Low brain serotonin transporter binding in major depressive disorder

Myrna Brind Center of Integrative Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Psychiatry Research (Impact Factor: 2.47). 06/2012; 202(2):161-7. DOI: 10.1016/j.pscychresns.2011.12.015
Source: PubMed


We examined midbrain, medial temporal lobe, and basal ganglia serotonin transporter (SERT) distribution volume ratio (DVR) values in subjects with major depressive disorder versus healthy volunteers using a selective SERT radioligand and single photon emission computed tomography (SPECT). We hypothesized that the DVR value for SERT binding would be lower in depressed versus non-depressed subjects. [(123)I]-ADAM SPECT scans were acquired from 20 drug free, depressed subjects and 20 drug-free depressed subjects and 10 drug-free healthy volunteers. The primary outcome measure was the DVR value for [(123)I]-ADAM uptake in the midbrain, medial temporal lobe, and basal ganglia regions. Depressed subjects demonstrated significantly lower DVR values in the midbrain, right and left medial temporal lobe, and right and left basal ganglia. There was significant probability that lower DVR values could distinguish between depressed and non-depressed subjects in the midbrain, medial temporal lobe, and the right and left basal ganglia. These findings confirm prior observations of lower SERT binding in depression, and suggest that low SERT binding may represent a putative biomarker of depression. Future studies are needed to confirm these observations.

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    • "Newberg et al. [26] used SPET to demonstrate alterations in SERT binding in patients with major depression; in this study, SERT binding was decreased in the midbrain region of patients with major depressive disorder and the degree of decrease correlated significantly with the severity of depressive symptoms [26]. These findings were generally corroborated by a later study by the same group using a larger sample size [27]. However, to our knowledge, no studies of SERT binding have been conducted in patients with epilepsy. "
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    ABSTRACT: Purpose of the study was to investigate alterations in midbrain serotonin transporter (SERT) binding in patients with epilepsy and symptoms of depression compared to patients with epilepsy with no symptoms of depression. We studied 12 patients with epilepsy (7 patients had focal and 5 had generalized epilepsy syndromes). The presence of self-reported symptoms of depression was assessed using Beck Depression Inventory (BDI) and the Emotional State Questionnaire (EST-Q). The binding potential of the SERT was assessed by performing brain single photon emission tomography (SPET) using the SERT radioligand 2-((2-((dimethylamino)methyl)phenyl)thio)-5-(123)iodophenylamine (123I-ADAM). Seven patients had BDI and EST-Q subscale scores greater than 11 points, which was interpreted as the presence of symptoms of depression. We found that 123I-ADAM binding was not significantly different between patients with epilepsy with and without symptoms of depression. In addition, 123I-ADAM binding did not show a significant correlation to either BDI or EST-Q depression subscale scores and did not differ between patients with focal vs. generalized epilepsy. The results of our study failed to demonstrate alterations of SERT binding properties in patients with epilepsy with or without symptoms of depression.
    BMC Neurology 12/2013; 13(1):204. DOI:10.1186/1471-2377-13-204 · 2.04 Impact Factor
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    • "This is primarily based on human studies of 5-HTT binding using positron emission tomography (PET). These studies showed both increases and decreases in 5-HTT binding, as well as negative findings (Newberg et al., 2012; Savitz and Drevets, 2012). These results may be due in part to methodological differences, disease heterogeneity, prior drug exposure , gender and age of the participants (Malison et al., 1998; Newberg et al., 2005; Reimold et al., 2008). "
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    ABSTRACT: The serotonin transporter (5-HTT) regulates the extracellular concentration of serotonin, influencing neurotransmission. Evidence suggests that 5-HTT is altered during depression, but the precise changes in 5-HTT expression in the pathogenesis and treatment of depression are not clear. We investigated the protein expression of hippocampal 5-HTT in CD-1 mice exposed to unpredictable chronic mild stress for 10 continuous weeks. Following 6 weeks of the stress procedure, the mice were separated into anhedonic and non-anhedonic groups, which were then treated with fluoxetine (FLX, 10mg/kg/day, i.p.) for 4 weeks. Behavioral state and therapeutic efficacy of the drug treatment were assessed using sucrose preference, physical state of the coat and body weight. Our results show that changes in hippocampal 5-HTT protein expression correlated with stress-induced behavioral states. Decreases in 5-HTT expression were associated with the stress-induced anhedonic state, whereas increases were associated with the stress-induced non-anhedonic state. Following FLX treatment, the changes in 5-HTT expression were reversed in a subpopulation of anhedonic mice, i.e. the treatment-responsive anhedonic mice. The treatment did not alter the changes in the treatment-resistant anhedonic mice or in the non-anhedonic mice. The data indicate that down-regulation of hippocampal 5-HTT protein expression is a signature change associated with anhedonia, a key endophenotype of clinical depression. Differential changes in 5-HTT expression may contribute to variations in the susceptibility to anhedonia.
    Brain research 04/2013; 1513. DOI:10.1016/j.brainres.2013.03.042 · 2.84 Impact Factor
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    ABSTRACT: Alterations in serotonergic activity have been observed in many pathological conditions, including neuropsychiatric diseases, irritable bowel syndrome, and hypertension. The serotonin (5-hydroxytryptamine; 5-HT) transporter (SERT) in the brain clears 5-HT from extracellular spaces, modulating the strength and duration of serotonergic signaling. Outside the central nervous system, it is also present in platelets, where it takes up 5-HT from plasma, keeping levels very low (i.e., ~1 nM). Importantly, it is generally accepted that SERT protein expressed in platelets is identical to the one found in neurons, displaying similar structural and functional properties in both tissues. At the present time, it is technically difficult to measure SERT binding and function in vivo since imaging methods are limited by a number of factors, especially the cost and the selectivity of the available radioligands. One of the most frequently used molecular imaging techniques to study SERT is positron emission tomography (PET). Although an impressive number of PET radioligands have been synthesized and validated, there is still a lack of suitable ligands for a large part of the 5-HT system. Interest in determining both the molecular characteristics and the regulation of SERT has been enormous over the last decade, but the difficulty in obtaining human tissues and the ethical limitations in human experiments have turned researchers to look for alternative models. This review summarizes recent clinical and preclinical data relevant to the use of blood platelets as a peripheral marker for the central 5-HT system, and outlines future directions in this field.
    Current Medicinal Chemistry 01/2013; 20(11). DOI:10.2174/0929867311320110003 · 3.85 Impact Factor
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