Novel psychoactive substances: What educators need to know.

Novel psychoactive substances (NPS) are synthetic, psychoactive drugs that are generally not under international regulatory control. NPS are frequently sold as alternatives to classic "street drugs" such as ecstasy or LSD. However, little is known about their pharmacology and toxicity and they therefore pose unknown health risks. Further, risk for harms are elevated because users often do not know what they are taking, and therefore cannot predict dose, potency, or other potential properties.

Young brains on cannabis: It's time to clear the smoke.

Cannabis is the most commonly used illicit substance among youth. Recent policy developments and ongoing debate related to this drug underscore the urgent need to "clear the smoke" and better understand what the scientific evidence says about the health and behavioral effects of cannabis use, particularly on youth whose brains are undergoing rapid and extensive development.

Homological scaffolds of brain functional networks.

Networks, as efficient representations of complex systems, have appealed to scientists for a long time and now permeate many areas of science, including neuroimaging (Bullmore and Sporns 2009 Nat. Rev. Neurosci. 10, 186-198. (doi:10.1038/nrn2618)). Traditionally, the structure of complex networks has been studied through their statistical properties and metrics concerned with node and link properties, e.g. degree-distribution, node centrality and modularity. Here, we study the characteristics of functional brain networks at the mesoscopic level from a novel perspective that highlights the role of inhomogeneities in the fabric of functional connections. This can be done by focusing on the features of a set of topological objects-homological cycles-associated with the weighted functional network. We leverage the detected topological information to define the homological scaffolds, a new set of objects designed to represent compactly the homological features of the correlation network and simultaneously make their homological properties amenable to networks theoretical methods. As a proof of principle,we apply these tools to compare resting state functional brain activity in 15 healthy volunteers after intravenous infusion of placebo and psilocybin-the main psychoactive component of magic mushrooms. The results show that the homological structure of the brain's functional patterns undergoes a dramatic change post-psilocybin, characterized by the appearance of many transient structures of low stability and of a small number of persistent ones that are not observed in the case of placebo.

Polymorphism of the serotonin-2A receptor gene (HTR2A) associated with childhood attention deficit hyperactivity disorder (ADHD) in adult women with seasonal affective disorder.

INTRODUCTION: Several lines of research point to a possible overlap between seasonal affective disorder (SAD) and attention deficit hyperactivity disorder (ADHD), particularly in females. There is also emerging evidence that variation of the 5-HT2A receptor gene (HTR2A) contributes to both SAD and ADHD. The current study investigated whether variation in HTR2A was associated with symptoms of childhood ADHD in adult women with SAD. METHOD: Sixty-six women with SAD were administered the Wender-Utah Rating Scale (WURS), which retrospectively assesses childhood ADHD, as part of an ongoing genetic study of SAD. WURS scores were compared across the three genotypic groups defined by the T102C polymorphism of HT2RA. RESULTS: Analysis of variance indicated a significant difference in mean 25-item WURS scores across the three genotypic groups (p = 0.035). Post-hoc tests revealed that the C/C genotypic group had a significantly higher mean score than both the T/T group and T/C group. Based on previously established WURS criteria, 38% of subjects with the C/C genotype, and none with the T/T genotype, had scores consistent with childhood ADHD. LIMITATIONS: The current sample size is small, and childhood ADHD diagnoses were based on retrospective recall. CONCLUSION: These preliminary results suggest a possible association between variation in HTR2A, childhood ADHD, and the later development of SAD in women.

Chronic hypoxia up-regulates fibroblast growth factor ligands in the perinatal brain and induces fibroblast growth factor-responsive radial glial cells in the sub-ependymal zone.

A number of signaling molecules have been implicated in the acute response to hypoxia/ischemia in the adult brain. In contrast, the reaction to chronic hypoxemia is largely unexplored. We used a protocol of chronic hypoxia in rat pups during the first three postnatal weeks, encompassing the period of cellular plasticity in the cerebral cortex. We find that the levels of fibroblast growth factor 1 (FGF1) and FGF2, two members of the FGF family, increase after 2 weeks of chronic hypoxia. In contrast, members of the neurotrophin family are unaffected. FGF2 is normally expressed in the nucleus of mature, glial fibrillary acidic protein (GFAP)-containing astrocytes. Under hypoxia, most FGF2-containing cells do not express detectable levels of GFAP, suggesting that chronic low O(2) induces their transformation into more immature glial phenotypes. Remarkably, hypoxia promotes the appearance of radial glia throughout the sub-ventricular and ependymal zones. Most of these cells express vimentin and brain lipid binding protein. A subset of these radial glial cells expresses FGF receptor 1, and are in close contact with FGF2-positive cells in the sub-ventricular zone. Thus, FGF receptor signaling in radial glia may foster cell genesis after chronic hypoxic damage. From the results of this study we suggest that after the chronic exposure to low levels of oxygen during development, the expression of radial glia increases in the forebrain periventricular region. We envision that astroglia, which are the direct descendants of radial glia, are reverting back to immature glial cells. Alternatively, hypoxia hinders the normal maturation of radial glia into GFAP-expressing astrocytes. Interestingly, hypoxia increases the levels of expression of FGF2, a factor that is essential for neuronal development. Furthermore, chronic hypoxia up-regulated FGF2's major receptor in the periventricular region. Because radial glia have been suggested to play a key role in neurogenesis and cell migration, our data suggests that hypoxia-induced FGF signaling in radial glia may represent part of a conserved program capable of regenerating neurons in the brain after injury.

Stem cells in neurodevelopment and plasticity.

The processes of stem cell proliferation and differentiation during embryogenesis are governed by transcription factors that regulate the regional differentiation of the central nervous system (CNS). Do neural "stem" cells persisting in the postnatal CNS disobey this sequence of events? The division of neural progenitor cells is promoted by basic Fibroblast Growth Factor Fgf2 or Epidermal Growth Factor Egf. However, while the intraventricular administration of FgF2 during embryogenesis increases the generation of cortical pyramidal neurons, the same treatment in the adult CNS produces interneurons of the olfactory bulb. The competence of neural progenitor cells to respond to Fgf is dictated by nuclear transcription factors that constrain neuronal fates through time. Developmentally regulated transcriptional programs are regulated by cell interactions, as dividing cells check their molecular signature against that of their environment. Thus, cell surface interactions account for competitive phenomena among pools of cells, including the inhibitory effect of neurons on the division of their progenitors, and may also explain the "permissive" effects of non-CNS environments. The challenge remains to understand the genetic programs that control the fate of progenitor cells within the postnatal CNS and their regulation by stress, apoptosis and environmental perturbations. These programs are likely to be similar to gene cascades that control proliferation, differentiation and migration of progenitor cells at earlier stages of development.

Changes in regional brain glucose metabolism measured with positron emission tomography after paroxetine treatment of major depression.

OBJECTIVE: Depression is commonly associated with frontal hypometabolic activity accompanied by hypermetabolism in certain limbic regions. It is unclear whether successful antidepressant treatments reverse these abnormalities or create new resting levels of metabolism. The aim of the present study was to assess the effects of successful paroxetine treatment on regional glucose metabolism in patients with major depression. METHOD: Positron emission tomography with [(18)F]fluorodeoxyglucose was performed on 13 male patients before and after 6 weeks of paroxetine therapy. Resting state scans were also acquired under similar conditions in 24 healthy male subjects for comparison. RESULTS: After successful paroxetine therapy, increased glucose metabolism occurred in dorsolateral, ventrolateral, and medial aspects of the prefrontal cortex (left greater than right), parietal cortex, and dorsal anterior cingulate. Areas of decreased metabolism were noted in both anterior and posterior insular regions (left) as well as right hippocampal and parahippocampal regions. In comparison to metabolism levels in a group of healthy volunteers, the increase in prefrontal metabolic activity represented a normalization of previously reduced metabolic activity, whereas the reduction in pregenual anterior cingulate activity represented a decrease from previously elevated metabolic levels. CONCLUSIONS: These results provide further support for a dysfunction in cortical-limbic circuitry in depression, which is at least partly reversed after successful paroxetine treatment.

Analysis of amino acids and catecholamines, 5-hydroxytryptamine and their metabolites in brain areas in the rat using in vivo microdialysis.

In vivo microdialysis, using dialysis probes inserted into discrete brain areas and subsequent analysis of neurotransmitters and related substances in the dialysates (usually with HPLC), has yielded a great deal of important information about the actions of psychotropic drugs and endogenous neurotransmitter systems and about the functional interactions between various brain areas. This paper reviews the principles involved in in vivo microdialysis, its advantages and disadvantages, and recent innovations in methodology and applications. The first section includes brief discussions of principles and applications of dialysis, use of anesthetized versus conscious freely moving animals, and methods used to determine the neural origin of neurotransmitters in the dialysate. The subsequent sections provide detailed descriptions, based largely on our own studies in rats, of stereotaxic surgery, in vivo microdialysis, and dialysate analysis, with an emphasis on amino acids and biogenic amines and their metabolites. A discussion of methodological problems which may be encountered in the analysis of amino acids and biogenic amines is also included.

Cholecystokinin modulates both the development and the expression of behavioral sensitization to amphetamine in the rat.

RATIONALE: Repeated administration of psychostimulants such as amphetamine (AMPH) produces an enduring augmentation of their locomotor effects. Previous research suggests that this phenomenon, termed sensitization, is related to changes within the mesolimbic dopamine (DA) system. OBJECTIVES: The present experiments were designed to investigate the contribution of endogenous cholecystokinin (CCK), a neuropeptide co-localized with DA in the mesolimbic system, to the development (experiment 1) and the expression (experiment 2) of locomotor sensitization to AMPH. METHODS: In experiment 1, rats were injected (IP) with the CCK(A) antagonist devazepide (0, 0.001, 0.01, or 0.1 mg/kg) or the CCK(B) antagonist L-365,260 (0, 0.001, 0.01, 0.1, or 1.0 mg/kg) followed by AMPH (1.5 mg/kg) once daily for seven days. Following 10 days withdrawal, rats were administered AMPH (0.75 mg/kg) and their locomotor activity recorded. In experiment 2, rats were administered AMPH (1.5 mg/kg) once daily for 7 days. Following 10 days withdrawal, rats were injected with devazepide (0, 0.0001, 0.001, 0.01, 0.1, or 1.0 mg/kg) or L-365,260 (0, 0.001, 0.01, or 0.1 mg/kg) followed 30 min later by AMPH (0.75 mg/kg) and their locomotor activity recorded. RESULTS: When administered during the AMPH pretreatment phase of experiment 1, the two highest doses of L-365,260 attenuated, and the lowest dose of L-365,260 potentiated, the sensitized locomotor response to AMPH challenge. When administered prior to the AMPH challenge phase of experiment 2, devazepide attenuated the sensitized locomotor response to AMPH. CONCLUSIONS: These results suggest that CCK(B) and CCK(A) receptors modulate the development and the expression of behavioral sensitization to AMPH, respectively.

Dopamine D2 receptor occupancy predicts catalepsy and the suppression of conditioned avoidance response behavior in rats.

RATIONALE: Human positron emission tomography (PET) shows that striatal dopamine D2 receptor occupancy predicts extrapyramidal side effects (EPS). Patients showed a clinical response with > or = 65% D2 occupancy, but EPS only when D2 occupancy >78%. Catalepsy and the selective suppression of conditioned avoidance response (CAR) are often used as animal models to predict EPS and antipsychotic effect, respectively. However, the quantitative relationship between striatal D2 occupancy and effects in these models is not known. OBJECTIVES: The present study intended to investigate the relationship between animal catalepsy, suppression of CAR, and D2 receptor blockade using a method of evaluating D2 receptor occupancy similar in principle to that used in patients. METHODS: In vivo binding of [11C]-raclopride and [3H]-raclopride was compared. Doses of cold raclopride were chosen to provide a D2 occupancy from 0 to 95%. The relationship between dose/time course of catalepsy and D2 occupancy was assessed. Effects of raclopride on conditioned avoidance response (CAR) behavior were tested. RESULTS: In vivo binding of [11C]-raclopride compared to [3H]-raclopride was virtually the same. Using [3H]-raclopride, cold raclopride (0.01-0.2 mg/kg) produced 16-77% D2 receptor occupancy and no catalepsy. Raclopride (0.5-2 mg/kg) produced 83-95% D2 occupancy and significant catalepsy. Raclopride (2 mg/kg) produced on average 95% and 87% D2 receptor occupancy 1 and 2 h after administration, respectively, and maximum catalepsy. D2 occupancy at 4, 8 and 24 h was on average 58%, 46%, and 4%, respectively. No catalepsy was observed. Raclopride (0.2 mg/kg), estimated at 70-75% D2 occupancy, produced suppression of CAR. CONCLUSIONS: In vivo D2 occupancy measurements in rats using [3H]-raclopride is analogous to using [11C]-raclopride in human PET scanning. Suppression of CAR occurred at a D2 occupancy of around 70-75%, and catalepsy at D2 occupancy >80%. Results closely resembled human studies where 65-70% D2 occupancy was required for antipsychotic response, while > or = 80% D2 occupancy led to EPS. Brain mechanisms involved in mediation of catalepsy in rats and EPS in humans might indeed be similar. Both suppression of CAR in rats and antipsychotic response in humans might share an underlying construct, i.e. the need for around 70% D2 receptor blockade.

The subcellular localization of Otx2 is cell-type specific and developmentally regulated in the mouse retina.

Recent evidence implicates homeodomain-containing proteins in the specification of cell fates in the central nervous system. Here we report that in the embryonic mouse eye Otx2, a paired homeodomain transcription factor, was found in retinal pigment epithelial cells and a restricted subset of retinal neurons, including ganglion cells. In the postnatal and adult eye, however, both the cellular and subcellular distribution of the Otx2 protein were cell type-specific. Otx2 was detected only in the nuclei of retinal pigment epithelial and bipolar cells, but was present in the cytoplasm of rod photoreceptors. Immunohistochemical studies of retinal explants and transfected cell lines both suggested that the retention of Otx2 in the cytoplasm of immature rods is a developmentally regulated process. The differential distribution of Otx2 in the cytoplasm of rods and the nucleus of other cell types, suggests that subcellular localization of this transcription factor may participate cell fate determination during specific phases of retinal development.

Neurohormonal responses to cholecystokinin tetrapeptide: a comparison of younger and older healthy subjects.

We recently found that, compared with younger healthy subjects, older healthy subjects had less symptomatic and cardiovascular response to the panicogenic agent cholecystokinin tetrapeptide (CCK-4). As an exploratory part of that study, we also evaluated the effect of aging on neurohormonal responses to CCK-4. These hormonal data are the focus of this article. Forty healthy volunteers aged 20-35 years and 40 healthy volunteers aged 65-81 years, divided equally between men and women, were compared on their hormonal responses (maximum change from baseline in growth hormone [GH], prolactin, adrenocorticotropic hormone [ACTH], and cortisol) to the intravenous administration of 50 microg of CCK-4 or placebo. Blood samples for serum hormone determination were collected at 2 minutes prior to the intravenous challenge (baseline) and at 2, 5, and 10 minutes after the challenge. In both age groups, maximum increase in prolactin, ACTH and cortisol was significantly greater with CCK-4 than with placebo. Following administration of CCK-4, younger and older groups did not significantly differ in maximum increase in prolactin, ACTH, or cortisol. Older subjects had a statistically significant smaller increase in GH compared with younger subjects but the magnitude of the difference was small and of doubtful clinical relevance. Older subjects who had a panic attack had significantly greater elevations of all hormones compared with those who did not panic and younger panickers had a significantly greater elevation of GH compared with young nonpanickers. For the most part, maximum changes in hormonal levels were not correlated with symptom severity, suggesting that other factors may have contributed to the differential effect of panic on the HPA axis.

Basic fibroblast growth factor (Fgf2) is necessary for cell proliferation and neurogenesis in the developing cerebral cortex.

Little is known about regionally specific signals that control the number of neuronal progenitor cells in vivo. We have previously shown that the germline mutation of the basic fibroblast growth factor (Fgf2) gene results in a reduction in the number of cortical neurons in the adult. We show here that Fgf2 is expressed in the pseudostratified ventricular epithelium (PVE) in a dorsoventral gradient and that Fgf2 and its receptor, Fgfr-1, are downregulated by mid to late stages of neurogenesis. In Fgf2 knockout mice, the volume and cell number of the dorsal PVE (the cerebral cortical anlage) are substantially smaller, whereas the volume of the basal PVE is unchanged. The dorsal PVE of Fgf2 knockout mice has a 50% decrease in founder cells and a reduced expansion of the progenitor pool over the first portion of neurogenesis. Despite this reduction, the degree of apoptosis within the PVE is not changed in the Fgf2 knockouts. Cortical neuron number was decreased by 45% in Fgf2 knockout mice by the end of neurogenesis, whereas the number of neurons in the basal ganglia was unaffected. Microscopically, the frontal cerebral cortex of neonatal Fgf2 null mutant mice lacked large neurons in deep cortical layers. We suggest that Fgf2 is required for the generation of a specific class of cortical neurons arising from the dorsal PVE.

Self-administration of intravenous amphetamine is predicted by individual differences in sucrose feeding in rats.

RATIONALE: Previous studies have shown that individual differences in oral sucrose consumption are predictive of the psychomotor and dopamine (DA) stimulant properties of amphetamine in rats. OBJECTIVES: The present experiment was designed to examine the relationship between sucrose feeding and the reinforcing properties of amphetamine using the intravenous (i.v.) drug self-administration paradigm. METHODS: Based on a median split of sucrose intake during a final 1-h feeding test session, male Wistar rats were designated as either low (LSF) or high sucrose feeders (HSF). Acquisition of i. v.-amphetamine self-administration across ten daily 30-min sessions was then assessed. Following acquisition, i.v. self-administration of several doses of amphetamine was similarly tested across daily 30-min sessions. RESULTS: Data from this experiment revealed augmented responding in HSF compared with LSF during acquisition of amphetamine self-administration. Correspondingly, when given access to different doses of amphetamine, responding was greater in HSF than in LSF across several doses (3 microg and 10 microg per infusion). CONCLUSIONS: These data support the notion that individual differences in oral sucrose consumption are predictive of the reinforcing properties of psychostimulant drugs.

Neuroendocrine function and response to stress in mice with complete disruption of glucagon-like peptide-1 receptor signaling.

Glucagon-like peptide-1 (GLP-1), a potent regulator of glucose homeostasis, is also produced in the central nervous system, where GLP-1 has been implicated in the neuroendocrine control of hypothalamic-pituitary function, food intake, and the response to stress. The finding that intracerebroventricular GLP-1 stimulates LH, TSH, corticosterone, and vasopressin secretion in rats prompted us to assess the neuroendocrine consequences of disrupting GLP-1 signaling in mice in vivo. Male GLP-1 receptor knockout (GLP-1R-/-) mice exhibit reduced gonadal weights, and females exhibit a slight delay in the onset of puberty; however, male and female GLP-1R-/- animals reproduce successfully and respond appropriately to fluid restriction. Although adrenal weights are reduced in GLP-1R-/- mice, hypothalamic CRH gene expression and circulating levels of corticosterone, thyroid hormone, testosterone, estradiol, and progesterone are normal in the absence of GLP-1R-/- signaling. Intriguingly, GLP-1R-/- mice exhibit paradoxically increased corticosterone responses to stress as well as abnormal responses to acoustic startle that are corrected by glucocorticoid treatment. These findings suggest that although GLP-1R signaling is not essential for development and basal function of the murine hypothalamic-pituitary-adrenal axis, abrogation of GLP-1 signaling is associated with impairment of the behavioral and neuroendocrine responses to stress.

Progressive impairment of developing neuroendocrine cell lineages in the hypothalamus of mice lacking the Orthopedia gene.

Development of the neuroendocrine hypothalamus is characterized by a precise series of morphogenetic milestones culminating in terminal differentiation of neurosecretory cell lineages. The homeobox-containing gene Orthopedia (Otp) is expressed in neurons giving rise to the paraventricular (PVN), supraoptic (SON), anterior periventricular (aPV), and arcuate (ARN) nuclei throughout their development. Homozygous Otp(-/-) mice die soon after birth and display progressive impairment of crucial neuroendocrine developmental events such as reduced cell proliferation, abnormal cell migration, and failure in terminal differentiation of the parvocellular and magnocellular neurons of the aPV, PVN, SON, and ARN. Moreover, our data provide evidence that Otp and Sim1, a bHLH-PAS transcription factor that directs terminal differentiation of the PVN, SON, and aPV, act in parallel and are both required to maintain Brn2 expression which, in turn, is required for neuronal cell lineages secreting oxytocin (OT), arginine vasopressin (AVP), and corticotropin-releasing hormone (CRH).

Identification, chromosomal assignment, and expression analysis of the human homeodomain-containing gene Orthopedia (OTP).

Homeodomain (HD) genes are helix-turn-helix transcription factors that play key roles in the specification of cell fates. In the central nervous system (CNS), HD genes not only position cells along an axis, but also specify cell migration patterns and may influence axonal connectivity. In an effort to identify novel HD genes involved in the development of the human CNS, we have cloned, characterized, and mapped the human homologue of the murine HD gene Orthopedia (Otp), whose product is found in multiple cell groups within the mouse hypothalamus, amygdala, and brain stem. Human cDNA and genomic libraries were screened with probes derived from mouse Otp sequences to find the human homologue, OTP. The deduced amino acid sequence of the open reading frame of the human cDNA is 99% homologous to mouse Otp and demonstrates a high degree of conservation when compared to sea urchin and Drosophila. OTP was mapped to human chromosome 5q13.3 using radiation hybrid panel mapping and fluorescence in situ hybridization. Flanking markers were identified from YAC clones containing OTP. A single putative OTP gene product was found in 17-week human fetal brain tissue by Western blot analysis using a novel polyclonal antibody raised against a conserved 13-amino-acid sequence at the C-terminus of the OTP protein. Expression in the developing human hypothalamus was confirmed by immunohistochemistry.

Fibroblast growth factor signaling regulates growth and morphogenesis at multiple steps during brain development.

The fibroblast growth factor (FGF) family comprises several members with distinct patterns of expression in the developing central nervous system. FGFs regulate the early specification and the subsequent growth of central nervous system regions. These different actions require the coordinated activation of distinct sets of target genes by FGFs at the appropriate stage of development. The role of FGF2 in the growth and morphogenesis of the cerebral cortex is reviewed in detail. The cellular and molecular mechanisms that underlie the action of FGF2 on cortical development are discussed.

Changes in cerebral cortex size are governed by fibroblast growth factor during embryogenesis.

We show that fibroblast growth factor 2 (FGF2) and FGF receptors are transiently expressed by cells of the pseudostratified ventricular epithelium (PVE) during early neurogenesis. A single microinjection of FGF2 into cerebral ventricles of rat embryos at E15.5 increased the volume and total number of neurons in the adult cerebral cortex by 18% and 87%, respectively. Microinjection of FGF2 by the end of neurogenesis, at E20.5, selectively increased the number of glia. Mice lacking the FGF2 gene had fewer cortical neurons and glia at maturity. BrdU studies in FGF2-microinjected and FGF2-null animals suggested that FGF2 increases the proportion of dividing cells in the PVE without affecting the cell-cycle length. Thus, FGF2 increases the number of rounds of division of cortical progenitors.