PREFRONTAL CORRELATES OF FEAR GENERALIZATION DURING ENDOCANNABINOID DEPLETION

Maladaptive fear generalization is one of the hallmarks of trauma-related disorders. The endocannabinoid 2-arachidonoylglycerol (2-AG) is crucial for modulating anxiety, fear, and stress adaptation but its role in balancing fear discrimination versus generalization is not known. To address this, we used a combination of plasma endocannabinoid measurement and neuroimaging from a childhood maltreatment exposed and non-exposed mixed population combined with human and rodent fear conditioning models. Here we show that 2-AG levels are inversely associated with fear generalization at the behavioral level in both mice and humans. In mice, 2-AG depletion increases the proportion of neurons, and the similarity between neuronal representations, of threat-predictive and neutral stimuli within prelimbic prefrontal cortex ensembles. In humans, increased dorsolateral prefrontal cortical-amygdala resting state connectivity is inversely correlated with fear generalization. These data provide convergent cross-species evidence that 2-AG is a key regulator of fear generalization and suggest 2-AG deficiency could represent a trauma-related disorder susceptibility endophenotype.

Blood-brain barrier remodeling in an organ-on-a-chip device shows Dkk1 to be a regulator of early metastasis

Brain metastases are the most lethal progression event, in part because the biological processes underpinning brain metastases are poorly understood. There is a paucity of realistic models of metastasis, as current in vivo murine models are slow to manifest metastasis. We set out to delineate metabolic and secretory modulators of brain metastases by utilizing two models consisting of in vitro microfluidic devices: 1) a blood brain niche (BBN) chip that recapitulates the blood-brain-barrier and niche; and 2) a migration chip that assesses cell migration. We report secretory cues provided by the brain niche that attract metastatic cancer cells to colonize the brain niche region. Astrocytic Dkk-1 is increased in response to brain-seeking breast cancer cells and stimulates cancer cell migration. Brain-metastatic cancer cells under Dkk-1 stimulation increase gene expression of FGF-13 and PLCB1. Further, extracellular Dkk-1 modulates cancer cell migration upon entering the brain niche.

Targeting diacylglycerol lipase reduces alcohol consumption in preclinical models

Alcohol use disorder (AUD) is associated with substantial morbidity, mortality, and societal cost, and pharmacological treatment options for AUD are limited. The endogenous cannabinoid (eCB) signaling system is critically involved in reward processing and alcohol intake is positively correlated with release of the eCB ligand 2-Arachidonoylglycerol (2-AG) within reward neurocircuitry. Here we show that genetic and pharmacological inhibition of diacylglycerol lipase (DAGL), the rate limiting enzyme in the synthesis of 2-AG, reduces alcohol consumption in a variety of preclinical models ranging from a voluntary free-access model to aversion resistant-drinking and dependence-like drinking induced via chronic intermittent ethanol vapor exposure in mice. DAGL inhibition during either chronic alcohol consumption or protracted withdrawal was devoid of anxiogenic and depressive-like behavioral effects. Lastly, DAGL inhibition also prevented ethanol-induced suppression of GABAergic transmission onto midbrain dopamine neurons, providing mechanistic insight into how DAGL inhibition could affect alcohol reward. These data suggest reducing 2-AG signaling via inhibition of DAGL could represent an effective approach to reduce alcohol consumption across the spectrum of AUD severity.

An endocannabinoid-regulated basolateral amygdala-nucleus accumbens circuit modulates sociability

Deficits in social interaction (SI) are a core symptom of autism spectrum disorders (ASDs); however, treatments for social deficits are notably lacking. Elucidating brain circuits and neuromodulatory signaling systems that regulate sociability could facilitate a deeper understanding of ASD pathophysiology and reveal novel treatments for ASDs. Here we found that in vivo optogenetic activation of the basolateral amygdala-nucleus accumbens (BLA-NAc) glutamatergic circuit reduced SI and increased social avoidance in mice. Furthermore, we found that 2-arachidonoylglycerol (2-AG) endocannabinoid signaling reduced BLA-NAc glutamatergic activity and that pharmacological 2-AG augmentation via administration of JZL184, a monoacylglycerol lipase inhibitor, blocked SI deficits associated with in vivo BLA-NAc stimulation. Additionally, optogenetic inhibition of the BLA-NAc circuit markedly increased SI in the Shank3B-/- mouse, an ASD model with substantial SI impairment, without affecting SI in WT mice. Finally, we demonstrated that JZL184 delivered systemically or directly to the NAc also normalized SI deficits in Shank3B-/- mice, while ex vivo JZL184 application corrected aberrant NAc excitatory and inhibitory neurotransmission and reduced BLA-NAc-elicited feed-forward inhibition of NAc neurons in Shank3B-/- mice. These data reveal circuit-level and neuromodulatory mechanisms regulating social function relevant to ASDs and suggest 2-AG augmentation could reduce social deficits via modulation of excitatory and inhibitory neurotransmission in the NAc.

Cyclooxygenase-2 inhibition prevents stress induced amygdala activation and anxiety-like behavior

Stress is a major risk factor for the development and exacerbation of mood and anxiety disorders, and recent studies have suggested inflammatory contributions to the pathogenesis of depression. Interestingly, pharmacological inhibition of cyclooxygenase-2 (COX-2) has shown promise in the treatment of affective disorders in small scale clinical studies; however, the mechanisms by which COX-2 inhibition affects behavioral domains relevant to affective disorders are not well understood. Here, we examined the effects of pharmacological inhibition of COX-2 with the highly selective inhibitor Lumiracoxib (LMX) on anxiety-like behavior and in vivo basolateral amygdala (BLA) neural activity in response to acute restraint stress exposure. In male mice, pretreatment with LMX prevented the increase in BLA calcium transients induced by restraint stress and prevented anxiogenic behavior seen after restraint stress exposure. Specifically, acute injection of LMX 5 mg kg^-1 reduced anxiety-like behavior in the light-dark box (LD) and elevated-zero maze (EZM). In addition, in vivo fiber photometry studies showed that acute stress increased calcium transients and the predicted action potential frequency of BLA neurons, which was also normalized by acute LMX pretreatment. These findings indicate pharmacological inhibition of COX-2 can prevent acute stress-induced increase in BLA cellular activity and anxiety-like behavior and provides insights into the neural mechanisms by which COX-2 inhibition could affect anxiety domain symptoms in patients with affective disorders.

Endocannabinoid Signaling Collapse Mediates Stress-Induced Amygdalo-Cortical Strengthening

Functional coupling between the amygdala and the dorsomedial prefrontal cortex (dmPFC) has been implicated in the generation of negative affective states; however, the mechanisms by which stress increases amygdala-dmPFC synaptic strength and generates anxiety-like behaviors are not well understood. Here, we show that the mouse basolateral amygdala (BLA)-prelimbic prefrontal cortex (plPFC) circuit is engaged by stress and activation of this pathway in anxiogenic. Furthermore, we demonstrate that acute stress exposure leads to a lasting increase in synaptic strength within a reciprocal BLA-plPFC-BLA subcircuit. Importantly, we identify 2-arachidonoylglycerol (2-AG)-mediated endocannabinoid signaling as a key mechanism limiting glutamate release at BLA-plPFC synapses and the functional collapse of multimodal 2-AG signaling as a molecular mechanism leading to persistent circuit-specific synaptic strengthening and anxiety-like behaviors after stress exposure. These data suggest that circuit-specific impairment in 2-AG signaling could facilitate functional coupling between the BLA and plPFC and the translation of environmental stress to affective pathology.

Detection of Cyclooxygenase-2-Derived Oxygenation Products of the Endogenous Cannabinoid 2-Arachidonoylglycerol in Mouse Brain

Cyclooxygenase-2 (COX-2) catalyzes the formation of prostaglandins, which are involved in immune regulation, vascular function, and synaptic signaling. COX-2 also inactivates the endogenous cannabinoid (eCB) 2-arachidonoylglycerol (2-AG) via oxygenation of its arachidonic acid backbone to form a variety of prostaglandin glyceryl esters (PG-Gs). Although this oxygenation reaction is readily observed in vitro and in intact cells, detection of COX-2-derived 2-AG oxygenation products has not been previously reported in neuronal tissue. Here we show that 2-AG is metabolized in the brain of transgenic COX-2-overexpressing mice and mice treated with lipopolysaccharide to form multiple species of PG-Gs that are detectable only when monoacylglycerol lipase is concomitantly blocked. Formation of these PG-Gs is prevented by acute pharmacological inhibition of COX-2. These data provide evidence that neuronal COX-2 is capable of oxygenating 2-AG to form a variety PG-Gs in vivo and support further investigation of the physiological functions of PG-Gs.

Abstract 3103: Analysis of breast cancer lines and PDXs using a blood brain niche (µm-BBN) microfluidic device and algorithms to aid diagnosis of brain metastatic potential

Metastasis from the primary tumor site to the brain is the most lethal complication of advanced breast cancer. There is no translational approach to detect if a primary tumor has brain metastatic potential. This is due to a lack of blood brain barrier (BBB) models that can classify a cells metastatic potential. Moreover, the mechanisms by which circulating cancer cells extravasate through the BBB are unknown. Currently used in vivo murine models are slow to manifest metastasis therefore, an alternative approach is an in vitro microfluidic model that re-capitulates the BBB niche micro-environment. Our goal is to develop and use this model to identify the metastatic potential of cancer cell populations. Therefore, we have developed a blood brain niche (µm-BBN) on-a-chip and studied the phenotypic differences between cancer cells in the µm-BBN. The device has two chambers separated by a 5µm porous membrane coated with Matrigel and a BB human endothelial cell (hCMEC/D3) mono-layer. The bottom chamber contains a brain stromal ECM and Normal Human Astrocytes (NHA), while the top chamber acts as the blood vessel. Cancer cells are introduced into the top chamber and allowed to extravasate into the brain like stroma. We measured the ability of the endothelial layer to prevent fluorescent small molecules from diffusing into the brain stromal space. The barrier measured 8.3X lower max fluorescent values than when no barrier was present and were confirmed by TEER. Using this model, we characterized the MDA-231 breast cancer cell line against a brain-seeking subclone (MDA-231-BR), normal-like cell lines (MCF10A) and brain met patient derived xenografts (PDXs) in terms of their ability to extravasate, migrate and survive in the niche for 24-48 hrs. Phenotypic and migratory behavior was recorded using confocal tomography to measure cancer cell properties (volume, shape, position) relative to the endothelial layer. Brain-seeking subclones cluster around the endothelial layer, the MCF10A cell line has no preferred location and the parent line (MDA-231) extravasates deeper into the brain stromal space than the other two cell lines. We also found significant variation in the shape of each cell line before and during extravasation suggesting differences in plasticity. The effects of chemoattractants within the µm-BBN on extravasation have been explored by omitting astrocytes in the collagen-infused brain niche and replacing with astrocyte conditioned media. These findings confirm that the system is capable of measuring both variations in cancer cell populations and individual cells. This approach may enable classification of subclone populations with higher metastatic potential, meeting a major need in Oncology. Future work will employ this emerging tool to study the mechanisms by which the cancer cells extravasate and survive in the niche.

Citation Format: Christopher Ryan Oliver, Megan Altemus, Trisha Westerhof, Aki Morikawa, Xu Cheng, Jason Heth, Shuichi Takayama, Maria Castro, Sofia Merajver. Analysis of breast cancer lines and PDXs using a blood brain niche (µm-BBN) microfluidic device and algorithms to aid diagnosis of brain metastatic potential [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3103.

Loss of PTEN promotes formation of signaling-capable clathrin-coated pits

Defective endocytosis and vesicular trafficking of signaling receptors has recently emerged as a multifaceted hallmark of malignant cells. Clathrin-coated pits (CCPs) display highly heterogeneous dynamics on the plasma membrane where they can take from 20 s to over 1 min to form cytosolic coated vesicles. Despite the large number of cargo molecules that traffic through CCPs, it is not well understood whether signaling receptors activated in cancer, such as epidermal growth factor receptor (EGFR), are regulated through a specific subset of CCPs. The signaling lipid phosphatidylinositol (3,4,5)-trisphosphate [PI(3,4,5)P₃], which is dephosphorylated by phosphatase and tensin homolog (PTEN), is a potent tumorigenic signaling lipid. By using total internal reflection fluorescence microscopy and automated tracking and detection of CCPs, we found that EGF-bound EGFR and PTEN are enriched in a distinct subset of short-lived CCPs that correspond with clathrin-dependent EGF-induced signaling. We demonstrated that PTEN plays a role in the regulation of CCP dynamics. Furthermore, increased PI(3,4,5)P₃ resulted in higher proportion of short-lived CCPs, an effect that recapitulates PTEN deletion. Altogether, our findings provide evidence for the existence of short-lived 'signaling-capable' CCPs.

Abstract 433: Glycogen accumulation in aggressive breast cancers during hypoxic exposure

Isolation of specific metabolic alterations in aggressive triple negative and inflammatory breast cancers represents a compelling avenue for the development of treatments for these diseases. The ability of cancer to utilize diverse metabolic pathways to modulate increased survival and proliferation is well established. Indeed, we have previously described a series of metabolic adaptations in the triple negative inflammatory breast cancer cell line SUM149 and demonstrated a role for the small GTPase RhoC in the metabolic phenotype of the cell line.

In this work we seek to describe a survival mechanism for cancer cells that are subjected to hypoxic environments. Hypoxic survival or growth is often necessitated at the center of a growing tumor mass or if the tumor is growing in the lymphatic system, as is often the case for inflammatory breast cancers. Here we investigate the regulation of glycogen levels in breast cancer and normal-like cell lines in atmospheric and 1% oxygen environments. Reserves of glucose are typically stored in liver and muscle cells as the polysaccharide glycogen. Elevated levels of glycogen have previously been observed in various cancers, and recent studies have implicated the importance of glycogen metabolism in promoting cancer cell survival. We hypothesize that aggressive breast cancers utilize modifications of the glycogen synthesis and degradation pathways to provide nutritional flexibility as they proliferate and invade into diverse environments. MCF10A, SUM149, and SUM190 cell lines demonstrate a greater than 10-fold increase in glycogen accumulation when subjected to hypoxic growth conditions. MDA-MB-231 cells also increase glycogen storage, though at levels on the order of 2-3 times higher in hypoxia when compared to normoxic growth. Conditioned media for all cell lines in normoxic and hypoxic conditions were analyzed for glucose and lactate levels to determine changes in metabolite consumption.

The data presented indicate an unexpected accumulation of glycogen in response to hypoxic conditions. Studies to determine the mechanisms through which these changes occur and why they are important for continued survival and growth of the cancer cells are ongoing and will be presented.

Citation Format: Megan Altemus, Joel Yates, ZhiFen Wu, LiWei Bao, Sofia Merajver. Glycogen accumulation in aggressive breast cancers during hypoxic exposure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 433. doi:10.1158/1538-7445.AM2017-433

Abstract 5769: Modeling the tumor invasion front using 3D fluidic tumoroid culture of cancer cells

To realize the promise of precision medicine, it is important to integrate phenotypic assessment of cell populations to genomic data. The analysis of invading leader cells at the tumor invasion front is of interest as they may be guided by a targetable molecular phenotype. However, there is a lack of suitable platforms on which to analyze the tumor invasion front. In this study, we have designed and constructed a fluidic device for long-term (several days to weeks) 3-dimensional tumoroid culture of diverse cancer cells. Using this device, we can recapitulate the tumor invasion front and at the same time quantify the invasive potential of different breast cancer cell line models. Analyses of the tumor invasion front indicated a region of higher proliferation and suggest that the leader cells possess a different molecular phenotype from the tumoroid mass. Interestingly, significant heterogeneity among invading cells was still observed, suggesting that there could be: 1) the presence of multiple subpopulations of invasive cells, each with a different clonal genetic signature; and/or 2) reversible phenotypic switching occurring among invading cells due to phenotypic plasticity. These results obtained using this innovative device highlight and present a promising solution to the challenges developing adequate therapeutics accounting for tumor phenotypic heterogeneity. There is potential for the device for use in personalized medicine at diagnosis, allowing for both the quantification of disease progression risk as well as the molecular characterization of the invasive subpopulations from patient samples and their response to tailored therapies.

Citation Format: Koh Meng Aw Yong, Christopher Oliver, Megan Altemus, Zhi Fen Wu, Sofia Merajver. Modeling the tumor invasion front using 3D fluidic tumoroid culture of cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5769. doi:10.1158/1538-7445.AM2017-5769

Abstract 3910: Analysis of metastatic potential by breast cancer type through a microfluidic blood-brain niche

Metastasis from the primary tumor site to the brain is the most lethal complication from advanced cancer. 15% of breast cancers metastasize in the brain with a median survival of 5-14 months depending on the subtype. Therefore it is critical to identify when a tumor has the clonal potential to metastasize to the brain. Current detection methods and treatment therapies have continued to improve but do not shed light on clonal metastatic potential. Models for characterizing metastatic potential of clonal populations currently used include murine in vivo and simple in vitro systems. Murine models are costly, time intensive, slow to manifest metastasis and are not easy to analyze. On the other hand, in vitro systems are faster and more cost effective but currently do not recapitulate the complexity of the “live” micro-environment. We have developed a microfluidic device that mimics the cellular and physical components of the human blood-brain niche to study the brain metastatic process. The device is composed of two chambers separate by a porous membrane. The top chamber and apical side of the membrane is seeded with human brain endothelial cells and uses flow to mimic shear stress encountered within the vasculature. Cancer cells are introduced into this chamber in which they adhere to and migrate through the endothelium into the bottom chamber. The bottom chamber contains astrocytes suspended in a collagen gel to mimic the brain stroma and provide room for invading cancer cells to colonize and grow. Barrier integrity is monitored using TEER (trans-endothelial electrical resistance), and fluctuates as the tight junctions of the endothelium are compromised by invading cancer cells. This is characterized by IF and tight junction staining. Throughout all time points, from introduction into the flow chamber, adherence to the endothelium, extravasation through the barrier, migration into the stroma, and proliferation the cancer cells can be monitored via both microscopy and TEER. We have applied this microfluidic blood-brain niche model to compare brain-seeking subclones of breast cancer cell lines of known whole exome sequence and normal-like cell lines (MCF10A) in terms of their ability to extravasate, migrate and survive in the niche. We characterize their migratory behavior from live-cell microscopy and correlate it to the TEER measurements to establish a metastatic model. We then compare metastatic markers for ∝BBN traversing and non-traversing cells when appropriate.

Citation Format: Christopher Ryan Oliver, Megan Altemus, Brendan Leung, Aki Morikawa, Michele Dziubinski, Maria Castro, Sofai Merajver. Analysis of metastatic potential by breast cancer type through a microfluidic blood-brain niche [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3910. doi:10.1158/1538-7445.AM2017-3910

The impact of education, country, race and ethnicity on the self-report of postpartum depression using the Edinburgh Postnatal Depression Scale

BACKGROUND

Universal screening for postpartum depression is recommended in many countries. Knowledge of whether the disclosure of depressive symptoms in the postpartum period differs across cultures could improve detection and provide new insights into the pathogenesis. Moreover, it is a necessary step to evaluate the universal use of screening instruments in research and clinical practice. In the current study we sought to assess whether the Edinburgh Postnatal Depression Scale (EPDS), the most widely used screening tool for postpartum depression, measures the same underlying construct across cultural groups in a large international dataset.

METHOD

Ordinal regression and measurement invariance were used to explore the association between culture, operationalized as education, ethnicity/race and continent, and endorsement of depressive symptoms using the EPDS on 8209 new mothers from Europe and the USA.

RESULTS

Education, but not ethnicity/race, influenced the reporting of postpartum depression [difference between robust comparative fit indexes (∆*CFI) 0.01), but not between European countries (∆*CFI < 0.01).

CONCLUSIONS

Investigators and clinicians should be aware of the potential differences in expression of phenotype of postpartum depression that women of different educational backgrounds may manifest. The increasing cultural heterogeneity of societies together with the tendency towards globalization requires a culturally sensitive approach to patients, research and policies, that takes into account, beyond rhetoric, the context of a person's experiences and the context in which the research is conducted.

Abstract 1040: Differential levels of glycogen in breast cancer cell lines: A potential new target

Cancer cells have been known to alter their metabolic processes in order to survive and proliferate. Normally in muscle and liver, excess glucose is stored within the cells as glycogen. Elevated levels of glycogen have also been found in various cancers, including breast cancers. Recent studies have implicated glycogen metabolism as important in promoting survival of cancer cells, suggesting targeting of glycogen metabolism as a possible treatment to inhibit cancer cell growth. In general, modulation of cancer metabolism is believed to be an attractive adjunct strategy to conventional or targeted therapies. Here we set out to investigate glycogen levels as well as levels of proteins involved in glycogen synthesis and degradation vary across different breast cancer cell lines.

A glucose metabolism qPCR array found differential levels of the alpha subunit of phosphorylase kinase 1, a key enzyme involved in glycogen degradation among three different breast cancer cell lines. Expression levels of glycogen synthesis and degradation enzymes were assessed using qPCR and immunoblot in various breast cancer cell lines. Glycogen levels in these breast cancer cell lines were quantified using an amyloglucosidase reaction coupled with other enzymatic reactions to produce a fluorescent product. It was found that MDA-MB-231, SUM149, and MCF7 cell lines had increased levels of glycogen, between 6.5 and 23.5 μg glycogen per mg protein, whereas SUM190 and normal-like breast epithelial cell line MCF10A had undetectable levels of glycogen. These findings demonstrate that glycogen metabolism can vary widely amongst cancer types, indicating that therapies targeted to disrupt glycogen degradation may produce differential results and that further study of the role of glycogen metabolism in cancer is warranted.

Citation Format: Joel A. Yates, Megan Altemus, Zhifen Wu, Michelle L. Wynn, Sofia D. Merajver. Differential levels of glycogen in breast cancer cell lines: A potential new target. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1040.

Abstract 1700: Novel microfluidic blood-brain niche to study breast cancer metastasis to the brain

Metastasis from the primary tumor site to the brain is the most lethal complication of advanced cancer. Once a patient has developed brain metastasis, treatment involves surgical resection or radiation and is often only palliative. Poor prognosis following these therapies as well as the presence of concurrent disease outside of the nervous system emphasize the need for new systemic therapies that can reach and are active within the brain. In order to study the process of brain metastasis and develop potential therapies, models that mimic the human blood-brain niche must be used. Models currently utilized are murine in vivo models and various in vitro methods that do not accommodate all the biophysical characteristics of a blood-brain barrier. In vivo murine models are costly, time intensive, very slow to manifest metastases, and the metastatic process is seldom amenable to monitoring in real time. Current in vitro models are faster and more cost effective; however the models currently used do not have the same micro-environment complexity as “live” models. Here we describe a novel microfluidic device that accurately mimics the physical and cellular components of the human blood-brain niche to study the brain metastatic process.

This device is composed of two chambers separated by a porous membrane. The top chamber and apical side of the membrane is seeded with human brain endothelial cells with and uses flow to mimic shear stress encountered within the vasculature. Cancer cells are introduced into this chamber in which they adhere to and migrate through the endothelium into the bottom chamber. The bottom chamber contains astrocytes suspended in a collagen gel to mimic the brain stroma and provide room for invading cancer cells to colonize and grow. Barrier integrity is monitored using TEER (trans-endothelial electrical resistance), and fluctuates as the tight junctions of the endothelium are compromised by invading cancer cells. Throughout all time points, from introduction into the flow chamber, adherence to the endothelium, extravasation through the barrier, migration into the stroma, and proliferation the cancer cells can be monitored via microscopy or TEER.

This device provides a powerful novel tool to study the brain metastatic process and can be used to determine differences in brain metastatic potential of various cell lines or patient derived material, study the molecular mechanisms that promote brain metastasis, and test potential new therapies.

Citation Format: Megan Altemus, Brendan Leung, Aki Morikawa, Michele Dziubinski, Maria Castro, Sofia Merajver. Novel microfluidic blood-brain niche to study breast cancer metastasis to the brain. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1700.

Presymptomatic glutamate levels in prefrontal cortex in the Hdh(CAG150) mouse model of Huntington's disease

BACKGROUND

Huntington's disease (HD) is a genetic neurodegenerative disorder with few available treatments. Clinical observations suggest prefrontal dysfunction in early stages of HD is associated with altered glutamate transport. Evidence from the R6/2 mouse model suggests an abnormal increase in glutamate signaling in the sensorimotor cortex and striatum.

OBJECTIVE

The present study was designed to determine if a similar deficit in glutamate function occurs in the prefrontal cortex (PFC) of Hdh(CAG150) mice.

METHODS

We used the following groups of 40 week old male and female Hdh(CAG150) mice: homozygote n = 7, heterozygote n = 7, wild type n = 6. Motor coordination was evaluated using a hanging wire grid test and a balance beam. Microdialysis measurements were taken from the PFC of freely moving mice while glutamate transporters were inhibited by L-trans-pyrrolidine-2, 4-dicarboxylate (PDC) and compared to baseline glutamate levels.

RESULTS

RESULTS indicated an elevation in glutamate levels in response to PDC but no significant difference among genotype groups. When comparing wild type and homozygote alone, a significant difference in total extracellular glutamate was observed. Contrary to our original hypothesis, the homozygote group had lower glutamate levels compared to their wild type counterparts. Furthermore, there was a significant difference in GABA measurements across genotypes.

CONCLUSIONS

Our results suggest a mechanistic dichotomy between R6/2 and Hdh(CAG150) mice and underscores the need to select the appropriate HD mouse model when assessing therapeutic interventions. In particular, the time when animals are evaluated can have a significant impact on behavioral and physiological measures and so should be carefully considered.

Brain-derived neurotrophic factor as a model system for examining gene by environment interactions across development

There has been a dramatic rise in gene x environment studies of human behavior over the past decade that have moved the field beyond simple nature versus nurture debates. These studies offer promise in accounting for more variability in behavioral and biological phenotypes than studies that focus on genetic or experiential factors alone. They also provide clues into mechanisms of modifying genetic risk or resilience in neurodevelopmental disorders. Yet, it is rare that these studies consider how these interactions change over the course of development. In this paper, we describe research that focuses on the impact of a polymorphism in a brain-derived neurotrophic factor (BDNF) gene, known to be involved in learning and development. Specifically we present findings that assess the effects of genotypic and environmental loadings on neuroanatomic and behavioral phenotypes across development. The findings illustrate the use of a genetic mouse model that mimics the human polymorphism, to constrain the interpretation of gene-environment interactions across development in humans.

Effects of estrogen antagonists and agonists on the ACTH response to restraint stress in female rats

Previous studies have found that female rats are less sensitive than males to hypothalamic-pituitary-adrenal axis feedback inhibition by exogenous glucocorticoid administration. To determine whether estrogen contributes to this sex difference, we examined the effects of the estrogen antagonists tamoxifen and C1628 on the ACTH and corticosterone responses to restraint stress. CI628 increased both the ACTH and corticosterone response to restraint stress, and tamoxifen increased the ACTH response to restraint. Using overiectomized female rats, we also examined the effects of seven days of estradiol and/or progesterone replacement. Low dose estradiol decreased the ACTH but not the corticosterone response to restraint stress while progesterone had no effect on ACTH or corticosterone responses. The combination of estradiol and progesterone also decreased the ACTH response to stress, and the magnitude of the effect did not differ from that found with estradiol treatment alone. These data suggest that in the physiological range estradiol is an important inhibitory factor in the hypothalamic-pituitary-adrenal stress response of females.

Neuroendocrine and emotional changes in the post-partum period

As well as having widespread effects on many aspects of mammalian physiology, the hormones of both the reproductive and stress axes can directly and indirectly influence behavior. Here we review possible mechanisms through which centrally active hormones of the female reproductive system and the hypothalamo-pituitary-adrenal stress axis may interact to influence behavior and mood states during the post-partum period. We will focus primarily on the behavioral effects of selected neuropeptide hormones, in particular oxytocin, vasopressin and corticotrophin-releasing hormone. The literature documenting central behavioral effects of these neuropeptides arises almost exclusively from research in experimental animals. In particular, it has been reported that during lactation in rats there are high blood and brain levels of oxytocin. At the same time there is a reduction in corticotrophin-releasing hormone in the brain and in its secretion in response to stress. These changes may contribute to optimal maternal care of the offspring. Correlational studies of peptides and behavior in the post-partum period also support the hypothesis that neuropeptides may influence human physiology and behavior. Studies of post-partum women reveal powerful regulatory effects of lactation on the reactivity of the hypothalamo-pituitary-adrenal axis and of autonomic and immune systems, especially in the face of challenge. The integrative function of neural systems that influence both reproduction and the hypothalamo-pituitary-adrenal axis suggests one central mechanism for mediating the effects of environmental challenges.

Responses to laboratory psychosocial stress in postpartum women

OBJECTIVE

Lactation has been associated with attenuated hormonal responses to exercise stress in humans. This study was designed to determine the effect of lactation on hypothalamic-pituitary-adrenal axis, autonomic nervous system, and anxiety responses to psychological stress.

METHOD

The Trier Social Stress Test was administered to 24 lactating women, 13 postpartum nonlactating women, and 14 healthy control women in the early follicular phase of the menstrual cycle. Lactating women were stressed at least 40 minutes after last feeding their infant.

RESULTS

ACTH, cortisol, heart rate, diastolic blood pressure, systolic blood pressure, and subjective anxiety ratings were all significantly increased in response to the psychological stress (all p <.0001). There were no differences among the three groups in any of these responses to the stress. However, postpartum nonlactating women did have a persistently higher systolic blood pressure and lower cardiac vagal tone than the lactating women and control subjects. In addition, the typical negative correlation between cardiac vagal tone and heart rate was consistently higher in lactating women than nonlactating postpartum women and controls, which suggests stronger vagal control of heart rate in lactating women. In addition, there was no change in oxytocin or allopregnanolone in response to the stress, and baseline oxytocin and allopregnanolone levels did not differ among the three groups.

CONCLUSIONS

These results indicate that physiological and subjective responses to social stress are not attenuated in lactating women tested at least one hour after feeding their infant. However, enhanced vagal control of cardiac reactivity was observed in lactating women. In addition, postpartum women who did not lactate showed evidence of increased sympathetic and decreased parasympathetic nervous system tone.

Variable foraging demand rearing: sustained elevations in cisternal cerebrospinal fluid corticotropin-releasing factor concentrations in adult primates

BACKGROUND

The authors previously reported elevated cerebrospinal fluid (CSF) corticotropin-releasing factor (CRF) concentrations in juvenile primates nursed by mothers undergoing experimentally imposed unpredictable foraging conditions in comparison to normally reared controls. The purpose of the present study was to determine if these changes would endure into young adulthood.

METHODS

Cisternal CSF samples were obtained from those unpredictably reared young adult primates who had been previously studied as juveniles and age-matched ad libitum normally reared controls. Samples were assayed for CSF CRF.

RESULTS

Concentrations of CSF CRF were significantly elevated in the unpredictably reared sample in comparison to the ad libitum-reared control group. A significant positive correlation was noted between juvenile and young adult CSF CRF values within the unpredictably reared cohort.

CONCLUSIONS

Disturbances of maternal-infant attachment processes have an enduring impact on primate CRF function into young adulthood. The CRF elevations following unpredictable maternal foraging conditions appear traitlike in nature.

Stress-induced changes in skin barrier function in healthy women

Despite clear exacerbation of several skin disorders by stress, the effect of psychologic or exertional stress on human skin has not been well studied. We investigated the effect of three different stressors, psychologic interview stress, sleep deprivation, and exercise, on several dermatologic measures: transepidermal water loss, recovery of skin barrier function after tape stripping, and stratum corneum water content (skin conductance). We simultaneously measured the effects of stress on plasma levels of several stress-response hormones and cytokines, natural killer cell activity, and absolute numbers of peripheral blood leukocytes. Twenty-five women participated in a laboratory psychologic interview stress, 11 women participated in one night of sleep deprivation, and 10 women participated in a 3 d exercise protocol. The interview stress caused a delay in the recovery of skin barrier function, as well as increases in plasma cortisol, norepinephrine, interleukin-1beta and interleukin-10, tumor necrosis factor-alpha, and an increase in circulating natural killer cell activity and natural killer cell number. Sleep deprivation also decreased skin barrier function recovery and increased plasma interleukin-1beta, tumor necrosis factor-alpha, and natural killer cell activity. The exercise stress did not affect skin barrier function recovery, but caused an increase in natural killer cell activity and circulating numbers of both cytolytic T lymphocytes and helper T cells. In addition, cytokine responses to the interview stress were inversely correlated with changes in barrier function recovery. These results suggest that acute psychosocial and sleep deprivation stress disrupts skin barrier function homeostasis in women, and that this disruption may be related to stress-induced changes in cytokine secretion.

Increased vasopressin and adrenocorticotropin responses to stress in the midluteal phase of the menstrual cycle

Accumulating evidence indicates that gonadal steroids modulate functioning of the hypothalamic-pituitary-adrenal (HPA) axis, which has been closely linked to the pathophysiology of anxiety and depression. However, the effect of the natural menstrual cycle on HPA axis responsivity to stress has not been clearly described. In nine healthy women, metabolic and hormonal responses to treadmill exercise stress during the early follicular phase of the menstrual cycle, when gonadal steroid levels are low, were compared with responses in the midluteal phase of the cycle, when both progesterone and estrogen levels are relatively high. Exercise intensity was gradually increased over 20 min to reach 90% of each subject's maximal oxygen consumption during the final 5 min of exercise. Basal plasma lactate, glucose, ACTH, vasopressin, oxytocin, and cortisol levels were similar in the two cycle phases. However, in response to exercise stress, women in the midluteal phase had enhanced ACTH (P < 0.0001), vasopressin (P < 0.01), and glucose (P < 0.001) secretion. These findings suggest that relatively low levels of gonadal steroids during the early follicular phase of the menstrual cycle provide protection from the impact of stress on the HPA axis.

Lymphocyte responses to stress in postpartum women: relationship to vagal tone

Although women spend their lives in various phases of the reproductive cycle, including menstrual, pregnancy, postpartum, lactation and menopause, few studies have examined immune responses to stress in women as a function of events associated with reproduction. The objective of this study was to evaluate differential effects of breastfeeding (n = 16), bottlefeeding (n = 10) and non-postpartum (n = 10) status on lymphocyte responses to stressful tasks (public speaking and mental arithmetic). To measure cellular immune responses, lymphocyte proliferation to plant lectins, poke weed mitogen (PWM) and phytohemagglutinin (PHA) were used. The autonomic measures, heart rate, vagal tone, blood pressure and the hormones of the HPA axis, ACTH and cortisol, were measured and their possible roles in mediating lymphocyte proliferation responses were examined. Recently parturient women who were breastfeeding or bottlefeeding had attenuated stress-induced change in lymphocyte responses to PWM compared with non-postpartum women, tested in the follicular phase of their cycle (P < 0.05). Also, lymphocyte responses to PHA were higher in the breastfeeding group compared with non-postpartum controls (P < 0.05). Regression analyses revealed that an index of cardiac vagal tone, but not other autonomic or endocrine measures, was positively predictive of lymphocyte proliferation to PWM. To summarize, these findings suggest that lactation and parturition can influence lymphocyte proliferation and that activity in the vagal system may influence lymphocyte responses to stress.

Abnormalities in response to vasopressin infusion in chronic fatigue syndrome

Several neuroendocrine studies have suggested hypoactivation of the hypothalamic-pituitary-adrenal axis in chronic fatigue syndrome. One possible determinant of this neuroendocrine abnormality, as well as the primary symptom of fatigue, is reduced hypothalamic secretion of corticotropin-releasing hormone (CRH). Because CRH and vasopressin secreted from the hypothalamus act synergistically at the pituitary to activate ACTH secretion, the ACTH response to peripheral infusion of vasopressin can provide an indirect measure of hypothalamic CRH secretion. We measured the ACTH and cortisol response to a one hour infusion of arginine vasopressin in 19 patients with chronic fatigue syndrome and 19 age and sex matched healthy volunteers. Patients with chronic fatigue syndrome had a reduced ACTH response to the vasopressin infusion and a more rapid cortisol response to the infusion. These results provide further evidence of reduced hypothalamic CRH secretion in patients with chronic fatigue syndrome.

Growth hormone response to clonidine in adversely reared young adult primates: relationship to serial cerebrospinal fluid corticotropin-releasing factor concentrations

A reduction of the growth hormone (GH) response to the alpha(2) adrenergic agonist clonidine is a neuroendocrine abnormality observed with reasonable consistency among human patients with mood and anxiety disorders. In previous primate studies, in comparison to predictably reared controls, monkeys exposed as infants to maternal variable foraging demand (VFD) rearing exhibited persistent elevations of cerebrospinal fluid (CSF) corticotropin-releasing factor (CRF), as well as other biological disturbances. As CRF has been demonstrated to inhibit GH release, the authors hypothesized that within VFD-reared subjects, animals with relatively high CRF concentrations would exhibit relatively diminished GH responses to clonidine. The current study examined the relationship between the GH response to clonidine in VFD-reared adult primates in relation to a range of both juvenile and follow-up CSF CRF concentrations. Nine bonnet macaques (Macaca radiata) were given ascending dosages of clonidine under ketamine anesthesia. Plasma samples for GH-like immunoreactivity were obtained throughout the session. A significant positive correlation was noted between juvenile CSF CRF concentrations and the levels of the neuropeptide observed in young adults. The mean of the serial CSF CRF concentrations exhibited a significant inverse relationship towards the GH response to clonidine in young adulthood, with relatively high CSF CRF associated with relatively attenuated GH responses to clonidine. These data raise the possibility that a reduced GH response to clonidine may inversely reflect trait-like increases of central nervous system (CNS) CRF activity.

CSF oxytocin and vasopressin levels after recovery from bulimia nervosa and anorexia nervosa, bulimic subtype

BACKGROUND

When ill, people with eating disorders have disturbances of the neuropeptides vasopressin and oxytocin.

METHODS

To avoid the confounding effects of the ill state, we studied women who were recovered (more than 1 year, normal weight, and regular menstrual cycles, no bingeing or purging) from bulimia nervosa (rBN) or binge eating/purging-type anorexia nervosa (rAN-BN), and matched healthy control women.

RESULTS

Vasopressin was elevated in rAN-BN and showed a trend towards elevation in rBN. In rBN, elevated cerebrospinal fluid vasopressin may be related to having a lifetime history of major depression. In comparison, cerebrospinal fluid oxytocin was normal in recovered subjects, but elevated levels in some rBN might be related to birth control pill use.

CONCLUSIONS

These data confirm and extend the possibility that elevated cerebrospinal fluid vasopressin may be related to the pathophysiology of eating disorders, and/or a lifetime history of major depression.

Autoimmune mechanisms in movement disorders

A number of disorders, including childhood-onset obsessive compulsive disorder (OCD) and Gilles de la Tourette's syndrome (TS), are known to be neurobiological in nature. Both TS and OCD are neuropsychiatric diagnoses that involve congitive and perceptual dysfunction in addition to motor and psychiatric manifestations. The association of the B-cell marker with both Sydenham's chorea and a group of neuropsychiatric disorders, such as OCD, tics, and TS, has been useful as a marker in these diseases. This evidence, coupled with the recent finding of anti-brain antibodies in the sera of these patients, raises a number of interesting questions concerning the pathological mechanisms involved in these diseases. Thus, further molecular characterization of the brain and streptococcal antigens will be crucial to our understanding of the neurophysiological processes involved in these disorders.

Association of the serotonin transporter promoter regulatory region polymorphism and obsessive-compulsive disorder

Although modulation of symptoms of obsessive-compulsive disorder (OCD) by serotonergic agents is well established, it is unclear whether an abnormality in the central serotonergic system is involved in its etiology. The serotonin (5-HT) transporter (5-HTT), which is the key modulator of serotonergic neurotransmission, is the target for serotonin reuptake inhibiting drugs (SRIs) that are uniquely effective in the treatment of OCD. In this preliminary study we report an association of a functional polymorphism in the 5-HTT 5' regulatory-region and OCD. Seventy-five OCD Caucasian patients and 397 ethnically-matched individuals from a non-patient control group were genotyped for the 5-HTTLPR. Population-based association analysis revealed that patients with OCD were more likely to carry two copies of the long allele (l) as compared to controls (46.7% vs 32.3%: chi2 = 5.19, P = 0.023). This finding replicates a recent family-based study of this polymorphism in OCD, and thus indicates that the 5-HTTLPR may be associated with susceptibility to OCD.

Leptin, neuropeptide Y, and peptide YY in long-term recovered eating disorder patients

BACKGROUND

Disturbances of leptin, neuropeptide Y (NPY), and peptide YY (PYY) have been found in women who are ill with anorexia or bulimia nervosa. It is not certain whether peptide disturbances are cause or consequence of eating disorders.

METHODS

Plasma leptin and cerebrospinal fluid leptin, NPY, and PYY concentrations were measured in women who were recovered from anorexia or bulimia nervosa to determine whether alterations persisted after recovery.

RESULTS

NPY, PYY, and leptin concentrations were similar across all diagnostic groups.

CONCLUSIONS

Alterations in NPY, PYY, and serum leptin concentrations are probably secondary to pathological eating behaviors. Alterations of these peptides are unlikely to be trait-related disturbances that contribute to the etiology of eating disorders.

Open trial of flutamide for treatment of obsessive-compulsive disorder

BACKGROUND

Several lines of evidence suggest that gonadal steroid hormones play a role in the onset and exacerbation of obsessive-compulsive disorder (OCD). In this study, we examined the effects of treatment with flutamide, a synthetic, nonsteroidal, competitive antagonist of the androgen receptor, on OCD symptoms.

METHOD

Eight outpatients meeting DSM-III-R criteria for OCD participated in an 8-week open trial of flutamide. The dose was increased from 250 mg/day to 750 mg/day over the first 4 weeks and maintained at 750 mg/day for the final 4 weeks. The primary outcome measures for OCD symptoms were the Yale-Brown Obsessive Compulsive Scale and the Maudsley Inventory and for anxiety symptoms, the Beck Anxiety Inventory and the Hamilton Rating Scale for Anxiety. Subjects also provided self-ratings of aggression and sexual interest and activity.

RESULTS

There were no reductions in measures of obsession and compulsions or measures of anxiety over the 8-week trial. However, self-ratings of feelings of aggression did fall significantly over the 8-week trial (p < .001).

CONCLUSION

The lack of response to treatment with flutamide, an androgen receptor antagonist, suggests that any effects of gonadal steroids to exacerbate OCD symptoms are more likely to be mediated through estrogen receptors or through mechanisms that do not involve classical intracellular androgen receptors. Future treatment trials should examine agents that antagonize estrogen receptors or otherwise inhibit estrogen activity.

Normal CSF oxytocin and NPY levels in OCD

BACKGROUND

Attention has recently been focused on central nervous system neuropeptides as potential mediators of the symptom profile of obsessive-compulsive disorder (OCD). Increased CSF levels of the anxiolytic neuropeptide oxytocin have been reported in OCD. CSF levels of NPY, another anxiolytic neuropeptide, have not been studied.

METHODS

We measured CSF oxytocin and NPY in 14 OCD patients and 26 healthy normal volunteers.

RESULTS

There were no significant differences between the OCD patients and control subjects in CSF oxytocin or NPY levels. In both the OCD and control groups, women had significantly higher CSF oxytocin levels than men.

CONCLUSIONS

These results do not support a prior finding of elevated CSF oxytocin in OCD patients and do not provide any evidence for an abnormality of NPY regulation in OCD.

No coding variant of the tryptophan hydroxylase gene detected in seasonal affective disorder, obsessive-compulsive disorder, anorexia nervosa, and alcoholism

BACKGROUND

The goal of this study was to evaluate the role of genetic variation in the coding sequence of tryptophan hydroxylase (TPH) in the pathogenesis of several psychiatric diseases in which altered serotonin function has been implicated: bipolar affective disorder (BP), obsessive-compulsive disorder (OCD), anorexia nervosa (AN), seasonal affective disorder (SAD), panic disorder (PD), and alcoholism (Alc).

METHODS

Ninety-three percent of the TPH coding sequence was screened by polymerase chain reaction single-strand conformation polymorphism (SSCP) for DNA sequence variations in 128 AN, 88 OCD, 72 SAD, 45 PD, and 36 BP patients and 142 normal volunteers. Also included in the screening were 61 Alc randomly selected from a Finnish alcoholic population in which an association of a TPH intron 7 polymorphism with suicidality was previously observed. Polymorphisms detected by SSCP were characterized by DNA sequencing and by allele-specific restriction enzyme digestion. Genotyping was then performed in 34 Finnish alcoholic suicide attempters.

RESULTS

A rare silent mutation was identified in exon 10 and is designated T1095C. The C1095 allele was found in 1 OCD and in 2 AN subjects; all 3 individuals were heterozygous (C1095/T1095) for the variant allele. No association was observed between this TPH T1095C variant with either OCD, AN, Alc, or suicidality.

CONCLUSION

These results suggest that the coding sequence of the TPH gene does not contain abundant variants, and may not play a major role in vulnerability to several psychopathologies in which reduced serotonin turnover has been implicated.

Preliminary research on plasma oxytocin in normal cycling women: investigating emotion and interpersonal distress

The neurohormone oxytocin is responsible for initiating childbirth and the let-down reflex in lactating women and is released during sexual orgasm. Oxytocin has been thought of as an affiliation hormone because research on nonhuman mammals has demonstrated that it plays a key role in the initiation of maternal behavior and the formation of adult pair bonds. It has been speculated that social stimuli may induce oxytocin release and that oxytocin may make positive social contact more rewarding. Data are presented from an initial study to examine change in plasma oxytocin in response to a standard imagery task that elicits emotion related to attachment. Twenty-five normal cycling, healthy women underwent imagery tasks and completed questionnaires on attachment and interpersonal problems. Blood draws (5 ml) were bone via an indwelling catheter before, during, and after three interventions (massage, positive emotion, and negative emotion) and to establish baselines. Overall, the data showed a tendency for oxytocin levels to be elevated in response to relaxation massage and decreased in response to sad emotion. There were individual differences in response to the interventions. Those who showed evidence of increased oxytocin levels for positive emotion and massage and who maintained oxytocin levels during negative emotion were less likely to report interpersonal problems associated with intrusiveness. Maintaining oxytocin levels during sadness was also correlated with lower anxiety in close relationships. Women who were in a couple relationship had greater increases in oxytocin in response to positive emotion. In contrast, higher basal levels of oxytocin were associated with greater interpersonal distress. These data suggest that peripheral secretion of oxytocin in response to emotional stimuli is associated with the individual's interpersonal characteristics.

Delayed obsessive-compulsive disorder symptom exacerbation after a single dose of a serotonin antagonist in fluoxetine-treated but not untreated patients

Enhanced serotonergic transmission may underlie therapeutic effects of serotonin reuptake inhibitors in obsessive-compulsive disorder. However, such treatment may decrease serotonin receptor responsivity. We investigated whether the serotonin antagonist metergoline would exacerbate or further improve systems in fluoxetine-responsive patients. Pilot results suggested open metergoline produced delayed symptom worsening in fluoxetine-treated patients. Fourteen patients continuing fluoxetine received metergoline and placebo (double-blind, randomized). Symptom ratings continued for 1 week afterwards. Ten unmedicated patients underwent the same procedures. Symptoms improved 4 h after both metergoline and placebo. The day after metergoline but not placebo, fluoxetine-treated patients had significantly increased anxiety, obsessions and compulsions, abating over several days. Depression was unchanged. Metergoline had no similar delayed effects in unmedicated patients. Metergoline levels were higher in fluoxetine-treated patients. These results, consistent with less conclusive earlier findings, suggest that prolonged changes in brain serotonin function underlie symptom re-emergence following administration of metergoline to fluoxetine-treated patients with obsessive-compulsive disorder.

Reduced sensitivity to glucocorticoid feedback and reduced glucocorticoid receptor mRNA expression in the luteal phase of the menstrual cycle

We examined the effects of the menstrual cycle on hypothalamic-pituitary adrenal axis regulation in healthy women with no history of psychiatric illness by measuring plasma cortisol responses to a low-dose (0.25 mg) of dexamethasone (N = 23) and by measuring glucocorticoid receptor (type II) mRNA expression in lymphocytes using Northern blotting (N = 19). Both measures were performed in the early follicular and mid-luteal phases of the menstrual cycle. Dexamethasone suppression of plasma cortisol was greater in the follicular phase of the menstrual cycle compared to the mid-luteal phase (p < .01). In addition, type II glucocorticoid receptor mRNA expression in lymphocytes was 78% higher in the follicular phase compared to the mid-luteal phase (p < .02). These results indicate that glucocorticoid feedback regulation of the hypothalamic-pituitary-adrenal axis is reduced in the mid-luteal phase of the menstrual cycle. Reduced feedback regulation of central stress response systems may play a role in generation of common premenstrual symptoms of irritability and dysphoria.

Central nervous system actions of oxytocin and modulation of behavior in humans

The posterior pituitary hormone oxytocin has modulatory effects on neural functioning that are significant to the regulation of behavior. Basic research in animals has established the importance of oxytocin in affiliation, including mating, pair bonding and parenting behaviors. It is also an important regulator of feeding, grooming and responses to stress. The actions of oxytocin in the brain are regulated by gonadal steroid hormones, particularly estrogen. Oxytocin might also influence normal behavior in humans, and dysfunctions in the oxytocin system might be involved in the etiology and expression of neuropsychiatric disorders.

Effect of prefrontal repetitive transcranial magnetic stimulation in obsessive-compulsive disorder: a preliminary study

OBJECTIVE

Prefrontal mechanisms are implicated in obsessive-compulsive disorder. The authors investigated whether prefrontal repetitive transcranial magnetic stimulation influenced obsessive-compulsive disorder symptoms.

METHOD

Twelve patients with obsessive-compulsive disorder were given repetitive transcranial magnetic stimulation (80% motor threshold, 20 Hz/2 seconds per minute for 20 minutes) to a right lateral prefrontal, a left lateral prefrontal, and a midoccipital (control) site on separate days, randomized. The patients' symptoms and mood were rated for 8 hours afterward.

RESULTS

Compulsive urges decreased significantly for 8 hours after right lateral prefrontal repetitive transcranial magnetic stimulation, but there were nonsignificant increases in compulsive urges after repetitive transcranial magnetic stimulation of the midoccipital site. A shorter-lasting (30 minutes), modest, and nonsignificant reduction in compulsive urges occurred after left lateral prefrontal repetitive transcranial magnetic stimulation. Mood improved during and 30 minutes after right lateral prefrontal stimulation.

CONCLUSIONS

These preliminary results suggest that right prefrontal repetitive transcranial magnetic stimulation might affect prefrontal mechanisms involved in obsessive-compulsive disorder.

Tamoxifen prevents sulpiride-induced weight gain in female rats

To evaluate its potential utility in counteracting neuroleptic-induced obesity, the effects of long-term administration of tamoxifen (TAM) on body weight (BW) and food intake (FI) of gonadally intact and sulpiride-treated (SUL) female rats were assessed. In addition, estradiol and prolactin serum levels were measured in rats treated with SUL. SUL plus TAM and SUL plus bromocriptine (BR). TAM, at doses of 10, 50 and 100 micrograms, significantly decreased BW gain: FI was significantly reduced at the doses of 50 and 100 micrograms. In addition, doses of TAM ranging from 5-100 micrograms completely prevented SUL-induced BW gain and hyperphagia. BR also prevented SUL effects on BW and FI. In contrast to BR, concomitant administration of TAM did not prevent SUL-induced hyperprolactinemia. Estradiol levels were not modified by SUL alone or SUL plus BR, but they were significantly increased in the animals treated with TAM plus SUL. Neuroleptic-induced obesity in female rats might be related to an alteration in gonadal steroid balance secondary to hyperprolactinemia. While BR might counteract neuroleptic-induced weight gain by preventing hyperprolactinemia, TAM might directly interact with estrogen receptors, or indirectly increase estradiol levels. The use of TAM in preventing neuroleptic-induced obesity in humans warrants further investigation.

Genotype determining low catechol-O-methyltransferase activity as a risk factor for obsessive-compulsive disorder

In the present study, we address the role of the gene for catechol-O-methyltransferase (COMT), a key modulator of dopaminergic and noradrenergic neurotransmission, in the genetic predisposition to obsessive-compulsive disorder (OCD). We show that a common functional allele of this gene, which results in a 3- to 4-fold reduction in enzyme activity, is significantly associated in a recessive manner with susceptibility to OCD, particularly in males. This association is further supported by psychiatric evaluation of patients who carry microdeletions encompassing the comt gene. The mechanism underlying this sex-selective association remains to be defined and may include a sexual dimorphism in COMT activity, although close linkage with a nearby disease susceptibility locus cannot be excluded at this point.

Integrative functions of lactational hormones in social behavior and stress management

For mammalian reproduction to succeed, self-defense and asociality must be subjugated to positive social behaviors, at least during birth, lactation, and sexual behavior. Perhaps the important task of regulating the interaction between social and agonistic behaviors is managed, in part, by interactions between two related neurochemical systems that incorporate oxytocin and vasopressin in their functions. The neuropeptides oxytocin and vasopressin participate in important reproductive functions, such as parturition and lactation, and homeostatic responses, including modulation of the adrenal axis. Recent evidence also implicates these hormones in social aspects of reproductive behaviors. For example, oxytocin is important for a variety of positive social behaviors, including the regulation of maternal-infant interactions. In adult animals, oxytocin may facilitate both social contact and selective social interactions associated with social attachment and pair bonding, and it participates in the regulation of parasympathetic functions. Vasopressin, in contrast, is associated with behaviors that might be broadly classified as "defensive" including enhanced arousal, attention, or vigilance, increased aggressive behavior, and a general increase in sympathetic functions. On the basis of the literature on the functions of these hormones and our own recent findings, we propose that dynamic interactions between oxytocin and vasopressin are components of a larger system which integrates the neuroendocrine and autonomic changes associated with mammalian social behaviors and the concurrent regulation of the stress axis. In addition, studies of lactating females provide a valuable model for understanding the more general neuroendocrinology of the stress axis. Peptide hormones, including oxytocin and vasopressin, do not readily cross the blood-brain barrier and must be administered centrally (i.c.v.) to reach the brain. Nasal sprays have been used to promote milk let down and have been used in some behavioral studies, but the extent to which such compounds reach the brain is not known. Therefore, virtually nothing is known regarding the effects in humans of centrally administered oxytocin. The study of human lactation, in conjunction with animal research, provides an opportunity to begin to develop viable hypotheses regarding the behavioral effects of oxytocin.

Naloxone-induced pituitary-adrenal activation does not differ in patients with depression, obsessive compulsive disorder, and healthy controls

Adrenocorticotropic hormone (ACTH) and cortisol secretion have been shown to be abnormal in approximately half of depressed patients. Information from pituitary and adrenal studies suggests that the locus of this dysregulation is at or above the level of the hypothalamus; however, direct evidence from provocative studies of the hypothalamic corticotropin releasing hormone (CRH) neuron does not exist. The current study was designed to stimulate hypothalamic CRH release using the opiate antagonist naloxone in patients with depression and elevated urinary-free cortisols as well as healthy and psychiatric controls. All subjects received naloxone and placebo on separate days in a double-blinded, randomized fashion at a dose determined previously to reliably induce significant increases in ACTH and cortisol secretion. No significant differences were noted among groups. We conclude that although naloxone is an effective central stimulant of the hypothalamic CRH neuron, stimulation of the hypothalamic CRH neuron with naloxone does not provide evidence of dysregulation of the HPA axis in depression.

Intact coding region of the serotonin transporter gene in obsessive-compulsive disorder

Epidemiologic studies indicate that obsessive-compulsive disorder is genetically transmitted in some families, although no genetic abnormalities have been identified in individuals with this disorder. The selective response of obsessive-compulsive disorder to treatment with agents which block serotonin reuptake suggests the gene coding for the serotonin transporter as a candidate gene. The primary structure of the serotonin-transporter coding region was sequenced in 22 patients with obsessive-compulsive disorder, using direct PCR sequencing of cDNA synthesized from platelet serotonin-transporter mRNA. No variations in amino-acid sequence were found among the obsessive-compulsive disorder patients or healthy controls. These results do not support a role for alteration in the primary structure of the coding region of the serotonin-transporter gene in the pathogenesis of obsessive-compulsive disorder.

Comparison of obsessions and compulsions in patients with anorexia nervosa and obsessive compulsive disorder

Patients with anorexia nervosa (n = 18) and patients with obsessive-compulsive disorder (OCD) (n = 16) had similar scores on the Yale-Brown Obsessive Compulsive Scale (19 + or - 9 vs. 22 + or - 6). This suggests that these disorders have similar magnitude of impairment from obsessions and compulsions; however, OCD patients endorsed a wide variety of obsessions and compulsions, whereas anorexics tended to endorse symptoms that were related to symmetry and order.

Thyroid function in bulimia nervosa

Basal thyroid-stimulating hormone (TSH) and thyroid hormone levels were evaluated in 18 women with bulimia nervosa during a period of active binging and vomiting and again after 7 weeks of abstinence from these behaviors and compared to measures in 27 control women. In 10 of the patients and 11 of the controls, the TSH nocturnal surge was calculated from hourly TSH measurements obtained in the afternoon from 1500 to 1900 h and in the night from 2300 to 0400 h. During the binging phase of the illness patients had lower total triiodothyronine (T3) values than controls (p < .001). After 7 weeks without binge eating or purging, patients had lower T3, total thyroxine (T4), free triiodothyronine, free thyroxine (FT4), reverse triiodothyronine and thyroid-binding globulin (TBG) values compared to controls (p < .01) and significant reductions in T3, T4, FT4 and TBG compared to themselves in the active phase of the illness (p < .02). The reduction in thyroid hormone levels was not due to a reduction in the nocturnal thyrotropin surge, since surge values did not differ between normals and patients at either phase of the illness. Bulimics in the binging phase of the illness showed a positive correlation between caloric intake and TSH values (p < .01), suggesting that food binging may stimulate thyroid activity. In sum, these results show a substantial reduction in thyroid hormone levels after 7 weeks of abstinence from binging and vomiting behaviors.

Effects of serotonergic agents on food-restriction-induced hyperactivity

Rats that are fed for 90 min per day can stabilize their weight after an initial drop; however, if rats on this feeding schedule are also given access to a running wheel, they run excessively, eat less, lose weight, and often die. To investigate this phenomenon as a possible animal model of obsessive-compulsive disorder (OCD), rats were treated for 5 weeks with fluoxetine, an antidepressant that relieves OCD symptoms in humans (5 mg/kg, 2.5 mg/kg), or imipramine, an antidepressant that does not affect OCD symptoms (5 mg/kg), or saline prior to exposure to food restriction and the running wheel. In addition, because chronic fluoxetine treatment is thought to enhance serotonergic neurotransmission, for contrast an additional group of rats were treated with parachlorophenylalanine (PCPA), a tryptophan hydroxylase inhibitor that depletes serotonin. Rats treated with fluoxetine lost significantly less weight, ran significantly less, and increased food intake more rapidly during restriction of food availability than saline-treated rats. Rats treated with imipramine did not differ from those treated with saline on these parameters. Compared to saline-treated rats, rats treated with PCPA lost more weight, ate less food, and increased running more rapidly. These effects of pharmacological treatment indicate an inverse relationship between central serotonergic activity and vulnerability to develop food-restriction-induced anorexia and compulsive running. In addition, like OCD in humans, this phenomenon in rats seems to be blocked by chronic treatment with a serotonin selective reuptake inhibitor but not a less selective monoamine reuptake inhibitor.