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Query: UMLS:C0004352 (autism)
 32,579 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Repetitive thoughts and behavior are considered integral and core components of autistic disorder. Results from recent studies suggest that the types of repetitive thoughts and behavior of adults with autism and those with obsessive-compulsive disorder (OCD) may be different. Serotonin reuptake inhibitors (SRIs), the primary drug treatment for patients with OCD, may reduce the repetitive phenomena of some autistic patients. Two controlled studies of the nonselective SRI clomipramine have shown the drug to be more efficacious than the relatively selective norepinephrine reuptake inhibitor desipramine and placebo in children with autism. One controlled study of the selective SRI fluvoxamine found it to be significantly better than placebo for reducing repetitive phenomena and aggression in adults with autistic disorder. Additional research is needed.
J Autism Dev Disord 2000 Oct
PMID:Repetitive thoughts and behavior in pervasive developmental disorders: treatment with serotonin reuptake inhibitors. 1109 79

Serotonin (5-hydroxytryptamine, 5-HT) appears to play a role in the pathophysiology of a range of neuropsychiatric disorders, and serotonergic agents are of central importance in neuropharmacology. Genes encoding various components of the 5-HT system are being studied as risk factors in depression, schizophrenia, obsessive-compulsive disorder, aggression, alcoholism, and autism. Recently, pharmacogenetic research has begun to examine possible genetic influences on therapeutic response to drugs affecting the serotonin system. Genes regulating the synthesis (TPH), storage (VMAT2), membrane uptake (HTT), and metabolism (MAOA) of 5-HT, as well as a number of 5-HT receptors (HTR1A, HTR1B, HTR2A, HTR2C, and HTR5A), have been studied and this initial research is reviewed here. After a brief introduction to serotonin neurobiology and a general discussion of appropriate genetic methodology, each of the major 5-HT-related genes and their encoded proteins are reviewed in turn. For each gene, relevant polymorphisms and research on functional variants are discussed; following brief reviews of the disorder or trait association and linkage studies, pharmacogenetic studies performed to date are covered. The critical and manifold roles of the serotonin system, the great abundance of targets within the system, the wide range of serotonergic agents-available and in development-and the promising preliminary results suggest that the serotonin system offers a particularly rich area for pharmacogenetic research.
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PMID:Pharmacogenetics and the serotonin system: initial studies and future directions. 1113 68

This article critically reviews research done in the past 2 years concerning the pathophysiology and treatment of autism. Recent research in genetics, neuroimaging, neurochemistry, and pharmacologic treatment has advanced the body of knowledge about the pathophysiology of autism. Relatively new imaging technologies (eg, positron emission tomography) are increasingly being applied to the study of subjects with autism and have produced promising results that await replication. Neurochemical and challenge studies continue to suggest a role for 5-HT dysregulation in autism. Additional research is needed to determine the role of neuroendocrine and autoimmune factors in autism. Significant gains have been made in determining which pharmacologic treatments are efficacious in autism. Additional research is needed on agents that might ameliorate the core and associated symptoms of autism.
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PMID:The pathophysiology and treatment of autism. 1127 4

We have examined three functional polymorphisms, serotonin transporter promoter region polymorphism (5-HTTLPR), dopamine D4 exon III repeat region (DRD4), and catechol-O-methyltransferase (COMT), in a small family-based design toward identifying candidate genes that confer risk for autism. A significant excess of the long/long 5-HTTLPR genotype was observed (likelihood ratio = 7.18; P = 0.027; 2 df; n = 33 families) as well as preferential transmission of the long allele of the 5-HTTLPR (TDT chi-square = 5.44; P<0.025; 1 df). No association was observed between the COMT and DRD4 polymorphisms and autism in this sample. Some previous studies have observed linkage between autism and the 5-HTTLPR polymorphism and the current results are similar to those first reported by Klauck et al. [1997: Hum Genet 100:224-229; 1997: Hum Mol Genet 6:2233-2238]. Additionally, elevated serotonin levels have been consistently found in 30%-50% of autistic patients and may represent a marker for familial autism. Hyperserotonemia in autism appears to be due to enhanced 5-HT uptake, as free 5-HT levels are normal and the current report of an excess of the long/long 5-HTTLPR genotype in autism could provide a partial molecular explanation for high platelet serotonin content in autism.
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PMID:Evidence for an association with the serotonin transporter promoter region polymorphism and autism. 1137 54

The maturational changes in the brain and spinal cord do not linearly proceed from immature in infants to mature in adults. Dendrites dynamically extend or retract as neurotrophic factors fluctuate. In certain cases mature neurons can be seen soon after birth, and in other cases immature neurons can be identified in the aged brain. Monoamine 'neurotransmitter'; such as serotonin (5-HT), dopamine and norepinephrine appear to function as Maintenance Growth Factors since they must be present in order to produce their maturational actions. Serotonin neurons contain TRK-B receptors and are sensitive to availability of the trophic factor, BDNF. 5-HT also functions by promoting the release of the glial extension factor, S-100beta. 5-HT and S-100beta can provide maturational signals to a variety of neurons, in both cortical and subcortical areas, and appear to be involved in regulating the maturation and release of acetylcholine and dopamine. We have shown that activation of the 5-HT1A receptor is particularly effective in inducing growth of stunted neurons. The mechanism of action of the 5-HT1A receptor involves both a direct inhibition on c-AMP and pCREB formation in postsynaptic neurons and a release of S-100beta from glial cells. Both these events are capable of stabilization and elaboration of the cytoskeleton of the neuron and inhibition of apoptosis. 5-HT1A receptors have been shown to effectively reverse stunted neurons and microencephaly produced in animal models of fetal alcohol syndrome and prenatal cocaine administration. I discuss the implications for regressive disorders such as Rett's syndrome and autism, and the feasibility of treatments with 5-HT1A agonists in children with developmental disorders.
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PMID:Neuronal instability: implications for Rett's syndrome. 1173 34

Serotonin is known to play a role in brain development prior to the time it assumes its role as a neurotransmitter in the mature brain. Serotonin regulates both the development of serotonergic neurons (termed autoregulation of development) and the development of target tissues. In both cases, the astroglial-derived protein, S-100beta plays a role. Disruption of serotonergic development can leave permanent alterations in brain function and behavior. This may be the case in such human developmental illnesses as autism and Down Syndrome.
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PMID:Serotonin and brain development: role in human developmental diseases. 1175 Jul 93

Previous studies have provided conflicting evidence regarding the association of the serotonin transporter (5-HTT) gene with autism. Two polymorphisms have been identified in the human 5-HTT gene, a VNTR in intron 2 and a functional deletion/insertion in the promoter region (5-HTTLPR) with short and long variants. Positive associations of the 5-HTTLPR polymorphism with autism have been reported by two family-based studies, but one found preferential transmission of the short allele and the other of the long allele. Two subsequent studies failed to find evidence of transmission disequilibrium at the 5-HTTLPR locus. These conflicting results could be due to heterogeneity of clinical samples with regard to serotonin (5-HT) blood levels, which have been found to be elevated in some autistic subjects. Thus, we examined the association of the 5-HTTLPR and VNTR polymorphisms of the 5-HTT gene with autism, and we investigated the relationship between 5-HTT variants and whole-blood 5-HT. The transmission/disequilibrium test (TDT) revealed no linkage disequilibrium at either loci in a sample of 96 families comprising 43 trios and 53 sib pairs. Furthermore, no significant relationship between 5-HT blood levels and 5-HTT gene polymorphisms was found. Our results suggest that the 5-HTT gene is unlikely to play a major role as a susceptibility factor in autism.
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PMID:Serotonin transporter gene polymorphisms and hyperserotonemia in autistic disorder. 1180 47

Neuropathological studies in autistic brains have shown small neuronal size and increased cell packing density in a variety of limbic system structures including the hippocampus, a change consistent with curtailment of normal development. Based on these observations in the hippocampus, a series of quantitative receptor autoradiographic studies were undertaken to determine the density and distribution of eight types of neurotransmitter receptors from four neurotransmitter systems (GABAergic, serotoninergic [5-HT], cholinergic, and glutamatergic). Data from these single concentration ligand binding studies indicate that the GABAergic receptor system (3[H]-flunitrazepam labeled benzodiazepine binding sites and 3[H]-muscimol labeled GABA(A) receptors) is significantly reduced in high binding regions, marking for the first time an abnormality in the GABA system in autism. In contrast, the density and distribution of the other six receptors studied (3[H]-80H-DPAT labeled 5-HT1A receptors, 3[H]-ketanserin labeled 5-HT2 receptors, 3[H]-pirenzepine labled M1 receptors, 3[H]-hemicholinium labeled high affinity choline uptake sites, 3[H]-MK801 labeled NMDA receptors, and 3[H]-kainate labeled kainate receptors) in the hippocampus did not demonstrate any statistically significant differences in binding.
J Autism Dev Disord 2001 Dec
PMID:Density and distribution of hippocampal neurotransmitter receptors in autism: an autoradiographic study. 1181 63

The human 5-HT(1B) and 5-HT(1D) receptors are especially similar in sequence despite being encoded by two distinct genes. Although, human 5-HT(1B) and 5-HT(1D) receptors have been pharmacologically differentiated using nonselective 5-HT(1B/D) receptor antagonists such as ketanserin (1), ritanserin (2) and methiothepin (3), the precise function of these receptors remains undefined, and progress toward this has been hampered by the lack of selective ligands. The interest of the major pharmaceutical companies in 5-HT(1B/1D) antagonists increased by the discovery of potent and selective tools, combined with the fact that the blockade of terminal 5-HT(1B) receptors by selective antagonists has been proposed as a new approach for more efficient and/or fast-acting antidepressant drugs, since the acute blockade of these 5-HT autoreceptors will, in theory, immediately mimic their desensitization. Furthermore, it has been also suggested that supersensitive 5-HT(1B/1D) receptors may be involved in the pathophysiology of obsessive compulsive disorders (OCD). In the 5-HT(1B/1D) agonist field, since the discovery of sumatriptan (26) (a 5-HT(1B/1D) receptor agonist) as an effective treatment for migraine headache, intensive research in this area has led to several second-generation compounds, a few of which have either entered the market place or are in late clinical trials. Beside the antimigraine activity of the 5-HT(1B/1D) agonists in clinical evaluation or already on the market, other potential therapeutic evaluations (such as gastric motor effect, bipolar disorder, autism, anti-aggressive effects) with these drugs are being investigated. This article highlights and reviews the research advances published in the 5-HT(1B/1D) antagonist and agonist literature. The article is supplemented with selected references on the design, synthesis and development of novel 5-HT(1B/1D) agents, and on studies to understand their mechanism and pathophysiology. Emphasis is given to recent advances in the potential therapeutic applications of 5-HT(1B/1D) serotonergic agents. By no means has any attempt been made to exhaustively review the literature but rather, primary references along with citations to recent literature reviews have been included in each section.
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PMID:Recent advances in 5-HT1B/1D receptor antagonists and agonists and their potential therapeutic applications. 1205 94

Autism is a biologically-heterogeneous disease. Distinct subgroups of autistic patients may be marked by intermediate phenotypes, such as elevated serotonin (5-HT) blood levels, potentially associated with different underlying disease mechanisms. This could lead to inconsistent genetic association results, such as those of prior studies on serotonin transporter (5-HTT) gene promoter variants and autistic disorder. Contributions of 5-HTT gene promoter alleles to 5-HT blood levels were thus investigated in 134 autistic patients and 291 first-degree relatives. Mean 5-HT blood levels are 11% higher in autistic patients carrying the L/L genotype, compared to patients with the S/S or S/L genotype; this trend is not observed in first-degree relatives. The probability of inheriting L or S alleles is significantly enhanced in patients with 5-HT blood levels above or below the mean, respectively (P < 0.05), but quantitative TDT analyses yield a non-significant trend (P = 0.10), as this polymorphism explains only 2.5% of the variance in 5-HT blood levels of autistic patients. In conclusion, 5-HTT gene promoter variants seemingly exert a small effect on 5-HT blood levels in autistic children, which largely does not account for hyperserotoninemia. Nonetheless, the inconsistent outcome of prior association studies could partly stem from a selection bias of hyper- or hypo-serotoninemic probands.
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PMID:Serotonin transporter gene promoter variants do not explain the hyperserotoninemia in autistic children. 1219 26


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