calcineurin activity in AD brain may be beneficial for improving AD-related cognitive decline.

BACKGROUND: A variety of pain conditions have been found to be associated with depressed mood in clinical studies. Depression-like behaviors have also been described in animal models of persistent or chronic pain. In rodent chronic neuropathic pain models, elevated levels of GluA1 subunits of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the nucleus accumbens (NAc) have been found to inhibit depressive symptoms. However, the effect of reversible post-surgical pain or inflammatory pain on affective behaviors such as depression has not been well characterized in animal models. Neither is it known what time frame is required to elicit AMPA receptor subunit changes in the NAc in various pain conditions. RESULTS: In this study, we compared behavioral and biochemical changes in three pain models: the paw incision (PI) model for post-incisional pain, the Complete Freund's Adjuvant (CFA) model for persistent but reversible inflammatory pain, and the spared nerve injury (SNI) model for chronic postoperative neuropathic pain. In all three models, rats developed depressive symptoms that were concurrent with the presentation of sensory allodynia. GluA1 levels at the synapses of the NAc, however, differed in these three models. The level of GluA1 subunits of AMPA-type receptors at NAc synapses was not altered in the PI model. GluA1 levels were elevated in the CFA model after a period (7 d) of persistent pain, leading to the formation of GluA2-lacking AMPA receptors. As pain symptoms began to resolve, however, GluA1 levels returned to baseline. Meanwhile, in the SNI model, in which pain persisted beyond 14 days, GluA1 levels began to rise after pain became persistent and remained elevated. In addition, we found that blocking GluA2-lacking AMPA receptors in the NAc further decreased the depressive symptoms only in persistent pain models. CONCLUSION: Our study shows that while both short-term and persistent pain can trigger depression-like behaviors, GluA1 upregulation in the NAc likely represents a unique adaptive response to minimize depressive symptoms in persistent pain states.

The envelope glycoprotein gp120 of HIV can play an important role in the generation of pain. Intrathecal administration gp120 induces the production of cytokines, including IL-1, IL-6 and TNF, which in turn induces neuroinflammation and hyperalgesia. A previous study from our group demonstrated antihyperalgesic and antidepressive actions of limonene administered orally in a neuropathic pain model. The present work has investigated the antihyperalgesic effects of (R)-(+)-limonene in mice that received intrathecal gp120 by analyzing the roles of cytokines involved in these processes as well as the mechanisms. Male Swiss mice (n = 6) received gp120 (50-500 ng) intrathecally or sterile saline as a control. Intrathecal administration of gp120 increased mechanical sensitivity measured with an electronic Von Frey apparatus, but not cold hypersensitivity (measured by the acetone test), at 2 and 3 h after the injections. Limonene significantly decreased this mechanical sensitivity at 3 h after of the injection. In addition, intrathecal injection of gp120 increased IL-1beta (measured by the ELISA test) in the serum of mice, and limonene prevented the ability of gp120 to increase this cytokine. Limonene also inhibited TNF and IL-1beta-induced mechanical hyperalgesia and IL-1beta-induced cold hypersensitivity. Western blot assay demonstrated limonene was capable of significantly decreasing the expression of NF-kB while limonene increased SOD expression in cytoplasm of cells from spinal cord at 4 h after intrathecal IL-1beta injection. These results demonstrate that gp120 administered intrathecally causes mechanical hyperalgesia and a peripheral increase in IL-1beta, and that limonene inhibits this change. Also limonene modulates the activation of NF-kB and SOD expression in the spinal cord after spinal IL-1beta application. The ability of limonene to inhibit the mechanical hyperalgesia induced by TNF and IL-1beta emphasizes the anti-inflammatory action of limonene, specifically its ability to inhibit cytokine production

Objectives Previous studies have shown that essential oil containing (R)-(+)-limonene and alpha-phellandrene, extracted from fruits of Schinus terebinthifolius Raddi, exhibit anti-inflammatory activity. This work aimed to verify the antihyperalgesic and antidepressive actions of (R)-(+)-limonene, alpha-phellandrene, and essential oil from S. terebinthifolius fruits in spared nerve injury (SNI) model of neuropathic pain in rats. Methods In the present work, essential oil from fruits of S. terebinthifolius, as well as the pure (R)-(+)-limonene and alpha-phellandrene compounds, were assayed for their effects on SNI-induced mechanical and cold hyperalgesia, and depressive-like behavior (immobility in forced swim test) in rats. The locomotor activity was evaluated in open-field test. Results Oral administration for up to 15 days of essential oil of S. terebinthifolius (100 mg/kg), (R)-(+)-limonene (10 mg/kg), alpha-phellandrene (10 mg/kg), and also subcutaneous 10 mg/kg dose of ketamine (positive control) significantly inhibited SNI-induced mechanical hyperalgesia and increased immobility in the forced swim test. On the 15th day of oral treatment, alpha-phellandrene, but neither the essential oil from S. terebinthifolius nor (R)-(+)-limonene, prevented the SNI-induced increase in sensitivity to a cold stimulus. The oral treatment with essential oil (100 mg/kg) or with compounds (10 mg/kg) did not interfere on locomotor activity. Discussion Together, the results of the present work show that essential oil of S. terebinthifolius and compounds present in this oil, including (R)-(+)-limonene and alpha-phellandrene, exhibit antihyperalgesic effects against mechanical hyperalgesia, and are antidepressive, while only alpha-phellandrene inhibited cold hyperalgesia in SNI rats.