GLUT8 glucose transporter is localized to excitatory and inhibitory neurons in the rat hippocampus

Fluorescence immunohistochemistry was performed to characterize the distribution and phenotype of GLUT8-positive neurons in rat brain and to compare the cellular distribution of GLUT8 with GLUT3 in the hippocampus. Based upon the absence of co-localization with the non-neuronal markers GFAP (astroglial) and OX42 (microglial), it appears that GLUT8 is expressed exclusively in neurons. At the cellular level, GLUT8 immunofluorescence was localized to neuronal cell bodies and the most proximal dendrites of inhibitory and excitatory neurons while GLUT3 immunofluorescence was localized to the neuropil in the hippocampus. These results demonstrate that GLUT8 is a neuron-specific glucose transporter expressed in the neuronal cell bodies of excitatory and inhibitory neurons in the rat hippocampus.     

Immunocytochemical distribution of the brain glucose transporter (GLUT 1) in experimental gliosis

The present study has examined the immunocytochemical expression of the blood-brain barrier glucose transporter GLUT 1 as compared with GFAP in models of experimental gliosis. In neocortical grafts, gliosis was prominent at the graft-host interface mostly associated with blood vessels. Consecutive sections examined for anti-GLUT 1 showed that the protein was distributed in nearly an identical pattern to the anti-GFAP, staining fibrillar processes and all vessels and also appeared extracellularly. In stab wounds, GLUT 1 immunoexpression was similar to GFAP reactivity and stained injured vessels and glial-like processes that were reminiscent of astrocytic end-feet. Normal glial cells and processes in unaffected neuropil, however, were never stained. This report suggests that GLUT 1 protein may be upregulated in non-endothelial components, such as reactive astroglia or possibly microglia, that are associated with injured or angiogenic vessels.     

葡萄糖转运蛋白1型在脑肿瘤中的表达及意义

目的探讨葡萄糖转运蛋白1型(Glucose transporter-1,GLUT1)在脑肿瘤中的表达及其意义。方法 收集55例颅脑手术标本,包括46例脑肿瘤患者和9例正常脑组织,采用单克隆抗体的GLUT1免疫组织化学SP法进行染色。结果 7例低度恶性胶质瘤中的3例和全部13例高度恶性胶质瘤不同程度的表达GLUT1;10例良性脑膜瘤中的3例和全部5例恶性脑膜瘤为阳性表达;6例垂体瘤中的3例和5例表皮样囊肿也异常表达;所有正常脑组织均未见表达。结论 四种脑肿瘤均可不同程度表达GLUT1,尤其在恶性肿瘤为明显,其与脑肿瘤的恶性程度相关。     

Glucose transporter 2 (GLUT 2): expression in specific brain nuclei

In the brain, certain neurons appear to be sensitive to changes in local and/or plasma glucose concentration. The alterations in the electrical activity of these neurons probably depend on the existence of ‘glucose sensors’, which may be one of the glucose transporters described so far. Because of suitable kinetic properties, we hypothesized that the glucose transporter 2 (GLUT 2) may well constitute one of the cerebral ‘glucose sensors’. In this study, it was demonstrated, using the polymerase chain reaction, that GLUT 2 mRNAs are present in a limited number of brain nuclei, including the nucleus tractus solitarius, the motor nucleus of the vagus, the paraventricular hypothalamic nucleus, the lateral hypothalamic area, the arcuate nucleus and the olfactory bulbs. These localizations were confirmed by immunocytochemistry, but the cerebral distribution of GLUT 2-like immunoreactivity was far larger than initially expected. Furthermore, electron microscopic observations showed that, within the regions examined, GLUT 2 was localized to a restricted population of astrocytes. The localization of GLUT 2 in regions previously connected with feeding behavior supports an indirect role for GLUT 2 in ‘glucose sensing’ in these specific cerebral structures.     

Altered DNA methylation of glucose transporter 1 and glucose transporter 4 in patients with major depressive disorder

Alterations in brain glucose metabolism and in peripheral glucose metabolism have frequently been observed in major depressive disorder (MDD). The insulin independent glucose transporter 1 (GLUT1) plays a key role in brain metabolism while the insulin-dependent GLUT4 is the major glucose transporter for skeletal and cardiac muscle. We therefore examined methylation of GLUT1 and GLUT4 in fifty-two depressed inpatients and compared data to eighteen healthy comparison subjects. DNA methylation of the core promoter regions of GLUT1 and GLUT4 was assessed by bisulfite sequencing. Further factors determined were fasting glucose, cortisol, insulin, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). We found significantly increased methylation of the GLUT1 in depressed inpatients compared to healthy comparison subjects (CG). Further findings comprise increased concentrations of fasting cortisol, glucose, insulin, and increased IL-6 and TNF-α. After six weeks of inpatient treatment, significantly lower GLUT1 methylation was observed in remitted patients compared to non-remitters. GLUT4 methylation was not different between depressed patients and CG, and did not differ between remitted and non-remitted patients. Although preliminary we conclude from our results that the acute phase of major depressive disorder is associated with increased GLUT1 methylation and mild insulin resistance. The successful treatment of depression is associated with normalization of GLUT1 methylation in remitters, indicating that this condition may be reversible. Failure of normalization of GLUT1 methylation in non-remitters may point to a possible role of impeded brain glucose metabolism in the maintenance of MDD.     

Ultrastructural localization of GLUT 1 and GLUT 3 glucose transporters in rat brain

Precise localization of glucose transport proteins in the brain has proved difficult, especially at the ultrastructural level. This has limited further insights into their cellular specificity, subcellular distribution, and function. In the present study, preembedding ultrastructural immunocytochemistry was used to localize the major brain glucose transporters, GLUTs 1 and 3, in vibratome sections of rat brain. Our results support the view that, besides being present in endothelial cells of central nervous system (CNS) blood vessels, GLUT 1 is present in astrocytes. GLUT 1 was detected in astrocytic end feet around blood vessels, and in astrocytic cell bodies and processes in both gray and white matter. GLUT 3, the neuronal glucose transporter, was located primarily in pre- and postsynaptic nerve endings and in small neuronal processes. This study: (1) affirms that GLUT 3 is neuron-specific, (2) shows that GLUT 1 is not normally expressed in detectable quantities by neurons, (3) suggests that glucose is readily available for synaptic energy metabolism based on the high concentration of GLUT 3 in membranes of synaptic terminals, and (4) demonstrates significant intracellular and mitochondrial localization of glucose transport proteins. J. Neurosci. Res. 49:617–626, 1997. © 1997 Wiley-Liss, Inc.     

The human blood-brain barrier glucose transporter (GLUT1) is a glucose transporter of gray matter astrocytes

Human and monkey brain sections were examined by immunohistochemical light and electron microscopy to determine the distribution of GLUT1, a glucose transporter isoform associated with erythrocytes and endothelial cells of the human blood-brain barrier. Protein immunoblotting of fractionated human brain membranes was performed to determine the distribution of molecular forms of the transporter. GLUT1 staining was abundant in erythrocytes and cerebral endothelium of gray and white matter but was also present diffusely in gray matter neuropil when viewed by light microscopy. Immunoelectron microscopy confirmed the gray matter and vascular localization of GLUT1, with specific GLUT1 staining seen in erythrocytes, gray and white matter endothelial cells, astrocyte foot processes surrounding gray matter blood vessels, and in astrocyte processes adjacent to synaptic contacts. No astrocytic staining was identified in white matter. Astrocyte GLUT1 staining was identified only in mature gray matter regions; undifferentiated regions of preterm (22–23 weeks gestation) cortex had GLUT1 staining only in blood vessels and erythrocytes, as did germinal matrix. Immunoblots of adult human frontal cortex revealed that two forms of GLUT1 (45 and 52 kDa) were present in unfractionated brain homogenates. Immunoblots of vessel-depleted frontal lobe revealed only the 45 kDa form in gray matter fractions, and depleted in membranes prepared from white matter regions. We conclude that the GLUT1 isoform of glucose transporter is present both in endothelium of the blood-brain barrier and in astrocytes surrounding gray matter blood vessels and synapses. Furthermore, the form present in astrocytes is likely to have a lower molecular weight than the form found in cerebral endothelium. The GLUT1 transporter may play an important role not only in astrocyte metabolism, but also in astrocyte-associated pathways supporting neuronal energy metabolism. © 1995 Wiley-Liss, Inc.     

创伤性脑损伤急性期高血糖对葡萄糖转运蛋白1表达的影响

目的探讨大鼠创伤性脑损伤急性期高血糖对皮层葡萄糖转运蛋白1(glucose transporter1,GLUT-1)表达的影响。方法成年雄性SD大鼠180只,随机分成正常对照组,创伤性脑损伤(traumatic brain injury,TBI)组,胰岛素治疗组,分别测定各组伤前伤后血糖值,采用RT-PCR法和Western-blot法测定各组伤侧及健侧皮层GLUT-1基因和蛋白的表达,应用TUNEL法测定各组伤侧及健侧皮层凋亡细胞数。结果TBI组伤后血糖明显升高,伤侧皮层GLUT-1表达明显减少,凋亡细胞数明显增多;胰岛素治疗组血糖变化不明显(P0.05),伤后12h,24h,48h,72hGLUT-1表达明显多于TBI组(P均0.01),凋亡细胞数明显少于TBI组(P均0.01);各组健侧皮层GLUT-1表达和凋亡细胞数未见明显变化(P0.05)。结论TBI急性期高血糖可增加伤后脑细胞凋亡,其机制可能与TBI急性期高血糖下调GLUT-1表达有关。     

Distribution and pharmacology of alanine-serine-cysteine transporter 1 (asc-1) in rodent brain

A polyclonal antibody against the Na+-independent alanine-serine-cysteine transporter 1 (asc-1) was raised and the specificity of the antibody verified by Western blots performed on membranes prepared from HEK293 cells transiently transfected with the cloned murine asc-1. The antibody was then used to localize the transporter in the brain of two rodent species by using immunohistochemistry at the light and electron microscopical level. asc-1-immunoreactivity (asc-1-ir) was widely distributed throughout the mouse and rat brain. Areas with high levels of asc-1-ir included hypothalamus, the medial septal area, globus pallidus, entopeduncular nucleus, cingulate and retrosplenial cortices. Moderate asc-1-ir was observed in several areas including layers III and V of the neocortex, thalamus, nucleus accumbens, caudate putamen, bed nucleus of stria terminalis, all amygdaloid nuclei, hippocampus (CA1-CA3 and hilus of the dentate gyrus), as well as several brainstem nuclei. asc-1-ir was observed as punctuate staining consistent with varicosities matching neuronal cell bodies and dendritic fields. At the ultrastructural level, asc-1-ir was mainly confined to presynaptic terminals. Immunostaining in either glial cell bodies or perivascular sites was not observed and white matter was completely devoid of asc-1-ir. Furthermore, the pharmacology of the Na+-independent uptake site for [3H]d-serine in rat brain synaptosomal P2 fractions was compared with the substrate specificity of the cloned human asc-1 transporter and a high degree of correlation was demonstrated. We conclude that asc-1-ir is widespread in the brain and limited to neuronal structures and that asc-1 may contribute to synaptic clearance of d-serine in brain.     

The basic amino acid transporter (rBAT) -like immunoreactivity in paraventricular and supraoptic magnocellular neurons of the rat hypothalamus

In the rat hypothalamus, the basic amino acid transporter (rBAT)-like immunoreactivity was analyzed by immunohistochemistry using an antibody against the 15-amino acid sequence of the deduced rat rBAT protein. In the supraoptic and the paraventricular nuclei, magnocellular neurons exhibited the marked rBAT-like immunoreactivity in intracellular structures but not in the plasma membrane. The results suggest that the rBAT serves as an intracellular amino acid transport system in magnocellular neurons.     

Pentylenetetrazol-induced status epilepticus up-regulates the expression of glucose transporter mRNAs but not proteins in the immature rat brain

Prolonged pentylenetetrazol (PTZ)-induced seizures increase cerebral energy demands in a region-specific manner. During PTZ seizures, cerebral glucose utilization increases over control levels in all brain regions at 10 days while 21-day-old rats exhibit increases, decreases or no change. To explore the effects of such acute changes in metabolic demand on the expression of glucose transporter proteins mediating glucose delivery to brain, we studied the consequences of PTZ seizures on GLUT1 and GLUT3 mRNAs and proteins between 1 and 72 h after seizure induction. At both ages, seizures induced a rapid up-regulation of GLUT1 and GLUT3 mRNAs which was prominent at 1 and 4 h, and was greater at 10 than at 21 days. By 24 h and 72 h, the levels of the mRNAs of the two transporter returned to control levels or were slightly down-regulated. The levels of GLUT1 and GLUT3 proteins were not affected by the seizures and only scattered decreases in GLUT3 protein were recorded, mainly in midbrain-brainstem areas. These data show that acute pentylenetetrazol seizures induce a rapid up-regulation of the GLUT1 and GLUT3 mRNAs, but do not result in measurable increases in protein levels, suggesting translational regulation.     

Selectively increased expression of the astrocytic/endothelial glucose transporter protein GLUT1 in acute liver failure

Acute liver failure (ALF) is consistently accompanied by alterations in brain energy metabolites and recent nuclear magnetic resonance (NMR) studies suggest disturbances in brain oxidative metabolism in experimental ALF. Glucose transport across the blood-brain barrier is essential to sustain brain energy metabolism and is accomplished by the facilitative glucose transporter GLUT1. To investigate alterations in brain glucose uptake in acute liver failure further, GLUT1 expression and [14C]-2-deoxy-D-glucose uptake were measured in the brains of rats with hepatic devascularization. RT-PCR and Western blot analyses showed significant increases in steady-state levels of GLUT1 mRNA and protein in frontal cortex as early as 6 h following hepatic devascularization, (prior to the onset of brain edema and encephalopathy) which remained elevated at coma stages of encephalopathy. Expression of the astrocytic (45-kDa) and endothelial (55-kDa) forms of GLUT1 was increased as a result of hepatic devascularization. Exposure of cultured astrocytes to pathophysiologically relevant concentrations of ammonia resulted in increased GLUT1 expression, suggesting that elevated ammonia levels are responsible for GLUT1 upregulation in ALF. Increased GLUT1 expression in ALF was selective, since expression of the neuronal glucose transporter GLUT3 and other glucose-regulated proteins (GRP-78 and GRP-94) was unaltered. [14C]-2-deoxy-D-glucose autoradiography revealed increases in cerebral glucose uptake following the induction of GLUT1 in ALF. These results suggest that ammonia-induced increases of GLUT1 expression resulting in increased cerebral glucose uptake occur in ALF and could contribute to the pathophysiological mechanisms responsible for the neurological complications of this condition.     

Cocaine,but not amphetamine,short term treatment elevates the density of rat brain vesicular monoamine transporter 2

Summary We compared the effect of 5 days D-amphetamine (5 mg/kg/day i.p.) and cocaine (15 mg/kg/day i.p.) administration on the vesicular monoamine transporter 2 (VMAT2) density in rat brain. VMAT2 expression was assessed by [³H]dihydrotetrabenazine high affinity binding. Cocaine administration led to significant increases in VMAT2 density in both prefrontal cortex (+40%, p < 0.01) and striatum (+23%, p < 0.05), while amphetamine did not affect VMAT2 expression. The upregulation of VMAT2 may serve as compensatory mechanism aimed to enhance the vesicular monoamine storage capacity.     

Heptanoate as a neural fuel: energetic and neurotransmitter precursors in normal and glucose transporter I-deficient (G1D) brain

It has been postulated that triheptanoin can ameliorate seizures by supplying the tricarboxylic acid cycle with both acetyl-CoA for energy production and propionyl-CoA to replenish cycle intermediates. These potential effects may also be important in other disorders associated with impaired glucose metabolism because glucose supplies, in addition to acetyl-CoA, pyruvate, which fulfills biosynthetic demands via carboxylation. In patients with glucose transporter type I deficiency (G1D), ketogenic diet fat (a source only of acetyl-CoA) reduces seizures, but other symptoms persist, providing the motivation for studying heptanoate metabolism. In this work, metabolism of infused [5,6,7-¹³C₃]heptanoate was examined in the normal mouse brain and in G1D by ¹³C-nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS). In both groups, plasma glucose was enriched in ¹³C, confirming gluconeogenesis from heptanoate. Acetyl-CoA and glutamine levels became significantly higher in the brain of G1D mice relative to normal mice. In addition, brain glutamine concentration and ¹³C enrichment were also greater when compared with glutamate in both animal groups, suggesting that heptanoate and/or C5 ketones are primarily metabolized by glia. These results enlighten the mechanism of heptanoate metabolism in the normal and glucose-deficient brain and encourage further studies to elucidate its potential antiepileptic effects in disorders of energy metabolism.     

Safety aspects of chronic low-frequency transcranial magnetic stimulation based on localized proton magnetic resonance spectroscopy and histology of the rat brain

Because repetitive transcranial magnetic stimulation (rTMS) is capable of inducing lasting alterations of cortical excitability, it represents a promising therapeutic tool in several neuropsychiatric disorders. However, rTMS, especially when applied chronically, may cause harmful effects in the stimulated tissue. To study the safety of chronic rTMS we used a novel small stimulation coil, which was specially designed to treat rats, and investigated brain tissue using in vivo localized proton magnetic resonance spectroscopy (MRS) and post mortem histological analysis. Histology was based on a modified stereology method in combination with immunohistochemistry applying antibodies against OX-6, OX-42, ED, and GFAP to detect any microglial and/or astrocytic activation 48 h after the last TMS session. Conscious rats were treated with a daily suprathreshold rTMS regimen of 1000 stimuli applied on 5 consecutive days at a frequency of 1 Hz. In comparison with control animals receiving magnetic stimulation over the lumbar spine, quantitative evaluations of cerebral metabolite concentrations by proton MRS revealed no significant alterations of N-acetyl-aspartate, creatine and phosphocreatine, choline-containing compounds, myo-inositol, glucose and lactate after chronic rTMS. Similarly to the in vivo results, post mortem histology revealed no changes in microglial and astrocytic activation after rTMS. In conclusion, these data provide support for the safety of chronic rTMS. However, they do not exclude acute changes on neurotransmitters systems or other physiologic responses during or directly after the rTMS treatment.     

Immunocytochemical localization of 205 kDa microtubule-associated protein (205 kDa MAP) in the guinea pig organ of Corti

We have studied the immunocytochemical localization of microtubule-associated proteins (MAPs) in the guinea pig organ of Corti. Using immunological methods with antibodies against MAP1A, MAP1B, MAP2, tau and 205 kDa MAP, we have identified 205 kDa MAP as a major MAP of the sensory epithelium in the organ of Corti. Immunoperoxidase microscopic study has shown that both cochlear hair cells and supporting cells reacted with anti-205 kDa MAP antibody. Immunoelectron microscopy revealed that 205 kDa MAP was associated with most microtubules in the sensory epithelial cells. It was also associated with the microtubules of bundle structures within supporting cells, suggesting that this MAP might form a part of cross-bridges between microtubules and between microtubules and actin filaments in the bundle structure. In contrast, MAP1A, MAP1B and tau, which are known to be expressed in neuronal tissue, were localized only in nerve fibers in the organ of Corti, not in the sensory epithelium. MAP2, which is known to be localized in dendrites and soma of nerve cells, was not distributed in nerve fibers in the organ of Corti. These results suggest possible roles of the 205 kDa MAP in the formation and maintenance of the highly polarized morphology of the epithelial cells of the organ of Corti, through stabilization and modulation of microtubule networks of these cells.     

Expression of the hexose transporters GLUT1 and GLUT2 during the early development of the human brain

We used immunohistochemistry with anti-glucose transporter antibodies to document the presence of facilitative hexose transporters in the fetal human brain. GLUT1 is expressed in all regions of the fetal brain from ages 10 to 21 weeks. GLUT1 was present in the endothelial cells of the brain capillaries, the epithelial cells of the choroid plexus and neurons. High expression of GLUT2 was observed in the granular layer of the cerebellum in brains 21 weeks old, but GLUT2 immunoreactivity was absent at earlier stages. GLUT3 and GLUT4 immunoreactivities were absent at all stages studied. GLUT5 immunoreactivity was evident only in the cerebellar region of 21-week old fetal brains. We conclude that GLUT1 plays a fundamental role in early human brain development. The data also suggest that the cerebellum of the developing brain has the capacity to transport fructose, a substrate that has not been previously identified as a source of metabolic energy in the adult human brain.     

Developmental and age-related changes of dopamine transporter, and dopamine D1 and D2 receptors in human basal ganglia

The developmental and age-related changes of the dopamine transporter (DAT), and the dopamine D1 and D2 receptor (D1R and D2R) subtypes were investigated in basal ganglia (BG) of human brain. DAT immunostaining was mainly observed in the neuropil, neurons, and glia of the striatum. The DAT-positive neuropil was detectable at 32 GW, a peak being reached at 9–10 years of age, with a decrease to 50–63 years of age. The developmental pattern of DAT immunoreactivity in neuron was similar to that of the neuropil. DAT-positive glia were observed in the BG at 32 GW, which increased slightly at 38–40 GW, and then did not obviously change until 6–8 months after birth. D2R-positive neurons were clearly observed at 19 GW, a peak being reached at 32 GW and 1–3 months of age in the globus pallidus and striatum, respectively, with a decrease after 9–10 years of age. D1R was expressed as early as D2R, but decreased after 6–8 months. Our results suggest that D1R and D2R expression is an intrinsic property of striatal neurons and is independent of dopaminergic innervation. D1R may play a more important role in neuronal maturation of the BG than D2R. D2R may be closely correlated with late neuronal development. The higher expression of DAT during adolescence may be related to function of the BG which learns complex behavioral patterns. The significance of the age-related decreases in DAT, D1R and D2R in the BG remains to be further investigated.     

The role of SLC2A1 mutations in myoclonic astatic epilepsy and absence epilepsy,and the estimated frequency of GLUT1 deficiency syndrome

The first mutations identified in SLC2A1, encoding the glucose transporter type 1 (GLUT1) protein of the blood–brain barrier, were associated with severe epileptic encephalopathy. Recently, dominant SLC2A1 mutations were found in rare autosomal dominant families with various forms of epilepsy including early onset absence epilepsy (EOAE), myoclonic astatic epilepsy (MAE), and genetic generalized epilepsy (GGE). Our study aimed to investigate the possible role of SLC2A1 in various forms of epilepsy including MAE and absence epilepsy with early onset. We also aimed to estimate the frequency of GLUT1 deficiency syndrome in the Danish population. One hundred twenty patients with MAE, 50 patients with absence epilepsy, and 37 patients with unselected epilepsies, intellectual disability (ID), and/or various movement disorders were screened for mutations in SLC2A1. Mutations in SLC2A1 were detected in 5 (10%) of 50 patients with absence epilepsy, and in one (2.7%) of 37 patient with unselected epilepsies, ID, and/or various movement disorders. None of the 120 MAE patients harbored SLC2A1 mutations. We estimated the frequency of SLC2A1 mutations in the Danish population to be approximately 1:83,000. Our study confirmed the role of SLC2A1 mutations in absence epilepsy with early onset. However, our study failed to support the notion that SLC2A1 aberrations are a cause of MAE without associated features such as movement disorders.     

3,4-methylenedioxymethamphetamine (MDMA) administration to rats decreases brain tissue serotonin but not serotonin transporter protein and glial fibrillary acidic protein

Previous experiments conducted in this laboratory showed that administration of high-dose D-fenfluramine (D-FEN) and p-chloroamphetamine (PCA) decreased 5-HT transporter (SERT) binding and tissue 5-HT by 30-60% in caudate and whole brain tissue 2 days and 2 weeks after drug administration. However, protein expression as determined by Western blot analysis did not change in either tissue or time point, except for a 30% decrease in the caudate 2 days after PCA administration. In the present study, we studied the effect of MDMA and 5,7-dihydroxytryptamine (5,7-DHT) on tissue 5-HT levels and the protein expression level of SERT and glial fibrillary acidic protein (GFAP), a validated neurotoxicity marker. HYPOTHESIS: MDMA administration decreases SERT expression. METHODS: Two weeks after MDMA administration (7.5 mg/kg i.p., q 2 h x 3 doses) or 2 weeks after i.c.v. administration of 5,7,-DHT (150 microg/rat), male Sprague-Dawley rats were sacrificed and the caudate, cortex, and hippocampal tissue collected. Western blots for SERT and GFAP were generated using published methods. Tissue 5-HT levels were determined by HPLC coupled to electrochemical detection. RESULTS: MDMA treatment decreased tissue 5-HT in cortex, hippocampus, and caudate by about 50%. However, MDMA treatment had no significant effect on expression level of SERT and GFAP in any brain region. In contrast, 5,7-DHT reduced tissue 5-HT by more than 90%, decreased SERT protein expression by 20-35%, and increased GFAP by 30-39%. CONCLUSION: These data suggest the MDMA treatment regimen used here does not cause degeneration of 5-HT nerve terminals. Viewed collectively with our previous results and other published data, these data indicate that MDMA-induced persistent 5-HT depletion may occur in the absence of axotomy.