By F. Hassan. Auburn University, Montgomery. 2018.
The data were buy cheap super avana 160mg online, therefore buy super avana 160mg fast delivery, collapsed across groups and daily cocaine can reasonably validate animal models for different symp- sessions for the purpose of this illustration. Extinction phase: ex- toms of mental disorders (32). In the realm of addiction tinction responses at criterion. The extinction criterion ( 4 re- research, the observation that animals readily self-administer sponses per session over 3 consecutive days) was reached within 16. Although intra- the S versus S condition during the reinstatement phase). Rein- venous drug self-administration meets the criteria of reliabil- statement phase: responses under the S (n 7) and S (n 8) ity, predictability, and face validity, it does not represent reinstatement conditions. Exposure to the S elicited significant recovery of responding in the absence of further drug availability. Other Responding in the presence of the S remained at extinction lev- aspects of the addiction syndrome can indeed be modeled, els. Taken with permission from Weiss F, Maldonado-Vlaar CS, but again, it is incorrect to consider any one of these an Parsons LH, et al. Control of cocaine-seeking behavior by drug- associated stimuli in rats: effects on recovery of extinguished op- animal model of addiction. The DSM-IV criteria for sub- erant-responding and extracellular dopamine levels in amygdala stance dependence and animal models relevant to their and nucleus accumbens. Proc Natl Acad Sci USA 2000;97: study are summarized in Table 97. Tolerance (criterion 1) and withdrawal (criterion 2) no longer define addiction, as illustrated by the change in crite- ria outlined in DSM-III versus DSM-IIIR and DSM-IV (5–7); however, evidence is accumulating to suggest that a a powerful model for elucidating the neuropharmacologic common element associated with addiction is a motiva- basis for such effects that are related to the human concepts tional form of withdrawal that is reflected in a compromised of relapse and craving (97). This not only reaf- Cues associated with oral self-administration and avail- firms the importance of withdrawal in addiction (e. In addition, and the dimension of a persistent motivational change that may consistent with the well-established conditioned cue reactiv- be reflected in criteria 7 of the DSM-IV: 'continued use Chapter 97: Recent Advances in Animal Models of Drug Addiction 1393 TABLE 97. ANIMAL MODELS FOR THE CRITERIA OF DSM-IV DSM-IV Animal Models A. A maladaptive pattern of substance use, leading to clinically significant impairment or distress as occurring at any time in the same 12-month period: (1) Need for markedly increased amounts of substance to achieve (1) Tolerance to reinforcing effects: intoxication or desired effect; or markedly diminished effect with Cocaine continued use of the same amount of substance Opiates (2) The characteristic withdrawal syndrome for substance; or substance (2) Increased: (or closely related substance) is taken to relieve or avoid withdrawal Reward thresholds Anxiety-like responses symptoms Cocaine Cocaine Opiates Opiates Alcohol Alcohol Nicotine Tetrahydrocannabinol Tetrahydrocannabinol (3) Persistent desire or one or more unsuccessful efforts to cut down (3) Conditional positive reinforcing effects: or control substance use Cocaine Opiates Alcohol (4) Substance used in larger amounts or over a longer period than (4) Cocaine binge the person intended Opiate intake (dependent animals) Alcohol intake (dependent animals) Alcohol Deprivation Effect (5) Important social, occupational, or recreational activities given up (5) Choice paradigms or reduced because of substance use Behavioral economics—loss of elasticity (6) A great deal of time spent in activities necessary to obtain (6) Opiate self-administration during withdrawal substance, to use substance, or to recover from its effect Alcohol self-administration during withdrawal Progressive-ratio responding (7) Continued substance use despite knowledge of having a (7) Cocaine binge toxicity persistent problem that is likely to be caused or exacerbated by substance use From: American Psychiatric Association, 1994. Second-order schedules can be used as a measure of persistent desire to cut down or control substance use' and the conditioned reinforcing properties of drugs (43). Recent 'the substance taken in larger amounts than intended. The in general, drugs that are self-administered correspond to conditioned place preference paradigm also provides a mea- those that have high abuse potential in humans (60,61). Presumably, such states reflect some prolonged post acute The remaining criterion for substance dependence as de- withdrawal perturbation or vulnerability to reinstatement fined by DSM-IV can be linked to animal models by exten- of drug-seeking behavior and ultimately compulsive use. However, drug administration in the context of digms (20). Finally, 'continued substance use despite implementation of procedures designed to assess functional knowledge of having a persistent or recurrent physical or genomic activity (e. Drug addiction in humans has been characterized as oc- curring in several stages, although progress from one stage ACKNOWLEDGMENTS to the next is not inevitable. The first stage is initiation or acquisition, which may lead to habitual use, physical or The authors would like to thank Mike Arends for his help psychic dependence, and loss of control. An individual may with the preparation of this manuscript. This is publication stop taking a drug at any stage; however, relapse to drug number 13454-NP from The Scripps Research Institute. The extent Research was supported by National Institutes of Health to which the procedures discussed here model the human grants AA06420 and AA08459 from the National Institute condition to the point of reliability and predictive validity on Alcohol Abuse and Alcoholism, DK26741 from the Na- requires further assessment. Addiction is a chronic relapsing dis- search Program from the National Institute on Drug Abuse. As discussed, the motivating factors for the development, maintenance, and persistence of drug addic- REFERENCES tion can be broken down into four major sources of rein- 1. Transition from moderate to excessive forcement: positive reinforcement, negative reinforcement, drug intake: change in hedonic set point. Science 1998;282: conditioned positive reinforcement, and conditioned nega- 298–300.
Significance is shown only between cortical Total daily dose: levels achieved after continuous infusion and single injections (aster- 10 mg/kg i discount 160mg super avana with visa. Thus cheap super avana 160 mg with amex, a given daily drug does not produce the same ** degree of toxicity when it is given by different routes. Indeed, renal cortical uptake is “less efficient” at high serum concentration than at 200 low ones. A single injection results in high peak serum levels that over- come the saturation limits of the renal uptake mechanism. The high plasma concentrations are followed by fast elimination and, finally, 0 absence of the drug for a while. This contrasts with the continuous 1 2 4 6 8 low serum levels obtained with more frequent dosing when the uptake B Days of administration at the level of the renal cortex is not only more efficient but remains available throughout the treatment period. Subjects were patients with norm al renal 25 function (serum creatinine concentration between 0. Before surgery, patients received 40 gentam icin (4. The single-injection 10 schedule resulted in 30% to 50% lower cortical drug concentra- 20 Continuous infusion tions of netilm icin, gentam icin, and am ikacin as com pared with Continuous infusion continuous infusion. For tobram ycin, no difference in renal accu- 5 10 m ulation could be found, indicating the linear cortical uptake of 0 0 this particular am inoglycoside. These data, which supported 0 4 8 12 16 20 24 0 4 8 12 16 20 24 decreased nephrotoxic potential of single-dose regim ens, coincided Time, hrs with new insights in the antibacterial action of am inoglycosides A (concentration-dependent killing of gram -negative bacteria and prolonged postantibiotic effect). Renal Injury Due To Environmental Toxins, Drugs, and Contrast Agents 11. Several risk factors have been identified and classified as patient related, Patient-Related Factors Aminoglycoside-Related Factors Other Drugs am inoglycoside related, or related to con- current adm inistration of certain drugs. Older age* Recent aminoglycoside therapy Amphotericin B The usual recom m ended am inoglycoside Preexisting renal disease Cephalosporins dose m ay be excessive for older patients Female gender Larger doses* Cisplatin because of decreased renal function and Magnesium, potassium, or Treatment for 3 days or more* Clindamycin decreased regenerative capacity of a dam - calcium deficiency* aged kidney. Preexisting renal disease Intravascular volume depletion* Cyclosporine clearly can expose patients to inadvertent Hypotension* Dose regimen* Foscarnet overdosing if careful dose adjustm ent is Hepatorenal syndrome Furosemide not perform ed. H ypom agnesem ia, Sepsis syndrome Piperacillin hypokalem ia, and calcium deficiency m ay Radiocontrast agents be predisposing risk factors for conse- Thyroid hormone quences of am inoglycoside-induced dam - age. Liver disease is an im portant clinical risk factor for am inoglycoside * Similar to experimental data. Acute or chronic endotoxem ia am plifies the nephrotoxic potential of the am inoglycosides. FIGURE 11-9 PREVENTION OF AM INOGLYCOSIDE Prevention of am inoglycoside nephrotoxicity. Coadm inistration NEPHROTOXICITY of other potentially nephrotoxic drugs enhances or accelerates the nephrotoxicity of am inoglycosides. Com prehension of the phar- m acokinetics and renal cell biologic effects of am inoglycosides, Identify risk factor allows identification of am inoglycoside-related nephrotoxicity risk Patient related factors and m akes possible secondary prevention of this im portant clinical nephrotoxicity. Drug related Other drugs Give single daily dose of gentamicin, netilmicin, or amikacin Reduce the treatment course as much as possible Avoid giving nephrotoxic drugs concurrently Make interval between aminoglycoside courses as long as possible Calculate glomerular filtration rate out of serum creatinine concentration 11. The drug acts as a counterfeit phospholipid, with the C15 hydroxyl, C16 carboxyl, and C19 m ycosam ine groups situated at the m em brane-water interface, and the C1 to C14 and C20 to C33 chains aligned in parallel within the m em brane. The heptaene chain seeks a hydrophobic environm ent, and the hydroxyl groups seek a hydrophilic environm ent. Thus, a cylindrical pore is form ed, Cholesterol the inner wall of which consists of the hydroxyl-substituted carbon chains of the Am B m olecules and the outer wall of which is form ed by the heptaene chains of the m olecules and by sterol nuclei. C20-C33 heptaene segment Amphotericin B Pore C O N H Renal Injury Due To Environmental Toxins, Drugs, and Contrast Agents 11. N ephrotoxicity of Am B is a m ajor problem associated with clin- ical use of this im portant drug. Disturbances in both glom erular and tubule function are well described. The nephrotoxic effect of Age Am B is initially a distal tubule phenom enon, characterized by a loss Concurrent use of diuretics of urine concentration, distal renal tubule acidosis, and wasting of potassium and m agnesium , but it also causes renal vasoconstriction Abnormal baseline renal function leading to renal ischem ia. Initially, the drug binds to m em brane Larger daily doses sterols in the renal vasculature and epithelial cells, altering its m em - Hypokalemia brane perm eability. Am B-induced vasoconstriction and ischem ia to Hypomagnesemia very vulnerable sections of the nephron, such as m edullary thick Other nephrotoxic drugs (aminoglycosides, cyclosporine) ascending lim b, enhance the cell death produced by direct toxic action of Am B on those cells.
This finding and other both norepinephrine and dopamine are potent agonists of features of the genetic epidemiology of ADHD suggest that DRD4 (132) discount super avana 160 mg online. Moreover discount 160mg super avana free shipping, the segrega- model, dopamine synthesis increases in the dorsal striatum, tion studies indicated that about 2% of people without the and the mice show locomotor supersensitivity to ethanol, ADHD gene would develop ADHD, a finding suggesting cocaine, and methamphetamine. D4 knockout mice that nongenetic forms of ADHD may exist. This finding was replicated by Gill usually lead to very early-onset disorders having severe clini- et al. In the study by Waldman et Four human studies of ADHD have examined the cate- al. Further support for a link between the DAT inephrine. Although one study found that ADHD was asso- gene and ADHD comes from a study that relates this gene ciated with the Val allele (153), others have found no associ- to poor methylphenidate response in children with ADHD ation between the COMT polymorphism and ADHD in (139) and from the neuroimaging study (Table 43. Studies of that encode enzymes that metabolize dopamine and other this knockout mouse model show the potential complexities neurotransmitters (157). Finally, Comings and colleagues of gene–disease associations. The loss of the DAT gene has found associations and additive effects of polymorphisms many biological effects: increased extracellular dopamine, a at three noradrenergic genes (the adrenergic 2A, adrenergic doubling of the rate of dopamine synthesis (141), decreased 2C, and dopamine- -hydroxylas) on ADHD symptoms in dopamine and tyrosine hydoxylase in striatum (142), and a sample of patients with Tourette syndrome (158), but a nearly complete loss of functioning of dopamine autore- they found no association between the tyrosine hydroxylase ceptors (143). Because ADHD is believed to be a hypodopa- gene and ADHD in this sample (159). These researchers attributed this spontaneous hyperactivity (which is reversed by stimulants), to the effects of stimulants on the serotonin transporter. To delays in achieving complex neonatal motor abilities, defi- complicate matters further, Bezard et al. These latter findings suggest that individual differ- cytotic neurotransmitter release. Absence of the D2 gene in mice leads to significantly other work suggested that reduced SNAP-25 expression reduced spontaneous movements, a finding suggesting that leads to striatal dopamine and serotonin deficiencies, which D2 plays a role in the regulation of activity levels (147, may be involved in hyperactivity (162). Mice without D2 genes also show decreased striatal Hess et al. ADHD by using markers on human chromosome 20p11- used the D2 knockout mouse to study the role of the D2 p12, which is syntenic to the coloboma deletion region receptor in striatal synaptic plasticity (150). These investigators used five families for which segre- these researchers found abnormal synaptic plasticity at corti- gation analysis suggested that ADHD was the result of a costriatal synapses and long-term changes in synaptic effi- sex-influenced, single gene. However, no significant linkage cacy in the striatum. However, homozygous mice lacking D3 receptors displayed increased locomotor activity, and heterozygous mice showed less pro- ENVIRONMENTAL RISK FACTORS nounced hyperactivity. This conclusion follows from studies ily history of ADHD. This less than hypothesis was not confirmed in another study by the same perfect identical twin concordance implicates environmen- group (167). The latter study found that children with tal risk factors. The nature of these risk factors has emerged ADHD and a history of PDCs showed more school failure from studies assessing features of the biological and psycho- and psychometric evidence of cognitive impairment than social environment that may increase the risk of ADHD. In addition to confirming the etiologic role of medical complications, this study showed that psychosocial stress during pregnancy predicted subse- Biological Adversity quent ADHD and poor cognitive performance in children. The idea that certain foods could cause ADHD received Notably, catecholamines are secreted in response to stress, much attention in the popular press after claims were made and mouse studies showed that catecholamine administra- that ADHD could be cured by eliminating food additives tion produces uterine vasoconstriction and fetal hypoxia from the diet. Systematic studies, however, showed the diet was smoking during pregnancy. By exposing the fetus to nico- not effective and concluded that food additives do not cause tine, maternal smoking can damage the brain at critical ADHD (163). Another popular theory posited that exces- times in the developmental process. The smoking mother sive sugar intake would lead to ADHD symptoms. Although is at increased risk of antepartum hemorrhage, low maternal some positive studies supported this idea, the bulk of sys- weight, and abruptio placentae (173). Her fetus is at risk of tematic, controlled research did not (164).
The role of RNA editing in controlling glutamate cuits; (b) the finding that 5-HT receptors have a dramatic receptor channel properties generic super avana 160 mg with mastercard. Localization and functional significance influence on cortical information processing 160 mg super avana fast delivery, which has al- 2 of the Na /Ca exchanger in presynaptic boutons of hippo- lowed new insights into the mechanism of action of halluci- campal cells in culture. Regulation of serotonin- in molecular and cellular research on individual receptor 2C receptor G-protein coupling by RNA editing [see Com- subtypes have provided new experimental tools for the be- ments]. Messenger RNA editing of the human serotonin 5-HT2C receptor. Neuropsycho- agents with more precisely defined actions and gene knock- pharmacology 1999;21:82S–90S. The question remains of whether the diverse cellular 16. RNA and molecular actions of 5-HT mediated by the various editing of the human serotonin 5-hydroxytryptamine 2C recep- receptor subtypes can be incorporated into a holistic scheme tor silences constitutive activity. J Biol Chem 1999;274: that can define the overall function of the 5-HT system. Serotonin 5-HT2C Selected examples have been given of how the 5-HT system receptor RNA editing alters receptor basal activity: implications can be seen as modulating, in a complex but coordinated for serotoninergic signal transduction. Neurochemistry 1999;73: fashion, a number of motor, sensory, and other systems to 1711–1717. The recombinant molecular and cellular advances, by enabling a more com- 5-HT1A receptor: G protein coupling and signalling pathways. Autoregulation of serotonin neurons: role in 5-HT-receptor subtypes, have set the stage for a more pre- antidepressant drug action. Structure and func- tion of the third intracellular loop of the 5-hydroxytryptamine2A This work was supported by grants from the National Insti- receptor: the third intracellular loop is alpha-helical and binds tute of Mental Health, the National Institute on Drug purified arrestins. Rapid agonist-induced Chapter 2: Serotonin 29 internalization of the 5-hydroxytryptamine2A receptor occurs 40. Quantitative autoradiographic mapping via the endosome pathway in vitro. Mol Pharmacol 1996;50: of serotonin receptors in the rat brain. Lysergic acid diethyl- tors: molecular biology and mechanisms of regulation. Crit Rev amide: sensitive neuronal units in the midbrain raphe. Lysergic acid diethyl- hydroxytryptamine-2A receptor antagonists alter the subcellular amide and serotonin: direct actions on serotonin-containing distribution of 5-hydroxytryptamine-2A receptors in vitro and neurons in rat brain. Serotonin receptors: signal transduc- ergic neurons in the rat midbrain raphe: evidence for collateral tion pathways. Hyperpolarization of serotoniner- activated state of the beta 2-adrenergic receptor. Extending the gic neurons by serotonin and LSD: studies in brain slices show- ternary complex model. Voltage- and ligand-acti- the constitutive activity of human 5-HT1A receptors by the vated inwardly rectifying currents in dorsal raphe neurons in inverse agonist spiperone but not the neutral antagonist WAY vitro. Labelling of raphe neurons: activation of an inwardly rectifying potassium recombinant human and native rat serotonin 5-HT1A receptors current. Modulation by seroto- binding profile using agonists, antagonists and inverse agonists. Neuro- Naunyn Schmiedebergs Arch Pharmacol 1998;357:205–217. Whole-cell recordings of in- (human) 5-HT receptor antagonist with negative intrinsic wardly rectifying K currents activated by 5-HT receptors 1B 1A activity. Electrophysiological and histochemical properties ovary cell membranes stably expressing cloned human 5-HT1D of postnatal rat serotoninergic neurons in dissociated cell cul- receptor subtypes. Creation of a constitu- sium channels activated by 5-HT in acutely isolated rat dorsal tively activated state of the 5-hydroxytryptamine2A receptor by raphe neurones. Neuropsycho- tion of adenylyl cyclase activity in guinea pig hippocampus: pharmacology 1988;27:707–715. GR127935: effects on 5-hydroxytryptamine-containing neu- 34. HT(2A/2C) antagonists on associative learning in the rabbit.