By Z. Karmok. Indiana University. 2018.
In contrast viagra vigour 800 mg generic, MDMA-induced prolac- gic properties of MDMA purchase viagra vigour 800 mg, include nausea, vomiting, jaw tin responses are not attenuated by either 5-HT -receptor clenching, bruxism, hypertension, palpitations, headaches, 1A or 5-HT -receptor antagonists, which suggests that the two hyperreflexia, difficulty walking, urinary urgency, diaphore- 2 MDMA-induced neuroendocrine responses involve differ- sis, anorexia, muscle aches or tension, hot and cold flashes, ent 5-HT receptors. Several studies have evaluated the neuroendocrine effects Aside from one report of an acute hypertensive crisis in of MDMA in humans. MDMA doses of up to 75 mg are a prospective study (84), serious acute medical complica- associated with increases in cortisol, and higher doses lead tions of MDMA use have appeared in the literature as case to increases in both cortisol and prolactin (83,85). Notably, reports or reports from poison centers and coroners. Among evidence in both animals and humans is increasing that the serious problems that have been associated with MDMA previous exposure to MDMA leads to alterations in neu- use are cerebrovascular incidents (100) and arrhythmias roendocrine responses (87–92), possibly as a consequence (101), likely related to the potent sympathomimetic and of long-term effects on brain 5-HT neurons. Electrolyte imbalance or the syndrome of inappropriate secretion of antidiuretic Biodisposition in Animals hormone, sometimes associated with cerebral edema or sei- zures, has been reported by numerous authors (102,103). The metabolic pathways of MDMA have been well charac- Numerous reports of chronic medical sequelae of terized in several animal species. In vivo studies in rats have MDMA have also been published, and readers are referred shown that MDMA is metabolized via N-demethylation, elsewhere for a more comprehensive review of this topic O-dealkylation, deamination, and conjugation (O-methyla- (98,99). One serious adverse medical event associated with tion, O-glucuronidation, and O-sulfation) (93). The (S)- MDMA, multiple organ system failure, appears to be di- ( )-MDMA isomer of MDMA appears to be metabolized rectly related to the use of MDMA in raves, where users more rapidly (94) and extensively (95) than the (R)-(-)- become hot and dehydrated in crowded conditions. In this MDMA isomer, with half-life estimates being 73. Nonconjugated metabolites of MDMA are pres- domyolysis, disseminated intravascular coagulation, renal ent in blood, brain, liver, feces, and urine for a 24-hour failure, and death (104–106). This is reminiscent of the period following drug administration, with the exception phenomenon of aggregation toxicity in animals (107), in of the O-dealkylated catechol metabolite, which is found which the lethality of amphetamines is greatly potentiated only in brain tissue (93). This latter pathway, mediated via by crowded housing conditions. Reports of hepatotoxicity, constitutive cytochrome P-450 isozymes, is a primary route aplastic anemia, and toxic leukoencephalopathy in MDMA of metabolism in rat brain microsomes. Biodisposition in Humans Adverse neuropsychiatric effects have also been associ- Three studies have evaluated the biodisposition of MDMA ated with MDMA. Acute psychiatric complications of in humans (85,96,97). In the neuroendocrine study by Mas MDMA include panic attacks (110), psychosis (111), delir- 1552 Neuropsychopharmacology: The Fifth Generation of Progress ium (112), and impulsive irrational behavior with subse- roendocrine responses to the serotonin-releasing drugs fen- quent severe medical consequences or death (101,113). In the case of m-CPP, users include panic disorder (114), psychosis (115), aggres- MDMA users also differ in their behavioral responses to sive outbursts (116), flashbacks (111), major depressive dis- drug. Several research groups have found cognitive impair- order (117), and cognitive disturbances (117). MDMA users have also Serotonin Neurotoxicity been found to score higher on measures of impulsivity (88, Like its structural relative methylenedioxyamphetamine 135,136, but not 130), consistent with work showing an (118), MDMA is a well-documented serotonin neurotoxin inverse relationship between 5-HT markers and impulsivity in a variety of animal species (119–122). The administration of MDMA in animals leads to the persistent loss of a variety of markers specific to brain seroto- FUTURE RESEARCH DIRECTIONS nin neurons. Despite advances in understanding the mechanism evidence also indicates a persistent loss of brain serotonin of hallucinogenic action, many questions remain unan- axons and axon terminals. During the next decade, it should be possible to administration, quantitative autoradiographic studies with refine further the 5-HT2A/1C hypothesis of psychedelic ac- radioligands that bind to the SERT, and immunocytochem- tivity, to characterize better the neuroanatomy of the phar- ical studies in which antibodies are directed at either seroto- macologic action of LSD, and to use modern neuroimaging nin or the SERT, show pronounced, long-lasting reductions techniques to compare and contrast the effects of LSD with of the SERT and reduced density of serotonin axons with those of idiopathic psychiatric illnesses in which hallucina- sparing of serotonin cell bodies (127). Similarly, future studies of PCP may tonin deficits have been observed up to 7 years after drug elucidate certain aspects of idiopathic psychotic illnesses. Clinical studies in PCP users, like those previously con- Efforts to determine whether selective serotonin neuro- ducted in MDMA users, should be directed toward deter- toxicity develops in human MDMA users, as in animals mining whether humans, like rodents, are susceptible to exposed to MDMA, have been limited by the paucity of PCP neurotoxic injury and defining the functional conse- available methods for assessing the status of central nervous quences of such injury if it occurs. MDMA research during the next decade should also At present, two methods for detecting MDMA-induced yield significant advances. Preclinical studies aimed at deter- brain 5-HT neurotoxicity in living humans have been vali- mining the mechanism of MDMA-induced 5-HT neuro- dated. These include measurement of spinal fluid 5-HIAA toxicity may not only increase our understanding of seroto- and PET neuroimaging of the SERT.
In the imaging studies of pa- fects on other neuronal systems buy viagra vigour 800mg visa, which are more primarily tients with anxiety disorders best viagra vigour 800mg, progress has been made in related to the pathogenesis of anxiety disorders. Functional relationships In summary, a reading of these chapters reveals that there among the amygdala, hippocampus, and medial prefrontal have not been fundamental advances in our ability to diag- cortex have been reported in patients with posttraumatic nose anxiety disorders based on known etiology. The imaging findings in patients stay of medication treatment continues to be classes of medi- with obsessive-compulsive disorder (OCD) are consistent cations that have existed for decades. There are major gaps with 'pathology' in cortico-striatal-thalamo-cortical circui- in our knowledge of anxiety disorders in children. Unfortunately, a critical gap in knowledge exists regard- mechanisms responsible for the occurrence of anxiety disor- ing the relevant neural circuits involved in panic disorder, ders in childhood and adolescence leading to increased risk social anxiety disorder, and generalized anxiety disorder. The neurochemical systems associated with anxiety and fear However, the potential for progress is great. A multidiscipli- circuits are reviewed in the chapter by Charney and Drevets. However, most of the findings reviewed should be genomics, and novel drug design and testing will be a deemed preliminary, and they require replication. LANG This chapter traces the course and trajectory of anxiety dis- risk of development of childhood anxiety. The chapter discusses these disor- tion (EE), which is an interactional style composed of emo- ders in three age groups: (a) childhood, (b) young adulthood tional overinvolvement and high levels of criticism, has been to middle age, and (c) older adulthood. The There are a number of factors that relate to the development answer is a qualified yes. The last decade or so of research of anxiety in general. Although this remains a controversial by Jerome Kagan and colleagues has led to the identification area, current evidence suggests that anxiety does not appear of a temperament, 'behavioral inhibition' (BI), that ap- to be specifically heritable; what clusters in families is a pears to be related to the subsequent onset of anxiety disor- more general predisposition to mood or anxiety disorders. BI involves reacting to unfamiliar or novel situations Evidence of this comes from twin studies (1) as well as with behavioral restraint and physiologic arousal (5). When from studies of the incidence of disorders in the families of confronted with an unfamiliar person or object, a BI child anxious patients (2). Specific phobia, however, may be an will withdraw, cling, be reluctant to interact, show emo- exception to this general heritability; family members with tional distress, and stop other activities. BI has also been specific phobias tend to be associated with increased risk associated with physiologic differences, such as high and only for specific phobias (3). These findings have led to the hypothesis that BI is found that parental psychopathology was a risk factor for related to a lowthreshold for arousal in the amygdala and the development of disorder only among the lower socioeco- hypothalamus (8). This characteristic, which appears to be nomic status (STS) portion of their sample. It has been present in 10% to 15% of children, has been identified in suggested that environmental factors play a significant role children as young as 14 months, has been shown to persist in the manifestation of specific psychopathology (1). Anxi- throughout childhood (9), and is more commonly found ety in particular is believed to be related to a combination in offspring of anxious parents (8). The inhibited tempera- of negative affect, a sense of lack of control over situations ment has been associated with risk of developing an anxiety or environments, and attentional self-focus. Early experi- disorder, most commonly social phobia (10). This lack of differentiation appears to be character- istic of younger children, with increased specificity develop- Murray B. Lang: Department of Psychiatry, University ing over time (11,12). At least by middle childhood, there of California–San Diego, San Diego, California. Spence (12) conducted a confirmatory 11 to 16), but that there was a substantial amount of new factor analysis with data from children of 8 to 12 years. Their con- best model included six correlated factors—panic-agora- clusion was that the disorder may be trait-like for those who phobia, social phobia, separation anxiety, obsessive-compul- exhibit symptoms early and that the development of the sive problems, generalized anxiety, and fear of physical in- disorder in others may be triggered in adolescence. Cantwell jury (including dogs, dentists, heights, doctors)—and a and Baker (23) also found considerable stability; 25% of single higher-order factor reflecting overall anxiety.
Schemeof intracellular pathwaysunderlying regu- trated Fig buy generic viagra vigour 800 mg on line. In one mechanism viagra vigour 800mg visa, transcription fac- lation of gene expression. Activation of neurotransmitter, hor- tors that are present at significant levels in cells under basal mone, or neurotrophic factor receptors leads to the activation of conditions are rapidly activated by signaling cascades to acti- specific second messenger and protein phosphorylation path- ways, which produce multiple effects on neuronal function vate or repress transcription of responsive target genes. In through the phosphorylation of numerous proteins. Among the the other major mechanism, transcription factors that are effects of these intracellular pathways on neuronal function is expressed at very low levels under basal conditions are them- the regulation of gene expression. This can be accomplished by two basic types of mechanisms. In one case, transcription factors, selves induced by a physiologic signal, after which they can already in the nucleus, are phosphorylated by protein kinases; regulate expression of a series of additional genes. CREBis an example of a transcription factor that functions in this manner. Among the sion is the transduction of signals from the cell membrane target genes for CREBfamily transcription factors are those for to the nucleus; this can be accomplished by several different other transcription factors, for example, Fos and Jun family pro- types of mechanisms. IncreasedexpressionofFosand Junthenleadstoalterations in the expression of additional target genes. One example is provided by the steroid hormone receptor transcription fac- tors, discussed at length later. Another example is the tran- scription factor nuclear factor- B (NF- B)(15). This tran- scription factor is retained in the cytoplasm by its binding elements termed cAMP-response elements (CREs)(Fig. Signal-regulated phosphorylation of I Bby tion step in CREB activation involves not the transcription protein kinase C leads to dissociation of NF- B, which per- factor itself, but activated protein kinases (cAMP-dependent mits it to enter the nucleus, where it can bind DNA; I B protein kinase; also called protein kinase A)that, on entering is then proteolyzed within the cytoplasm. Alternatively, CREB ac- Other transcription factors must be directly phosphory- tivation can involve the nuclear translocation of second mes- sengers, such as Ca2 bound to calmodulin, which, on en- lated or dephosphorylated to bind DNA. For example, phosphorylation of STATs (signal transducers and activa- tering the nucleus activate protein kinases that then tors of transcription)by protein tyrosine kinases in the cyto- phosphorylate CREB (Fig. As stated earlier, phos- plasm permits their multimerization, which, in turn, per- phorylation converts CREB into a transcriptional activator mits nuclear translocation and construction of an effective by permitting it to recruit CBP into the transcription com- DNA binding site within the multimer (16). Still other transcription factors are already bound to their The remainder of this chapter provides a more in-depth cognate cis-regulatory elements in the nucleus under basal discussion of several transcription factor families that have conditions and are converted into transcriptional activators received a great deal of attention as mediators of neural and by phosphorylation. CREB, for example, is bound to DNA behavioral plasticity in the adult. Chapter 17: Regulation of Gene Expression 221 nervous system, including those encoding neuropeptides (e. The consensus CRE sequence illustrates an important principle, the palindromic nature of many tran- scription factor–binding sites. Examining the sequence TGACGTCA, it can be readily observed that the sequence on the two complementary DNA strands, which run in opposite directions, is identical. Many regulatory elements are perfect or approximate palindromes because many tran- scription factors bind DNA as dimers, with each member of the dimer recognizing one of the half-sites. CREB binds to a CRE as a homodimer, with a higher affinity for palindromic than for asymmetric CREs. When bound to a CRE, CREB activates transcription only when it is phosphorylated on its critical ser133. It does so, as described earlier, because phosphorylated CREB, but not dephosphorylated CREB, can recruit the adapter pro- tein, CBP, into the transcription complex. CBP, in turn, interacts with the basal transcription complex. Scheme of the regulation of CREBphosphoryla- tion by several signaling pathways.
Thus discount 800 mg viagra vigour free shipping, although comorbidity between Reactions to threatening stimuli among various organisms buy viagra vigour 800mg cheap, anxiety and both depression and substance problems is quite including primates and lower mammals, involve changes in common in children and adolescents, further research on the autonomic nervous system. These changes can be de- the mechanisms for links between specific disorders both tected through an analysis of time series for heart rate, heart across and within genders is necessary. Children with behavioral inhibition exhibit an auto- episodes of anxiety, both in the laboratory and in natural nomic physiology characteristic of the profile found during settings, are typically characterized by acute changes in heart acute anxiety. Specifically, behaviorally inhibited children rate, blood pressure, and heart period variability (107). Such abnormalities in autonomic physiology are anxiety states has attempted to identify specific physiologic viewed as downstream reflections of perturbations based within the limbic system. In terms of family history, Bellodi patterns associated with one or another emotion. Such data are consistent with other studies finding high example, some forms of anxiety, such as acute panic, may rates of behavioral inhibition among offspring of patients be characterized by marked parasympathetic withdrawal in with anxiety disorders. Finally, in terms of traumatic events, the face of sympathetic enhancement. Other emotions, such physiologic reactions to an acute stress may index underly- as anger, may be characterized by a distinct physiologic 'fin- ing vulnerability to develop anxiety states. Consistent with ger print,' reflecting the involvement of distinct brain sys- this possibility, Shalev et al. In general, consistent as- cardiovascular activity in the emergency room immediately sociations are found across development between acute following a motor vehicle accident predicted the develop- anxiety states and changes in peripheral autonomic indices, ment of PTSD. As a result, some suggest that perturbations in auto- tions between acute anxiety and autonomic physiology pro- nomic regulation may index an underlying vulnerability to files, but the implications of this work for the study of risk develop anxiety disorders. Moreover, the underlying assumption in thought to relate to the functioning of particular neural this work posits an effect of perturbations in brain systems circuits within the brain that exert effects on both subjective on both autonomic physiology and anxiety symptoms. Potentially relevant such, more work is also needed relating brain function to neural circuits have been identified through basic science autonomic physiology. Despite consistent evidence of an association between acute anxiety states and changes in autonomic physiology, Psychophysiologic Function the degree to which such changes index vulnerability for Research on fear conditioning has facilitated an integration anxiety, as opposed to the acute state of anxiety, remains of basic and clinical work on vulnerability for anxiety. If such changes in autonomic physiology primarily conditioning develops following the pairing of a neutral reflect downstream manifestations of relatively high degrees 'conditioned' stimulus (CS ), such as a tone or a light, of acute fear, they would provide limited advantages as vul- and an aversive 'unconditioned' stimulus (UCS), such as nerability markers. On the other hand, at least some of a shock, a loud noise, or an air puff. Across a range of the underlying autonomic abnormalities in panic disorder mammalian species, including humans, fear conditioning persist after remission and may be independent of the cur- results from changes in a relatively simple neural circuit that rent state. This suggests that changes in autonomic physiol- involves distinct amygdala nuclei, including the basolateral ogy may mirror subtle person-specific differences in brain and central nucleus. Basic science research on the role of processes related to the processing of risk or to the experi- this circuit in learned fears has also called attention to the ence of fear. As such, autonomic indices might index vulner- role played by related but relatively distinct neural circuits ability in a fashion that is more sensitive than indices derived in the responses to other forms of danger. A series of recent studies pro- reactions to intrinsically dangerous contexts, such as a vide preliminary evidence consistent with this possibility. These reactions may more intimately individuals who face high risk for anxiety disorders. Physio- involve the basolateral nucleus and the bed nucleus of the logic profiles have been tied to at least three indicators of stria terminalis than the central nucleus of the amygdala. In terms of temperamental factors, Kagan (111) characteristically found in many anxiety disorders (114). Chapter 61: Genetic and Other Vulnerability Factors for Anxiety and Stress Disorders 875 Similarly, acute reactions to intrinsically dangerous stimuli broader contextual stimuli that are mediated by different often involve rapid changes in behavior designed to facilitate neurobiologic pathways, and (b) different developmental escape or defense. Such reactions in animals may involve levels in males and females in which the vulnerability to the hypothalamus and lower brainstem structures; such re- anxiety may be physiologically expressed earlier in females. Much of this work quanti- also consistent with the findings of Watson et al. Based on skin conductance data, Eysenck circuits broadly related to mood and anxiety regulation.
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