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Major depressive disorder represents a serious public health challenge worldwide; however, the underlying cellular and molecular mechanisms are mostly unknown. Here, we profile the dorsolateral prefrontal cortex of female cynomolgus macaques with social stress-associated depressive-like behaviors using single-nucleus RNA-sequencing and spatial transcriptomics. We find gene expression changes associated with depressive-like behaviors mostly in microglia, and we report a pro-inflammatory microglia subpopulation enriched in the depressive-like condition. Single-nucleus RNA-sequencing data result in the identification of six enriched gene modules associated with depressive-like behaviors, and these modules are further resolved by spatial transcriptomics. Gene modules associated with huddle and sit alone behaviors are expressed in neurons and oligodendrocytes of the superficial cortical layer, while gene modules associated with locomotion and amicable behaviors are enriched in microglia and astrocytes in mid-to-deep cortical layers. The depressive-like behavior associated microglia subpopulation is enriched in deep cortical layers. In summary, our findings show cell-type and cortical layer-specific gene expression changes and identify one microglia subpopulation associated with depressive-like behaviors in female non-human primates.

In the aftermath of the COVID-19 pandemic, we are witnessing an unprecedented wave of post-infectious complications. Most prominently, millions of patients with Long-Covid complain about chronic fatigue and severe post-exertional malaise. Therapeutic apheresis has been suggested as an efficient treatment option for alleviating and mitigating symptoms in this desperate group of patients. However, little is known about the mechanisms and biomarkers correlating with treatment outcomes. Here, we have analyzed in different cohorts of Long-Covid patients specific biomarkers before and after therapeutic apheresis. In patients that reported a significant improvement following two cycles of therapeutic apheresis, there was a significant reduction in neurotransmitter autoantibodies, lipids, and inflammatory markers. Furthermore, we observed a 70% reduction in fibrinogen, and following apheresis, erythrocyte rouleaux formation and fibrin fibers largely disappeared as demonstrated by dark field microscopy. This is the first study demonstrating a pattern of specific biomarkers with clinical symptoms in this patient group. It may therefore form the basis for a more objective monitoring and a clinical score for the treatment of Long-Covid and other postinfectious syndromes.

Clinical and animal studies have shown that gut microbiome disturbances can affect neural function and behaviors via the microbiota–gut–brain axis, and may be implicated in the pathogenesis of several brain diseases. However, exactly how the gut microbiome modulates nervous system activity remains obscure. Here, using a single-cell nucleus sequencing approach, we sought to characterize the cell type–specific transcriptomic changes in the prefrontal cortex and hippocampus derived from germ-free (GF), specific pathogen free, and colonized-GF mice. We found that the absence of gut microbiota resulted in cell-specific transcriptomic changes. Furthermore, microglia transcriptomes were preferentially influenced, which could be effectively reversed by microbial colonization. Significantly, the gut microbiome modulated the mutual transformation of microglial subpopulations in the two regions. Cross-species analysis showed that the transcriptome changes of these microglial subpopulations were mainly associated with Alzheimer’s disease (AD) and major depressive disorder (MDD), which were further supported by animal behavioral tests. Our findings demonstrate that gut microbiota mainly modulate the mutual transformation of microglial subtypes, which may lead to new insights into the pathogenesis of AD and MDD.

The gut microbiome exerts a considerable influence on human neurophysiology and mental health. Interactions between intestinal microbiology and host regulatory systems have now been implicated both in the development of psychiatric conditions and in the efficacy of many common therapies. With the growing acceptance of the role played by the gut microbiome in mental health outcomes, the focus of research is now beginning to shift from identifying relationships between intestinal microbiology and pathophysiology, and towards using this newfound insight to improve clinical outcomes. Here, we review recent advances in our understanding of gut microbiome–brain interactions, the mechanistic underpinnings of these relationships, and the ongoing challenge of distinguishing association and causation. We set out an overarching model of the evolution of microbiome–CNS interaction and examine how a growing knowledge of these complex systems can be used to determine disease susceptibility and reduce risk in a targeted manner.

The neuropeptide oxytocin (OXT) is well recognized for eliciting anxiolytic effects and promoting social reward. However, emerging evidence shows that OXT increases aversive events. These seemingly inconsistent results may be attributable to the broad OXT receptor (OXTr) expression in the central nervous system. This study selectively activated septal neurons expressing OXTr using chemogenetics. We found that chemogenetic activation of septal OXTr neurons induced anxiety- but not depressive-like behavior. In addition, septal OXTr neurons projected dense fibers to the horizontal diagonal band of Broca (HDB), and selective stimulation of those HDB projections also elicited anxiety-like behaviors. We also found that septal OXTr neurons express the vesicular GABA transporter (vGAT) protein and optogenetic stimulation of septal OXTr projections to the HDB inactivated HDB neurons. Our data collectively reveal that septal OXTr neurons increase anxiety by projecting inhibitory GABAergic inputs to the HDB.

It is essential to elucidate brain-adipocyte interactions in order to tackle obesity and its comorbidities, as the precise control of brain-adipose tissue cross-talk is crucial for energy and glucose homeostasis. Recent studies show that in the peripheral adipose tissue, adenosine induces adipogenesis through peripheral adenosine A1receptor (pADORA1) signaling; however, it remains unclear whether systemic and adipose tissue metabolism would also be under the control of central (c) ADORA1signaling. Here, we use tissue-specific pharmacology and metabolic tools to clarify the roles of cADORA1signaling in energy and adipocyte physiology. We found that cADORA1signaling reduces body weight while also inducing adipose tissue lipolysis. cADORA1signaling also increases adipose tissue sympathetic norepinephrine content. In contrast, pADORA1signaling facilitates a high-fat diet-induced obesity (DIO). We propose here a novel mechanism in which cADORA1and pADORA1signaling hinder and aggravate DIO, respectively.

Schizophrenia (SCZ) is a neuropsychiatric disorder with aberrant expression of multiple genes. However, identifying its exact causal genes remains a considerable challenge. The brain-specific transcription factor POU3F2 (POU domain, class 3, transcription factor 2) has been recognized as a risk factor for SCZ, but our understanding of its target genes and pathogenic mechanisms are still limited. Here we report that POU3F2regulates 42 SCZ-related genes in knockdown and RNA-sequencing experiments of human neural progenitor cells (NPCs). Among those SCZ-related genes, TRIM8(Tripartite motif containing 8) is located in SCZ-associated genetic locus and is aberrantly expressed in patients with SCZ. Luciferase reporter and electrophoretic mobility shift assays (EMSA) showed that POU3F2 induces TRIM8expression by binding to the SCZ-associated SNP (single nucleotide polymorphism) rs5011218, which affects POU3F2-binding efficiency at the promoter region of TRIM8. We investigated the cellular functions of POU3F2and TRIM8as they co-regulate several pathways related to neural development and synaptic function. Knocking down either POU3F2or TRIM8promoted the proliferation of NPCs, inhibited their neuronal differentiation, and impaired the excitatory synaptic transmission of NPC-derived neurons. These results indicate that POU3F2regulates TRIM8expression through the SCZ-associated SNP rs5011218, and both genes may be involved in the etiology of SCZ by regulating neural development and synaptic function.

Emerging research demonstrates that microbiota-gut–brain (MGB) axis changes are associated with depression onset, but the mechanisms underlying this observation remain largely unknown. The gut microbiome of nonhuman primates is highly similar to that of humans, and some subordinate monkeys naturally display depressive-like behaviors, making them an ideal model for studying these phenomena. Here, we characterized microbial composition and function, and gut–brain metabolic signatures, in female cynomolgus macaque (Macaca fascicularis) displaying naturally occurring depressive-like behaviors. We found that both microbial and metabolic signatures of depressive-like macaques were significantly different from those of controls. The depressive-like monkeys had characteristic disturbances of the phylum Firmicutes. In addition, the depressive-like macaques were characterized by changes in three microbial and four metabolic weighted gene correlation network analysis (WGCNA) clusters of the MGB axis, which were consistently enriched in fatty acyl, sphingolipid, and glycerophospholipid metabolism. These microbial and metabolic modules were significantly correlated with various depressive-like behaviors, thus reinforcing MGB axis perturbations as potential mediators of depression onset. These differential brain metabolites were mainly mapped into the hippocampal glycerophospholipid metabolism in a region-specific manner. Together, these findings provide new microbial and metabolic frameworks for understanding the MGB axisʼ role in depression, and suggesting that the gut microbiome may participate in the onset of depressive-like behaviors by modulating peripheral and central glycerophospholipid metabolism.

The GABABreceptor (GABABR) agonist baclofen has been used to treat alcohol and several other substance use disorders (AUD/SUD), yet its underlying neural mechanism remains unclear. The present study aimed to investigate cortical GABABR dynamics following chronic alcohol exposure. Ex vivo brain slice recordings from mice chronically exposed to alcohol revealed a reduction in GABABR-mediated currents, as well as a decrease of GABAB1/2R and G-protein-coupled inwardly rectifying potassium channel 2 (GIRK2) activities in the motor cortex. Moreover, our data indicated that these alterations could be attributed to dephosphorylation at the site of serine 783 (ser-783) in GABAB2subunit, which regulates the surface expression of GABABR. Furthermore, a human study using paired-pulse-transcranial magnetic stimulation (TMS) analysis further demonstrated a reduced cortical inhibition mediated by GABABR in patients with AUD. Our findings provide the first evidence that chronic alcohol exposure is associated with significantly impaired cortical GABABR function. The ability to promote GABABR signaling may account for the therapeutic efficacy of baclofen in AUD.

Current therapeutic approaches to Alzheimer disease (AD) remain disappointing and, hence, there is an urgent need for effective treatments. Here, we provide a perspective review on the emerging role of “metabolic inflammation” and stress as a key factor in the pathogenesis of AD and propose a novel rationale for correction of metabolic inflammation, increase resilience and potentially slow-down or halt the progression of the neurodegenerative process. Based on recent evidence and observations of an early pilot trial, we posit a potential use of extracorporeal apheresis in the prevention and treatment of AD. Apolipoprotein E, lipoprotein(a), oxidized LDL (low density lipoprotein)'s and large LDL particles, as well as other proinflammatory lipids and stress hormones such as cortisol, have been recognized as key factors in amyloid plaque formation and aggravation of AD. Extracorporeal lipoprotein apheresis systems employ well-established, powerful methods to provide an acute, reliable 60–80% reduction in the circulating concentration of these lipid classes and reduce acute cortisol levels. Following a double-membrane extracorporeal apheresis in patients with AD, there was a significant reduction of proinflammatory lipids, circulating cytokines, immune complexes, proinflammatory metals and toxic chaperones in patients with AD. On the basis of the above, we suggest designing clinical trials to assess the promising potential of such “cerebropheresis” treatment in patients with AD and, possibly, other neurodegenerative diseases.

Processing liquid chromatography–mass spectrometry-based metabolomics data using computational programs often introduces additional quantitative uncertainty, termed computational variation in a previous work. This work develops a computational solution to automatically recognize metabolic features with computational variation in a metabolomics data set. This tool, AVIR (short for “Accurate eValuation of alIgnment and integRation”), is a support vector machine-based machine learning strategy (https://github.com/HuanLab/AVIR). The rationale is that metabolic features with computational variation have a poor correlation between chromatographic peak area and peak height-based quantifications across the samples in a study. AVIR was trained on a set of 696 manually curated metabolic features and achieved an accuracy of 94% in a 10-fold cross-validation. When tested on various external data sets from public metabolomics repositories, AVIR demonstrated an accuracy range of 84%–97%. Finally, tested on a large-scale metabolomics study, AVIR clearly indicated features with computational variation and thus guided us to manually correct them. Our results show that 75.3% of the samples with computational variation had a relative intensity difference of over 20% after correction. This demonstrates the critical role of AVIR in reducing computational variation to improve quantitative certainty in untargeted metabolomics analysis.

Major depressive disorder (MDD) is a common psychiatric illness with significant medical and socioeconomic impact. Genetic factors are likely to play important roles in the development of this condition. DNA sequencing technology has the ability to identify all private genetic mutations and provides new channels for studying the biology of MDD. In this proof-of-concept study we proposed a novel concept, single-nucleotide variant proportion (SNVP), to investigate MDD based on whole-genome sequencing (WGS) data. Our SNVP-based approach can be used to test newly found candidate genes as a complement to genome-wide genotyping analysis. Furthermore, we performed cluster analysis for MDD patients and ethnically matched healthy controls, and found that clusters based on SNVP may predict MDD diagnosis. Our results suggest that SNVP may be used as a potential biomarker associated with major depression. Our methodology could be a valuable predictive/diagnostic tool as one can test whether a new subject falls within or close to an existing MDD cluster. Advances in this study design have the potential to personalized treatments and could include the ability to diagnose patients based on their full or part DNA sequencing data.

Deficits in neuroplasticity are hypothesized to underlie the pathophysiology of major depressive disorder (MDD): the effectiveness of antidepressants is thought to be related to the normalization of disrupted synaptic transmission and neurogenesis. The cyclic adenosine monophosphate (cAMP) signaling cascade has received considerable attention for its role in neuroplasticity and MDD. However components of a closely related pathway, the cyclic guanosine monophosphate (cGMP) have been studied with much lower intensity, even though this signaling transduction cascade is also expressed in the brain and the activity of this pathway has been implicated in learning and memory processes. Cyclic GMP acts as a second messenger; it amplifies signals received at postsynaptic receptors and activates downstream effector molecules resulting in gene expression changes and neuronal responses. Phosphodiesterase (PDE) enzymes degrade cGMP into 5GMP and therefore they are involved in the regulation of intracellular levels of cGMP. Here we review a growing body of evidence suggesting that the cGMP signaling cascade warrants further investigation for its involvement in MDD and antidepressant action.

There has been considerable promise and hope that pharmacogenomics will optimize existing treatments for major depression, as well as identify novel targets for drug discovery. Immediately after the sequencing of the human genome, there was much hope that tremendous progress in pharmacogenomics would rapidly be achieved. In the past 10 years this initial enthusiasm has been replaced by a more sober optimism, as we have gone a long way towards the goal of guiding therapeutics based on genomics. While the effort to translate discovery to clinical applications is ongoing, we now have a vast body of knowledge as well as a clear direction forward. This article will provide a critical appraisal of the state of the art in the pharmacogenomics of depression, both in terms of pharmacodynamics and pharmacokinetics.

Melanocortin 1 receptor (MC1R) is involved in various functions, such as pigmentation, antipyretic and anti-inflammatory actions, development of melanoma, susceptibility to ultraviolet-induced sun damage, modification of oculocutaneous albinism, development of freckles, and mediation of female-specific mechanisms of analgesia. MC1R's natural agonists include -melanocyte-stimulating hormone and corticotrophin (ACTH1-39), which are important components of hypothalamic pituitary adrenal axis and increase in response to stress. Given the multiple relevant roles of MC1R, we studied whether the MC1Rgene would be associated with susceptibility to major depressive disorder or with response to antidepressant treatment.

Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) are synthesized by adenylate cyclase and guanylyl cyclase and degraded by phosphodiesterases. Antidepressant treatment action is hypothesized to occur through increased cAMP signaling; however, antidepressants are also reported to increase phosphodiesterase-4 expression. We addressed this paradox by systematically studying elements of intracellular signaling in the hippocampus of rats chronically treated with imipramine. We observed decreases in cAMP levels, which were congruent with our findings of increased gene expression for phosphodiesterases and decreased adenylate cyclase. Immunoassay results showed unchanged cGMP and brain-derived neurotrophic factor levels. We conclude that in contrast with the assumption of antidepressant-mediated increases in cAMP levels, long-term imipramine treatment may have the opposite effect, namely decreased hippocampal cAMP.

There is growing consensus on the potential use of pharmacogenetics in clinical practice, and hopes have been expressed for application to the improvement of global health. However, two major challenges may lead to widening the “biotechnological gap” between the developing and the industrial world; first the unaffordability of some current technologies for poorer countries, and second the necessity of analyzing all described alleles for every clinical case due to the inability to predict the ethnic group of a given patient. Because of its role in the metabolism of a number of drugs, cytochrome P450 2D6 (CYP2D6) is an excellent candidate for use in the optimization of drug therapy. CYP2D6 is a highly polymorphic gene locus with more than 50 variant alleles, and subjects can be classified as poor metabolizers (PM), extensive metabolizers (EM), or ultrarapid metabolizers (UM) of a given CYP2D6 substrate. Several strategies and methods for CYP2D6 genotyping exist. Some, however, are expensive and laborious. The aim of this study was to design a PCR-based genotyping methodology to allow rapid, straightforward, and inexpensive identification of 90%–95% of CYP2D6 PM or UM genotypes for routine clinical use, independent of the individual's ethnic group. CYP2D6 is amplified in initial extra longPCRs (XL-PCRs), which subsequently undergo fragment-length polymorphism analysis for the determination of carriers of CYP2D6 allelic variants. The same XL-PCRs are also used for the determination of CYP2D6 multiplication and 2D6*5 allele (abolished activity). The application of this new strategy for the detection of CYP2D6 mutated alleles and multiplications to routine clinical analysis will enable the PM and UM phenotypes to be predicted and identified at a reasonable cost in a large number of individuals at most locations.

NEUTROPHIL-ACTIVATING peptide-1/interleukin-8 (NAP-1/IL-8) is a cytokine synthesized by various cell types. In the immune system NAP-l/IL-8 is part of an immune cascade initiated by IL-1 production. NAP-1/ IL-8 affects hypothalamic function and its production is suppressed by steroids. Therefore, it might be expected that NAP-1/IL-8 would be produced in brain areas involved in the control of the hypothalamic-pituitary-adrenocortical axis (HPA). NAP-1/IL-8 mRNA was localized by in situhybridization in the paraventricular nucleus of the hypothalamus and hippocampus. Those areas also express the genes encoding interleukin-1-alpha (IL-1α), IL-1β, IL-1 receptors, and IL-1 receptor antagonist (IL-1ra). This suggests that an immune cascade, which is well characterized in the immune system, may exist in brain, in areas of relevance to the regulation of stress-related neuroendocrine function.

Identification of quantitative changes in gene expression that occur in the brain after antidepressant treatment can yield novel molecular markers that may be useful in the diagnosis and treatment of major depression. Using a modification of the differential display polymerase chain reaction, we describe the isolation of two transcripts that are differentially expressed in the brain after an 8-week course of antidepressant administration, compared to saline-treated control animals.

Interleukin-1 (IL-1) has been implicated in chronic and acute cerebral neuropathologies. IL-1 receptor antagonist (IL-1ra), a naturally occurring protein that binds to IL-1 receptors without inducing signal transduction, blocks several actions of IL-1. IL-1ra acts at the local level and it also circulates in the bloodstream. We now report evidence for a biological function of IL-1ra in the brain as an endogenous neuroprotective molecule. Cerebral expression of IL-1ra mRNA is induced rapidly by focal cerebral ischemia in rats, and inhibition of the action of IL-1ra, by passive immunoneutralization, markedly enhances ischemic damage. To our knowledge this is the first report of an action of endogenous IL-1ra in the brain. Control of IL-1ra expression or action may therefore provide a useful therapeutic strategy to limit acute neurodegeneration.

CORTICOTROPIN-releasing hormone (CRH) antagonism has neuroprotective effects in models of ischemia. We examined CRH mRNA by in situhybridization in a well- established rat model of focal cerebral ischemia caused by permanent middle cerebral artery occlusion (MCAo). In ischemic cortex CRH mRNA levels were elevated 2.6-fold 60min after MCAo, compared with sham operated animals. CRH mRNA was also induced in the amygdala, 60min following ischemia, in a pattern which was qualitatively different from that of sham operated animals. This rapid and profound increase in CRH mRNA levels during focal cerebral ischemia is likely to be associated with neurotoxicity, as CRH antagonism has been reported to cause a significant reduction in neuronal loss during ischemia.

THE mechanism by which IL-1β exerts its actions in the brain during systemic inflammation is not fully understood, as neither IL-1 receptor gene expression nor IL-1 binding have been identified in significant levels in key areas that respond to IL-1β. Having hypothesized that perivascular nitric oxide (NO) might modulate the effects of systemic IL-1β in the brain, we studied the expression of the genes encoding for IL-1β, the signal-transducing IL-1 receptor type I (IL-1RI) and inducible NO synthase (iNOS) constitutively and during systemic inflammation in vascular and perivascular regions of the rat brain. Our results show that IL-1RI is constitutively expressed at the interface of the vascular wall and perivascular glia. During systemic inflammation there is induction of IL-1 (3 gene expression in the vascular wall, accompanied by perivascular induction of iNOS mRNA. We conclude that during systemic inflammation vascular IL-1 (3, binding to vascular and perivascular IL-1RI receptors, may induce perivascular iNOS gene expression, leading to the production of NO and modulation of the effects of IL-1 (3 in the brain. We propose that the vascular and perivascular induction of iNOS mRNA by IL-1β might represent a mechanism for the modulation of the central nervous system effects of peripheral inflammatory mediators.

Receptor ligand binding and functional studies indicate that somatostatin (SRIF) receptors belong to the G protein coupled receptor superfamily. Using the polymerase chain reaction (PCR) and degenerate primers to the third and sixth transmembrane domains of G protein coupled receptors, we have isolated a SRIF receptor cDNA from bovine locus coeruleus (LC). This SRIF receptor (referred to as LCR9) encodes a protein of 368 amino acids and is 94% identical to a human SRIF receptor recently isolated from pancreatic islet cells. Levels of LCR9 mRNA are highest in cerebral cortex, intermediate in thalamus and cerebellum, and lower in pons, LC, dorsal raphe, and substantia nigra. Expression in CHO cells demonstrates that LCR9 binds ¹²⁵I-Tyr¹-SRIF with high affinity (K_d ~ 0.5 nM). SRIF, SRIF28, and MK 678 (a SRIF₁ selective ligand) potently displaced SRIF ligand binding, while a CGP-23996 like compound (compound 1), which displays higher affinity for SRIF2, did not significantly influence ligand binding at concentrations up to 1 µM. Ligand binding to the expressed receptor was also significantly reduced by GTP. Unlike the receptor isolated from pancreas, expression of LCR9 resulted in SRIF receptor inhibition of adenylyl cyclase. SRIF, SRIF28, and MK 678 all potently inhibited forskolin-stimulated adenylyl cyclase in membranes from LCR9 transfected cells; in contrast the CGP-23996 like compound did not influence adenylyl cyclase activity. SRIF receptor inhibition of adenylyl cyclase was dependent on GTP and was sensitive to pretreatment of membranes with pertussis toxin. The results demonstrate that LCR9 encodes a high-affinity SRIF receptor that is negatively coupled to adenylyl cyclase. Copyright 1993, 1999 Academic Press

Leptin communicates nutritional status to regulatory centers in the brain1,2. Because peripheral leptin influences the activity of the highly pulsatile adrenal and gonadal axes3,4, we sought to determine whether leptin levels in the blood are pulsatile. We measured circulating leptin levels every 7 minutes for 24 hours, in six healthy men, and found that total circulating leptin levels exhibited a pattern indicative of pulsatile release, with 32.0 ± 1.5 pulses every 24 hours and a pulse duration of 32.8 ± 1.6 minutes. We also show an inverse relation between rapid fluctuations in plasma levels of leptin and those of adrenocorticotropic hormone (ACTH) and cortisol that could not be accounted for on the basis of glucocorticoid suppression of leptin. As leptin levels are pulsatile, we propose that a key function of the CNS is regulated by a peripheral pulsatile signal. In a separate pilot study we compared leptin pulsatility in 414 plasma samples collected every 7 minutes for 24 hours from one obese woman and one normal-weight woman. We found that high leptin levels in the obese subject were due solely to increased leptin pulse height; all concentration-independent pulsatility parameters were almost identical in the two women. Leptin pulsatility therefore can be preserved in the obese.

Inducible nitric oxide synthase (iNOS) is a transcriptionally regulated enzyme that synthesizes nitric oxide from L–arginine1that has a key role in the pathophysiology of systemic inflammation and sepsis. Transgenic animals with a null mutation for the iNOS gene are resistant to hypotension and death caused by Escherichia coli lipopolysaccharide (IPS)2,3. The regulation of peripheral iNOS has been well studied in sepsis, but little is known about iNOS regulation in the brain during systemic inflammation or sepsis. We show that at baseline there is no detectable iNOS gene expression in the brain, but a detailed neuroanatomical study reveals that early in the course of systemic inflammation there is a profound induction of iNOS messenger RNA in vascular, glial and neuronal structures of the rat brain, accompanied by the production of nitric oxide (NO) metabolites in brain parenchyma and cerebrospinal fluid (CSF). We propose that the spillover of nitrite into the CSF has the potential to be a diagnostic marker for systemic inflammation and sepsis. Pharmacological interventions aimed at regulating iNOS function in the brain might represent a new treatment strategy in sepsis. Brain iNOS may be relevant to the pathophysiology, diagnosis and treatment of systemic inflammation and sepsis.

The hypothesis that brain-derived neurotrophic factor (BDNF) is involved in the pathogenesis of major depression is supported by several research findings; however, genetic studies assessing the relationship between BDNF and psychiatric disorders have produced conflicting results. We examined the effect of a BDNF polymorphism on depression susceptibility in Mexican-Americans. The single nucleotide polymorphism (Val66Met), which has been shown to have functional and behavioral effects, was genotyped in 284 depressed participants and 331 controls, showing association with depression (P0.005). Individuals homozygous for the major allele (GG) had an increased chance of being depressed (OR1.7 95 CI 1.17–2.47). Our findings support the association of BDNF single nucleotide polymorphism rs6265 and depression, suggesting that this polymorphism may increase susceptibility to major depression in Mexican-Americans.

Recombinant poxviruses expressing soluble interleukin–1 receptors show that interleukin-1 β is the predominant pyrogen during poxvirus infection.

TO THE EDITOR.— It is interesting to note that while the existence of dementia or cognitive deficits affecting chronic psychiatric patients is common anecdotal knowledge among psychiatrists, it has been very difficult to specify and quantify those deficits.In the November 1987 issue of the Archives, Goldberg et al1 presented data based on Wisconsin Card Sorting test (WCS) results reinforcing the hypothesis of prefrontal-type cognitive deficits in a group of chronic schizophrenics who were receiving neuroleptic drugs. Previously, Weinberger et al2,3 presented regional cerebral blood flow data as evidence of a physiologic dysfunction of dorsolateral prefrontal cortex also related to the performance on the WCS.Although the data presented by Goldberg et al1 and Weinberger et al2,3 were carefully obtained, one should always keep in mind that they studied patients with chronic conditions who had received or were receiving neuroleptic medication. Could similar data be obtained