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Background: Human and animal studies suggest that testosterone may have antidepressant effects. In this study, we sought to investigate the molecular mechanisms underlying the antidepressant effects of testosterone within the hippocampus, an area that is fundamental in the etiology of depression., Methods: The effects of testosterone replacements in gonadectomized adult male rats were investigated using the sucrose preference and forced swim tests. We explored possible effects of testosterone on hippocampal neurogenesis and gene expression of stress-related molecules. Through the use of viral vectors, we pursued the antidepressant molecular mechanism(s) of testosterone in mediating anhedonia and manipulated extracellular signal-regulated kinase 2 (ERK2) expression in the dentate gyrus in gonadectomized rats with testosterone replacements., Results: Testosterone had antidepressant effects, likely mediated by aromatization to estrogen metabolites, in the sucrose preference and forced swim tests despite having no effects on hippocampal cell proliferation or survival. We found a testosterone-dependent regulation of hippocampal ERK2 expression. Functionally, reducing ERK2 activity within the dentate gyrus induced anhedonia in gonadectomized rats receiving testosterone supplementation, whereas the overexpression of ERK2 rescued this behavior in gonadectomized rats., Conclusions: These results implicate a role for ERK2 signaling within the dentate gyrus area of the hippocampus as a key mediator of the antidepressant effects of testosterone., (Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

This paper highlights a symposium on stress risk factors and stress susceptibility, presented at the Neurobiology of Stress workshop in Boulder, CO, in June 2010. This symposium addressed factors linking stress plasticity and reactivity to stress pathology in animal models and in humans. Dr. J. Radley discussed studies demonstrating prefrontal cortical neuroplasticity and prefrontal control of hypothalamo-pituitary-adrenocortical axis function in rats, highlighting the emerging evidence of the critical role that this region plays in normal and pathological stress integration. Dr. M. Kabbaj summarized his studies of possible epigenetic mechanisms underlying behavioral differences in rat populations bred for differential stress reactivity. Dr. L. Jacobson described studies using a mouse model to explore the diverse actions of antidepressants in brain, suggesting mechanisms whereby antidepressants may be differentially effective in treating specific depression endophenotypes. Dr. R. Yehuda discussed the role of glucocorticoids in post-traumatic stress disorder (PTSD), indicating that low cortisol level may be a trait that predisposes the individual to development of the disorder. Furthermore, she presented evidence indicating that traumatic events can have transgenerational impact on cortisol reactivity and development of PTSD symptoms. Together, the symposium highlighted emerging themes regarding the role of brain reorganization, individual differences, and epigenetics in determining stress plasticity and pathology.

Most neuropsychiatric disorders, including stress-related mood disorders, are complex multi-parametric syndromes. Diagnoses are therefore hard to establish and current therapeutic strategies suffer from significant variability in effectiveness, making the understanding of inter-individual variations crucial to unveiling effective new treatments. In rats, such individual differences are observed during exposure to a novel environment, where individuals will exhibit either high or low locomotor activity and can thus be separated into high (HR) and low (LR) responders, respectively. In rodents, a long-lasting, psychosocial, stress-induced depressive state can be triggered by exposure to a social defeat procedure. We therefore analyzed the respective vulnerabilities of HR and LR animals to long-lasting, social defeat-induced behavioral alterations relevant to mood disorders. Two weeks after four daily consecutive social defeat exposures, HR animals exhibit higher anxiety levels, reduced body weight gain, sucrose preference, and a marked social avoidance. LR animals, however, remain unaffected. Moreover, while repeated social defeat exposure induces long-lasting contextual fear memory in both HR and LR animals, only HR individuals exhibit marked freezing behavior four weeks after a single social defeat. Combined, these findings highlight the critical involvement of inter-individual variations in novelty-seeking behavior in the vulnerability to stress-related mood disorders, and uncover a promising model for posttraumatic stress disorder., (Copyright © 2010 Elsevier Inc. All rights reserved.)

We have studied the distribution of HLA-A, -B and DRB1 alleles and haplotypes by sequence specific oligonucleotide amplification in a sample of 125 unrelated healthy Moroccan individuals from Casablanca in Morocco. The city of Casablanca is known of its big ethnic diversity, especially Arabs and Berbers. The most frequent alleles found were: HLA-A*02 (18.4%), -A*01 (11.2%), -A*03 (10.8%), -B*51 (8.06%),-B*44 (7.66%), -B*08 (6.85%), -DRB1*04 (15.98%), DRB1*03 and DRB1*07 (13.92%) and -DRB1*01 (10%). High frequency for five two-locus haplotypes was observed for A*03-B*51 (5%), A*02-DRB1*03 (5.5%), A*02-DRB1*04 and A*01-DRB1*04 (5%) and B*35-DRB1*04 (4%). No predominant haplotype was observed for HLA A-B-DRB1. Our results confirm and extend the current knowledge about genetic pattern of the Moroccan of Casablanca. This study will serve as a reference for further anthropological studies, as well as studies of HLA and disease associations in the Moroccan population.

We have recently established the socially monogamous prairie vole (Microtus ochrogaster) as an animal model with which to investigate the involvement of mesocorticolimbic dopamine (DA) in the amphetamine (AMPH)-induced impairment of social behavior. As the majority of our work, to date, has focused on males, and sex differences are commonly reported in the behavioral and neurobiological responses to AMPH, the current study was designed to examine the behavioral and neurobiological effects of AMPH treatment in female prairie voles. We used a conditioned place preference (CPP) paradigm to determine a dose-response curve for the behavioral effects of AMPH in female prairie voles, and found that conditioning with low to intermediate (0.2 and 1.0 mg/kg), but not very low (0.1 mg/kg), doses of AMPH induced a CPP. We also found that exposure to a behaviorally relevant dose of AMPH (1.0 mg/kg) induced an increase in DA concentration in the nucleus accumbens (NAcc) and caudate putamen but not the medial prefrontal cortex or ventral tegmental area (VTA). Finally, repeated AMPH exposure (1.0 mg/kg once per day for 3 consecutive days; an injection paradigm that has been recently shown to alter DA receptor expression and impair social bonding in male prairie voles) increased D1, but not D2, receptor mRNA in the NAcc, and decreased D2 receptor mRNA and D2-like receptor binding in the VTA. Together, these data indicate that AMPH alters mesocorticolimbic DA neurotransmission in a region- and receptor-specific manner, which, in turn, could have profound consequences on social behavior in female prairie voles., (Copyright © 2010. Published by Elsevier B.V.)

Despite abundant expression of DNA methyltransferases (Dnmts) in brain, the regulation and behavioral role of DNA methylation remain poorly understood. We found that Dnmt3a expression was regulated in mouse nucleus accumbens (NAc) by chronic cocaine use and chronic social defeat stress. Moreover, NAc-specific manipulations that block DNA methylation potentiated cocaine reward and exerted antidepressant-like effects, whereas NAc-specific Dnmt3a overexpression attenuated cocaine reward and was pro-depressant. On a cellular level, we found that chronic cocaine use selectively increased thin dendritic spines on NAc neurons and that DNA methylation was both necessary and sufficient to mediate these effects. These data establish the importance of Dnmt3a in the NAc in regulating cellular and behavioral plasticity to emotional stimuli.

Rationale: Social stress has been linked to several neuropsychiatric diseases, including depression, which is a debilitating disease that has genetic, environmental, and epigenetic underpinnings., Objectives: This study examined the effects of repeated social defeat on both depressive-like behaviors and histone acetylation in the hippocampus, amygdala, and dorsal prefrontal cortex of male Sprague-Dawley rats., Materials and Methods: Subjects were exposed to four consecutive social defeats. Depressive-like behaviors were assayed in the sucrose preference, forced swim, contextual fear, and social approach and avoidance tests. Histone H3 and H4 acetylation in the hippocampus, amygdala, and prefrontal cortex were examined by Western blots under basal conditions and at several time points. We also investigated the potential involvement of N-methyl-D: -aspartic acid (NMDA) receptors and glucocorticoid receptors (GR) by injecting respective antagonists prior to each social defeat and examining their effect on histone acetylation in the hippocampus., Results: Social defeat resulted in behavioral changes in the forced swim, social avoidance, and contextual fear tests nearly 6 weeks after defeat, with no change in sucrose preference. Additionally, histone H3 acetylation was increased in the hippocampus 30 min following the last defeat and was not blocked by antagonism of either NMDA or GR receptors. There were no changes in histone H4 acetylation., Conclusions: These results indicate that social defeat induces several long-lasting depressive-like behaviors in rats and induces a significant, short-lived increase in H3 acetylation in the hippocampus, although the underlying mechanism behind this change warrants further investigation.

Previous studies have demonstrated some significant differences in HLA allele frequencies in leukemic patients and normal subjects. In Moroccan leukemic patients, the frequency of HLA alleles has not already been determined. We have analyzed HLA class I and class II alleles and haplotypes in 62 Moroccan leukemic patients and 98 unrelated normal subjects using PCR-SSO method. Significant positive association with the disease, in patients compared to controls, was found for three alleles: HLA-B*44 (12.7% vs 6.6%; p = 0.02), HLA-DRB1*13 (11.8% vs 9.79%; p = 0.04) and HLA-DRB*01 (4.5% vs 10.7%; p = 0.05). Regarding haplotypes analysis, no significant association was found between patients and control groups. It is suggested that HLA-B*44 and HLA-DRB1*13 alleles may play a presumptive predisposing factor while the HLA-DRB*01 allele could be a protective genetic factor against leukemia.

The prairie vole (Microtus ochrogaster) is a socially monogamous rodent species that forms pair bonds after mating, a behavior in which central dopamine (DA) has been implicated. Here, we used male prairie voles to examine the effects of drug exposure on pair bonding and related neural circuitry. In our first experiment, amphetamine (AMPH) motivated behavior was examined using a conditioned place preference (CPP) paradigm and was shown to be mediated by activation of D1-like DA receptors. Next, we examined the effects of repeated AMPH exposure on pair bonding. Intact and saline pretreated control males displayed mating-induced partner preferences, whereas males pretreated with AMPH at the doses effective to induce CPP failed to show mating-induced partner preferences. Such AMPH treatment also enhanced D1, but not D2, DA receptor expression in the nucleus accumbens (NAcc). Furthermore, pharmacological blockade of D1-like DA receptors in the NAcc rescued mating-induced partner preferences in AMPH-treated males. Together, our data indicate that repeated AMPH exposure may narrow the behavioral repertoire of male prairie voles via a DA receptor-specific mechanism in the NAcc, resulting in the impairment of pair bond formation.

Given both the high prevalence of anxiety disorders in women and the fact that little is known about the mechanisms of gender differences in anxiety, our primary aim in this study was to investigate the neurobiological mechanisms underlying sex differences in social anxiety-like behavior in rats. Through the use of zif268 antisense oligodeoxynucleotides (zif ASO), we induced a temporary downregulation of zif268 expression in the medial prefrontal cortex of male and female rats and found that zif268 ASO male rats show more social anxiety-like behaviors when compared with control male rats in the social interaction test. In fact, zif268 ASO males displayed social anxiety-like behaviors, which were similar to control females, thus downregulation of zif268 expression in the mPFC of male rats eliminated sex differences previously found in the social anxiety-like behavior tests. Interestingly, zif268 ASO in female rats had no effect on their social interaction. Our novel findings have led us to ascertain that sexually dimorphic zif268 expression in the mPFC is a key molecular factor in mediating sex-specific anxiety-like behavior in the social interaction test.

Diffuse arterial calcified elastopathy is a very rare and little known hereditary disease, characterized by diffuse calcifications of the arterial wall. It seems common in North Africa and in the Caucasian region. Its incidence appears to be underestimated in Morocco. Clinical pattern is dominated by renovascular hypertension often associated with symptoms of heart failure. Risk of sudden death from myocardial infarction is particularly important. Thus, the diagnosis of diffuse arterial calcified elastopathy must always be suspected in front of an apparently unexplained heart failure or renovascular hypertension occurring in an infant. We report a case of diffuse arterial calcified elastopathy discovered in a neonatal intensive care unit, during management of a cardiogenic shock in a 3-months old infant. This observation demonstrates the importance of systematic measurement of the arterial tension, family screening and the impact of the ultrasound in the detection of vascular calcifications. Treatment remains essentially symptomatic.

This study compares the ability of 2 semiautomated methods with a fully automated method for QT measurement to minimize the sample size required to detect a moxifloxacin effect and exclude a placebo effect in a thorough QT/QTc study. The fully automated and 1 of 2 semiautomated methods used a global QT measurement in 12 leads, whereas the other semiautomated method used a tangent method on single lead raw complexes. Mean QTcF intervals were greater when measured on a global QT electrocardiogram than on raw complexes, but the mean magnitudes of DeltaQTcF were similar for all methods. The 3 methods detected a statistically significant increase in QTcF for moxifloxacin compared to placebo and were able to exclude a placebo effect on QTcF in all 62 participants. However, due to a smaller variability, the semiautomated methods allowed these detections with fewer than 20 participants, whereas the fully automated required at least 27 participants.

Changes in gene expression contribute to the long-lasting regulation of the brain's reward circuitry seen in drug addiction; however, the specific genes regulated and the transcriptional mechanisms underlying such regulation remain poorly understood. Here, we used chromatin immunoprecipitation coupled with promoter microarray analysis to characterize genome-wide chromatin changes in the mouse nucleus accumbens, a crucial brain reward region, after repeated cocaine administration. Our findings reveal several interesting principles of gene regulation by cocaine and of the role of DeltaFosB and CREB, two prominent cocaine-induced transcription factors, in this brain region. The findings also provide comprehensive insight into the molecular pathways regulated by cocaine-including a new role for sirtuins (Sirt1 and Sirt2)-which are induced in the nucleus accumbens by cocaine and, in turn, dramatically enhance the behavioral effects of the drug.

Rationale: In some rats, the hormone corticosterone is reinforcing. High novelty-seeking rats (high responders, HR) self-administered corticosterone at a much higher rate than low novelty-seeking rats (low responders, LR) do [Piazza PV, Deroche V, Deminiere JM, Maccari S, Le Moal M, Simon H, Corticosterone in the range of stress-induced levels possesses reinforcing properties: implications for sensation-seeking behaviors, Proc Natl Acad Sci USA 1993;90:11738-42]. While previous studies demonstrated that corticosterone reinforces nose poking in a self-administration paradigm, no studies to date have examined whether corticosterone is rewarding., Objective: Using the conditioned place preference (CPP) paradigm, we examined the rewarding effects of corticosterone in HR and LR rats., Methods: Male Sprague-Dawley rats were classified into HR and LR groups based on their locomotor activity in a novel environment. Subsequently, independent groups of HR and LR rats underwent CPP for corticosterone (0, 2.5 or 10 mg/kg; i.p.) or cocaine (12 mg/kg; i.p). CPP for cocaine was used as a positive control., Results: While cocaine produced a strong CPP in both HR and LR rats, corticosterone failed to produce either preference or aversion in both phenotypes., Conclusion: Corticosterone is neither rewarding nor aversive in either behavioral phenotype.

The aim of this study was to investigate the noradrenergic regulation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in high responder (HR) and low responder (LR) male rats, an animal model of individual differences in hypothalamo-pituitary-adrenal axis activity and vulnerability to drugs of abuse. The effects of a chronic treatment with the noradrenergic alpha(1) antagonist (1-[4-amino-6,7-dimethoxy-2-quinazolinyl]-4-[2-furanylcarbonyl] piperazine) hydrochloride (prazosin) (0.5 mg/kg, i.p., 35 days) were assessed on stress-induced corticosterone (CORT) secretion and on hippocampal MRs and GRs in adrenally intact rats. In order to ascertain whether the effects of chronic prazosin treatment on hippocampal MRs and GRs were direct or indirect, through prazosin-induced CORT secretion, we also assessed the effects of the same treatment on adrenalectomized rats with CORT substitutive therapy. When compared with LR rats, HR rats exhibited a delayed return to the basal level of CORT following acute restraint stress; this was associated with a lower binding of MRs and GRs in HR rats than in LR rats. Chronic prazosin treatment had no effect in HR animals but markedly reduced hippocampal MRs and GRs, and increased stress-induced CORT secretion in LR rats. In LR adrenalectomized rats, prazosin reduced hipppocampal MRs but did not change GRs. Our results provide evidence of a differential regulation by noradrenaline of hippocampal MRs and GRs in HR and LR rats. These data could have clinical implications in terms of individual differences in the resistance to antidepressant treatments and individual differences in drug abuse.

Numerous studies have demonstrated that Sprague-Dawley rats exhibit a wide range of locomotor reactivity when placed in a novel environment. High Responder (HR) rats show exaggerated locomotor response to novelty, enhanced neuroendocrine stress reactivity, decreased anxiety-like behavior, and propensity to self-administer psychostimulants, compared to the less active Low Responder (LR) animals. Few studies have explored the early environmental factors which may underlie the HR-LR differences in emotional reactivity. Considering the enormous impact of maternal care on rodent neurodevelopment, we sought to examine maternal behavior in HR-LR dams to determine whether they exhibit differences which could contribute to their offspring's differential temperaments. Females, like males, can be classified as HR versus LR, showing marked differences in novelty-induced locomotor activity and anxiety-like behavior. HR-LR mothers behaved differently with their pups during the first two postpartum weeks. LR dams spent greater time licking and nursing their pups compared to HR dams, with the most prominent differences occurring during the second postpartum week. By contrast, when non-lactating HR-LR females were presented with orphaned pups, the pattern of maternal response was reversed. HR females were more responsive and showed greater maternal care of the novel pups compared to LR females, which were probably inhibited due to fear of the unfamiliar pups. This underscores the critical interplay between the female's emotional phenotype, her hormonal status and her familiarity with the pup as key factors in determining maternal behavior. Future work should explore neural and hormonal mechanisms which drive these HR-LR differences in maternal behavior and their impact on the development of the offspring.

In this review we shall attempt to summarize the literature published on the high responders/low responders' animal model of drug addiction. This model is based on the locomotor activity of rats in the mild stress of a novel environment. Rats that exhibit high rates of exploratory behaviours are deemed high responders (HR) and rats that exhibit low exploratory behaviours are deemed low responders (LR). Interestingly, the rate of these exploratory behaviours predicts the response of these animals to drugs of abuse. In this manuscript we will review the behavioural and physiological differences between HR and LR rats in response to d-amphemtamine, cocaine, morphine, alcohol and nicotine.

Background: This study elucidates the impact of sampling site when estimating pharmacokinetic-pharmacodynamic (PK-PD) parameters of drugs such as remifentanil that undergo tissue extraction in the biophase. The interrelationship between the concentrations of remifentanil predicted for the effect compartment and those measured in arterial, venous, and cerebrospinal fluid were investigated under steady-state conditions., Methods: Following induction of anaesthesia with pentobarbital, an arterial cannula (femoral) and two venous catheters (jugular and femoral) were inserted. Electrodes were placed for EEG recording of theta wave activity. Each dog received two consecutive 5-min infusions for the PK-PD study and a bolus followed by a 60-min infusion was started for the steady-state study. Cerebrospinal fluid, arterial and venous blood samples were drawn simultaneously after 30, 40, and 50 min. At the end of the infusion, arterial blood samples were collected for pharmacokinetic analysis., Results: Remifentanil PK-PD parameters based on theta wave activity were as follows: apparent volume of distribution at steady-state (V(ss)) (231+/-37 ml kg(-1)), total body clearance (Cl) (63+/-16 ml min(-1) kg(-1)), terminal elimination half-life (t(1/2 beta)) (7.71 min), effect compartment concentration at 50% of maximal observed effect (EC(50)) (21+/-13 ng ml(-1)), and equilibration rate constant between plasma and effect compartment (k(e0)) (0.48+/-0.24 min). The mean steady-state cerebrospinal fluid concentration of 236 ng ml(-1) represented 52 and 74% of that in arterial and venous blood, respectively., Conclusions: Our study re-emphasizes the importance of a sampling site when performing PK-PD modelling for drugs undergoing elimination from the effect compartment. For a drug undergoing tissue elimination such as remifentanil, venous rather than arterial concentrations will reflect more exactly the effect compartment concentrations, under steady-state conditions.

Until recently, the synthetic glucocorticoid dexamethasone was commonly used to lessen the morbidity of chronic lung disease in premature infants. This practice diminished as dexamethasone use was linked to an increased incidence of cerebral palsy and short-term neurodevelopmental delay. Of more concern is the fact that we know little regarding dexamethasone effects on long-term neurodevelopment. To study the effects of neonatal dexamethasone exposure on long-term neurodevelopment, we have developed a rat model where newborn pups are exposed to tapering doses of dexamethasone at time points corresponding to the neurodevelopmental age when human infants are traditionally exposed to this drug in the neonatal intensive care unit. Using a within-litter design, pups were assigned to one of three groups on postnatal day 2 (P2): handled controls, saline-injected controls, and animals receiving intramuscular dexamethasone between P3 and P6. Somatic growth was decreased in dexamethasone-treated animals. Dexamethasone-treated animals demonstrated slight delays in indexes of neurodevelopment and physical maturation at P7 and P14, but not P20. In adolescence (P45), there was no difference between groups in an open field test. However, as adult dexamethasone-treated animals were less active in the open field and spent more time in closed arms of the elevated plus maze. The serum corticosterone response to crowding stress in dexamethasone-treated animals was no different from controls, but they demonstrate a delay in return of corticosterone levels to baseline. These differences in behavior and hormonal stress responsiveness suggest that neonatal dexamethasone exposure may permanently alter function of the neuroendocrine stress axis.

Animal studies on the effects of chronic variable stress during the peripubertal-juvenile period on hippocampal structure and function are lacking. Twenty-eight-day-old Sprague-Dawley rats were subjected to random, variable physical or social stress regimens for 4 weeks. Hippocampal volume was found to continue to grow in all lamina examined during the transition into young adulthood. Our variable physical stress paradigm led to inhibition of this growth in the CA1 pyramidal cell layer (PCL) and in the dentate gyrus-granular cell layer (DG-GCL), which reached full arrest in the CA3-PCL. Volume deficits were first observed after chronic stress exposure when 3 weeks, but not 24 h, of recovery had elapsed. Moreover, these volume deficits were associated with impairments in the Morris water-maze navigation, sustained down-regulation in the basal hippocampal glucocorticoid receptor gene expression, and deficits in the shutdown of acute stress-induced corticosterone secretion. Volume changes both due to normal maturation and after chronic stress exposure were independent of neuron number. Thus, a peripubertal-juvenile chronic stress paradigm that leads to significant alterations in the limbic-hypothalamic-pituitary-adrenal axis can produce robust effects in hippocampal structure and cognitive ability, lasting into adulthood.

Fischer 344 (F344) and Lewis (LEW) rats differ in physiological regulation of the limbic-hypothalamo-pituitary-adrenal (LHPA) axis, such that F344 rats exhibit greater LHPA axis responses to a variety of stimuli. Furthermore, LHPA axis activity has been implicated in the development of sensitization to abused drugs, and F344 rats exhibit greater behavioral sensitization to psychostimulants. Accordingly, we hypothesized that there may be some overlap between the neurobiological mechanisms that underlie these strain differences in LHPA axis activity and in behavioral sensitization to psychostimulants. We examined the effects of acute and repeated methamphetamine (4 mg/kg) treatments on the regulation of hippocampal glucocorticoid receptors (GR mRNA) and mineralocorticoid receptors (MR mRNA) in F344 and LEW rats. Our results showed that acute treatment with methamphetamine (MAP) does not alter the level of expression of GR or MR mRNA in both strains. However, repeated treatments with MAP decreased the expression of hippocampal GR, but not MR mRNA specifically in F344 rats. The same repeated treatments had no effect on either GR or MR mRNA in LEW rats. This selective MAP regulation of the level of expression of hippocampal GR mRNA in F344 suggests that these receptors may play a role in the development of behavioral sensitization to MAP in this strain. The lack of alteration in hippocampal GR mRNA in LEW rats suggests that plasticity of hippocampal GR may not be critical for the development of behavioral sensitization to MAP in this strain.

The function of the second nuclear estrogen receptor, estrogen receptor beta (ERbeta), in the brain is largely unknown. The present study tested whether 1) ERbeta in the paraventricular nucleus (PVN) of the hypothalamus has a direct role in the hypothalamic-pituitary-adrenal (HPA) axis-mediated stress function, and 2) whether corticosterone (CORT) can regulate ERbeta gene expression in the PVN in the intact, cycling female rat. To test the first hypothesis a pure estrogen receptor antagonist, ICI182, 780, was microinjected into the PVN bilaterally and stress-induced CORT response to an acute stressor (15 min restraint) was measured at 0, 15, 30, 60 and 90 min time points. Estrogen antagonist-injected rats showed inhibited CORT levels at the peak (15 min) of the stress response compared with vehicle-injected animals. To test the second hypothesis, ERbeta mRNA levels were measured in the PVN using in situ hybridization histochemistry following sham surgery, adrenalectomy, and adrenalectomy with low or high CORT replacement. Adrenalectomy reduced ERbeta mRNA expression in the PVN, whereas CORT replacement fully reversed this effect in a dose-dependent fashion. Both antagonist inhibition of CORT response and CORT-mediated regulation of ERbeta mRNA were found to be estrus cycle-dependent in the intact, cycling female. These data suggest that ERbeta in the PVN may critically modulate the HPA axis response to stress and is, in turn, regulated by circulating CORT.

In the present study we examined the diurnal patterns of agouti-related protein (AGRP) and proopiomelanocortin (POMC) mRNA expression in the arcuate nucleus and their relation to circulating glucocorticoids and food intake. Animals were killed at 4-h intervals throughout the 24-h diurnal cycle, and the expression of AGRP and POMC mRNA was evaluated by semiquantitative in situ hybridization analysis. We observed a significant diurnal rhythm in AGRP mRNA expression, with a marked peak at 2200 h (4 h after lights off) and a trough at 1000 h (4 h after lights on), consistent with the overall day-night rhythm of food intake. In contrast, POMC mRNA levels did not show a significant fluctuation across the diurnal cycle, although there was a tendency for levels to decrease after the onset of the dark cycle. Corticosterone secretion temporally coincided with the rising phase of AGRP mRNA expression. Depletion of corticosterone by adrenalectomy abolished the AGRP diurnal rhythm by suppressing the nighttime expression, but did not alter the feeding rhythm. Exposure of adrenalectomized rats to constant corticosterone replacement (10 or 50 mg continuous release corticosterone pellet) resulted in fixed AGRP mRNA expression throughout the 12-h light, 12-h dark cycle. A relatively high level of corticosterone (50 mg) significantly increased AGRP mRNA expression, with a positive correlation between these two measures. These results indicate that 1) the diurnal expression of AGRP mRNA is regulated by corticosterone independently of the light/dark cue; and 2) a normal endogenous corticosterone rhythm is required for generating the diurnal AGRP rhythm.

DNA microarrays are a powerful tool for monitoring thousands of transcript levels simultaneously. However, the use of DNA microarrays in studying the central nervous system faces several challenges. These include the detection of low-abundance transcripts in highly complex tissue as well as estimating relatively low-magnitude changes in transcript levels in response to experimental manipulation. Many transcripts important to brain function have low expression levels or are expressed in relatively few cells, making them difficult to detect in the complex background of brain tissue. The aim of the present study is to evaluate the sensitivity of Gene Chip detection of transcripts in brain by using results from serial analysis of gene expression (SAGE) studies. The results of this comparison indicate that Affymetrix Gene Chips, like SAGE, only reliably detect medium- to high-abundance transcripts and that detection of low-abundance transcripts, many of which have great relevance to biological function in brain, is inconsistent. Specifically, we estimate that Gene Chips reliably detect no more than 30% of the hippocampal transcriptome when using a gross hippocampal dissection as the source tissue. This report provides the first broad evaluation of Affymetrix Gene Chip sensitivity relevant to studying the brain.

Mycobacterium phlei (M. phlei) DNA inhibits cancer cell division but is susceptible to degradation by DNase. Chitosan forms nanoparticulate polyelectrolyte complexes with DNA, and may thus reduce nuclease degradation. We have characterized chitosan-DNA nanoparticle formation, determined DNase susceptibility, and evaluated their antiproliferative activity. Nanoparticle diameter initially decreased with increasing phosphate charge density. However nanoparticle diameter increased above 6 micromol of phosphate. Particle aggregation occurred at 16.2 micromol phosphate and was related to reduced surface charge. Incorporation of DNA within chitosan nanoparticles significantly decreased degradation by DNase. The ability of M. phlei DNA-chitosan nanoparticles to inhibit melanoma cell division was determined relative to M. phlei DNA and a cationic liposomal M. phlei DNA formulation. M. phlei DNA had antiproliferative activity (MTT reduction, IC50 = 0.9 mg/ml) without intrinsic cytotoxicity (LDH release, ED50 > 50 microg/ml). Cationic polyphosphate chitosan nanoparticles were inert (antiproliferative IC50 > 1 mg/ml, ED50 > 1 mg/ml). M. phlei DNA-chitosan nanoparticles were 20-fold more potent than M. phlei DNA. Cationic DOTAP/DOPE liposomes were cytostatic (IC50 = 49 microg/ml) and cytotoxic (ED50 = 87 microg/ml), and complexation of M. phlei DNA resulted in a significant reduction of antiproliferative activity. Chitosan nanoparticles may therefore be appropriate delivery vehicles for M. phlei DNA.

Central corticosteroid receptors play an important role in the regulation of the secretion of corticosterone. Although these receptors are thought to be regulated by circulating levels of corticosterone, there is evidence for direct neural control. For example, it has been shown that noradrenergic lesions can both increase and decrease corticosteroid receptors depending on the brain structure involved. In the present study, we investigated the role of different noradrenergic receptors in the rat, by examining the effect of the acute administration of agonists and antagonists of beta and alpha 1 noradrenergic receptors on hippocampal type I and type II corticosteroid receptor levels. The effects of these drugs were studied in adrenalectomized animals whose plasma levels of corticosterone were maintained in the physiological range by implantation of coritcosterone pellets. Our results show that the beta receptor agonist salbutamol (5 mg/kg) increased the number of type I and type II hippocampal corticosteroid receptors. This effect was blocked by the beta receptor antagonist propranolol (5 mg/kg), which had no effect on its own. In contrast, the alpha 1 receptor agonist phenylephrine (100 micrograms) reduced the number of type I and type II corticosteroid receptors, whereas the alpha 1 receptor antagonist prazosin (0.5 mg/kg) increased type I receptors. The effect of prazosin was attributed to an increase in the relative beta tonus resulting from blockade of alpha 1 receptors. Its effect was reversed by the simultaneous injection of the beta receptor antagonist propranolol. In conclusion, our results show that noradrenergic transmission can have both a facilitatory and an inhibitory action on central corticosteroid receptors by acting respectively on beta and alpha 1 noradrenergic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal stress is considered as an early epigenetic factor able to induce long-lasting alterations in brain structures and functions. It is still unclear whether prenatal stress can induce long-lasting modifications in the hypothalamo-pituitary-adrenal axis. To test this possibility the effects of restraint stress in pregnant rats during the third week of gestation were investigated in the functional properties of the hypothalamo-pituitary-adrenal axis and hippocampal type I and type II corticosteroid receptors in the male offspring at 3, 21 and 90 days of age. Plasma corticosterone was significantly elevated in prenatally-stressed rats at 3 and 21 days after exposure to novelty. At 90 days of age, prenatally-stressed rats showed a longer duration of corticosterone secretion after exposure to novelty. No change was observed for type I and type II receptor densities 3 days after birth, but both receptor subtypes were decreased in the hippocampus of prenatally-stressed offspring at 21 and 90 days of life. These findings suggest that prenatal stress produces long term changes in the hypothalamo-pituitary-adrenal axis in the offspring.

Depending on the basis of the technique used, an estimation of 2 to 6 lecithin molecules are required for reactivation of purified D-beta-hydroxybutyrate apodehydrogenase (apoBDH). 60 to 70 mitochondrial phospholipid molecules are necessary for insertion of one BDH polypeptide chain where 16 molecules would be in direct interaction with the enzyme. Results show off the cofactor role of lecithin and also the requirement of an amphiphilic environment, essential for the enzyme function.